ContextMenu,称为上下文菜单,也就是长按界面不放,弹出的菜单。使用ContextMenu有三个步骤:
(1)调用registerForContextMenu()方法,为视图注册上下文菜单;
(2)重写Activity的onCreateContextMenu(ContextMenu menu,View v,ContextMenuInfo menuInfo)方法,调用Menu的add方法添加菜单项(MenuItem)
(3)重写onContextItemSelected(MenuItem item)方法,响应菜单单击事件;
注:步骤(2)中的方法参数ContextMenuInfo menuInfo有什么作用?
有时候,视图元素需要向上下文菜单传递一些信息,比如该View对应DB记录的ID等,这就要使用ContextMenuInfo。需要传递额外信息的View需要重写getContextMenuInfo()方法,返回一个带有数据的ContextMenuInfo实现类对象。
以下程序参考自《android应用开发详解》
MainActivity.java
import android.os.Bundle;
import android.app.Activity;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast; public class MainActivity extends Activity {
private TextView contextMenuView; //定义TextView
private static final int ITEM1=Menu.FIRST;
private static final int ITEM2=Menu.FIRST+1;
private static final int ITEM3=Menu.FIRST+2;
private static final int ITEM4=Menu.FIRST+3; @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
contextMenuView=(TextView)findViewById(R.id.contextTest);
//注册上下文菜单
registerForContextMenu(contextMenuView); } //重写方法,并添加菜单选项
public void onCreateContextMenu(ContextMenu menu,View v,ContextMenuInfo menuInfo){
menu.add(0,ITEM1,0,"复制");
menu.add(0,ITEM2,0,"全选");
menu.add(0,ITEM3,0,"分享");
menu.add(0,ITEM4,0,"搜索");
}
//响应菜单事件
public boolean onContextItemSelected(MenuItem item){
switch(item.getItemId()){
case ITEM1:
Toast.makeText(this, "You have click 'copy'",Toast.LENGTH_SHORT ).show();
break;
case ITEM2:
Toast.makeText(this, "You have click 'all copy'",Toast.LENGTH_SHORT ).show();
break;
case ITEM3:
Toast.makeText(this, "You have click 'share'",Toast.LENGTH_SHORT ).show();
break;
case ITEM4:
Toast.makeText(this, "You have click 'search'",Toast.LENGTH_SHORT ).show();
break; }
return true;
}
}
activity_main.xml如下 :
<TextView
android:id="@+id/contextTest"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="长按屏幕显示ContextMenu" />
代码运行结果如下: