android的上下文菜单-context menu_Android

android的上下文菜单---context menu

android的菜单有三种：

Options Menu

当用户按下menu button按钮时显示的菜单

Context Menu

?? ? ? 当用户长久按住屏幕，即被注册显示上下文菜单的视图时显示的菜单

Submenu

当用户按下一个菜单的某个选项时弹出的子菜单

现在演示一个上下文菜单。

main.xml布局文件：此布局文件定义了listview，用来显示一组列表，稍后上下文菜单将被注册到该listview，并且响应该listview。

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"	android:id="@+id/layout" 	android:layout_width="fill_parent" android:layout_height="fill_parent">	<ListView android:id="@+id/lv_list" android:layout_width="wrap_content"		android:layout_height="fill_parent">	</ListView></RelativeLayout>

item.xml布局文件，用来显示listview中的一个单独的控件

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"	android:id="@+id/layout"	android:layout_width="fill_parent" android:layout_height="fill_parent">		<TextView android:id="@+id/tv" android:layout_width="wrap_content"			android:layout_height="fill_parent"			android:textSize="20dip"			>		</TextView></RelativeLayout>

?在layout下新建一个menu文件夹，在建一个menu.xml布局文件

<?xml version="1.0" encoding="utf-8"?><menu xmlns:android="http://schemas.android.com/apk/res/android">	<item android:id="@+id/new_game" android:title="新游戏" />	<item android:id="@+id/help" android:title="寻求帮助" />	<item android:id="@+id/addnew" android:title="添加新游戏" />	<item android:id="@+id/delete" android:title="删除游戏" /></menu>

?主activity代码

package org.ynu.android;import java.util.ArrayList;import java.util.HashMap;import android.app.Activity;import android.os.Bundle;import android.view.ContextMenu;import android.view.ContextMenu.ContextMenuInfo;import android.view.Menu;import android.view.MenuInflater;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.AdapterView.AdapterContextMenuInfo;import android.widget.Button;import android.widget.ListView;import android.widget.SimpleAdapter;import android.widget.TextView;import android.widget.Toast;public class MenuActivity extends Activity {	private ListView lv;	    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);             //如定义了一个listview控件        ArrayList<HashMap<String, String>> list = new ArrayList<HashMap<String,String>>();        HashMap<String, String> map1 = new HashMap<String, String>();        map1.put("item", "第一个菜单项");        HashMap<String, String> map2 = new HashMap<String, String>();        map2.put("item", "第二个菜单项");        HashMap<String, String> map3 = new HashMap<String, String>();        map3.put("item", "第三个菜单项");        HashMap<String, String> map4 = new HashMap<String, String>();        map4.put("item", "第四个菜单项");        HashMap<String, String> map5 = new HashMap<String, String>();        map5.put("item", "第五个菜单项");        list.add(map1);        list.add(map2);        list.add(map3);        list.add(map4);        list.add(map5);                //初始化该控件        lv=(ListView)findViewById(R.id.lv_list);                //定义适配器 参数为该显示信息用的布局文件 以及显示信息用的控件，这里是一个textview控件        SimpleAdapter adapter = new SimpleAdapter(this, list, R.layout.item, new String[]{"item"}, new int[]{R.id.tv});        lv.setAdapter(adapter);                //注册上下文菜单显示用的view        registerForContextMenu(this.lv);    }    //该方法在注册的view被被长按时创建该view的上下文菜单	@Override	public void onCreateContextMenu(ContextMenu menu, View v,			ContextMenuInfo menuInfo) {		// TODO Auto-generated method stub		MenuInflater inflater = getMenuInflater();		inflater.inflate(R.menu.menu, menu);		super.onCreateContextMenu(menu, v, menuInfo);	}	//当菜单某个选项被点击时调用该方法	@Override	public boolean onContextItemSelected(MenuItem item) {		// TODO Auto-generated method stub		AdapterContextMenuInfo infor = (AdapterContextMenuInfo)item.getMenuInfo();		switch(item.getItemId())		{		case R.id.help:			Toast.makeText(this, "请求帮助", Toast.LENGTH_LONG).show();			return true;		case R.id.addnew:			Toast.makeText(this, "添加新的", Toast.LENGTH_LONG).show();			return true;		case R.id.delete:			Toast.makeText(this, "删除信息", Toast.LENGTH_LONG).show();			return true;		case R.id.new_game:			Toast.makeText(this, "新游戏", Toast.LENGTH_LONG).show();			return true;			default:				return super.onContextItemSelected(item);		}	}	//当上下文菜单关闭时调用的方法	@Override	public void onContextMenuClosed(Menu menu) {		// TODO Auto-generated method stub		super.onContextMenuClosed(menu);	}}

?效果图