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现在很多android的应用都采用底部导航栏的功能，这样可以使得用户在使用过程中随意切换不同的页面，现在我采用TabHost组件来自定义一个底部的导航栏的功能。
我们先看下该demo实例的框架图：


 
其中各个类的作用以及资源文件就不详细解释了，还有资源图片(在该Demo中借用了其它应用程序的资源图片)也不提供了，大家可以自行更换自己需要的资源图片。直接上各个布局文件或各个类的代码：
[1]  res/layout目录下的maintabs.xml  ：
[html]
<?xml version="1.0" encoding="UTF-8"?> 
<TabHost android:id="@android:id/tabhost" android:layout_width="fill_parent" android:layout_height="fill_parent" 
  xmlns:android="http://schemas.android.com/apk/res/android"> 
    <LinearLayout android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> 
        <FrameLayout android:id="@android:id/tabcontent" android:layout_width="fill_parent" android:layout_height="0.0dip" android:layout_weight="1.0" /> 
        <TabWidget android:id="@android:id/tabs" android:visibility="gone" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_weight="0.0" /> 
            <RadioGroup  
                android:gravity="center_vertical" android:layout_gravity="bottom" android:orientation="horizontal" android:id="@id/main_radio" android:background="@drawable/maintab_toolbar_bg"  
                android:layout_width="fill_parent" android:layout_height="wrap_content"> 
                <RadioButton  android:id="@id/radio_button0" android:layout_marginTop="2.0dip" android:text="@string/main_home" android:drawableTop="@drawable/icon_1_n" style="@style/main_tab_bottom" /> 
                <RadioButton  android:id="@id/radio_button1" android:layout_marginTop="2.0dip" android:text="@string/main_news" android:drawableTop="@drawable/icon_2_n" style="@style/main_tab_bottom" /> 
                <RadioButton  android:id="@id/radio_button2" android:layout_marginTop="2.0dip" android:text="@string/main_manage_date" android:drawableTop="@drawable/icon_3_n" style="@style/main_tab_bottom" /> 
                <RadioButton  android:id="@id/radio_button3" android:layout_marginTop="2.0dip" android:text="@string/main_friends" android:drawableTop="@drawable/icon_4_n" style="@style/main_tab_bottom" /> 
                <RadioButton  android:id="@id/radio_button4" android:layout_marginTop="2.0dip" android:text="@string/more" android:drawableTop="@drawable/icon_5_n" style="@style/main_tab_bottom" /> 
            </RadioGroup> 
    </LinearLayout> 
</TabHost> 
[2] res/drawable 下的home_btn_bg.xml 源码：www.2cto.com
[html]
<?xml version="1.0" encoding="UTF-8"?> 
<selector 
  xmlns:android="http://schemas.android.com/apk/res/android"> 
    <item android:state_focused="true" android:state_enabled="true" android:state_pressed="false" android:drawable="@drawable/home_btn_bg_s" /> 
    <item android:state_enabled="true" android:state_pressed="true" android:drawable="@drawable/home_btn_bg_s" /> 
    <item android:state_enabled="true" android:state_checked="true" android:drawable="@drawable/home_btn_bg_d" /> 
    <item android:drawable="@drawable/transparent" /> 
</selector> 
[3] res/values 下的源码：
dimens.xml源码
[html]
<?xml version="1.0" encoding="utf-8"?> 
<resources> 
 
