Baca / Tulis String dari / ke File di Android

Saya ingin menyimpan file ke penyimpanan internal dengan memasukkan teks yang dimasukkan dari EditText. Lalu saya ingin file yang sama untuk mengembalikan teks yang dimasukkan dalam bentuk String dan menyimpannya ke String lain yang akan digunakan nanti.

Berikut kodenya:

package com.omm.easybalancerecharge;


import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.telephony.TelephonyManager;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final EditText num = (EditText) findViewById(R.id.sNum);
        Button ch = (Button) findViewById(R.id.rButton);
        TelephonyManager operator = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
        String opname = operator.getNetworkOperatorName();
        TextView status = (TextView) findViewById(R.id.setStatus);
        final EditText ID = (EditText) findViewById(R.id.IQID);
        Button save = (Button) findViewById(R.id.sButton);

        final String myID = ""; //When Reading The File Back, I Need To Store It In This String For Later Use

        save.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                //Get Text From EditText "ID" And Save It To Internal Memory
            }
        });
        if (opname.contentEquals("zain SA")) {
            status.setText("Your Network Is: " + opname);
        } else {
            status.setText("No Network");
        }
        ch.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                //Read From The Saved File Here And Append It To String "myID"


                String hash = Uri.encode("#");
                Intent intent = new Intent(Intent.ACTION_CALL);
                intent.setData(Uri.parse("tel:*141*" + /*Use The String With Data Retrieved Here*/ num.getText()
                        + hash));
                startActivity(intent);
            }
        });
    }

Saya telah menyertakan komentar untuk membantu Anda menganalisis poin saya lebih lanjut tentang di mana saya ingin operasi dilakukan / variabel yang akan digunakan.

Semoga ini bermanfaat bagi Anda.

Menulis file:

private void writeToFile(String data,Context context) {
    try {
        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(context.openFileOutput("config.txt", Context.MODE_PRIVATE));
        outputStreamWriter.write(data);
        outputStreamWriter.close();
    }
    catch (IOException e) {
        Log.e("Exception", "File write failed: " + e.toString());
    } 
}

Baca File:

private String readFromFile(Context context) {

    String ret = "";

    try {
        InputStream inputStream = context.openFileInput("config.txt");

        if ( inputStream != null ) {
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String receiveString = "";
            StringBuilder stringBuilder = new StringBuilder();

            while ( (receiveString = bufferedReader.readLine()) != null ) {
                stringBuilder.append("\n").append(receiveString);
            }

            inputStream.close();
            ret = stringBuilder.toString();
        }
    }
    catch (FileNotFoundException e) {
        Log.e("login activity", "File not found: " + e.toString());
    } catch (IOException e) {
        Log.e("login activity", "Can not read file: " + e.toString());
    }

    return ret;
}

Bagi mereka yang mencari strategi umum untuk membaca dan menulis string ke file:

Pertama, dapatkan objek file

Anda akan memerlukan jalur penyimpanan. Untuk penyimpanan internal, gunakan:

File path = context.getFilesDir();

Untuk penyimpanan eksternal (kartu SD), gunakan:

File path = context.getExternalFilesDir(null);

Kemudian buat objek file Anda:

File file = new File(path, "my-file-name.txt");

Tulis string ke file

FileOutputStream stream = new FileOutputStream(file);
try {
    stream.write("text-to-write".getBytes());
} finally {
    stream.close();
}

Atau dengan Google Jambu

Isi string = Files.toString (file, StandardCharsets.UTF_8);

Baca file ke string

int length = (int) file.length();

byte[] bytes = new byte[length];

FileInputStream in = new FileInputStream(file);
try {
    in.read(bytes);
} finally {
    in.close();
}

String contents = new String(bytes);   

Atau jika Anda menggunakan Google Guava

String contents = Files.toString(file,"UTF-8");

Untuk kelengkapan saya akan menyebutkan

String contents = new Scanner(file).useDelimiter("\\A").next();

yang tidak memerlukan pustaka, tetapi tolok ukur 50% - 400% lebih lambat dari opsi lain (dalam berbagai tes pada Nexus 5 saya).

Catatan

Untuk masing-masing strategi ini, Anda akan diminta untuk menangkap IOException.

