Baca / tulis ke registri Windows menggunakan Java

Bagaimana mungkin membaca / menulis ke registri Windows menggunakan Java?

Saya tahu pertanyaan ini sudah lama, tetapi ini adalah hasil pencarian pertama di google untuk "java read / write to registry". Baru-baru ini saya menemukan bagian kode yang luar biasa ini yang:

• Dapat membaca / menulis ke bagian APAPUN dari registri.
• JANGAN GUNAKAN JNI.
• TIDAK MENGGUNAKAN PARTAI 3 / APLIKASI EKSTERNAL UNTUK BEKERJA.
• JANGAN GUNAKAN API WINDOWS (langsung)

Ini murni, kode Java.

Ini menggunakan refleksi untuk bekerja, dengan benar-benar mengakses metode pribadi di java.util.prefs.Preferenceskelas. Internal kelas ini rumit, tetapi kelas itu sendiri sangat mudah digunakan.

Misalnya, kode berikut memperoleh distribusi windows yang tepat dari registri :

String value = WinRegistry.readString (
    WinRegistry.HKEY_LOCAL_MACHINE,                             //HKEY
   "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion",           //Key
   "ProductName");                                              //ValueName
    System.out.println("Windows Distribution = " + value);          

Ini kelas aslinya. Cukup salin tempel dan itu akan berfungsi:

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import java.util.ArrayList;
import java.util.List;
import java.util.prefs.Preferences;

public class WinRegistry {
  public static final int HKEY_CURRENT_USER = 0x80000001;
  public static final int HKEY_LOCAL_MACHINE = 0x80000002;
  public static final int REG_SUCCESS = 0;
  public static final int REG_NOTFOUND = 2;
  public static final int REG_ACCESSDENIED = 5;

  private static final int KEY_ALL_ACCESS = 0xf003f;
  private static final int KEY_READ = 0x20019;
  private static final Preferences userRoot = Preferences.userRoot();
  private static final Preferences systemRoot = Preferences.systemRoot();
  private static final Class<? extends Preferences> userClass = userRoot.getClass();
  private static final Method regOpenKey;
  private static final Method regCloseKey;
  private static final Method regQueryValueEx;
  private static final Method regEnumValue;
  private static final Method regQueryInfoKey;
  private static final Method regEnumKeyEx;
  private static final Method regCreateKeyEx;
  private static final Method regSetValueEx;
  private static final Method regDeleteKey;
  private static final Method regDeleteValue;

  static {
    try {
      regOpenKey = userClass.getDeclaredMethod("WindowsRegOpenKey",
          new Class[] { int.class, byte[].class, int.class });
      regOpenKey.setAccessible(true);
      regCloseKey = userClass.getDeclaredMethod("WindowsRegCloseKey",
          new Class[] { int.class });
      regCloseKey.setAccessible(true);
      regQueryValueEx = userClass.getDeclaredMethod("WindowsRegQueryValueEx",
          new Class[] { int.class, byte[].class });
      regQueryValueEx.setAccessible(true);
      regEnumValue = userClass.getDeclaredMethod("WindowsRegEnumValue",
          new Class[] { int.class, int.class, int.class });
      regEnumValue.setAccessible(true);
      regQueryInfoKey = userClass.getDeclaredMethod("WindowsRegQueryInfoKey1",
          new Class[] { int.class });
      regQueryInfoKey.setAccessible(true);
      regEnumKeyEx = userClass.getDeclaredMethod(  
          "WindowsRegEnumKeyEx", new Class[] { int.class, int.class,  
              int.class });  
      regEnumKeyEx.setAccessible(true);
      regCreateKeyEx = userClass.getDeclaredMethod(  
          "WindowsRegCreateKeyEx", new Class[] { int.class,  
              byte[].class });  
      regCreateKeyEx.setAccessible(true);  
      regSetValueEx = userClass.getDeclaredMethod(  
          "WindowsRegSetValueEx", new Class[] { int.class,  
              byte[].class, byte[].class });  
      regSetValueEx.setAccessible(true); 
      regDeleteValue = userClass.getDeclaredMethod(  
          "WindowsRegDeleteValue", new Class[] { int.class,  
              byte[].class });  
      regDeleteValue.setAccessible(true); 
      regDeleteKey = userClass.getDeclaredMethod(  
          "WindowsRegDeleteKey", new Class[] { int.class,  
              byte[].class });  
      regDeleteKey.setAccessible(true); 
    }
    catch (Exception e) {
      throw new RuntimeException(e);
    }
  }

  private WinRegistry() {  }

  /**
   * Read a value from key and value name
   * @param hkey   HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
   * @param key
   * @param valueName
   * @return the value
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static String readString(int hkey, String key, String valueName) 
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    if (hkey == HKEY_LOCAL_MACHINE) {
      return readString(systemRoot, hkey, key, valueName);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      return readString(userRoot, hkey, key, valueName);
    }
    else {
      throw new IllegalArgumentException("hkey=" + hkey);
    }
  }

  /**
   * Read value(s) and value name(s) form given key 
   * @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
   * @param key
   * @return the value name(s) plus the value(s)
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static Map<String, String> readStringValues(int hkey, String key) 
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    if (hkey == HKEY_LOCAL_MACHINE) {
      return readStringValues(systemRoot, hkey, key);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      return readStringValues(userRoot, hkey, key);
    }
    else {
      throw new IllegalArgumentException("hkey=" + hkey);
    }
  }

  /**
   * Read the value name(s) from a given key
   * @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
   * @param key
   * @return the value name(s)
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static List<String> readStringSubKeys(int hkey, String key) 
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    if (hkey == HKEY_LOCAL_MACHINE) {
      return readStringSubKeys(systemRoot, hkey, key);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      return readStringSubKeys(userRoot, hkey, key);
    }
    else {
      throw new IllegalArgumentException("hkey=" + hkey);
    }
  }

  /**
   * Create a key
   * @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
   * @param key
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static void createKey(int hkey, String key) 
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    int [] ret;
    if (hkey == HKEY_LOCAL_MACHINE) {
      ret = createKey(systemRoot, hkey, key);
      regCloseKey.invoke(systemRoot, new Object[] { new Integer(ret[0]) });
    }
    else if (hkey == HKEY_CURRENT_USER) {
      ret = createKey(userRoot, hkey, key);
      regCloseKey.invoke(userRoot, new Object[] { new Integer(ret[0]) });
    }
    else {
      throw new IllegalArgumentException("hkey=" + hkey);
    }
    if (ret[1] != REG_SUCCESS) {
      throw new IllegalArgumentException("rc=" + ret[1] + "  key=" + key);
    }
  }

