ViewPager无限轮播实现

以下代码是ViewPager无限滑动轮播的一个效果

在MainActivity类中

package com.example.smily.viewpager;

import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.LinearLayout;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

private ViewPager mViewPager;
private List<ImageView> mImageViewList;
private int[] images={R.drawable.a1,R.drawable.a2,R.drawable.a3,R.drawable.a4,R.drawable.a5};
private int currentPosition=1;
private int dotPosition=0;
private int prePosition=0;
private LinearLayout mLinearLayoutDot;
private List<ImageView> mImageViewDotList;
Handler handler=new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
if(msg.what==1){
mViewPager.setCurrentItem(currentPosition,false);
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

initView();

initData();

setDot();

setViewPager();

autoPlay();
}

private void initView() {
mViewPager= (ViewPager) findViewById(R.id.vp_main);
mLinearLayoutDot= (LinearLayout) findViewById(R.id.ll_main_dot);
}

private void initData() {
mImageViewList=new ArrayList<>();
mImageViewDotList=new ArrayList();
ImageView imageView;
for(int i=0;i<images.length+2;i++){
if(i==0){ //判断当i=0为该处的ImageView设置最后一张图片作为背景
imageView=new ImageView(this);
imageView.setBackgroundResource(images[images.length-1]);
mImageViewList.add(imageView);
}else if(i==images.length+1){ //判断当i=images.length+1时为该处的ImageView设置第一张图片作为背景
imageView=new ImageView(this);
imageView.setBackgroundResource(images[0]);
mImageViewList.add(imageView);
}else{ //其他情况则为ImageView设置images[i-1]的图片作为背景
imageView=new ImageView(this);
imageView.setBackgroundResource(images[i-1]);
mImageViewList.add(imageView);
}
}
}

// 设置轮播小圆点
private void setDot() {
// 设置LinearLayout的子控件的宽高，这里单位是像素。
LinearLayout.LayoutParams params=new LinearLayout.LayoutParams(15,15);
params.rightMargin=20;
// for循环创建images.length个ImageView（小圆点）
for(int i=0;i<images.length;i++){
ImageView imageViewDot=new ImageView(this);
imageViewDot.setLayoutParams(params);
// 设置小圆点的背景为暗红图片
imageViewDot.setBackgroundResource(R.drawable.red_dot_night);
mLinearLayoutDot.addView(imageViewDot);
mImageViewDotList.add(imageViewDot);
}
//设置第一个小圆点图片背景为红色
mImageViewDotList.get(dotPosition).setBackgroundResource(R.drawable.red_dot);
}

private void setViewPager() {
MyPagerAdapter adapter=new MyPagerAdapter(mImageViewList);

mViewPager.setAdapter(adapter);

mViewPager.setCurrentItem(currentPosition);
//页面改变监听
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

}

@Override
public void onPageSelected(int position) {
if(position==0){ //判断当切换到第0个页面时把currentPosition设置为images.length,即倒数第二个位置，小圆点位置为length-1
currentPosition=images.length;
dotPosition=images.length-1;
}else if(position==images.length+1){ //当切换到最后一个页面时currentPosition设置为第一个位置，小圆点位置为0
currentPosition=1;
dotPosition=0;
}else{
currentPosition=position;
dotPosition=position-1;
}
// 把之前的小圆点设置背景为暗红，当前小圆点设置为红色
mImageViewDotList.get(prePosition).setBackgroundResource(R.drawable.red_dot_night);
mImageViewDotList.get(dotPosition).setBackgroundResource(R.drawable.red_dot);
prePosition=dotPosition;
}

@Override
public voi
4000
d onPageScrollStateChanged(int state) {
//当state为SCROLL_STATE_IDLE即没有滑动的状态时切换页面
if(state==ViewPager.SCROLL_STATE_IDLE){
mViewPager.setCurrentItem(currentPosition,false);
}
}
});
}
// 设置自动播放
private void autoPlay() {
new Thread(){
@Override
public void run() {
super.run();

while(true){
SystemClock.sleep(3000);
currentPosition++;
handler.sendEmptyMessage(1);
}
}
}.start();
}
}

在ViewPager适配器中
package com.example.smily.viewpager;

import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

import java.util.List;

/**
* Created by zhpan on 2016/7/26.
*/
public class MyPagerAdapter extends PagerAdapter{
List<ImageView> list;

public MyPagerAdapter(List<ImageView> list) {
this.list = list;
}

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

@Override
public boolean isViewFromObject(View view, Object object) {
return view==object;
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
ImageView imageView=list.get(position);
container.addView(imageView);
return list.get(position);
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView(list.get(position));
}
}



在布局文件（acitivity_main）中
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">

<android.support.v4.view.ViewPager
android:id="@+id/vp_main"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

<LinearLayout
android:id="@+id/ll_main_dot"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignBottom="@id/vp_main"
android:layout_marginBottom="10dp"
android:gravity="center_horizontal"
android:orientation="horizontal"/>
</RelativeLayout>
</LinearLayout>


然后自己在drawable文件中放下自己的几张图片
然后就能实现一个简单的无限轮播效果了~