    <dimen name="bottom_tab_font_size">10.0sp</dimen> 
    <dimen name="bottom_tab_padding_up">5.0dip</dimen> 
    <dimen name="bottom_tab_padding_drawable">2.0dip</dimen> 
    <dimen name="switch_logo_bottom_padding">30.0sp</dimen> 
    <dimen name="widget_height">100.0dip</dimen> 
    <dimen name="sta_height">48.0dip</dimen> 
    <dimen name="large_padding_length">20.0dip</dimen> 
    <dimen name="widget_write_margin_top">19.0dip</dimen> 
    <dimen name="widget_write_margin_left">10.0dip</dimen> 
    <dimen name="widget_content_margin_top">20.0dip</dimen> 
    <dimen name="widget_content_margin_left">10.0dip</dimen> 
    <dimen name="widget_logo_size">35.0dip</dimen> 
    <dimen name="title_height">74.0dip</dimen> 
    <dimen name="new_blog_size">70.0dip</dimen> 
    <dimen name="emotion_item_view_height">13.299988dip</dimen> 
    <dimen name="splash_test_top_margin_top">20.0dip</dimen> 
    <dimen name="splash_test_center_margin_right">0.0dip</dimen> 
    <dimen name="title_text_size">20.0sp</dimen> 
    <dimen name="normal_padding_length">10.0dip</dimen> 
    <dimen name="no_result_padding_length">50.0dip</dimen> 
 
</resources> 
 
drawables.xml源码：
[html]
<?xml version="1.0" encoding="utf-8"?> 
<resources> 
 
    <item type="drawable" name="ltgray">#fff4f4f4</item> 
    <item type="drawable" name="ltyellow">#fffff4db</item> 
    <item type="drawable" name="black">#ff000000</item> 
    <item type="drawable" name="transparent">#00000000</item> 
    <item type="drawable" name="widget_edit_block_bg_normal">@android:color/transparent</item> 
    <item type="drawable" name="transparent_background">#99000000</item> 
    <item type="drawable" name="list_background">#fff4f4f4</item> 
    <item type="drawable" name="namcard_picker_bkg_normal">#ff272727</item> 
    <item type="drawable" name="namcard_picker_bkg_hover">#ff333333</item> 
 
</resources> 
 
ids.xml源码：
[html]
<?xml version="1.0" encoding="utf-8"?> 
<resources> 
 
    <item type="id" name="main_radio">false</item> 
    <item type="id" name="radio_button0">false</item> 
    <item type="id" name="radio_button1">false</item> 
    <item type="id" name="radio_button2">false</item> 
    <item type="id" name="radio_button3">false</item> 
    <item type="id" name="radio_button4">false</item> 
 
</resources> 
 
strings.xml源码：
[html]
<?xml version="1.0" encoding="utf-8"?> 
<resources> 
    <string name="hello">Hello World, MainTabActivity!</string> 
    <string name="app_name">TabDemo</string> 
    <string name="main_news">消息</string> 
    <string name="main_home">首页</string> 
    <string name="more">更多</string> 
    <string name="main_manage_date">时间</string> 
    <string name="main_friends">好友</string> 
</resources> 
 
styles.xml源码：
[html]
<?xml version="1.0" encoding="utf-8"?> 
<resources> 
 
     <style name="main_tab_bottom"> 
        <item name="android:textSize">@dimen/bottom_tab_font_size</item> 
        <item name="android:textColor">#ffffffff</item> 
        <item name="android:ellipsize">marquee</item> 
        <item name="android:gravity">center_horizontal</item> 
        <item name="android:background">@drawable/home_btn_bg</item> 
        <item name="android:paddingTop">@dimen/bottom_tab_padding_up</item> 
        <item name="android:paddingBottom">2.0dip</item> 
        <item name="android:layout_width">fill_parent</item> 
        <item name="android:layout_height">wrap_content</item>  
        <item name="android:layout_marginBottom">2.0dip</item> 
        <item name="android:button">@null</item> 
        <item name="android:singleLine">true</item> 
        <item name="android:drawablePadding">@dimen/bottom_tab_padding_drawable</item> 
        <item name="android:layout_weight">1.0</item> 
    </style> 
 
</resources> 
 
[4] src/com.andyidea.tabdemo包下面各个UI界面类源码：
MainTabActivity.java源码：
[html]
package com.andyidea.tabdemo; 
 
import android.app.TabActivity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.Window; 
import android.widget.CompoundButton; 
import android.widget.RadioButton; 
import android.widget.CompoundButton.OnCheckedChangeListener; 
import android.widget.TabHost; 
 
public class MainTabActivity extends TabActivity implements OnCheckedChangeListener{ 
     
    private TabHost mTabHost; 
    private Intent mAIntent; 
    private Intent mBIntent; 
    private Intent mCIntent; 
    private Intent mDIntent; 
    private Intent mEIntent; 
     