  /**
   * Write a value in a given key/value name
   * @param hkey
   * @param key
   * @param valueName
   * @param value
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static void writeStringValue
    (int hkey, String key, String valueName, String value) 
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    if (hkey == HKEY_LOCAL_MACHINE) {
      writeStringValue(systemRoot, hkey, key, valueName, value);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      writeStringValue(userRoot, hkey, key, valueName, value);
    }
    else {
      throw new IllegalArgumentException("hkey=" + hkey);
    }
  }

  /**
   * Delete a given key
   * @param hkey
   * @param key
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static void deleteKey(int hkey, String key) 
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    int rc = -1;
    if (hkey == HKEY_LOCAL_MACHINE) {
      rc = deleteKey(systemRoot, hkey, key);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      rc = deleteKey(userRoot, hkey, key);
    }
    if (rc != REG_SUCCESS) {
      throw new IllegalArgumentException("rc=" + rc + "  key=" + key);
    }
  }

  /**
   * delete a value from a given key/value name
   * @param hkey
   * @param key
   * @param value
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static void deleteValue(int hkey, String key, String value) 
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    int rc = -1;
    if (hkey == HKEY_LOCAL_MACHINE) {
      rc = deleteValue(systemRoot, hkey, key, value);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      rc = deleteValue(userRoot, hkey, key, value);
    }
    if (rc != REG_SUCCESS) {
      throw new IllegalArgumentException("rc=" + rc + "  key=" + key + "  value=" + value);
    }
  }

  // =====================

  private static int deleteValue
    (Preferences root, int hkey, String key, String value)
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
        new Integer(hkey), toCstr(key), new Integer(KEY_ALL_ACCESS) });
    if (handles[1] != REG_SUCCESS) {
      return handles[1];  // can be REG_NOTFOUND, REG_ACCESSDENIED
    }
    int rc =((Integer) regDeleteValue.invoke(root,  
        new Object[] { 
          new Integer(handles[0]), toCstr(value) 
          })).intValue();
    regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
    return rc;
  }

  private static int deleteKey(Preferences root, int hkey, String key) 
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    int rc =((Integer) regDeleteKey.invoke(root,  
        new Object[] { new Integer(hkey), toCstr(key) })).intValue();
    return rc;  // can REG_NOTFOUND, REG_ACCESSDENIED, REG_SUCCESS
  }

  private static String readString(Preferences root, int hkey, String key, String value)
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
        new Integer(hkey), toCstr(key), new Integer(KEY_READ) });
    if (handles[1] != REG_SUCCESS) {
      return null; 
    }
    byte[] valb = (byte[]) regQueryValueEx.invoke(root, new Object[] {
        new Integer(handles[0]), toCstr(value) });
    regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
    return (valb != null ? new String(valb).trim() : null);
  }

  private static Map<String,String> readStringValues
    (Preferences root, int hkey, String key)
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    HashMap<String, String> results = new HashMap<String,String>();
    int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
        new Integer(hkey), toCstr(key), new Integer(KEY_READ) });
    if (handles[1] != REG_SUCCESS) {
      return null;
    }
    int[] info = (int[]) regQueryInfoKey.invoke(root,
        new Object[] { new Integer(handles[0]) });

    int count = info[0]; // count  
    int maxlen = info[3]; // value length max
    for(int index=0; index<count; index++)  {
      byte[] name = (byte[]) regEnumValue.invoke(root, new Object[] {
          new Integer
            (handles[0]), new Integer(index), new Integer(maxlen + 1)});
      String value = readString(hkey, key, new String(name));
      results.put(new String(name).trim(), value);
    }
    regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
    return results;
  }

  private static List<String> readStringSubKeys
    (Preferences root, int hkey, String key)
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    List<String> results = new ArrayList<String>();
    int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
        new Integer(hkey), toCstr(key), new Integer(KEY_READ) 
        });
    if (handles[1] != REG_SUCCESS) {
      return null;
    }
    int[] info = (int[]) regQueryInfoKey.invoke(root,
        new Object[] { new Integer(handles[0]) });

    int count  = info[0]; // Fix: info[2] was being used here with wrong results. Suggested by davenpcj, confirmed by Petrucio
    int maxlen = info[3]; // value length max
    for(int index=0; index<count; index++)  {
      byte[] name = (byte[]) regEnumKeyEx.invoke(root, new Object[] {
          new Integer
            (handles[0]), new Integer(index), new Integer(maxlen + 1)
          });
      results.add(new String(name).trim());
    }
    regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
    return results;
  }

  private static int [] createKey(Preferences root, int hkey, String key)
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    return  (int[]) regCreateKeyEx.invoke(root,
        new Object[] { new Integer(hkey), toCstr(key) });
  }

  private static void writeStringValue 
    (Preferences root, int hkey, String key, String valueName, String value) 
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
        new Integer(hkey), toCstr(key), new Integer(KEY_ALL_ACCESS) });

    regSetValueEx.invoke(root,  
        new Object[] { 
          new Integer(handles[0]), toCstr(valueName), toCstr(value) 
          }); 
    regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
  }

  // utility
  private static byte[] toCstr(String str) {
    byte[] result = new byte[str.length() + 1];

    for (int i = 0; i < str.length(); i++) {
      result[i] = (byte) str.charAt(i);
    }
    result[str.length()] = 0;
    return result;
  }
}

Penulis Asli: Apache.

Sumber Perpustakaan: https://github.com/apache/npanday/tree/trunk/components/dotnet-registry/src/main/java/npanday/registry

Anda sebenarnya tidak membutuhkan paket pihak ke-3. Windows memiliki utilitas reg untuk semua operasi registri. Untuk mendapatkan format perintah, buka propmt DOS dan ketik:

reg /?

