RelativeLayout 的使用实例 类似自定义TabHost效果《》

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2011年08月12日

RelativeLayout 的使用实例 类似自定义TabHost效果

Filed under: Android开发 — 标签： RelativeLayout , TabHost , 自定义 — admin @ 17:27

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TabHost如果要自定义显示的效果,有点麻烦,而默认的样式有时候又与我们程序的风格不匹配.今天我们就用RelativeLayout来 实现与TabHost相同的功能.上效果图:

点击上面的tab,tab自身样式会改变,下面内容也会改变,功能完全与TabHost相同.
介绍一下RelativeLayout,RelativeLayout是相对布局,顾名思义,就是说里面的控件位置都是相对其他控件的位置而确定的.如上 面的效果,Tab相对于屏幕顶部对齐,底部按钮相对于屏幕底部对齐.而内容则放在顶部的Tab和底部的按钮中间.
所以所有被其他控件依赖定位的控件,必须先写,也就是说,要实现上面的效果,XML中不是从上往下写,而是先定上和下,再写中间,因为中间的内容高度,位 置都依赖于它的上下控件.
实现TabHost效果的原理也简单,点击tab时设置被点击和没被点击的的tab的背景,字体颜色即可显示点击效果.在点击事件中,用View的 removeAllViews()方法清除中间控件的所有内容,再用addView方法添加需要的内容.
下面上代码,布局XML:

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<?xml version ="1.0" encoding ="utf-8" ?> <RelativeLayout xmlns:android ="http://schemas.android.com/apk/res/android" android:layout_width ="fill_parent" android:layout_height ="fill_parent" android:weightSum ="1" android:background ="@color/white" > <LinearLayout android:id ="@+id/topmenu" android:orientation ="horizontal" android:layout_alignParentTop ="true" android:layout_width ="fill_parent" android:layout_height ="40dip" android:background ="@drawable/topback" android:gravity ="bottom" > <!-- android:layout_alignParentTop 与父元素顶部是否对齐,这里true,就是把这个topmenu放屏幕顶部 --> <LinearLayout android:id ="@+id/task" android:orientation ="horizontal" android:layout_height ="35dip" android:layout_width ="100dip" android:background ="@drawable/textback" > <TextView android:layout_width ="fill_parent" android:id ="@+id/taskText" android:layout_height ="fill_parent" android:text ="计划" android:gravity ="center" android:textSize ="20sp" android:textColor ="@color/white" /> </LinearLayout> <LinearLayout android:id ="@+id/accounts" android:orientation ="horizontal" android:layout_height ="35dip" android:layout_width ="100dip" > <TextView android:layout_width ="fill_parent" android:id ="@+id/accountsText" android:layout_height ="fill_parent" android:text ="帐号" android:gravity ="center" android:textSize ="20sp" android:textColor ="@color/green" /> </LinearLayout> <LinearLayout android:id ="@+id/sended" android:orientation ="horizontal" android:layout_height ="35dip" android:layout_width ="100dip" > <TextView android:layout_width ="fill_parent" android:id ="@+id/sendedText" android:layout_height ="fill_parent" android:text ="已发" android:gravity ="center" android:textSize ="20sp" android:textColor ="@color/green" /> </LinearLayout> </LinearLayout>     <Button android:id ="@+id/button" android:layout_alignParentBottom ="true" android:layout_width ="fill_parent" android:layout_height ="wrap_content" android:text ="底部按钮" /> <!-- layout_alignParentBottom 与父元素底部是否对齐,这里true,就是把这个Button放屏幕底部 -->   <!-- RelativeLayout必须先写四周的控件,再写中间的,这里先写顶部的Tab和底部的Button,再写中间的Content,因为中间的内容位置是不固定的 --> <LinearLayout android:id ="@+id/content" android:orientation ="vertical" android:layout_width ="fill_parent" android:layout_height ="fill_parent" android:layout_below ="@id/topmenu" android:layout_above ="@id/button" > </LinearLayout> <!-- layout_below,当前控件放在设定控件下方 . android:layout_above 当前控件放在设定控件上方 这里配合使用,就是放在顶部tab和底部Button的中间 -->   </RelativeLayout>

程序代码:

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package com.pocketdigi ;   import android.app.Activity ; import android.os.Bundle ; import android.view.LayoutInflater ; import android.view.View ; import android.view.View.OnClickListener ; import android.widget.LinearLayout ; import android.widget.TextView ;   public class Main extends Activity { /** Called when the activity is first created. */ LinearLayout task, accounts, sended, content; TextView taskText, accountsText, sendedText;   @Override public void onCreate( Bundle savedInstanceState) { super .onCreate ( savedInstanceState) ; setContentView( R.layout .main ) ; task = ( LinearLayout) findViewById( R.id .task ) ; accounts = ( LinearLayout) findViewById( R.id .accounts ) ; sended = ( LinearLayout) findViewById( R.id .sended ) ; content = ( LinearLayout) findViewById( R.id .content ) ;   taskText = ( TextView) findViewById( R.id .taskText ) ; accountsText = ( TextView) findViewById( R.id .accountsText ) ; sendedText = ( TextView) findViewById( R.id .sendedText ) ;   LayoutInflater factory = LayoutInflater.from ( this ) ; View taskView = factory.inflate ( R.layout .task , null ) ; View accountsView = factory.inflate ( R.layout .accounts , null ) ; View sendedView = factory.inflate ( R.layout .sended , null ) ; //把三个内容视图的XML文件转化成View   content.addView ( taskView) ; //启动时默认载入taskView   task.setOnClickListener ( new TabListener( task, taskText, taskView) ) ; accounts.setOnClickListener ( new TabListener( accounts, accountsText, accountsView) ) ; sended.setOnClickListener ( new TabListener( sended, sendedText, sendedView) ) ; //设置三个tab的点击监听器   }   class TabListener implements OnClickListener { LinearLayout layout; TextView tv; View subView;   TabListener( LinearLayout layout, TextView tv, View subView) { this .layout = layout; this .tv = tv; this .subView = subView; }   @Override public void onClick( View v) { // TODO Auto-generated method stub task.setBackgroundDrawable ( null ) ; accounts.setBackgroundDrawable ( null ) ; sended.setBackgroundDrawable ( null ) ; taskText.setTextColor ( getResources( ) .getColor ( R.color .green ) ) ; accountsText.setTextColor ( getResources( ) .getColor ( R.color .green ) ) ; sendedText.setTextColor ( getResources( ) .getColor ( R.color .green ) ) ; // 全部设为未选中状态   layout.setBackgroundResource ( R.drawable .textback ) ; tv.setTextColor ( getResources( ) .getColor ( R.color .white ) ) ; // 设置选中项   content.removeAllViews ( ) ; //移除所有内容 content.addView ( subView) ; //添加传入的View   }   } }

Strings.xml中存两个颜色值:

1 2	<color name ="white" > #ffffff</color> <color name ="green" > #0cc054</color>

三个内容视图的xml,只贴一个,另两个一样,名字不同而已:
task.xml:

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