Android之菜单一——选项菜单

Android平台下所提供的菜单大体上可分为三类：选项菜单、上下文菜单和子菜单。

当Activity在前台运行时，如果用户按下手机上的Menu键，此时就会在屏幕低端弹出相应的选项菜单。但这个功能需要开发人员编程来实现的，如果在开发应用程序时没有实现该功能，那么程序运行时按下手机的meun键是不会起作用的。

对于携带图标的选项菜单，每次最多只能显示6个，当菜单选项多于6个时，将只显示前5个和一个扩展菜单选项，点击扩展菜单选项将会弹出其余的菜单项。扩展菜单项中将不会显示图标，但是可以显示单选按钮和复选框。

以下模拟选项菜单

main.xml布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:id="@+id/LinearLayout01"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <ScrollView android:id="@+id/scrollView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">
        <EditText android:id="@+id/editText"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent" 
            android:editable="false"
            android:cursorVisible="false" 
            android:text="您的选择为\n">
        </EditText>
    </ScrollView>
</LinearLayout>

MeunActivity类

package com.ljq.activity;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.SubMenu;
import android.view.MenuItem.OnMenuItemClickListener;
import android.widget.EditText;

public class MeunActivity extends Activity {
    private final int MENU_GENDER_MALE = 0; 
    private final int MENU_GENDER_FEMALE = 1;
    private final int MENU_HOBBY1 = 2; 
    private final int MENU_HOBBY2 = 3;
    private final int MENU_HOBBY3 = 4; 
    
    private final int MENU_OK = 5; 
    
    private final int MENU_GENDER = 6;
    private final int MENU_HOBBY = 7; 
    
    private final int GENDER_GROUP = 0;
    private final int HOBBY_GROUP = 1; 
    private final int MAIN_GROUP = 2; 

    MenuItem[] hoddyMenuItems = new MenuItem[3];// 爱好菜单项组
    MenuItem maleMenuItem = null;// 男性菜单项

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

    /**j
     * 初始化选项菜单
     */
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        //单选菜单选项
        SubMenu genderMenu = menu.addSubMenu(MAIN_GROUP, MENU_GENDER, 0, "性别");
        genderMenu.setIcon(R.drawable.gender);
        genderMenu.setHeaderIcon(R.drawable.gender);
        maleMenuItem = genderMenu.add(GENDER_GROUP, MENU_GENDER_MALE, 0, "男");
        maleMenuItem.setChecked(true);
        genderMenu.add(GENDER_GROUP, MENU_GENDER_FEMALE, 0, "女");
        //设置菜单项为单选菜单项，互斥的
        genderMenu.setGroupCheckable(GENDER_GROUP, true, true);
        
        //复选菜单选项
        SubMenu hobbyMenu = menu.addSubMenu(MAIN_GROUP,MENU_HOBBY,0,"爱好");
        hobbyMenu.setIcon(R.drawable.hobby);
        hobbyMenu.setHeaderIcon(R.drawable.hobby);
        hoddyMenuItems[0]=hobbyMenu.add(HOBBY_GROUP, MENU_HOBBY1, 0, "游泳");
        hoddyMenuItems[1]=hobbyMenu.add(HOBBY_GROUP, MENU_HOBBY2, 0, "唱歌");
        hoddyMenuItems[2]=hobbyMenu.add(HOBBY_GROUP, MENU_HOBBY3, 0, "编程");
        //设置菜单项为复选菜单项
        hoddyMenuItems[0].setCheckable(true);
        hoddyMenuItems[1].setCheckable(true);
        hoddyMenuItems[2].setCheckable(true);
        
        //确定菜单项
        MenuItem ok=menu.add(MAIN_GROUP,MENU_OK,0,"确定");
        ok.setOnMenuItemClickListener(new OnMenuItemClickListener(){
            public boolean onMenuItemClick(MenuItem item) {
                appendStateStr();
                return true;
            }
        });
        //给确定菜单项添加快捷键
        ok.setAlphabeticShortcut('o');//设置字符快捷键
        //ok.setNumericShortcut('1');//设置数字快捷键
        //ok.setShortcut('a', '2');//同时设置两种快捷键。注意：同时设置多次时只有最后一个设置起作用
        return true; // 记得返回true，否则无效
    }
    
    /**
     * 在菜单选项中某个选项被选中时调用该事件
     */
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        case MENU_GENDER_MALE:
         case MENU_GENDER_FEMALE:
             item.setChecked(true); 
             appendStateStr();
             break;   
         case MENU_HOBBY1:
         case MENU_HOBBY2:
         case MENU_HOBBY3:
            item.setChecked(!item.isChecked());
            appendStateStr();
            break;   
        }
        return true;
    }
    
    public void appendStateStr() {
        String result = "您选择的性别为：";
        if (maleMenuItem.isChecked()) {
            result = result + "男";
        } else {
            result = result + "女";
        }
        
        
        String hobbyStr = "";
        for (MenuItem hoddy : hoddyMenuItems) {
            if (hoddy.isChecked()) {
                hobbyStr = hobbyStr + hoddy.getTitle() + "、";
            }
        }
        if (hobbyStr.length() > 0) {
            result = result + ",您的爱好为："
                    + hobbyStr.substring(0, hobbyStr.length() - 1) + "。\n";
        } else {
            result = result + "。\n";
        }
        EditText et = (EditText) MeunActivity.this.findViewById(R.id.editText);
        et.append(result);
    }
}