Anda dapat meminta reg melalui kelas Runtime:

Runtime.getRuntime().exec("reg <your parameters here>");

Mengedit kunci dan menambahkan yang baru sangat mudah menggunakan perintah di atas. Untuk membaca registri, Anda perlu mendapatkan keluaran reg , dan ini sedikit rumit. Ini kodenya:

import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;

/**
 * @author Oleg Ryaboy, based on work by Miguel Enriquez 
 */
public class WindowsReqistry {

    /**
     * 
     * @param location path in the registry
     * @param key registry key
     * @return registry value or null if not found
     */
    public static final String readRegistry(String location, String key){
        try {
            // Run reg query, then read output with StreamReader (internal class)
            Process process = Runtime.getRuntime().exec("reg query " + 
                    '"'+ location + "\" /v " + key);

            StreamReader reader = new StreamReader(process.getInputStream());
            reader.start();
            process.waitFor();
            reader.join();
            String output = reader.getResult();

            // Output has the following format:
            // \n<Version information>\n\n<key>\t<registry type>\t<value>
            if( ! output.contains("\t")){
                    return null;
            }

            // Parse out the value
            String[] parsed = output.split("\t");
            return parsed[parsed.length-1];
        }
        catch (Exception e) {
            return null;
        }

    }

    static class StreamReader extends Thread {
        private InputStream is;
        private StringWriter sw= new StringWriter();

        public StreamReader(InputStream is) {
            this.is = is;
        }

        public void run() {
            try {
                int c;
                while ((c = is.read()) != -1)
                    sw.write(c);
            }
            catch (IOException e) { 
        }
        }

        public String getResult() {
            return sw.toString();
        }
    }
    public static void main(String[] args) {

        // Sample usage
        String value = WindowsReqistry.readRegistry("HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\" 
                 + "Explorer\\Shell Folders", "Personal");
        System.out.println(value);
    }
}

Java Native Access (JNA) adalah proyek yang sangat baik untuk bekerja dengan perpustakaan asli dan memiliki dukungan untuk registri Windows di perpustakaan platform (platform.jar) melalui Advapi32Util dan Advapi32 .

Pembaruan: Berikut cuplikan dengan beberapa contoh betapa mudahnya menggunakan JNA untuk bekerja dengan registri Windows menggunakan JNA 3.4.1,

import com.sun.jna.platform.win32.Advapi32Util;
import com.sun.jna.platform.win32.WinReg;

public class WindowsRegistrySnippet {
    public static void main(String[] args) {
        // Read a string
        String productName = Advapi32Util.registryGetStringValue(
            WinReg.HKEY_LOCAL_MACHINE, "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion", "ProductName");
        System.out.printf("Product Name: %s\n", productName);

        // Read an int (& 0xFFFFFFFFL for large unsigned int)
        int timeout = Advapi32Util.registryGetIntValue(
            WinReg.HKEY_LOCAL_MACHINE, "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Windows", "ShutdownWarningDialogTimeout");
        System.out.printf("Shutdown Warning Dialog Timeout: %d (%d as unsigned long)\n", timeout, timeout & 0xFFFFFFFFL);

        // Create a key and write a string
        Advapi32Util.registryCreateKey(WinReg.HKEY_CURRENT_USER, "SOFTWARE\\StackOverflow");
        Advapi32Util.registrySetStringValue(WinReg.HKEY_CURRENT_USER, "SOFTWARE\\StackOverflow", "url", "http://stackoverflow.com/a/6287763/277307");

        // Delete a key
        Advapi32Util.registryDeleteKey(WinReg.HKEY_CURRENT_USER, "SOFTWARE\\StackOverflow");
    }
}

Saya telah menambahkan kode java murni yang semula diposting oleh David untuk memungkinkan mengakses bagian 32-bit dari registri dari JVM 64-bit, dan sebaliknya. Saya kira jawaban lain tidak membahas hal ini.

Ini dia:

/**
 * Pure Java Windows Registry access.
 * Modified by petrucio@stackoverflow(828681) to add support for
 * reading (and writing but not creating/deleting keys) the 32-bits
 * registry view from a 64-bits JVM (KEY_WOW64_32KEY)
 * and 64-bits view from a 32-bits JVM (KEY_WOW64_64KEY).
 *****************************************************************************/

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import java.util.ArrayList;
import java.util.List;
import java.util.prefs.Preferences;

public class WinRegistry {
  public static final int HKEY_CURRENT_USER = 0x80000001;
  public static final int HKEY_LOCAL_MACHINE = 0x80000002;
  public static final int REG_SUCCESS = 0;
  public static final int REG_NOTFOUND = 2;
  public static final int REG_ACCESSDENIED = 5;

  public static final int KEY_WOW64_32KEY = 0x0200;
  public static final int KEY_WOW64_64KEY = 0x0100;

  private static final int KEY_ALL_ACCESS = 0xf003f;
  private static final int KEY_READ = 0x20019;
  private static Preferences userRoot = Preferences.userRoot();
  private static Preferences systemRoot = Preferences.systemRoot();
  private static Class<? extends Preferences> userClass = userRoot.getClass();
  private static Method regOpenKey = null;
  private static Method regCloseKey = null;
  private static Method regQueryValueEx = null;
  private static Method regEnumValue = null;
  private static Method regQueryInfoKey = null;
  private static Method regEnumKeyEx = null;
  private static Method regCreateKeyEx = null;
  private static Method regSetValueEx = null;
  private static Method regDeleteKey = null;
  private static Method regDeleteValue = null;

  static {
    try {
      regOpenKey     = userClass.getDeclaredMethod("WindowsRegOpenKey",     new Class[] { int.class, byte[].class, int.class });
      regOpenKey.setAccessible(true);
      regCloseKey    = userClass.getDeclaredMethod("WindowsRegCloseKey",    new Class[] { int.class });
      regCloseKey.setAccessible(true);
      regQueryValueEx= userClass.getDeclaredMethod("WindowsRegQueryValueEx",new Class[] { int.class, byte[].class });
      regQueryValueEx.setAccessible(true);
      regEnumValue   = userClass.getDeclaredMethod("WindowsRegEnumValue",   new Class[] { int.class, int.class, int.class });
      regEnumValue.setAccessible(true);
      regQueryInfoKey=userClass.getDeclaredMethod("WindowsRegQueryInfoKey1",new Class[] { int.class });
      regQueryInfoKey.setAccessible(true);
      regEnumKeyEx   = userClass.getDeclaredMethod("WindowsRegEnumKeyEx",   new Class[] { int.class, int.class, int.class });  
      regEnumKeyEx.setAccessible(true);
      regCreateKeyEx = userClass.getDeclaredMethod("WindowsRegCreateKeyEx", new Class[] { int.class, byte[].class });
      regCreateKeyEx.setAccessible(true);  
      regSetValueEx  = userClass.getDeclaredMethod("WindowsRegSetValueEx",  new Class[] { int.class, byte[].class, byte[].class });  
      regSetValueEx.setAccessible(true); 
      regDeleteValue = userClass.getDeclaredMethod("WindowsRegDeleteValue", new Class[] { int.class, byte[].class });  
      regDeleteValue.setAccessible(true); 
      regDeleteKey   = userClass.getDeclaredMethod("WindowsRegDeleteKey",   new Class[] { int.class, byte[].class });  
      regDeleteKey.setAccessible(true); 
    }
    catch (Exception e) {
      e.printStackTrace();
    }
  }

