Android入门户十五篇之ActivityGroup + GridView 实现Tab分页标签[转]
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：
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。
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);
}
}
<?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>