初学Android,使用菜单资源(十九)

Android里面也可用XML定义菜单资源，菜单分两种，一种是OptionMenu(点系统"Menu"键出来)，一种是ContextMenu

下面定义两种菜单XML到res\menu文件夹下

my_menu为OptionMenu

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
  <item android:title="@string/font_size"
    android:icon="@drawable/font">
    <menu>
      <!-- 定义一组单选菜单项 -->
      <group android:checkableBehavior="single">
        <!-- 定义多个菜单项 -->
        <item android:id="@+id/font_10"
           android:title="@string/font_10"/>
        <item android:id="@+id/font_12"
           android:title="@string/font_12"/>
        <item android:id="@+id/font_14"
           android:title="@string/font_14"/>
        <item android:id="@+id/font_16"
           android:title="@string/font_16"/>
        <item android:id="@+id/font_18"
           android:title="@string/font_18"/>
      </group>
    </menu>
  </item>
  <item>
  </item>
  <!-- 定义一个普通菜单项 -->
  <item android:id="@+id/plain_item"
     android:title="@string/plain_item">
  </item>
  <item android:id="@string/font_color"
     android:title="@drawable/color">
    <menu>
      <!-- 定义一组普通的菜单项 -->
      <group>
        <!-- 定义3个菜单项 -->
        <item android:id="@+id/red_font"
          android:title="@string/red_title"/>
        <item android:id="@+id/green_font"
          android:title="@string/green_title"/>
        <item android:id="@+id/blue_font"
          android:title="@string/blue_title"/>
      </group>
    </menu>
  </item>
</menu>

context.xml为ContextMenu

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
    <!-- 定义一组单选菜单项目 -->
    <group android:checkableBehavior="single">
        <!-- 定义三个菜单项 -->
        <item android:id="@+id/red"
            android:title="@string/red_title"
            android:alphabeticShortcut="r"></item>
        <item android:id="@+id/green"
            android:title="@string/green_title"
            android:alphabeticShortcut="g"></item>
        <item android:id="@+id/blue"
            android:title="@string/blue_title"
            android:alphabeticShortcut="b"></item>
    </group>
</menu>

定义两个res\value下的xml，用来指定颜色，字体

colors.xml

<?xml version="1.0" encoding="UTF-8"?>
<resources>
	<color name="red">#ff0000</color>
	<color name="green">#00ff00</color>
	<color name="blue">#0000ff</color>
</resources>

strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
	<string name="hello">Hello World, ContextMenuTest!</string>
	<string name="app_name">上下文菜单</string>
	<string name="red_title">红色</string>
	<string name="blue_title">蓝色</string>
	<string name="green_title">绿色</string>
	<string name="font_size">字体大小</string>
	<string name="font_color">字体颜色</string>		
	<string name="plain_item">普通菜单项</string>
	<string name="font_10">10号字体</string>	
	<string name="font_12">12号字体</string>	
	<string name="font_14">14号字体</string>	
	<string name="font_16">16号字体</string>	
	<string name="font_18">18号字体</string>	
</resources>

下面代码将实现两种菜单

package WangLi.Resource.MenuResTest;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

public class MenuResTest extends Activity {
    /** Called when the activity is first created. */
	private TextView txt;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        txt = (TextView)findViewById(R.id.txt);
        //为文本框注册上下文菜单
        registerForContextMenu(txt);
    }

    public boolean onCreateOptionsMenu(Menu menu)
    {
    	MenuInflater inflator = new MenuInflater(this);
    	//装填R.menu.my_menu对应的菜单,并添加到menu中
    	inflator.inflate(R.menu.my_menu, menu);
    	return super.onCreateOptionsMenu(menu);
    }
    
    //每次创建上下文菜单时都会触发该方法
    public void onCreateContextMenu(ContextMenu menu,View source,
    		ContextMenu.ContextMenuInfo menuInfo)
    {
    	MenuInflater inflator = new MenuInflater(this);
    	//装填R.menu.context对应的菜单,并添加到menu中
    	inflator.inflate(R.menu.context, menu);
    	menu.setHeaderIcon(R.drawable.tools);
    	menu.setHeaderTitle("请选择背景色");
    }
    
    //上下文菜单中菜单项被单击时触发该方法
    public boolean onContextItemSelected(MenuItem mi)
    {
    	switch(mi.getItemId())
    	{
    	    case R.id.red:
    		    mi.setChecked(true);
    		    txt.setBackgroundColor(Color.RED);
    		    break;
    	    case R.id.green:
    	    	mi.setChecked(true);
    	    	txt.setBackgroundColor(Color.GREEN);
    	    	break;
    	    case R.id.blue:
    	    	mi.setChecked(true);
    	    	txt.setBackgroundColor(Color.BLUE);
    	    	break;
    	}
    	return true;
    }
    
    //菜单项被单击后的回调方法
    public boolean onOptionsItemSelected(MenuItem mi)
    {
    	//判断单击的是哪个菜单项,并针对性地做出响应
    	switch(mi.getItemId())
    	{
    	    case R.id.font_10:
    		    txt.setTextSize(10*2);
    		    break;
    	    case R.id.font_12:
    		    txt.setTextSize(12*2);
    		    break;
    	    case R.id.font_14:
    		    txt.setTextSize(14*2);
    		    break;
    	    case R.id.font_16:
    		    txt.setTextSize(16*2);
    		    break;
    	    case R.id.font_18:
    		    txt.setTextSize(18*2);
    		    break;
    	    case R.id.red_font:
    		    txt.setTextColor(Color.RED);
    		    mi.setChecked(true);
    		    break;
    	    case R.id.green_font:
    		    txt.setTextColor(Color.GREEN);
    		    mi.setChecked(true);
    		    break;
    	    case R.id.blue_font:
    		    txt.setTextColor(Color.BLUE);
    		    mi.setChecked(true);
    		    break;
    	    case R.id.plain_item:
    	    	Toast toast = Toast.makeText(MenuResTest.this, "您单击了普通项菜单", Toast.LENGTH_SHORT);
    	    	toast.show();
    	    	break;
    	}
    	return true;
    }
}

下面是程序运行效果图，刚启动时是一个TextView

点击后，在手机屏幕下方出现OptionMenu

点击字体大小或普通菜单项，出现子菜单

选择就可改变TextView的字体

如下点击"普通菜单项",会出现一个Toast提示,过几秒就会消失

那么怎么弹出ContextMenu呢，就是对着TextView长按就可以了

选择后，背景色就改变了