ActivityGroup + GridView 实现Tab分页标签

 很多客户端软件和浏览器软件都喜欢用Tab分页标签来搭建界面框架。读者也许会马上想到使用TabHost 与 TabActivity的组合，其实最常用的不是它们，而是由GridView与ActivityGroup的组合。每当用户在GridView选中一项，ActivityGroup就把该项对应的Activity的Window作为View添加到ActivityGroup所指定的容器(LinearLayout)中。

接下来贴出本例运行的效果图：

 

ImageAdapter是本实例的关键之一，它继承于BaseAdapter，并加入一些自定义的方法。ImageAdapter的源码如下：

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1. package com.ActivityGroupDemo;  
2.   
3. import android.content.Context;  
4. import android.graphics.drawable.ColorDrawable;  
5. import android.view.View;  
6. import android.view.ViewGroup;  
7. import android.widget.BaseAdapter;  
8. import android.widget.GridView;  
9. import android.widget.ImageView;  
10. /** 
11.  *  
12.  * @author GV 
13.  * 
14.  */  
15. public class ImageAdapter extends BaseAdapter {  
16.     private Context mContext;   
17.     private ImageView[] imgItems;  
18.     private int selResId;  
19.     public ImageAdapter(Context c,int[] picIds,int width,int height,int selResId) {   
20.         mContext = c;   
21.         this.selResId=selResId;  
22.         imgItems=new ImageView[picIds.length];  
23.         for(int i=0;i<picIds.length;i++)  
24.         {  
25.             imgItems[i] = new ImageView(mContext);   
26.             imgItems[i].setLayoutParams(new GridView.LayoutParams(width, height));//设置ImageView宽高    
27.             imgItems[i].setAdjustViewBounds(false);   
28.             //imgItems[i].setScaleType(ImageView.ScaleType.CENTER_CROP);    
29.             imgItems[i].setPadding(2, 2, 2, 2);   
30.             imgItems[i].setImageResource(picIds[i]);   
31.         }  
32.     }   
33.    
34.     public int getCount() {   
35.         return imgItems.length;   
36.     }   
37.    
38.     public Object getItem(int position) {   
39.         return position;   
40.     }   
41.    
42.     public long getItemId(int position) {   
43.         return position;   
44.     }   
45.    
46.     /**  
47.      * 设置选中的效果  
48.      */    
49.     public void SetFocus(int index)    
50.     {    
51.         for(int i=0;i<imgItems.length;i++)    
52.         {    
53.             if(i!=index)    
54.             {    
55.                 imgItems[i].setBackgroundResource(0);//恢复未选中的样式   
56.             }    
57.         }    
58.         imgItems[index].setBackgroundResource(selResId);//设置选中的样式   
59.     }    
60.       
61.     public View getView(int position, View convertView, ViewGroup parent) {   
62.         ImageView imageView;   
63.         if (convertView == null) {   
64.             imageView=imgItems[position];  
65.         } else {   
66.             imageView = (ImageView) convertView;   
67.         }   
68.         return imageView;   
69.     }   
70. }   

package com.ActivityGroupDemo;import android.content.Context;import android.graphics.drawable.ColorDrawable;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.GridView;import android.widget.ImageView;/** * * @author GV * */public class ImageAdapter extends BaseAdapter { private Context mContext; private ImageView[] imgItems; private int selResId; public ImageAdapter(Context c,int[] picIds,int width,int height,int selResId) { mContext = c; this.selResId=selResId; imgItems=new ImageView[picIds.length]; for(int i=0;i<picIds.length;i++) { imgItems[i] = new ImageView(mContext); imgItems[i].setLayoutParams(new GridView.LayoutParams(width, height));//设置ImageView宽高 imgItems[i].setAdjustViewBounds(false); //imgItems[i].setScaleType(ImageView.ScaleType.CENTER_CROP); imgItems[i].setPadding(2, 2, 2, 2); imgItems[i].setImageResource(picIds[i]); } } public int getCount() { return imgItems.length; } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } /** * 设置选中的效果 */ public void SetFocus(int index) { for(int i=0;i<imgItems.length;i++) { if(i!=index) { imgItems[i].setBackgroundResource(0);//恢复未选中的样式 } } imgItems[index].setBackgroundResource(selResId);//设置选中的样式 } public View getView(int position, View convertView, ViewGroup parent) { ImageView imageView; if (convertView == null) { imageView=imgItems[position]; } else { imageView = (ImageView) convertView; } return imageView; } }

