<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical"

    tools:context=".MainActivity" >

    <Button

        android:id="@+id/btn01"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:text="保存" />

    <Button

        android:id="@+id/btn02"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:text="读取" />

    <TextView

        android:id="@+id/msg"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content" />

</LinearLayout>

public class MainActivity extends Activity {

    private static final String FILENAME="Test01.txt";

    private Button btn01=null;

    private Button btn02=null;

    private TextView msg=null;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        super.setContentView(R.layout.activity_main);

        this.btn01=(Button)super.findViewById(R.id.btn01);

        this.btn02=(Button)super.findViewById(R.id.btn02);

        this.btn01.setOnClickListener(new OnClickListenerImpl());

        this.btn02.setOnClickListener(new OnClickListenerImpl());

        this.msg=(TextView)super.findViewById(R.id.msg);

    }

    private class OnClickListenerImpl implements OnClickListener{

        @Override

        public void onClick(View v) {

            // TODO Auto-generated method stub

            switch (v.getId()) {

            case R.id.btn01:

                FileOutputStream output=null;

                try {

                    output=MainActivity.this.openFileOutput(FILENAME, Activity.MODE_PRIVATE);

                } catch (FileNotFoundException e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

                }

                SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

                PrintStream out=new PrintStream(output);

                out.println(sdf.format(new Date()));

                out.println("文本内容aa");

                out.close();

                Toast.makeText(MainActivity.this, "文件已经保存", Toast.LENGTH_SHORT).show();

                break;

            case R.id.btn02:

                FileInputStream input=null;

                try {

                    input=MainActivity.this.openFileInput(FILENAME);

                } catch (FileNotFoundException e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

                }

                Scanner scanner=new Scanner(input);

                MainActivity.this.msg.setText("");

                MainActivity.this.msg.append("-------Start--------\n");

                while (scanner.hasNext()) {

                    MainActivity.this.msg.append(scanner.next()+"\n");

                }

                MainActivity.this.msg.append("-------End--------\n");

                Toast.makeText(MainActivity.this, "文件已经读取", Toast.LENGTH_SHORT).show();

                break;

            default:

                break;

            }

        }

    }

    @Override

    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.

        getMenuInflater().inflate(R.menu.main, menu);

        return true;

    }

}

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>