onCreateOptionsMenu与onCreateContextMenu差别

onCreateOptionsMenu只会在启动时调用一次，而onCreateContextMenu则每次都会调用，这是因为onCreateContextMenu需要为所有的View控件的上下文菜单服务，可能会在存在多个控件都绑定了上下文的情况，针对每个控件的上下文菜单事件都需要即时处理，但Android设计应该有个可以持久化的方案，从而避免每次都需要重新加载菜单项。

main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    android:orientation="vertical" >



    <TextView

        android:id="@+id/txt"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:text="可通过上下文菜单修改背景色"

        android:textSize="15pt" />



    <TextView

        android:id="@+id/txt2"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:text="可通过上下文菜单修改前景色"

        android:textSize="15pt" />



</LinearLayout>

my_menu.xml

<?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>

    <!-- 定义一个普通菜单项 -->

    <item android:id="@+id/plain_item"

        android:title="@string/plain_item">

    </item>

    <item android:title="@string/font_color"

        android:icon="@drawable/color">

        <menu>

            <!-- 定义一组允许复选的菜单项 -->

            <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

<?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3个菜单项 -->

        <item

            android:id="@+id/red"

            android:title="@string/red_title"

            android:alphabeticShortcut="r"/>

        <item

            android:id="@+id/green"

            android:title="@string/green_title"

            android:alphabeticShortcut="g"/>

        <item

            android:id="@+id/blue"

            android:title="@string/blue_title"

            android:alphabeticShortcut="b"/>                        

    </group>  

</menu>

context2.xml

<?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3个菜单项 -->

        <item

            android:id="@+id/white"

            android:title="@string/white_title"

            android:alphabeticShortcut="r"/>

        <item

            android:id="@+id/black"

            android:title="@string/black_title"

            android:alphabeticShortcut="g"/>

        <item

            android:id="@+id/gray"

            android:title="@string/gray_title"

            android:alphabeticShortcut="b"/>                        

    </group>  

</menu>

strings.xml

<?xml version="1.0" encoding="utf-8"?>

<resources>

    <string name="hello">Hello World, MenuResTest!</string>

    <string name="app_name">使用XML资源文件定义菜单</string>

    <string name="red_title">红色</string>

    <string name="blue_title">蓝色</string>

    <string name="green_title">绿色</string>

    <string name="white_title">白色</string>

    <string name="black_title">黑色</string>

    <string name="gray_title">灰色</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>

MenuResText.java

package org.crazyit.ui;



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;



/**

 * Description: <br/>

 * site: <a href="http://www.crazyit.org">crazyit.org</a> <br/>

 * Copyright (C), 2001-2014, Yeeku.H.Lee <br/>

 * This program is protected by copyright laws. <br/>

 * Program Name: <br/>

 * Date:

 * 

 * @author Yeeku.H.Lee [email protected]

 * @version 1.0

 */

public class MenuResTest extends Activity {

    private TextView txt,txt2;



    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        txt = (TextView) findViewById(R.id.txt);

        txt2 = (TextView) findViewById(R.id.txt2);

        // 为文本框注册上下文菜单

        registerForContextMenu(txt);

        registerForContextMenu(txt2);

    }



    @Override

    public boolean onCreateOptionsMenu(Menu menu) {

        MenuInflater inflator = new MenuInflater(this);

        // 状态R.menu.context对应的菜单，并添加到menu中

        inflator.inflate(R.menu.my_menu, menu);

        return super.onCreateOptionsMenu(menu);

    }



    int selectedIndex1 = -1;

    int selectedIndex2 = -1;



    // 创建上下文菜单时触发该方法

    @Override

    public void onCreateContextMenu(ContextMenu menu, View source,

            ContextMenu.ContextMenuInfo menuInfo) {

        int vId = source.getId();

        MenuInflater inflator = new MenuInflater(this);

        if (vId == R.id.txt) {

            // 状态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");

            if (selectedIndex1 >= 0) {

                menu.getItem(selectedIndex1).setChecked(true);

            }

        }

        else if(vId == R.id.txt2)

        {

            // 状态R.menu.context对应的菜单，并添加到menu中

            inflator.inflate(R.menu.context2, menu);

            menu.setHeaderTitle("请选择前景色");

            if (selectedIndex2 >= 0) {

                menu.getItem(selectedIndex2).setChecked(true);

            }

        }

    }



    // 上下文菜单中菜单项被单击时触发该方法。

    @Override

    public boolean onContextItemSelected(MenuItem mi) {

        switch (mi.getItemId()) {

        case R.id.red:

            selectedIndex1 = 0;

            txt.setBackgroundColor(Color.RED);

            break;

        case R.id.green:

            selectedIndex1 = 1;

            txt.setBackgroundColor(Color.GREEN);

            break;

        case R.id.blue:

            selectedIndex1 = 2;

            txt.setBackgroundColor(Color.BLUE);

            break;

        case R.id.white:

            selectedIndex2 = 0;

            txt2.setTextColor(Color.WHITE);

            break;

        case R.id.black:

            selectedIndex2 = 1;

            txt2.setTextColor(Color.BLACK);

            break;

        case R.id.gray:

            selectedIndex2 = 2;

            txt2.setTextColor(Color.GRAY);

            break;

        }

        return true;

    }



    @Override

    // 选项菜单的菜单项被单击后的回调方法

    public boolean onOptionsItemSelected(MenuItem mi) {

        if (mi.isCheckable()) {

            mi.setChecked(true); // ②

        }

        // 判断单击的是哪个菜单项，并针对性的作出响应。

        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, "您单击了普通菜单项",

                    Toast.LENGTH_SHORT);

            toast.show();

            break;

        }

        return true;

    }

}

截图：