ViewPager实现图片自动轮播和无限循环（完美流畅）

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 void 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(); } }