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        requestWindowFeature(Window.FEATURE_NO_TITLE); 
        setContentView(R.layout.maintabs); 
         
        this.mAIntent = new Intent(this,AActivity.class); 
        this.mBIntent = new Intent(this,BActivity.class); 
        this.mCIntent = new Intent(this,CActivity.class); 
        this.mDIntent = new Intent(this,DActivity.class); 
        this.mEIntent = new Intent(this,EActivity.class); 
         
        ((RadioButton) findViewById(R.id.radio_button0)) 
        .setOnCheckedChangeListener(this); 
        ((RadioButton) findViewById(R.id.radio_button1)) 
        .setOnCheckedChangeListener(this); 
        ((RadioButton) findViewById(R.id.radio_button2)) 
        .setOnCheckedChangeListener(this); 
        ((RadioButton) findViewById(R.id.radio_button3)) 
        .setOnCheckedChangeListener(this); 
        ((RadioButton) findViewById(R.id.radio_button4)) 
        .setOnCheckedChangeListener(this); 
         
        setupIntent(); 
    } 
 
    @Override 
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { 
        if(isChecked){ 
            switch (buttonView.getId()) { 
            case R.id.radio_button0: 
                this.mTabHost.setCurrentTabByTag("A_TAB"); 
                break; 
            case R.id.radio_button1: 
                this.mTabHost.setCurrentTabByTag("B_TAB"); 
                break; 
            case R.id.radio_button2: 
                this.mTabHost.setCurrentTabByTag("C_TAB"); 
                break; 
            case R.id.radio_button3: 
                this.mTabHost.setCurrentTabByTag("D_TAB"); 
                break; 
            case R.id.radio_button4: 
                this.mTabHost.setCurrentTabByTag("MORE_TAB"); 
                break; 
            } 
        } 
         
    } 
     
    private void setupIntent() { 
        this.mTabHost = getTabHost(); 
        TabHost localTabHost = this.mTabHost; 
 
        localTabHost.addTab(buildTabSpec("A_TAB", R.string.main_home, 
                R.drawable.icon_1_n, this.mAIntent)); 
 
        localTabHost.addTab(buildTabSpec("B_TAB", R.string.main_news, 
                R.drawable.icon_2_n, this.mBIntent)); 
 
        localTabHost.addTab(buildTabSpec("C_TAB", 
                R.string.main_manage_date, R.drawable.icon_3_n, 
                this.mCIntent)); 
 
        localTabHost.addTab(buildTabSpec("D_TAB", R.string.main_friends, 
                R.drawable.icon_4_n, this.mDIntent)); 
 
        localTabHost.addTab(buildTabSpec("MORE_TAB", R.string.more, 
                R.drawable.icon_5_n, this.mEIntent)); 
 
    } 
     
    private TabHost.TabSpec buildTabSpec(String tag, int resLabel, int resIcon, 
            final Intent content) { 
        return this.mTabHost.newTabSpec(tag).setIndicator(getString(resLabel), 
                getResources().getDrawable(resIcon)).setContent(content); 
    } 
} 
其中AActivity.java 与BActivity.java ，CActivity.java ，DActivity.java ，EActivity.java 中的源码都一样，只是用来表示不同的界面展示，故这里只列出AActivity.java的源码：
[html]
package com.andyidea.tabdemo; 
 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.Gravity; 
import android.widget.TextView; 
 
public class AActivity extends Activity{ 
     
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
         
        TextView tv = new TextView(this); 
        tv.setText("This is A Activity!"); 
        tv.setGravity(Gravity.CENTER); 
        setContentView(tv); 
    } 
 
} 
最后，大家别忘了在AndroidManifest.xml 文件中注册各个Activity 组件哦。好了，现在我们看下我们程序运行的效果图：
 
 
 
到此就实现了一个比较流行的底部导航栏的功能了，转载请注明出处，谢谢大家！