public class FileObserverTest extends Activity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MyFileObserver mfo = new MyFileObserver(getApplicationContext().getFilesDir() + "/data.txt");
mfo.startWatching();//启动文件监听
//mfo.stopWatching();//取消文件监听
}
public class MyFileObserver extends FileObserver {
public MyFileObserver(String path) {
    super(path);
}

@Override
public void onEvent(int event, String path) {
    switch (event) {
    case android.os.FileObserver.CREATE:
        // 文件被创建
        Log.d("FileObserver", "---file create---");
        break;
    case android.os.FileObserver.OPEN:
        // 文件被打开
        //Log.d("FileObserver", "---file open---");
        break;
    case android.os.FileObserver.ACCESS:
        // 打开文件后，读文件内容操作
        //Log.d("FileObserver", "---file access---");
        break;
    case android.os.FileObserver.MODIFY:
        //文件被修改
        Log.d("FileObserver", "---file MODIFY---");
        break;
    }

}

}
}