Android入门之ActivityGroup+GridView实现Tab分页标签的方法

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; 
  } 
} 

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);
 }
}