三行代码实现一个轮播 BannerView

   <p>自己简单封装了一个带hint的轮播ViewPager，用来展示app首页的Banner，先看效果图吧。</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/3b9fb502cd3b56b031d184ac200defd1.gif"></p>    <p>使用起来非常方便~~2至3行代码就能实现上述效果，只要传入一个list就可以（其中是你需要展示的ImageView），当然也可以自己在这基础上添加各种Transform动画。</p>    <pre>  <code class="language-java">bannerView = (BannerView) findViewById(R.id.banner);          bannerView.setViewList(viewList);          bannerView.startLoop(true);</code></pre>    <p>实现原理相信大家应该都知道，就是可能懒得去封装这种东西。</p>    <p>具体思路：</p>    <ul>     <li>      <ol>       <li>继承自FrameLayout，在下层填充一个ViewPager</li>      </ol> </li>     <li> <p>2.根据ViewPager的itemCount去动态生成底部hint小圆点</p> </li>    </ul>    <pre>  <code class="language-java">if (mLinearPosition.getChildCount() != viewSize) {                  int diffCnt = mLinearPosition.getChildCount() - viewSize;                  boolean needAdd = diffCnt < 0;                  diffCnt = Math.abs(diffCnt);                  for (int i = 0; i < diffCnt; i++) {                      if (needAdd) {                          ImageView img = new ImageView(getContext());                          LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);                          layoutParams.rightMargin = getResources().getDimensionPixelOffset(R.dimen.dimen_9dp);                          img.setLayoutParams(layoutParams);                          img.setBackgroundResource(R.drawable.banner_point);                          mLinearPosition.addView(img);                      } else {                          mLinearPosition.removeViewAt(0);                      }                  }              }</code></pre>    <ul>     <li>3.通过Handler去控制轮播的频率，重新设置ViewPager的currentItem以及hint小圆点的背景</li>    </ul>    <pre>  <code class="language-java">private static class BannerHandler extends Handler {          private WeakReference<BannerView> weakReference = null;            public BannerHandler(BannerView bannerView) {              super(Looper.getMainLooper());              this.weakReference = new WeakReference<BannerView>(bannerView);          }            @Override          public void handleMessage(Message msg) {              super.handleMessage(msg);              if (this.weakReference == null) {                  return;              }              BannerView bannerView = this.weakReference.get();              if (bannerView == null || bannerView.mViewPager == null || bannerView.mViewPager.getAdapter() == null || bannerView.mViewPager.getAdapter().getCount() <= 0) {                  sendEmptyMessageDelayed(MSG_LOOP, LOOP_INTERVAL);                  return;              }              int curPos = bannerView.mViewPager.getCurrentItem();              curPos = (curPos + 1) % bannerView.mViewPager.getAdapter().getCount();              bannerView.mViewPager.setCurrentItem(curPos);              sendEmptyMessageDelayed(MSG_LOOP, LOOP_INTERVAL);          }      }</code></pre>    <ul>     <li>4.具体细节，如无限轮播adapter的创建，handler中的弱引用，启动销毁loop等等</li>    </ul>    <p> </p>    <p> </p>    <p>项目主页：<a href="http://www.open-open.com/lib/view/home/1490082409129">http://www.open-open.com/lib/view/home/1490082409129</a></p>    <p> </p>