  private WinRegistry() {  }

  /**
   * Read a value from key and value name
   * @param hkey   HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
   * @param key
   * @param valueName
   * @param wow64  0 for standard registry access (32-bits for 32-bit app, 64-bits for 64-bits app)
   *               or KEY_WOW64_32KEY to force access to 32-bit registry view,
   *               or KEY_WOW64_64KEY to force access to 64-bit registry view
   * @return the value
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static String readString(int hkey, String key, String valueName, int wow64) 
    throws IllegalArgumentException, IllegalAccessException,
    InvocationTargetException 
  {
    if (hkey == HKEY_LOCAL_MACHINE) {
      return readString(systemRoot, hkey, key, valueName, wow64);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      return readString(userRoot, hkey, key, valueName, wow64);
    }
    else {
      throw new IllegalArgumentException("hkey=" + hkey);
    }
  }

  /**
   * Read value(s) and value name(s) form given key 
   * @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
   * @param key
   * @param wow64  0 for standard registry access (32-bits for 32-bit app, 64-bits for 64-bits app)
   *               or KEY_WOW64_32KEY to force access to 32-bit registry view,
   *               or KEY_WOW64_64KEY to force access to 64-bit registry view
   * @return the value name(s) plus the value(s)
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static Map<String, String> readStringValues(int hkey, String key, int wow64) 
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    if (hkey == HKEY_LOCAL_MACHINE) {
      return readStringValues(systemRoot, hkey, key, wow64);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      return readStringValues(userRoot, hkey, key, wow64);
    }
    else {
      throw new IllegalArgumentException("hkey=" + hkey);
    }
  }

  /**
   * Read the value name(s) from a given key
   * @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
   * @param key
   * @param wow64  0 for standard registry access (32-bits for 32-bit app, 64-bits for 64-bits app)
   *               or KEY_WOW64_32KEY to force access to 32-bit registry view,
   *               or KEY_WOW64_64KEY to force access to 64-bit registry view
   * @return the value name(s)
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static List<String> readStringSubKeys(int hkey, String key, int wow64) 
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    if (hkey == HKEY_LOCAL_MACHINE) {
      return readStringSubKeys(systemRoot, hkey, key, wow64);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      return readStringSubKeys(userRoot, hkey, key, wow64);
    }
    else {
      throw new IllegalArgumentException("hkey=" + hkey);
    }
  }

  /**
   * Create a key
   * @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
   * @param key
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static void createKey(int hkey, String key) 
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    int [] ret;
    if (hkey == HKEY_LOCAL_MACHINE) {
      ret = createKey(systemRoot, hkey, key);
      regCloseKey.invoke(systemRoot, new Object[] { new Integer(ret[0]) });
    }
    else if (hkey == HKEY_CURRENT_USER) {
      ret = createKey(userRoot, hkey, key);
      regCloseKey.invoke(userRoot, new Object[] { new Integer(ret[0]) });
    }
    else {
      throw new IllegalArgumentException("hkey=" + hkey);
    }
    if (ret[1] != REG_SUCCESS) {
      throw new IllegalArgumentException("rc=" + ret[1] + "  key=" + key);
    }
  }

  /**
   * Write a value in a given key/value name
   * @param hkey
   * @param key
   * @param valueName
   * @param value
   * @param wow64  0 for standard registry access (32-bits for 32-bit app, 64-bits for 64-bits app)
   *               or KEY_WOW64_32KEY to force access to 32-bit registry view,
   *               or KEY_WOW64_64KEY to force access to 64-bit registry view
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static void writeStringValue
    (int hkey, String key, String valueName, String value, int wow64) 
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    if (hkey == HKEY_LOCAL_MACHINE) {
      writeStringValue(systemRoot, hkey, key, valueName, value, wow64);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      writeStringValue(userRoot, hkey, key, valueName, value, wow64);
    }
    else {
      throw new IllegalArgumentException("hkey=" + hkey);
    }
  }

  /**
   * Delete a given key
   * @param hkey
   * @param key
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static void deleteKey(int hkey, String key) 
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    int rc = -1;
    if (hkey == HKEY_LOCAL_MACHINE) {
      rc = deleteKey(systemRoot, hkey, key);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      rc = deleteKey(userRoot, hkey, key);
    }
    if (rc != REG_SUCCESS) {
      throw new IllegalArgumentException("rc=" + rc + "  key=" + key);
    }
  }

  /**
   * delete a value from a given key/value name
   * @param hkey
   * @param key
   * @param value
   * @param wow64  0 for standard registry access (32-bits for 32-bit app, 64-bits for 64-bits app)
   *               or KEY_WOW64_32KEY to force access to 32-bit registry view,
   *               or KEY_WOW64_64KEY to force access to 64-bit registry view
   * @throws IllegalArgumentException
   * @throws IllegalAccessException
   * @throws InvocationTargetException
   */
  public static void deleteValue(int hkey, String key, String value, int wow64) 
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    int rc = -1;
    if (hkey == HKEY_LOCAL_MACHINE) {
      rc = deleteValue(systemRoot, hkey, key, value, wow64);
    }
    else if (hkey == HKEY_CURRENT_USER) {
      rc = deleteValue(userRoot, hkey, key, value, wow64);
    }
    if (rc != REG_SUCCESS) {
      throw new IllegalArgumentException("rc=" + rc + "  key=" + key + "  value=" + value);
    }
  }

  //========================================================================
  private static int deleteValue(Preferences root, int hkey, String key, String value, int wow64)
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
        new Integer(hkey), toCstr(key), new Integer(KEY_ALL_ACCESS | wow64)
    });
    if (handles[1] != REG_SUCCESS) {
      return handles[1];  // can be REG_NOTFOUND, REG_ACCESSDENIED
    }
    int rc =((Integer) regDeleteValue.invoke(root, new Object[] { 
          new Integer(handles[0]), toCstr(value) 
          })).intValue();
    regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
    return rc;
  }

  //========================================================================
  private static int deleteKey(Preferences root, int hkey, String key) 
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    int rc =((Integer) regDeleteKey.invoke(root, new Object[] {
        new Integer(hkey), toCstr(key)
    })).intValue();
    return rc;  // can REG_NOTFOUND, REG_ACCESSDENIED, REG_SUCCESS
  }