 SetFocus(int)这个方法是个关键点，即实现选中的效果。例如有ABCD4个Item，其中C被选中了，那么除C以外的Item都被设置为未被选中的样式，而C则设置为选中的样式。

接下来就开始写主Activity，主Activity包含GridView控件，名为gvTopBar，有2点是需要注意一下的。

• SetNumColumns()：必须要使用setNumColumns来设置列数，因为这个GridView只有一行，即所有的Item都在同一行，Item数量即为列数。
• setSelector(new ColorDrawable(Color.TRANSPARENT))：把系统默认选中的背景色透明化，因为我们已经在BaseAdapter中加入了SetFocus()来改变选中的样式。 

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1. package com.ActivityGroupDemo;  
2.   
3. import android.app.Activity;  
4. import android.app.ActivityGroup;  
5. import android.content.BroadcastReceiver;  
6. import android.content.Context;  
7. import android.content.Intent;  
8. import android.content.IntentFilter;  
9. import android.graphics.Color;  
10. import android.graphics.drawable.ColorDrawable;  
11. import android.os.Bundle;  
12. import android.util.Log;  
13. import android.view.Gravity;  
14. import android.view.View;  
15. import android.view.Window;  
16. import android.view.ViewGroup.LayoutParams;  
17. import android.widget.AdapterView;  
18. import android.widget.GridView;  
19. import android.widget.LinearLayout;  
20. import android.widget.Toast;  
21. import android.widget.AdapterView.OnItemClickListener;  
22. /** 
23.  *  
24.  * @author GV 
25.  * 
26.  */  
27. public class ActivityGroupDemo extends ActivityGroup {  
28.   
29.     private GridView gvTopBar;  
30.     private ImageAdapter topImgAdapter;  
31.     public LinearLayout container;// 装载sub Activity的容器   
32.   
33.     /** 顶部按钮图片 **/  
34.     int[] topbar_image_array = { R.drawable.topbar_home,  
35.             R.drawable.topbar_user, R.drawable.topbar_shoppingcart,  
36.             R.drawable.topbar_note };  
37.   
38.     @Override  
39.     public void onCreate(Bundle savedInstanceState) {  
40.         super.onCreate(savedInstanceState);  
41.         setContentView(R.layout.main);  
42.         gvTopBar = (GridView) this.findViewById(R.id.gvTopBar);  
43.         gvTopBar.setNumColumns(topbar_image_array.length);// 设置每行列数   
44.         gvTopBar.setSelector(new ColorDrawable(Color.TRANSPARENT));// 选中的时候为透明色   
45.         gvTopBar.setGravity(Gravity.CENTER);// 位置居中   
46.         gvTopBar.setVerticalSpacing(0);// 垂直间隔   
47.         int width = this.getWindowManager().getDefaultDisplay().getWidth()  
48.                 / topbar_image_array.length;  
49.         topImgAdapter = new ImageAdapter(this, topbar_image_array, width, 48,  
50.                 R.drawable.topbar_itemselector);  
51.         gvTopBar.setAdapter(topImgAdapter);// 设置菜单Adapter   
52.         gvTopBar.setOnItemClickListener(new ItemClickEvent());// 项目点击事件   
53.         container = (LinearLayout) findViewById(R.id.Container);  
54.         SwitchActivity(0);//默认打开第0页   
55.     }  
56.   
57.     class ItemClickEvent implements OnItemClickListener {  
58.   
59.         public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,  
60.                 long arg3) {  
61.             SwitchActivity(arg2);  
62.         }  
63.     }  
64.     /** 
65.      * 根据ID打开指定的Activity 
66.      * @param id GridView选中项的序号 
67.      */  
68.     void SwitchActivity(int id)  
69.     {  
70.         topImgAdapter.SetFocus(id);//选中项获得高亮   
71.         container.removeAllViews();//必须先清除容器中所有的View   
72.         Intent intent =null;  
73.         if (id == 0 || id == 2) {  
74.             intent = new Intent(ActivityGroupDemo.this, ActivityA.class);  
75.         } else if (id == 1 || id == 3) {  
76.             intent = new Intent(ActivityGroupDemo.this, ActivityB.class);  
77.         }   
78.         intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);  
79.         //Activity 转为 View   
80.         Window subActivity = getLocalActivityManager().startActivity(  
81.                 "subActivity", intent);  
82.         //容器添加View   
83.         container.addView(subActivity.getDecorView(),  
84.                 LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);  
85.     }  
86.   
87. }  

