android 文件内容和 textview 操作

public class CreateFile extends Activity {
    private BufferedReader reader;
    private TextView tvFileReader;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        tvFileReader = (TextView) findViewById(R.id.tvFileReader);
        String path = Environment.getExternalStorageDirectory()
                .getAbsolutePath() + "/hadatabase/";
        File fileDir = new File(path);
        // 如果目录不存在就新建目录
        if (!fileDir.exists()) {
            if (!fileDir.mkdirs()) {
                Log.i("创建目录", "创建目录失败，请检查是否有sdcard读写权限。");
            }
        }
        // 获取 textview 内容
        String str = tvFileReader.getText().toString().trim();
        try {
            FileWriter fw = new FileWriter(path + "bb.txt");
            fw.flush();
            fw.write(str); // 把textview 内容写入到bb.txt文件
            fw.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

        File readerFile = new File(path + "/bb.txt");
        try {
            reader = new BufferedReader(new FileReader(readerFile));
            String tempString = null;
            while ((tempString = reader.readLine()) != null) {
                // 把bb.txt文件里的内容添加到 TextView 里
                tvFileReader.append(tempString); 
            }
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (Exception e2) {
                    e2.printStackTrace();
                }
            }
        }
    }
}