  //========================================================================
  private static String readString(Preferences root, int hkey, String key, String value, int wow64)
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
        new Integer(hkey), toCstr(key), new Integer(KEY_READ | wow64)
    });
    if (handles[1] != REG_SUCCESS) {
      return null; 
    }
    byte[] valb = (byte[]) regQueryValueEx.invoke(root, new Object[] {
        new Integer(handles[0]), toCstr(value)
    });
    regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
    return (valb != null ? new String(valb).trim() : null);
  }

  //========================================================================
  private static Map<String,String> readStringValues(Preferences root, int hkey, String key, int wow64)
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    HashMap<String, String> results = new HashMap<String,String>();
    int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
        new Integer(hkey), toCstr(key), new Integer(KEY_READ | wow64)
    });
    if (handles[1] != REG_SUCCESS) {
      return null;
    }
    int[] info = (int[]) regQueryInfoKey.invoke(root, new Object[] {
        new Integer(handles[0])
    });

    int count  = info[2]; // count  
    int maxlen = info[3]; // value length max
    for(int index=0; index<count; index++)  {
      byte[] name = (byte[]) regEnumValue.invoke(root, new Object[] {
          new Integer(handles[0]), new Integer(index), new Integer(maxlen + 1)
      });
      String value = readString(hkey, key, new String(name), wow64);
      results.put(new String(name).trim(), value);
    }
    regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
    return results;
  }

  //========================================================================
  private static List<String> readStringSubKeys(Preferences root, int hkey, String key, int wow64)
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    List<String> results = new ArrayList<String>();
    int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
        new Integer(hkey), toCstr(key), new Integer(KEY_READ | wow64) 
        });
    if (handles[1] != REG_SUCCESS) {
      return null;
    }
    int[] info = (int[]) regQueryInfoKey.invoke(root, new Object[] {
        new Integer(handles[0])
    });

    int count  = info[0]; // Fix: info[2] was being used here with wrong results. Suggested by davenpcj, confirmed by Petrucio
    int maxlen = info[3]; // value length max
    for(int index=0; index<count; index++)  {
      byte[] name = (byte[]) regEnumKeyEx.invoke(root, new Object[] {
          new Integer(handles[0]), new Integer(index), new Integer(maxlen + 1)
          });
      results.add(new String(name).trim());
    }
    regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
    return results;
  }

  //========================================================================
  private static int [] createKey(Preferences root, int hkey, String key)
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    return (int[]) regCreateKeyEx.invoke(root, new Object[] {
      new Integer(hkey), toCstr(key)
    });
  }

  //========================================================================
  private static void writeStringValue(Preferences root, int hkey, String key, String valueName, String value, int wow64)
    throws IllegalArgumentException, IllegalAccessException, InvocationTargetException 
  {
    int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
        new Integer(hkey), toCstr(key), new Integer(KEY_ALL_ACCESS | wow64)
    });
    regSetValueEx.invoke(root, new Object[] { 
          new Integer(handles[0]), toCstr(valueName), toCstr(value) 
          }); 
    regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
  }

  //========================================================================
  // utility
  private static byte[] toCstr(String str) {
    byte[] result = new byte[str.length() + 1];

    for (int i = 0; i < str.length(); i++) {
      result[i] = (byte) str.charAt(i);
    }
    result[str.length()] = 0;
    return result;
  }
}

Saya sudah melakukan ini sebelum menggunakan jRegistryKey . Ini adalah perpustakaan LGPL Java / JNI yang dapat melakukan apa yang Anda butuhkan. Berikut adalah contoh bagaimana saya menggunakannya untuk mengaktifkan pengeditan Registry melalui regedit dan juga opsi "Tampilkan Folder Pilihan" untuk saya sendiri di Windows melalui registri.

import java.io.File;
import ca.beq.util.win32.registry.RegistryKey;
import ca.beq.util.win32.registry.RegistryValue;
import ca.beq.util.win32.registry.RootKey;
import ca.beq.util.win32.registry.ValueType;


public class FixStuff {

private static final String REGEDIT_KEY = "Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System";
private static final String REGEDIT_VALUE = "DisableRegistryTools";
private static final String REGISTRY_LIBRARY_PATH = "\\lib\\jRegistryKey.dll";
private static final String FOLDER_OPTIONS_KEY = "Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\Explorer";
private static final String FOLDER_OPTIONS_VALUE = "NoFolderOptions";

public static void main(String[] args) {
    //Load JNI library
    RegistryKey.initialize( new File(".").getAbsolutePath()+REGISTRY_LIBRARY_PATH );

    enableRegistryEditing(true);        
    enableShowFolderOptions(true);
}

private static void enableShowFolderOptions(boolean enable) {
    RegistryKey key = new RegistryKey(RootKey.HKEY_CURRENT_USER,FOLDER_OPTIONS_KEY);
    RegistryKey key2 = new RegistryKey(RootKey.HKEY_LOCAL_MACHINE,FOLDER_OPTIONS_KEY);
    RegistryValue value = new RegistryValue();
    value.setName(FOLDER_OPTIONS_VALUE);
    value.setType(ValueType.REG_DWORD_LITTLE_ENDIAN);
    value.setData(enable?0:1);

    if(key.hasValue(FOLDER_OPTIONS_VALUE)) {
        key.setValue(value);
    }
    if(key2.hasValue(FOLDER_OPTIONS_VALUE)) {
        key2.setValue(value);
    }           
}

private static void enableRegistryEditing(boolean enable) {
    RegistryKey key = new RegistryKey(RootKey.HKEY_CURRENT_USER,REGEDIT_KEY);
    RegistryValue value = new RegistryValue();
    value.setName(REGEDIT_VALUE);
    value.setType(ValueType.REG_DWORD_LITTLE_ENDIAN);
    value.setData(enable?0:1);

    if(key.hasValue(REGEDIT_VALUE)) {
        key.setValue(value);
    }
}

}

Ya, menggunakan java.util.Preferences API, karena implementasi Windows menggunakan Registry sebagai backend.

Pada akhirnya itu tergantung pada apa yang ingin Anda lakukan: menyimpan preferensi untuk aplikasi Anda merupakan hal yang luar biasa dari Preferensi. Jika Anda benar-benar ingin mengubah kunci registri yang tidak ada hubungannya dengan aplikasi Anda, Anda akan memerlukan beberapa aplikasi JNI, seperti yang dijelaskan oleh Mark (mencuri tanpa malu-malu di sini):

Dari google cepat: Periksa WinPack untuk JNIWrapper. Ini memiliki dukungan akses Windows Registry penuh termasuk Membaca dan Menulis.

