问在Android的外部存储中写入文件

EN

 public class WriteSDCard extends Activity {

 private static final String TAG = "MEDIA";
 private TextView tv;

  /** Called when the activity is first created. */
@Override
 public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);     
    tv = (TextView) findViewById(R.id.TextView01);
    checkExternalMedia();
    writeToSDFile();
    readRaw();
 }

/** Method to check whether external media available and writable. This is adapted from
   http://developer.android.com/guide/topics/data/data-storage.html#filesExternal */

 private void checkExternalMedia(){
      boolean mExternalStorageAvailable = false;
    boolean mExternalStorageWriteable = false;
    String state = Environment.getExternalStorageState();

    if (Environment.MEDIA_MOUNTED.equals(state)) {
        // Can read and write the media
        mExternalStorageAvailable = mExternalStorageWriteable = true;
    } else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
        // Can only read the media
        mExternalStorageAvailable = true;
        mExternalStorageWriteable = false;
    } else {
        // Can't read or write
        mExternalStorageAvailable = mExternalStorageWriteable = false;
    }   
    tv.append("\n\nExternal Media: readable="
            +mExternalStorageAvailable+" writable="+mExternalStorageWriteable);
}

/** Method to write ascii text characters to file on SD card. Note that you must add a 
   WRITE_EXTERNAL_STORAGE permission to the manifest file or this method will throw
   a FileNotFound Exception because you won't have write permission. */

private void writeToSDFile(){

    // Find the root of the external storage.
    // See http://developer.android.com/guide/topics/data/data-  storage.html#filesExternal

    File root = android.os.Environment.getExternalStorageDirectory(); 
    tv.append("\nExternal file system root: "+root);

    // See http://stackoverflow.com/questions/3551821/android-write-to-sd-card-folder

    File dir = new File (root.getAbsolutePath() + "/download");
    dir.mkdirs();
    File file = new File(dir, "myData.txt");

    try {
        FileOutputStream f = new FileOutputStream(file);
        PrintWriter pw = new PrintWriter(f);
        pw.println("Hi , How are you");
        pw.println("Hello");
        pw.flush();
        pw.close();
        f.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
        Log.i(TAG, "******* File not found. Did you" +
                " add a WRITE_EXTERNAL_STORAGE permission to the   manifest?");
    } catch (IOException e) {
        e.printStackTrace();
    }   
    tv.append("\n\nFile written to "+file);
}

/** Method to read in a text file placed in the res/raw directory of the application. The
  method reads in all lines of the file sequentially. */

private void readRaw(){
    tv.append("\nData read from res/raw/textfile.txt:");
    InputStream is = this.getResources().openRawResource(R.raw.textfile);
    InputStreamReader isr = new InputStreamReader(is);
    BufferedReader br = new BufferedReader(isr, 8192);    // 2nd arg is buffer size

    // More efficient (less readable) implementation of above is the composite expression
    /*BufferedReader br = new BufferedReader(new InputStreamReader(
            this.getResources().openRawResource(R.raw.textfile)), 8192);*/

    try {
        String test;    
        while (true){               
            test = br.readLine();   
            // readLine() returns null if no more lines in the file
            if(test == null) break;
            tv.append("\n"+"    "+test);
        }
        isr.close();
        is.close();
        br.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
    tv.append("\n\nThat is all");
}
}

MediaScannerConnection.scanFile(
        context,
        new String[]{myFile.getAbsolutePath()},
        null,
        null);