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：

[java] view plain copy print ?

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

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。

[java] view plain copy print ?

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

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：

[java] view plain copy print ?

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>