Demo WinPack menerapkan Penampil Registri sebagai contoh.

Periksa di http://www.teamdev.com/jniwrapper/winpack/#registry_access

Dan...

Ada juga yang mencoba JNIRegistry @ http://www.trustice.com/java/jnireg/

Ada juga opsi untuk menggunakan aplikasi eksternal, yang bertanggung jawab untuk membaca / menulis registri.

Dari google cepat:

Periksa WinPack untuk JNIWrapper. Ini memiliki dukungan akses Windows Registry penuh termasuk Membaca dan Menulis.

Demo WinPack menerapkan Penampil Registri sebagai contoh.

Periksa di http://www.teamdev.com/jniwrapper/winpack/#registry_access

Dan...

Ada juga yang mencoba JNIRegistry @ http://www.trustice.com/java/jnireg/

Ada juga opsi untuk menggunakan aplikasi eksternal, yang bertanggung jawab untuk membaca / menulis registri.

Ini adalah versi modifikasi dari solusi Oleg. Saya perhatikan bahwa pada sistem saya (Windows server 2003), output dari "reg query" tidak dipisahkan oleh tab ('\ t'), tetapi oleh 4 spasi.

Saya juga menyederhanakan solusinya, karena tidak diperlukan utas.

public static final String readRegistry(String location, String key)
{
  try
  {
      // Run reg query, then read output with StreamReader (internal class)
      Process process = Runtime.getRuntime().exec("reg query " + 
              '"'+ location + "\" /v " + key);

      InputStream is = process.getInputStream();
      StringBuilder sw = new StringBuilder();

      try
      {
         int c;
         while ((c = is.read()) != -1)
             sw.append((char)c);
      }
      catch (IOException e)
      { 
      }

      String output = sw.toString();

      // Output has the following format:
      // \n<Version information>\n\n<key>    <registry type>    <value>\r\n\r\n
      int i = output.indexOf("REG_SZ");
      if (i == -1)
      {
          return null;
      }

      sw = new StringBuilder();
      i += 6; // skip REG_SZ

      // skip spaces or tabs
      for (;;)
      {
         if (i > output.length())
             break;
         char c = output.charAt(i);
         if (c != ' ' && c != '\t')
             break;
         ++i;
      }

      // take everything until end of line
      for (;;)
      {
         if (i > output.length())
             break;
         char c = output.charAt(i);
         if (c == '\r' || c == '\n')
             break;
         sw.append(c);
         ++i;
      }

      return sw.toString();
  }
  catch (Exception e)
  {
      return null;
  }

}

Berkat posting asli. Saya telah mempelajari kembali kelas utilitas ini dan menemukan kekurangan yang sebelumnya, pikir itu mungkin membantu orang lain memposting di sini. Saya juga menambahkan beberapa metode utilitas tambahan. Sekarang ia dapat membaca file apa pun di registri windows (termasuk REG_DWORD, REG_BINARY, REG_EXPAND_SZ dll.). Semua metode bekerja seperti pesona. Cukup salin dan tempel dan itu akan berhasil. Berikut adalah kelas yang diubah dan dimodifikasi:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
import java.util.prefs.Preferences;

public class WinRegistry {

    private static final int REG_SUCCESS = 0;
    private static final int REG_NOTFOUND = 2;
    private static final int KEY_READ = 0x20019;
    private static final int REG_ACCESSDENIED = 5;
    private static final int KEY_ALL_ACCESS = 0xf003f;
    public static final int HKEY_CLASSES_ROOT = 0x80000000;
    public static final int HKEY_CURRENT_USER = 0x80000001;
    public static final int HKEY_LOCAL_MACHINE = 0x80000002;
    private static final String CLASSES_ROOT = "HKEY_CLASSES_ROOT";
    private static final String CURRENT_USER = "HKEY_CURRENT_USER";
    private static final String LOCAL_MACHINE = "HKEY_LOCAL_MACHINE";
    private static Preferences userRoot = Preferences.userRoot();
    private static Preferences systemRoot = Preferences.systemRoot();
    private static Class<? extends Preferences> userClass = userRoot.getClass();
    private static Method regOpenKey = null;
    private static Method regCloseKey = null;
    private static Method regQueryValueEx = null;
    private static Method regEnumValue = null;
    private static Method regQueryInfoKey = null;
    private static Method regEnumKeyEx = null;
    private static Method regCreateKeyEx = null;
    private static Method regSetValueEx = null;
    private static Method regDeleteKey = null;
    private static Method regDeleteValue = null;

    static {
        try {
            regOpenKey = userClass.getDeclaredMethod("WindowsRegOpenKey", new Class[] {int.class, byte[].class, int.class});
            regOpenKey.setAccessible(true);
            regCloseKey = userClass.getDeclaredMethod("WindowsRegCloseKey", new Class[] {int.class});
            regCloseKey.setAccessible(true);
            regQueryValueEx = userClass.getDeclaredMethod("WindowsRegQueryValueEx", new Class[] {int.class, byte[].class});
            regQueryValueEx.setAccessible(true);
            regEnumValue = userClass.getDeclaredMethod("WindowsRegEnumValue", new Class[] {int.class, int.class, int.class});
            regEnumValue.setAccessible(true);
            regQueryInfoKey = userClass.getDeclaredMethod("WindowsRegQueryInfoKey1", new Class[] {int.class});
            regQueryInfoKey.setAccessible(true);
            regEnumKeyEx = userClass.getDeclaredMethod("WindowsRegEnumKeyEx", new Class[] {int.class, int.class, int.class});  
            regEnumKeyEx.setAccessible(true);
            regCreateKeyEx = userClass.getDeclaredMethod("WindowsRegCreateKeyEx", new Class[] {int.class, byte[].class});  
            regCreateKeyEx.setAccessible(true);
            regSetValueEx = userClass.getDeclaredMethod("WindowsRegSetValueEx", new Class[] {int.class, byte[].class, byte[].class});  
            regSetValueEx.setAccessible(true);
            regDeleteValue = userClass.getDeclaredMethod("WindowsRegDeleteValue", new Class[] {int.class, byte[].class});  
            regDeleteValue.setAccessible(true);
            regDeleteKey = userClass.getDeclaredMethod("WindowsRegDeleteKey", new Class[] {int.class, byte[].class});  
            regDeleteKey.setAccessible(true);
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Reads value for the key from given path
     * @param hkey   HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
     * @param path
     * @param key
     * @return the value
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     * @throws IOException 
     */
    public static String valueForKey(int hkey, String path, String key) 
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, IOException {
        if (hkey == HKEY_LOCAL_MACHINE)
            return valueForKey(systemRoot, hkey, path, key);
        else if (hkey == HKEY_CURRENT_USER)
            return valueForKey(userRoot, hkey, path, key);
        else
            return valueForKey(null, hkey, path, key);
    }

