android 写到本地文件 安卓写入文件

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

==============================================
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();
}

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