Pengkodean karakter default di Android adalah UTF-8.

Jika Anda menggunakan penyimpanan eksternal, Anda harus menambahkan manifes Anda:

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

atau

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

Izin menulis menyiratkan izin baca, jadi Anda tidak perlu keduanya.

public static void writeStringAsFile(final String fileContents, String fileName) {
    Context context = App.instance.getApplicationContext();
    try {
        FileWriter out = new FileWriter(new File(context.getFilesDir(), fileName));
        out.write(fileContents);
        out.close();
    } catch (IOException e) {
        Logger.logError(TAG, e);
    }
}

public static String readFileAsString(String fileName) {
    Context context = App.instance.getApplicationContext();
    StringBuilder stringBuilder = new StringBuilder();
    String line;
    BufferedReader in = null;

    try {
        in = new BufferedReader(new FileReader(new File(context.getFilesDir(), fileName)));
        while ((line = in.readLine()) != null) stringBuilder.append(line);

    } catch (FileNotFoundException e) {
        Logger.logError(TAG, e);
    } catch (IOException e) {
        Logger.logError(TAG, e);
    } 

    return stringBuilder.toString();
}

Hanya sedikit modifikasi pada pembacaan string dari metode file untuk kinerja lebih

private String readFromFile(Context context, String fileName) {
    if (context == null) {
        return null;
    }

    String ret = "";

    try {
        InputStream inputStream = context.openFileInput(fileName);

        if ( inputStream != null ) {
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);               

            int size = inputStream.available();
            char[] buffer = new char[size];

            inputStreamReader.read(buffer);

            inputStream.close();
            ret = new String(buffer);
        }
    }catch (Exception e) {
        e.printStackTrace();
    }

    return ret;
}

periksa kode di bawah ini.

Membaca dari file di sistem file.

FileInputStream fis = null;
    try {

        fis = context.openFileInput(fileName);
        InputStreamReader isr = new InputStreamReader(fis);
        // READ STRING OF UNKNOWN LENGTH
        StringBuilder sb = new StringBuilder();
        char[] inputBuffer = new char[2048];
        int l;
        // FILL BUFFER WITH DATA
        while ((l = isr.read(inputBuffer)) != -1) {
            sb.append(inputBuffer, 0, l);
        }
        // CONVERT BYTES TO STRING
        String readString = sb.toString();
        fis.close();

    catch (Exception e) {

    } finally {
        if (fis != null) {
            fis = null;
        }
    }

kode di bawah ini adalah untuk menulis file ke sistem file internal.

FileOutputStream fos = null;
    try {

        fos = context.openFileOutput(fileName, Context.MODE_PRIVATE);
        fos.write(stringdatatobestoredinfile.getBytes());
        fos.flush();
        fos.close();

    } catch (Exception e) {

    } finally {
        if (fos != null) {
            fos = null;
        }
    }

Saya pikir ini akan membantu Anda.

Saya sedikit pemula dan berjuang untuk berhasil hari ini.

Di bawah ini adalah kelas yang saya ikuti. Ini bekerja tetapi saya bertanya-tanya seberapa tidak sempurna solusi saya. Bagaimanapun, saya berharap beberapa dari Anda yang lebih berpengalaman mungkin bersedia untuk melihat kelas IO saya dan memberi saya beberapa tips. Bersulang!

public class HighScore {
    File data = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator);
    File file = new File(data, "highscore.txt");
    private int highScore = 0;

    public int readHighScore() {
        try {
            BufferedReader br = new BufferedReader(new FileReader(file));
            try {
                highScore = Integer.parseInt(br.readLine());
                br.close();
            } catch (NumberFormatException | IOException e) {
                e.printStackTrace();
            }
        } catch (FileNotFoundException e) {
            try {
                file.createNewFile();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
            e.printStackTrace();
        }
        return highScore;
    }

    public void writeHighScore(int highestScore) {
        try {
            BufferedWriter bw = new BufferedWriter(new FileWriter(file));
            bw.write(String.valueOf(highestScore));
            bw.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

hal pertama yang kita butuhkan adalah izin di AndroidManifest.xml

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_INTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_INTERNAL_STORAGE" />