    /**
     * Reads all key(s) and value(s) from given path
     * @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
     * @param path
     * @return the map of key(s) and corresponding value(s)
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     * @throws IOException 
     */
    public static Map<String, String> valuesForPath(int hkey, String path) 
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, IOException {
        if (hkey == HKEY_LOCAL_MACHINE)
            return valuesForPath(systemRoot, hkey, path);
        else if (hkey == HKEY_CURRENT_USER)
            return valuesForPath(userRoot, hkey, path);
        else
            return valuesForPath(null, hkey, path);
    }

    /**
     * Read all the subkey(s) from a given path
     * @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
     * @param path
     * @return the subkey(s) list
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     */
    public static List<String> subKeysForPath(int hkey, String path)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        if (hkey == HKEY_LOCAL_MACHINE)
            return subKeysForPath(systemRoot, hkey, path);
        else if (hkey == HKEY_CURRENT_USER)
            return subKeysForPath(userRoot, hkey, path);
        else
            return subKeysForPath(null, hkey, path);
    }

    /**
     * Create a key
     * @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
     * @param key
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     */
    public static void createKey(int hkey, String key) 
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        int [] ret;
        if (hkey == HKEY_LOCAL_MACHINE) {
            ret = createKey(systemRoot, hkey, key);
            regCloseKey.invoke(systemRoot, new Object[] { new Integer(ret[0]) });
        } else if (hkey == HKEY_CURRENT_USER) {
            ret = createKey(userRoot, hkey, key);
            regCloseKey.invoke(userRoot, new Object[] { new Integer(ret[0]) });
        } else
            throw new IllegalArgumentException("hkey=" + hkey);
        if (ret[1] != REG_SUCCESS)
            throw new IllegalArgumentException("rc=" + ret[1] + "  key=" + key);
    }

    /**
     * Write a value in a given key/value name
     * @param hkey
     * @param key
     * @param valueName
     * @param value
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     */
    public static void writeStringValue(int hkey, String key, String valueName, String value) 
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        if (hkey == HKEY_LOCAL_MACHINE)
            writeStringValue(systemRoot, hkey, key, valueName, value);
        else if (hkey == HKEY_CURRENT_USER)
            writeStringValue(userRoot, hkey, key, valueName, value);
        else
            throw new IllegalArgumentException("hkey=" + hkey);
    }

    /**
     * Delete a given key
     * @param hkey
     * @param key
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     */
    public static void deleteKey(int hkey, String key) 
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        int rc = -1;
        if (hkey == HKEY_LOCAL_MACHINE)
            rc = deleteKey(systemRoot, hkey, key);
        else if (hkey == HKEY_CURRENT_USER)
            rc = deleteKey(userRoot, hkey, key);
        if (rc != REG_SUCCESS)
            throw new IllegalArgumentException("rc=" + rc + "  key=" + key);
    }

    /**
     * delete a value from a given key/value name
     * @param hkey
     * @param key
     * @param value
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     */
    public static void deleteValue(int hkey, String key, String value) 
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        int rc = -1;
        if (hkey == HKEY_LOCAL_MACHINE)
            rc = deleteValue(systemRoot, hkey, key, value);
        else if (hkey == HKEY_CURRENT_USER)
            rc = deleteValue(userRoot, hkey, key, value);
        if (rc != REG_SUCCESS)
            throw new IllegalArgumentException("rc=" + rc + "  key=" + key + "  value=" + value);
    }

    // =====================

    private static int deleteValue(Preferences root, int hkey, String key, String value)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {new Integer(hkey), toCstr(key), new Integer(KEY_ALL_ACCESS)});
        if (handles[1] != REG_SUCCESS)
            return handles[1];                                  // can be REG_NOTFOUND, REG_ACCESSDENIED
        int rc =((Integer) regDeleteValue.invoke(root, new Object[] {new Integer(handles[0]), toCstr(value)})).intValue();
        regCloseKey.invoke(root, new Object[] { new Integer(handles[0])});
        return rc;
    }

    private static int deleteKey(Preferences root, int hkey, String key) 
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        int rc =((Integer) regDeleteKey.invoke(root, new Object[] {new Integer(hkey), toCstr(key)})).intValue();
        return rc;                                                  // can REG_NOTFOUND, REG_ACCESSDENIED, REG_SUCCESS
    }

    private static String valueForKey(Preferences root, int hkey, String path, String key)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, IOException {
        int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {new Integer(hkey), toCstr(path), new Integer(KEY_READ)});
        if (handles[1] != REG_SUCCESS)
            throw new IllegalArgumentException("The system can not find the specified path: '"+getParentKey(hkey)+"\\"+path+"'");
        byte[] valb = (byte[]) regQueryValueEx.invoke(root, new Object[] {new Integer(handles[0]), toCstr(key)});
        regCloseKey.invoke(root, new Object[] {new Integer(handles[0])});
        return (valb != null ? parseValue(valb) : queryValueForKey(hkey, path, key));
    }

    private static String queryValueForKey(int hkey, String path, String key) throws IOException {
        return queryValuesForPath(hkey, path).get(key);
    }

    private static Map<String,String> valuesForPath(Preferences root, int hkey, String path)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, IOException {
        HashMap<String, String> results = new HashMap<String,String>();
        int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {new Integer(hkey), toCstr(path), new Integer(KEY_READ)});
        if (handles[1] != REG_SUCCESS)
            throw new IllegalArgumentException("The system can not find the specified path: '"+getParentKey(hkey)+"\\"+path+"'");
        int[] info = (int[]) regQueryInfoKey.invoke(root, new Object[] {new Integer(handles[0])});
        int count = info[2];                            // Fixed: info[0] was being used here
        int maxlen = info[4];                           // while info[3] was being used here, causing wrong results
        for(int index=0; index<count; index++) {
            byte[] valb = (byte[]) regEnumValue.invoke(root, new Object[] {new Integer(handles[0]), new Integer(index), new Integer(maxlen + 1)});
            String vald = parseValue(valb);
            if(valb == null || vald.isEmpty())
                return queryValuesForPath(hkey, path);
            results.put(vald, valueForKey(root, hkey, path, vald));
        }
        regCloseKey.invoke(root, new Object[] {new Integer(handles[0])});
        return results;
    }

