//复写onCreateOptionsMenu()方法,弹出菜单栏
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

//复写back按钮,如果只是复写返回按钮,复写Activity中的onBackPressed()方法就可以
   
    @Override
    public void onBackPressed() {
        // TODO Auto-generated method stub
        super.onBackPressed();

        Toast.makeText(MainActivity.this, "onBackPressed!!", Toast.LENGTH_SHORT).show();
    }

//   复写搜索按钮
//    复写onKeyDown()方法,该方法可以复写很多按钮：数字键、Menu键、返回键等等
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // TODO Auto-generated method stub
        if(keyCode==KeyEvent.KEYCODE_MENU){

            Toast.makeText(MainActivity.this, "Search Menu", Toast.LENGTH_SHORT).show();

        }

        return super.onKeyDown(keyCode, event);
    }