顶部导航栏

<!-- 菜单栏的设置 -->
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    >
    <!-- 默认的 -->
    <item android:id="@+id/action_settings"
        android:orderInCategory="100"
        android:title="@string/action_settings"
        app:showAsAction="always"
        ></item>

    <!-- 添加的按钮 -->
    <item android:id="@+id/action_add"
        app:showAsAction="always"
        android:title="添加"
        android:icon="@android:drawable/ic_input_add"></item>
</menu>

public class MainActivity extends ActionBarActivity{ // 这里需要继承 ActionBarActivity

    private Button bt = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        bt = (Button) this.findViewById(R.id.MyBtn);
        System.out.println("onCreate");
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) { //菜单组件创建
        this.getMenuInflater().inflate(R.menu.main, menu);
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {  // 导航栏按钮的监听

        int id = item.getItemId();
        if (id == R.id.action_add) {  // 根据id来判断
            bt.setText("click me");
        }
        return super.onOptionsItemSelected(item);
    }
}