    /**
     * Searches recursively into the path to find the value for key. This method gives 
     * only first occurrence value of the key. If required to get all values in the path 
     * recursively for this key, then {@link #valuesForKeyPath(int hkey, String path, String key)} 
     * should be used.
     * @param hkey
     * @param path
     * @param key
     * @param list
     * @return the value of given key obtained recursively
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     * @throws IOException
     */
    public static String valueForKeyPath(int hkey, String path, String key)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, IOException {
        String val;
        try {
            val = valuesForKeyPath(hkey, path, key).get(0);
        } catch(IndexOutOfBoundsException e) {
            throw new IllegalArgumentException("The system can not find the key: '"+key+"' after "
                    + "searching the specified path: '"+getParentKey(hkey)+"\\"+path+"'");
        }
        return val;
    }

    /**
     * Searches recursively into given path for particular key and stores obtained value in list
     * @param hkey
     * @param path
     * @param key
     * @param list
     * @return list containing values for given key obtained recursively
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     * @throws IOException
     */
    public static List<String> valuesForKeyPath(int hkey, String path, String key)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, IOException {
        List<String> list = new ArrayList<String>();
        if (hkey == HKEY_LOCAL_MACHINE)
            return valuesForKeyPath(systemRoot, hkey, path, key, list);
        else if (hkey == HKEY_CURRENT_USER)
            return valuesForKeyPath(userRoot, hkey, path, key, list);
        else
            return valuesForKeyPath(null, hkey, path, key, list);
    }

    private static List<String> valuesForKeyPath(Preferences root, int hkey, String path, String key, List<String> list)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, IOException {
        if(!isDirectory(root, hkey, path)) {
            takeValueInListForKey(hkey, path, key, list);
        } else {
            List<String> subKeys = subKeysForPath(root, hkey, path);
            for(String subkey: subKeys) {
                String newPath = path+"\\"+subkey;
                if(isDirectory(root, hkey, newPath))
                    valuesForKeyPath(root, hkey, newPath, key, list);
                takeValueInListForKey(hkey, newPath, key, list);
            }
        }
        return list;
    }

    /**
     * Takes value for key in list
     * @param hkey
     * @param path
     * @param key
     * @param list
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     * @throws IOException
     */
    private static void takeValueInListForKey(int hkey, String path, String key, List<String> list)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, IOException {
        String value = valueForKey(hkey, path, key);
        if(value != null)
            list.add(value);
    }

    /**
     * Checks if the path has more subkeys or not
     * @param root
     * @param hkey
     * @param path
     * @return true if path has subkeys otherwise false
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     */
    private static boolean isDirectory(Preferences root, int hkey, String path)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        return !subKeysForPath(root, hkey, path).isEmpty();
    }

    private static List<String> subKeysForPath(Preferences root, int hkey, String path)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        List<String> results = new ArrayList<String>();
        int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {new Integer(hkey), toCstr(path), new Integer(KEY_READ)});
        if (handles[1] != REG_SUCCESS)
            throw new IllegalArgumentException("The system can not find the specified path: '"+getParentKey(hkey)+"\\"+path+"'");
        int[] info = (int[]) regQueryInfoKey.invoke(root, new Object[] {new Integer(handles[0])});
        int count  = info[0]; // Fix: info[2] was being used here with wrong results. Suggested by davenpcj, confirmed by Petrucio
        int maxlen = info[3]; // value length max
        for(int index=0; index<count; index++) {
            byte[] valb = (byte[]) regEnumKeyEx.invoke(root, new Object[] {new Integer(handles[0]), new Integer(index), new Integer(maxlen + 1)});
            results.add(parseValue(valb));
        }
        regCloseKey.invoke(root, new Object[] {new Integer(handles[0])});
        return results;
    }

    private static int [] createKey(Preferences root, int hkey, String key)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        return (int[]) regCreateKeyEx.invoke(root, new Object[] {new Integer(hkey), toCstr(key)});
    }

    private static void writeStringValue(Preferences root, int hkey, String key, String valueName, String value) 
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {new Integer(hkey), toCstr(key), new Integer(KEY_ALL_ACCESS)});
        regSetValueEx.invoke(root, new Object[] {new Integer(handles[0]), toCstr(valueName), toCstr(value)}); 
        regCloseKey.invoke(root, new Object[] {new Integer(handles[0])});
    }

    /**
     * Makes cmd query for the given hkey and path then executes the query
     * @param hkey
     * @param path
     * @return the map containing all results in form of key(s) and value(s) obtained by executing query
     * @throws IOException
     */
    private static Map<String, String> queryValuesForPath(int hkey, String path) throws IOException {
        String line;
        StringBuilder builder = new StringBuilder();
        Map<String, String> map = new HashMap<String, String>();
        Process process = Runtime.getRuntime().exec("reg query \""+getParentKey(hkey)+"\\" + path + "\"");
        BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
        while((line = reader.readLine()) != null) {
            if(!line.contains("REG_"))
                continue;
            StringTokenizer tokenizer = new StringTokenizer(line, " \t");
            while(tokenizer.hasMoreTokens()) {
                String token = tokenizer.nextToken();
                if(token.startsWith("REG_"))
                    builder.append("\t ");
                else
                    builder.append(token).append(" ");
            }
            String[] arr = builder.toString().split("\t");
            map.put(arr[0].trim(), arr[1].trim());
            builder.setLength(0);
        }
        return map;
    }

    /**
     * Determines the string equivalent of hkey
     * @param hkey
     * @return string equivalent of hkey
     */
    private static String getParentKey(int hkey) {
        if(hkey == HKEY_CLASSES_ROOT)
            return CLASSES_ROOT;
        else if(hkey == HKEY_CURRENT_USER)
            return CURRENT_USER;
        else if(hkey == HKEY_LOCAL_MACHINE)
            return LOCAL_MACHINE;
        return null;
    }

    /**
     *Intern method which adds the trailing \0 for the handle with java.dll
     * @param str String
     * @return byte[] 
     */
    private static byte[] toCstr(String str) {
        if(str == null)
            str = "";
        return (str += "\0").getBytes();
    }

    /**
     * Method removes the trailing \0 which is returned from the java.dll (just if the last sign is a \0)
     * @param buf the byte[] buffer which every read method returns
     * @return String a parsed string without the trailing \0
     */
    private static String parseValue(byte buf[]) {
        if(buf == null)
            return null;
        String ret = new String(buf);
        if(ret.charAt(ret.length()-1) == '\0')
            return ret.substring(0, ret.length()-1);
        return ret;
    }
}