Android 写文件到手机

1)// 在手机中创建文件
FileOutputStream phone_outStream =this.openFileOutput("1.txt", Context.MODE_PRIVATE);
phone_outStream.write("HELLO".getBytes());

FileOutputStream phone_outStream1 =openFileOutput("1.txt", Context.MODE_APPEND); //追加模式继续写
phone_outStream1.write(" world".getBytes());

//读取并显示

byte[] s= new byte[80];
FileInputStream phone_inputStream =openFileInput("1.txt");
phone_inputStream.read(s);    
Toast.makeText(this, new String(s), Toast.LENGTH_SHORT).show();

结论:不管手机data文件夹是否能在DDMS中看到东西, (没有root权限就会空空如也.)程序能够正常运行,并toast出正确内容.

2)如果试图用该方法来写入到手机内部存储中,是不行的:

java.io.FileNotFoundException: /2.txt: open failed: EROFS (Read-only file system)

File f = new File("2.txt");
FileOutputStream fs = new FileOutputStream( f ); //这句导致异常

openFileOutput();是android的api, android.content.ContextWrapper.openFileOutput();

FileOutputStream .是Java的类.  java.io.FileOutputStream

此文转自：http://www.cnblogs.com/sinawear/archive/2012/11/26.html

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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();
    }