1 public class MenuBuilder implements Menu {
 2 ...
 3 private boolean mOptionalIconsVisible = false;
 4 ....
 5     void setOptionalIconsVisible(boolean visible) {
 6         mOptionalIconsVisible = visible;
 7     }
 8
 9     boolean getOptionalIconsVisible() {
10         return mOptionalIconsVisible;
11     }
12 ...
13 }  

 1 package com.stevenhu.mie;
 2
 3 import java.lang.reflect.Method;
 4
 5 import android.app.Activity;
 6 import android.os.Bundle;
 7 import android.util.Log;
 8 import android.view.Menu;
 9 import android.view.MenuItem;
10
11 public class MainActivity extends Activity
12 {
13     /** Called when the activity is first created. */
14     @Override
15     public void onCreate(Bundle savedInstanceState)
16     {
17         super.onCreate(savedInstanceState);
18         setContentView(R.layout.main);
19     }
20
21     @Override
22     public boolean onCreateOptionsMenu(Menu menu)
23     {
24         //运行时，参数Menu其实就是MenuBuilder对象
25         Log.d("MainActivity", "menu--->" + menu);
26
27         /*利用反射机制调用MenuBuilder的setOptionalIconsVisible方法设置mOptionalIconsVisible为true，
28          * 给菜单设置图标时才可见
29          */
30         setIconEnable(menu, true);
31
32         MenuItem item1 = menu.add(0, 1, 0, R.string.item1);
33         item1.setIcon(R.drawable.camera);
34
35         MenuItem item2 = menu.add(0, 1, 0, R.string.item2);
36         item2.setIcon(R.drawable.dial);
37
38         MenuItem item3 = menu.add(0, 1, 0, R.string.item3);
39         item3.setIcon(R.drawable.sms);
40
41         return super.onCreateOptionsMenu(menu);
42     }
43
44     @Override
45     public boolean onPrepareOptionsMenu(Menu menu)
46     {
47         // TODO Auto-generated method stub
48         return super.onPrepareOptionsMenu(menu);
49     }
50
51     //enable为true时，菜单添加图标有效，enable为false时无效。4.0系统默认无效
52     private void setIconEnable(Menu menu, boolean enable)
53     {
54         try
55         {
56             Class<?> clazz = Class.forName("com.android.internal.view.menu.MenuBuilder");
57             Method m = clazz.getDeclaredMethod("setOptionalIconsVisible", boolean.class);
58             m.setAccessible(true);
59
60             //MenuBuilder实现Menu接口，创建菜单时，传进来的menu其实就是MenuBuilder对象(java的多态特征)
61             m.invoke(menu, enable);
62
63         } catch (Exception e)
64         {
65             e.printStackTrace();
66         }
67     }
68 }