package com.ActivityGroupDemo;import android.app.Activity;import android.app.ActivityGroup;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.graphics.Color;import android.graphics.drawable.ColorDrawable;import android.os.Bundle;import android.util.Log;import android.view.Gravity;import android.view.View;import android.view.Window;import android.view.ViewGroup.LayoutParams;import android.widget.AdapterView;import android.widget.GridView;import android.widget.LinearLayout;import android.widget.Toast;import android.widget.AdapterView.OnItemClickListener;/** * * @author GV * */public class ActivityGroupDemo extends ActivityGroup { private GridView gvTopBar; private ImageAdapter topImgAdapter; public LinearLayout container;// 装载sub Activity的容器 /** 顶部按钮图片 **/ int[] topbar_image_array = { R.drawable.topbar_home, R.drawable.topbar_user, R.drawable.topbar_shoppingcart, R.drawable.topbar_note }; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); gvTopBar = (GridView) this.findViewById(R.id.gvTopBar); gvTopBar.setNumColumns(topbar_image_array.length);// 设置每行列数 gvTopBar.setSelector(new ColorDrawable(Color.TRANSPARENT));// 选中的时候为透明色 gvTopBar.setGravity(Gravity.CENTER);// 位置居中 gvTopBar.setVerticalSpacing(0);// 垂直间隔 int width = this.getWindowManager().getDefaultDisplay().getWidth() / topbar_image_array.length; topImgAdapter = new ImageAdapter(this, topbar_image_array, width, 48, R.drawable.topbar_itemselector); gvTopBar.setAdapter(topImgAdapter);// 设置菜单Adapter gvTopBar.setOnItemClickListener(new ItemClickEvent());// 项目点击事件 container = (LinearLayout) findViewById(R.id.Container); SwitchActivity(0);//默认打开第0页 } class ItemClickEvent implements OnItemClickListener { public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { SwitchActivity(arg2); } } /** * 根据ID打开指定的Activity * @param id GridView选中项的序号 */ void SwitchActivity(int id) { topImgAdapter.SetFocus(id);//选中项获得高亮 container.removeAllViews();//必须先清除容器中所有的View Intent intent =null; if (id == 0 || id == 2) { intent = new Intent(ActivityGroupDemo.this, ActivityA.class); } else if (id == 1 || id == 3) { intent = new Intent(ActivityGroupDemo.this, ActivityB.class); } intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); //Activity 转为 View Window subActivity = getLocalActivityManager().startActivity( "subActivity", intent); //容器添加View container.addView(subActivity.getDecorView(), LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT); }}

主Activity的布局XML文件源码如下：

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1. <?xml version="1.0" encoding="utf-8"?>  
2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
3.     android:orientation="vertical" android:layout_width="fill_parent"  
4.     android:layout_height="fill_parent">  
5.     <RelativeLayout android:layout_height="fill_parent"  
6.         android:layout_width="fill_parent">  
7.         <GridView android:layout_height="wrap_content" android:id="@+id/gvTopBar"  
8.             android:layout_alignParentTop="true" android:layout_width="fill_parent"  
9.             android:fadingEdgeLength="5dip" android:fadingEdge="vertical">  
10.         </GridView>  
11.         <LinearLayout android:id="@+id/Container"  
12.             android:layout_below="@+id/gvTopBar" android:layout_width="fill_parent"  
13.             android:layout_height="fill_parent">  
14.         </LinearLayout>  
15.     </RelativeLayout>  
16. </LinearLayout>  

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <RelativeLayout android:layout_height="fill_parent" android:layout_width="fill_parent"> <GridView android:layout_height="wrap_content" android:id="@+id/gvTopBar" android:layout_alignParentTop="true" android:layout_width="fill_parent" android:fadingEdgeLength="5dip" android:fadingEdge="vertical"> </GridView> <LinearLayout android:id="@+id/Container" android:layout_below="@+id/gvTopBar" android:layout_width="fill_parent" android:layout_height="fill_parent"> </LinearLayout> </RelativeLayout></LinearLayout>