ViewPager实现页面切换

先贴效果图（每个开关Tab债券。尾随页变化。效果图蓝条添加的用户体验）

首先看总体效果图的布局文件吧（非常easy，就三部分，各自是Tab栏目、定位蓝条、各个页面（是V4包下的ViewPager））

activity_tab_winter_main.xml

<?xml version="1.0" encoding="utf-8"?
><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:umadsdk="http://schemas.android.com/apk/res/com.LoveBus"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:background="#FF969696"    android:orientation="vertical" >    <LinearLayout        android:id="@+id/linearLayout1"        android:layout_width="fill_parent"        android:layout_height="45.0dip"        android:background="#FFDFD7D7" >        <TextView            android:id="@+id/text1"            android:layout_width="fill_parent"            android:layout_height="wrap_content"            android:layout_weight="1.0"            android:gravity="center"            android:text="\n广告"            android:textColor="#000000" />        <TextView            android:id="@+id/text2"            android:layout_width="fill_parent"            android:layout_height="wrap_content"            android:layout_weight="1.0"            android:gravity="center"            android:text="\n选项"            android:textColor="#000000" />        <TextView            android:id="@+id/text3"            android:layout_width="fill_parent"            android:layout_height="wrap_content"            android:layout_weight="1.0"            android:gravity="center"            android:text="\n关于作者"            android:textColor="#000000" />    </LinearLayout>    <ImageView        android:id="@+id/cursor"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:scaleType="matrix"        android:src="@drawable/icon_tab_winter_a" />    <android.support.v4.view.ViewPager        android:id="@+id/vPager"        android:layout_width="wrap_content"        android:layout_height="fill_parent"        android:layout_gravity="center"        android:layout_weight="1.0"        android:background="#FFDFD7D7"        android:flipInterval="30"        android:persistentDrawingCache="animation" /></LinearLayout>

接下来贴出每一个页面的布局文件

activity_tab_winter_lay1.xml–activity_tab_winter_lay2.xml—activity_tab_winter_lay3.xml（三个页面是一样的，就是text内容不一样。这样好区分）

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#FFDFD7D7"
    android:orientation="vertical" >

        <Button
        android:id="@+id/btn"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center"
        android:text="广告" />
</LinearLayout>

MainActivity（思路简单，代码有凝视）

package com.example.viewpagerdemo;

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

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Bundle;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.DisplayMetrics;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.TranslateAnimation;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {
	private ViewPager mPager;// 页卡内容
	private List<View> listViews; // Tab页面列表
	
	private TextView t1, t2, t3;// 页卡头标
	private int currIndex = 0;// 当前页卡编号
	
	private ImageView cursor;// 动绘图片
	private int bmpW;// 动绘图片宽度
	private int offset = 0;// 动绘图片偏移量

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_tab_winter_main);
		//初始化三部分
		InitImageView();
		InitTextView();
		InitViewPager();
	}
	/**
	 * 初始化动画
	 */
	private void InitImageView() {
		//获取空间
		cursor = (ImageView) findViewById(R.id.cursor);
		// 获取图片宽度
		bmpW = BitmapFactory.decodeResource(getResources(),
				R.drawable.icon_tab_winter_a).getWidth();
		//得到屏幕宽度
		DisplayMetrics dm = new DisplayMetrics();
		getWindowManager().getDefaultDisplay().getMetrics(dm);
		int screenW = dm.widthPixels;
		// 计算偏移量
		offset = (screenW / 3 - bmpW) / 2;
		Matrix matrix = new Matrix();
		matrix.postTranslate(offset, 0);
		// 设置动画初始位置
		cursor.setImageMatrix(matrix);
	}
	/**
	 * 初始化头标
	 */
	private void InitTextView() {
		t1 = (TextView) findViewById(R.id.text1);
		t2 = (TextView) findViewById(R.id.text2);
		t3 = (TextView) findViewById(R.id.text3);

		//加入监听事件
		t1.setOnClickListener(new MyOnClickListener(0));
		t2.setOnClickListener(new MyOnClickListener(1));
		t3.setOnClickListener(new MyOnClickListener(2));
	}

	/**
	 * 初始化ViewPager
	 */
	private void InitViewPager() {
		//viewPager
		mPager = (ViewPager) findViewById(R.id.vPager);
		//data
		listViews = new ArrayList<View>();
		LayoutInflater mInflater = getLayoutInflater();
		listViews.add(mInflater
				.inflate(R.layout.activity_tab_winter_lay2, null));
		listViews.add(mInflater
				.inflate(R.layout.activity_tab_winter_lay1, null));
		listViews.add(mInflater
				.inflate(R.layout.activity_tab_winter_lay3, null));
		//adapter
		mPager.setAdapter(new MyPagerAdapter(listViews));
		mPager.setCurrentItem(0);
		//监听事件
		mPager.setOnPageChangeListener(new MyOnPageChangeListener());
	}



	/**
	 * ViewPager适配器
	 */
	public class MyPagerAdapter extends PagerAdapter {
		public List<View> mListViews;

		public MyPagerAdapter(List<View> mListViews) {
			this.mListViews = mListViews;
		}

		@Override
		public void destroyItem(View view, int position, Object arg2) {
			((ViewPager) view).removeView(mListViews.get(position));
		}

		@Override
		public void finishUpdate(View arg0) {
		}

		@Override
		public int getCount() {
			return mListViews.size();
		}

		@Override
		public Object instantiateItem(ViewGroup container, int position) {
			container.addView(mListViews.get(position));
			return mListViews.get(position);
		}

		@Override
		public boolean isViewFromObject(View arg0, Object arg1) {
			return arg0 == (arg1);
		}

		@Override
		public void restoreState(Parcelable arg0, ClassLoader arg1) {
		}

		@Override
		public Parcelable saveState() {
			return null;
		}

		@Override
		public void startUpdate(View arg0) {
		}
	}

	/**
	 * 头标点击监听
	 */
	public class MyOnClickListener implements View.OnClickListener {
		private int index = 0;

		public MyOnClickListener(int i) {
			index = i;
		}

		public void onClick(View v) {
			mPager.setCurrentItem(index);
		}
	};

	/**
	 * 页卡切换监听
	 */
	public class MyOnPageChangeListener implements OnPageChangeListener {

		int one = offset * 2 + bmpW;// 页卡1 -> 页卡2 偏移量
		int two = one * 2;// 页卡1 -> 页卡3 偏移量

		public void onPageSelected(int position) {
			Animation animation = null;
			switch (position) {
			case 0:
				if (currIndex == 1) {
					animation = new TranslateAnimation(one, 0, 0, 0);
				} else if (currIndex == 2) {
					animation = new TranslateAnimation(two, 0, 0, 0);
				}
				break;
			case 1:
				if (currIndex == 0) {
					animation = new TranslateAnimation(offset, one, 0, 0);
				} else if (currIndex == 2) {
					animation = new TranslateAnimation(two, one, 0, 0);
				}
				break;
			case 2:
				if (currIndex == 0) {
					animation = new TranslateAnimation(offset, two, 0, 0);
				} else if (currIndex == 1) {
					animation = new TranslateAnimation(one, two, 0, 0);
				}
				break;
			}
			currIndex = position;
			animation.setFillAfter(true);
			animation.setDuration(300);
			cursor.startAnimation(animation);
		}

		public void onPageScrolled(int arg0, float arg1, int arg2) {
		}

		public void onPageScrollStateChanged(int arg0) {
		}
	}
}