自定义TabHost实现背景图片随选项卡切换滑动效果

先上效果图

本例子是对TabHost组件的自定义，实现标签居底显示；每个标签包含图片和文字。

布局文件

<?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/tabhost"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:background="#F8FFEE" >
		<!-- 内容显示 -->
        <FrameLayout
            android:id="@android:id/tabcontent"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content" >
            <TextView
                android:id="@+id/text1"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:text="@string/text1"
                android:textSize="32dp" />
            <TextView
                android:id="@+id/text2"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:text="@string/text2"
                android:textSize="32dp" />
            <TextView
                android:id="@+id/text3"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:text="@string/text3"
                android:textSize="32dp" />
        </FrameLayout>
        <TabWidget
            android:id="@android:id/tabs"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:background="@drawable/bottom_tab_bg" >
        </TabWidget>
		<!-- 选项卡背景图片 -->
        <ImageView
            android:id="@+id/tab_top_select"
            android:layout_width="45dp"
            android:layout_height="45dp"
            android:layout_alignParentBottom="true"
            android:src="@drawable/topbar_select" />
    </RelativeLayout>
</TabHost>

MainActivity.java

package com.suxh;

import java.util.ArrayList;
import java.util.List;

import android.app.TabActivity;
import android.graphics.Color;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.view.animation.TranslateAnimation;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TabHost;
import android.widget.TabHost.OnTabChangeListener;
import android.widget.TextView;

public class MainActivity extends TabActivity implements OnTabChangeListener {
	// 当前选中的Tab标号
	private int mCurSelectTabIndex = 0;
	// 默认选中第一个tab页 移动标志操作
	private final int INIT_SELECT = 0;
	// 滑动动画执行时间
	private final int DELAY_TIME = 500;
	private TabHost mTabHost;
	// 存放Tab页中ImageView信息
	public List<ImageView> imageList = new ArrayList<ImageView>();

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		// 取得TabHost对象
		mTabHost = getTabHost();
		/* 为TabHost添加标签 */
		mTabHost.addTab(mTabHost.newTabSpec("tab_1").setIndicator(composeLayout("优惠信息", R.drawable.pic1_s)).setContent(R.id.text1));
		mTabHost.addTab(mTabHost.newTabSpec("tab_2").setIndicator(composeLayout("银行公告", R.drawable.pic2_n)).setContent(R.id.text2));
		mTabHost.addTab(mTabHost.newTabSpec("tab_3").setIndicator(composeLayout("金融产品", R.drawable.pic3_n)).setContent(R.id.text3));
		// 设置TabHost的背景颜色
		mTabHost.setBackgroundColor(Color.argb(150, 22, 70, 150));
		// 设置当前选中的Tab页
		mTabHost.setCurrentTab(0);
		// TabHost添加事件
		mTabHost.setOnTabChangedListener(this);
		// 初始化移动标识这里移到第一个tab页
		initCurSelectTab();
	}
	/**
	 * 初始化选中Tab覆盖图片的Handler
	 */
	private Handler initSelectTabHandle = new Handler () {
		public void handleMessage (Message msg) {
			switch (msg.what) {
				case INIT_SELECT:
					moveTopSelect(INIT_SELECT);
					break;
				default:
					break;
			}
			super.handleMessage(msg);
		}
	};
	
	/**
	 * 初始化选中Tab覆盖图片
	 */
	public void initCurSelectTab(){
		// 默认选中移动图片位置
		Message msg = new Message();
        msg.what = INIT_SELECT;
        initSelectTabHandle.sendMessageDelayed(msg, DELAY_TIME);
	}
	

	/**
	 * Tab页改变
	 */
	public void onTabChanged(String tabId) {
		// 设置所有选项卡的图片为未选中图片
		imageList.get(0).setImageDrawable(getResources().getDrawable(R.drawable.pic1_n));
		imageList.get(1).setImageDrawable(getResources().getDrawable(R.drawable.pic2_n));
		imageList.get(2).setImageDrawable(getResources().getDrawable(R.drawable.pic3_n));
		
		if (tabId.equalsIgnoreCase("tab_1")) {
			imageList.get(0).setImageDrawable(getResources().getDrawable(R.drawable.pic1_s));
			// 移动底部背景图片
			moveTopSelect(0);
		} else if (tabId.equalsIgnoreCase("tab_2")) {
			imageList.get(1).setImageDrawable(getResources().getDrawable(R.drawable.pic2_s));
			// 移动底部背景图片
			moveTopSelect(1);
		} else if (tabId.equalsIgnoreCase("tab_3")) {
			imageList.get(2).setImageDrawable(getResources().getDrawable(R.drawable.pic3_s));
			// 移动底部背景图片
			moveTopSelect(2);
		}
	}

	/**
	 * 移动tab选中标识图片
	 * @param selectIndex
	 * @param curIndex
	 */
	public void moveTopSelect(int selectIndex) {
		View topSelect = (View) findViewById(R.id.tab_top_select);

		// 起始位置中心点
		int startMid = ((View) getTabWidget().getChildAt(mCurSelectTabIndex)).getLeft() + ((View) getTabWidget().getChildAt(mCurSelectTabIndex)).getWidth() / 2;
		// 起始位置左边位置坐标
		int startLeft = startMid - topSelect.getWidth() / 2;

		// 目标位置中心点
		int endMid = ((View) getTabWidget().getChildAt(selectIndex)).getLeft() + ((View) getTabWidget().getChildAt(selectIndex)).getWidth() / 2;
		// 目标位置左边位置坐标
		int endLeft = endMid - topSelect.getWidth() / 2;

		TranslateAnimation animation = new TranslateAnimation(startLeft, endLeft - topSelect.getLeft(), 0, 0);
		animation.setDuration(200);
		animation.setFillAfter(true);
		topSelect.bringToFront();
		topSelect.startAnimation(animation);

		// 改变当前选中按钮索引
		mCurSelectTabIndex = selectIndex;

		Log.i("fs", "endMid  " + endMid + "  startLeft  " + startLeft + "  endLeft" + (endLeft - topSelect.getLeft()));
	}

	/**
	 * 这个设置Tab标签本身的布局，需要TextView和ImageView不能重合 s:是文本显示的内容 i:是ImageView的图片位置
	 */
	public View composeLayout(String s, int i) {
		// 定义一个LinearLayout布局
		LinearLayout layout = new LinearLayout(this);
		// 设置布局垂直显示
		layout.setOrientation(LinearLayout.VERTICAL);
		ImageView iv = new ImageView(this);
		imageList.add(iv);
		iv.setImageResource(i);
		LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
		lp.setMargins(0, 5, 0, 0);
		layout.addView(iv, lp);
		// 定义TextView
		TextView tv = new TextView(this);
		tv.setGravity(Gravity.CENTER);
		tv.setSingleLine(true);
		tv.setText(s);
		tv.setTextColor(Color.WHITE);
		tv.setTextSize(10);
		layout.addView(tv, new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT));
		return layout;
	}
}