jadi di kelas Kotyn asyncTask, kami memperlakukan pembuatan file

    import android.os.AsyncTask
    import android.os.Environment
    import android.util.Log
    import java.io.*
    class WriteFile: AsyncTask<String, Int, String>() {
        private val mFolder = "/MainFolder"
        lateinit var folder: File
        internal var writeThis = "string to cacheApp.txt"
        internal var cacheApptxt = "cacheApp.txt"
        override fun doInBackground(vararg writethis: String): String? {
            val received = writethis[0]
            if(received.isNotEmpty()){
                writeThis = received
            }
            folder = File(Environment.getExternalStorageDirectory(),"$mFolder/")
            if(!folder.exists()){
                folder.mkdir()
                val readME = File(folder, cacheApptxt)
                val file = File(readME.path)
                val out: BufferedWriter
                try {
                    out = BufferedWriter(FileWriter(file, true), 1024)
                    out.write(writeThis)
                    out.newLine()
                    out.close()
                    Log.d("Output_Success", folder.path)
                } catch (e: Exception) {
                    Log.d("Output_Exception", "$e")
                }
            }
            return folder.path

    }

        override fun onPostExecute(result: String) {
            super.onPostExecute(result)

            if(result.isNotEmpty()){
                //implement an interface or do something
                Log.d("onPostExecuteSuccess", result)
            }else{
                Log.d("onPostExecuteFailure", result)
            }
        }

    }

Tentu saja jika Anda menggunakan Android di atas Api 23, Anda harus menangani permintaan untuk memungkinkan penulisan ke memori perangkat. Sesuatu seperti ini

    import android.Manifest
    import android.content.Context
    import android.content.pm.PackageManager
    import android.os.Build
    import androidx.appcompat.app.AppCompatActivity
    import androidx.core.app.ActivityCompat
    import androidx.core.content.ContextCompat

    class ReadandWrite {
        private val mREAD = 9
        private val mWRITE = 10
        private var readAndWrite: Boolean = false
        fun readAndwriteStorage(ctx: Context, atividade: AppCompatActivity): Boolean {
            if (Build.VERSION.SDK_INT < 23) {
                readAndWrite = true
            } else {
                val mRead = ContextCompat.checkSelfPermission(ctx, Manifest.permission.READ_EXTERNAL_STORAGE)
                val mWrite = ContextCompat.checkSelfPermission(ctx, Manifest.permission.WRITE_EXTERNAL_STORAGE)

                if (mRead != PackageManager.PERMISSION_GRANTED) {
                    ActivityCompat.requestPermissions(atividade, arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE), mREAD)
                } else {
                    readAndWrite = true
                }

                if (mWrite != PackageManager.PERMISSION_GRANTED) {
                    ActivityCompat.requestPermissions(atividade, arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE), mWRITE)
                } else {
                    readAndWrite = true
                }
            }
            return readAndWrite
        }
    }

lalu dalam suatu kegiatan, jalankan panggilan.

  var pathToFileCreated = ""
    val anRW = ReadandWrite().readAndwriteStorage(this,this)
    if(anRW){
        pathToFileCreated =  WriteFile().execute("onTaskComplete").get()
        Log.d("pathToFileCreated",pathToFileCreated)
    }

Kotlin

class FileReadWriteService {

    private var context:Context? = ContextHolder.instance.appContext

    fun writeFileOnInternalStorage(fileKey: String, sBody: String) {
        val file = File(context?.filesDir, "files")
        try {
            if (!file.exists()) {
                file.mkdir()
            }
            val fileToWrite = File(file, fileKey)
            val writer = FileWriter(fileToWrite)
            writer.append(sBody)
            writer.flush()
            writer.close()
        } catch (e: Exception) {
            Logger.e(classTag, e)
        }
    }

    fun readFileOnInternalStorage(fileKey: String): String {
        val file = File(context?.filesDir, "files")
        var ret = ""
        try {
            if (!file.exists()) {
                return ret
            }
            val fileToRead = File(file, fileKey)
            val reader = FileReader(fileToRead)
            ret = reader.readText()
            reader.close()
        } catch (e: Exception) {
            Logger.e(classTag, e)
        }
        return ret
    }
}