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Android|Android ViewPager小圆点指示器

一个很常用的功能，一个ViewPager会自动滚动，并且有一排小圆点黑和白来指示当前的滚动进度

首先写一个ViewPager的适配器，这里这个适配器为了方便里面的元素全都是ImageView

import android.content.Context; import android.os.Handler; import android.support.v4.view.PagerAdapter; import android.support.v4.view.ViewPager; import android.view.View; import android.view.ViewGroup; import android.view.animation.Interpolator; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.Scroller; /** * Created by Administrator on 2016/2/24. */public class HomeHomeBannerAdapter extends PagerAdapter{private Context context; private ImageView[] eventImageViews; private String[] eventUrls; int destWidth,destHeight; public HomeHomeBannerAdapter(Context context, String[] eventUrls,int destWidth,int destHeight) {this.context = context; this.eventUrls = eventUrls; this.destHeight = destHeight; this.destWidth = destWidth; initImageViews(); } /*** 初始化viewPager里的几张图*/private void initImageViews(){if(eventUrls==null)return; eventImageViews = new ImageView[eventUrls.length]; for (int i=0; i position && position >= 0)container.removeView(eventImageViews[position]); } @Overridepublic Object instantiateItem(ViewGroup container, int position) {container.addView(eventImageViews[position], 0); return eventImageViews[position]; } @Overridepublic int getCount() {return eventUrls==null?0:eventUrls.length; } @Overridepublic boolean isViewFromObject(View arg0, Object arg1) {return arg0 == arg1; }//ViewPager监听器集成到内部类去static public class EventViewPagerChangeListener implements ViewPager.OnPageChangeListener {LinearLayout llGuideGroup; int oldEventPosition; int currentItem; public EventViewPagerChangeListener(LinearLayout llGuideGroup){this.llGuideGroup = llGuideGroup; } @Overridepublic void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {} /*** 控制小点的白色还是黑色的显示* @param position*/public void onPageSelected(int position) {llGuideGroup.getChildAt(oldEventPosition).setBackgroundResource(R.drawable.dot_normal); //黑色点llGuideGroup.getChildAt(position).setBackgroundResource(R.drawable.dot_focused); //白色点oldEventPosition = position; currentItem = position; } @Overridepublic void onPageScrollStateChanged(int state) { }} /*** 控制viewpager自动滑动的定时任务*/public static class ScrollTask implements Runnable {EventViewPagerChangeListener listener; ViewPager vpEvent; int eventSize; Handler handler; public ScrollTask(EventViewPagerChangeListener listener,final ViewPager vpEvent, int eventSize){this.listener = listener; this.vpEvent = vpEvent; this.eventSize = eventSize; handler = new Handler(); }public void run() {if(listener==null||vpEvent==null||eventSize==0)return; listener.currentItem = (listener.currentItem + 1) % eventSize; Log.i("Alex","currentItem是"+listener.currentItem); handler.post(new Runnable() {@Overridepublic void run() {vpEvent.setCurrentItem(listener.currentItem); // 通过Handler切换图片}}); }} public static class FixedSpeedScroller extends Scroller {private static final int mDuration = 400; private int eventCount; public FixedSpeedScroller(Context context, Interpolator interpolator,int eventCount) {super(context, interpolator); this.eventCount = eventCount; } @Overridepublic void startScroll(int startX, int startY, int dx, int dy, int duration) {if (duration % 100 == 0 && duration > 0) {//"现在是自动划"if (duration / 100 == eventCount) super.startScroll(startX, startY, dx, dy, 1); //如果是最后一张else super.startScroll(startX, startY, dx, dy, mDuration); } else {// "现在是手动划"super.startScroll(startX, startY, dx, dy, 80); }}}}

在上面适配器的内部类有一个监听器，这个监听器里有一个成员LinearLayout llGuideGroup，这个线性布局里面装有几个小点，下面是这个布局的定义：


设置小圆点的数量并初始化监听器
/*** 向一个线性布局里添加小圆点，具体的控制逻辑在listener里* @param llGuideGroup* @param count 要添加多少个小圆点*/public EventViewPagerChangeListener addViewPagerDots(LinearLayout llGuideGroup,ViewPager vpEvents,int count){if(llGuideGroup==null||vpEvents==null||count<1)return null; LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(15, 15); lp.leftMargin = 5; lp.rightMargin = 5; for(int i=0; i
通过多线程实现定时切换页面
HomeHomeBannerAdapter.EventViewPagerChangeListener listener = producer.addViewPagerDots(holder.llGuideGroup,holder.viewPager,eventUrls.length); //添加用于指示的小圆点// 当Activity显示出来后，每3秒钟切换一次图片显示ScheduledExecutorService scheduledExecutorService = Executors.newSingleThreadScheduledExecutor(); scheduledExecutorService.scheduleAtFixedRate(new HomeHomeBannerAdapter.ScrollTask(listener,holder.viewPager,eventUrls.length), 3, 3, TimeUnit.SECONDS);

设置自定义滚动器降低viewPager的切换速度

/*** 给ViewPager设置自定义的滚动器，降低默认的滚动速度* @param vpEvent*/public void setViewPagerScroller(ViewPager vpEvent){if(vpEvent==null)return; Field mField; Scroller mScroller; try {mField = ViewPager.class.getDeclaredField("mScroller"); mField.setAccessible(true); mScroller = new HomeHomeBannerAdapter.FixedSpeedScroller(vpEvent.getContext(), new AccelerateInterpolator(),vpEvent.getChildCount()); try {mField.set(vpEvent, mScroller); } catch (IllegalAccessException e) {e.printStackTrace(); }} catch (NoSuchFieldException e) {e.printStackTrace(); }}

【Android|Android ViewPager小圆点指示器】以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。

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