使用ViewPager实现高仿launcher拖动效果

         前面一篇高仿launcher和墨迹左右拖动效果获得了很多朋友的好评，上一篇文章 主要是通过自定义ViewGroup实现的，有点麻烦。今天用ViewPager 这个类实现了同样的效果，这样代码更少，但是效果是一样的。ViewPager是实现左右两个屏幕平滑地切换的一个类，它是Google提供的。

       使用ViewPager首先需要引入android-support-v4.jar这个jar包。具体ViewPager的用法，这里不做介绍，自己从网上搜索吧！

       下面先看一下效果：

       

效果请自行体验和上一篇比较。下面上代码：

首先是layout下面的main.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"    android:orientation="vertical" >    <android.support.v4.view.ViewPager        android:id="@+id/viewPager"        android:layout_width="fill_parent"        android:layout_height="wrap_content" />    <RelativeLayout        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:orientation="vertical" >        <LinearLayout            android:id="@+id/viewGroup"            android:layout_width="fill_parent"            android:layout_height="wrap_content"            android:layout_alignParentBottom="true"            android:layout_marginBottom="30dp"            android:gravity="center_horizontal"            android:orientation="horizontal" >        </LinearLayout>    </RelativeLayout></FrameLayout>

接下来为每一个切换界面设置布局item1.xml

<?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:orientation="vertical" >    <ImageView        android:layout_width="fill_parent"        android:layout_height="fill_parent"        android:background="@drawable/guide01" >    </ImageView></LinearLayout>

其他的几个界面布局和这个一样 ，就是修改下背景图片，所以不再复述，

最后是核心代码：

import java.util.ArrayList;import android.app.Activity;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.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.view.ViewGroup.LayoutParams;import android.view.Window;import android.widget.ImageView;public class MainActivity extends Activity {ViewPager viewPager;ArrayList<View> list;ViewGroup main, group;ImageView imageView;ImageView[] imageViews;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);this.requestWindowFeature(Window.FEATURE_NO_TITLE);LayoutInflater inflater = getLayoutInflater();list = new ArrayList<View>();list.add(inflater.inflate(R.layout.item1, null));list.add(inflater.inflate(R.layout.item2, null));list.add(inflater.inflate(R.layout.item3, null));list.add(inflater.inflate(R.layout.item4, null));list.add(inflater.inflate(R.layout.item5, null));imageViews = new ImageView[list.size()];ViewGroup main = (ViewGroup) inflater.inflate(R.layout.main, null);// group是R.layou.main中的负责包裹小圆点的LinearLayout.ViewGroup group = (ViewGroup) main.findViewById(R.id.viewGroup);viewPager = (ViewPager) main.findViewById(R.id.viewPager);for (int i = 0; i < list.size(); i++) {imageView = new ImageView(MainActivity.this);imageView.setLayoutParams(new LayoutParams(10,10));imageView.setPadding(10, 0, 10, 0);imageViews[i] = imageView;if (i == 0) {// 默认进入程序后第一张图片被选中;imageViews[i].setBackgroundResource(R.drawable.guide_dot_white);} else {imageViews[i].setBackgroundResource(R.drawable.guide_dot_black);}group.addView(imageView);}setContentView(main);viewPager.setAdapter(new MyAdapter());viewPager.setOnPageChangeListener(new MyListener());}class MyAdapter extends PagerAdapter {@Overridepublic int getCount() {return list.size();}@Overridepublic boolean isViewFromObject(View arg0, Object arg1) {return arg0 == arg1;}@Overridepublic int getItemPosition(Object object) {// TODO Auto-generated method stubreturn super.getItemPosition(object);}@Overridepublic void destroyItem(View arg0, int arg1, Object arg2) {// TODO Auto-generated method stub((ViewPager) arg0).removeView(list.get(arg1));}@Overridepublic Object instantiateItem(View arg0, int arg1) {// TODO Auto-generated method stub((ViewPager) arg0).addView(list.get(arg1));return list.get(arg1);}@Overridepublic void restoreState(Parcelable arg0, ClassLoader arg1) {// TODO Auto-generated method stub}@Overridepublic Parcelable saveState() {// TODO Auto-generated method stubreturn null;}@Overridepublic void startUpdate(View arg0) {// TODO Auto-generated method stub}@Overridepublic void finishUpdate(View arg0) {// TODO Auto-generated method stub}}class MyListener implements OnPageChangeListener {@Overridepublic void onPageScrollStateChanged(int arg0) {// TODO Auto-generated method stub}@Overridepublic void onPageScrolled(int arg0, float arg1, int arg2) {// TODO Auto-generated method stub}@Overridepublic void onPageSelected(int arg0) {for (int i = 0; i < imageViews.length; i++) {imageViews[arg0].setBackgroundResource(R.drawable.guide_dot_white);if (arg0 != i) {imageViews[i].setBackgroundResource(R.drawable.guide_dot_black);}}}}}

最后在提醒一句，不要忘记加入android-support-v4.jar这个jar包。