Android UI之Tab(TabActivity+TabHost实现)

Tab标签页是UI设计时经常使用的UI控件，可以实现多个分页之间的快速切换，每个分页可以显示不同的内容。

TabHost相当于浏览器中标签页分布的集合，而Tabspec则相当于浏览器中的每一个分页面。在Android中，每一个TabSpec分布可以是一个组件，也可以是一个布局，然后将每一个分页装入TabHost中，TabHost即可将其中的每一个分页一并显示出来。

使用Tab标签页的一般步骤：
首先要设计所有的分页的界面布局
Activity继承TabActivity
调用TabActivity的getTabHost()方法获得TabHost对象
通过TabHost创建并添加Tab

实例：TabDemo
运行效果：

代码清单：
布局文件：tab.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <TextView android:id="@+id/view1"
        android:background="@drawable/blue"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:text="这里是Tab1里的内容。"/>

    <TextView android:id="@+id/view2"
        android:background="@drawable/red"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:text="这里是Tab2"/>

    <TextView android:id="@+id/view3"
        android:background="@drawable/green"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:text="Tab3"/>

</FrameLayout>

Java源代码文件：MainActivity.java

package com.rainsong.tabdemo;

import android.app.TabActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.widget.TabHost;

public class MainActivity extends TabActivity
{
    TabHost mTabHost;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        mTabHost = getTabHost();
        LayoutInflater.from(this).inflate(R.layout.tab,
                mTabHost.getTabContentView(), true);
        mTabHost.addTab(mTabHost.newTabSpec("tab1").setIndicator("Tab1")
                .setContent(R.id.view1));
        mTabHost.addTab(mTabHost.newTabSpec("tab3").setIndicator("Tab2")
                .setContent(R.id.view2));
        mTabHost.addTab(mTabHost.newTabSpec("tab3").setIndicator("Tab3")
                .setContent(R.id.view3));
    }
}

API知识点
public class
TabActivity
extends ActivityGroup

TabHost  getTabHost() 
Returns the TabHost the activity is using to host its tabs. 

public abstract class
LayoutInflater
extends Object

Class Overview
Instantiates a layout XML file into its corresponding View objects.

static LayoutInflater  from(Context context) 
Obtains the LayoutInflater from the given context. 

View  inflate(int resource, ViewGroup root, boolean attachToRoot) 
Inflate a new view hierarchy from the specified xml resource. 

public class
TabHost
extends FrameLayout
implements ViewTreeObserver.OnTouchModeChangeListener

Known Direct Subclasses 
FragmentTabHost  

Class Overview

Container for a tabbed window view. This object holds two children: a set of tab labels that the user clicks to select a specific tab, and a FrameLayout object that displays the contents of that page.

FrameLayout  getTabContentView() 
Get the FrameLayout which holds tab content  

void  addTab(TabHost.TabSpec tabSpec) 
Add a tab. 

TabHost.TabSpec  newTabSpec(String tag) 
Get a new TabHost.TabSpec associated with this tab host. 

public class
TabHost.TabSpec
extends Object

Class Overview
A tab has a tab indicator, content, and a tag that is used to keep track of it. 
This builder helps choose among these options. 
For the tab indicator, your choices are: 
1) set a label 
2) set a label and an icon 
For the tab content, your choices are: 
1) the id of a View 
2) a TabHost.TabContentFactory that creates the View content. 
3) an Intent that launches an Activity. 

TabHost.TabSpec  setIndicator(CharSequence label) 
Specify a label as the tab indicator. 


TabHost.TabSpec  setContent(int viewId) 

Specify the id of the view that should be used as the content of the tab.