添加BannerView

src/main/java/tech/starwin/widget/BannerView.java

+package tech.starwin.widget;
+
+import android.content.Context;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.v4.view.PagerAdapter;
+import android.support.v4.view.ViewPager;
+import android.util.AttributeSet;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Created by SiKang on 2018/12/17.
+ */
+public class BannerView extends ViewPager {
+    private BannerAdapter bannerAdapter;
+    private OnPageChangeListener pageChangeListener;
+
+    public BannerView(@NonNull Context context) {
+        super(context);
+    }
+
+    public BannerView(@NonNull Context context, @Nullable AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    /**
+     * 绑定数据
+     */
+    public <Data> void setData(List<Data> data, OnBannerChangedListener<Data> listener) {
+        bannerAdapter = new BannerAdapter<>(getContext(), data, listener);
+        setAdapter(bannerAdapter);
+    }
+
+
+    /**
+     * 开启循环
+     */
+    public void startLoop() {
+        if (bannerAdapter != null && !bannerAdapter.isLoopping()) {
+            bannerAdapter.openLoop();
+            setCurrentItem(1);
+            pageChangeListener = new OnPageChangeListener() {
+                @Override
+                public void onPageScrolled(int i, float v, int i1) {
+
+                }
+
+                @Override
+                public void onPageSelected(int i) {
+
+                }
+
+                @Override
+                public void onPageScrollStateChanged(int state) {
+                    //若viewpager滑动未停止，或没有开启循环，则不做处理
+                    if (state != ViewPager.SCROLL_STATE_IDLE || !bannerAdapter.isLoopping())
+                        return;
+                    //循环，若当前为第一张，设置页面为倒数第二张 反之同理
+                    int current = getCurrentItem();
+                    if (current == 0) {
+                        setCurrentItem(bannerAdapter.getCount() - 2, false);
+                    } else if (current == bannerAdapter.getCount() - 1) {
+                        // 若当前为倒数第一张，设置页面为第二张
+                        setCurrentItem(1, false);
+                    }
+                }
+            };
+            addOnPageChangeListener(pageChangeListener);
+        }
+    }
+
+    /**
+     * 停止循环
+     */
+    public void stopLoop() {
+        if (bannerAdapter != null && bannerAdapter.isLoopping) {
+            if (pageChangeListener != null) {
+                removeOnPageChangeListener(pageChangeListener);
+                pageChangeListener = null;
+            }
+            bannerAdapter.colseLoop();
+            setCurrentItem(0);
+        }
+    }
+
+    public interface OnBannerChangedListener<Data> {
+        void onPageCreate(ImageView imageView, int posigion, Data data);
+
+        void onPageClick(ImageView imageView, int posigion, Data data);
+    }
+
+    public static class BannerAdapter<Data> extends PagerAdapter {
+        private Context context;
+        /**
+         * Banner数据
+         */
+        private List<Data> dataList;
+        /**
+         * 缓存的Page
+         */
+        private List<ImageView> viewList;
+        /**
+         * 是否开启无线循环
+         */
+        private boolean isLoopping = false;
+
+        private OnBannerChangedListener<Data> pagerChangedListener;
+
+        /**
+         * 开启循环
+         */
+        public void openLoop() {
+            if (!isLoopping) {
+                isLoopping = true;
+                dataList.add(0, dataList.get(dataList.size() - 1));
+                dataList.add(dataList.get(1));
+                notifyDataSetChanged();
+            }
+        }
+
+        /**
+         * 关闭循环
+         */
+        public void colseLoop() {
+            if (isLoopping) {
+                isLoopping = false;
+                dataList.remove(0);
+                dataList.remove(dataList.size() - 1);
+                notifyDataSetChanged();
+            }
+        }
+
+        public BannerAdapter(Context context, List<Data> datas, OnBannerChangedListener<Data> listener) {
+            this.context = context;
+            this.dataList = datas;
+            this.viewList = new ArrayList<>();
+            this.pagerChangedListener = listener;
+        }
+
+        @Override
+        public int getCount() {
+            return dataList.size();
+        }
+
+
+        @NonNull
+        @Override
+        public Object instantiateItem(@NonNull ViewGroup container, final int position) {
+            final ImageView pagerView = new ImageView(context);
+            ViewGroup.LayoutParams layoutParams = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
+            pagerView.setLayoutParams(layoutParams);
+            pagerView.setScaleType(ImageView.ScaleType.FIT_XY);
+
+
+            pagerView.setTag(position);
+            container.addView(pagerView);
+            viewList.add(pagerView);
+
+            if (pagerChangedListener != null) {
+                pagerChangedListener.onPageCreate(pagerView, position, dataList.get(position));
+                pagerView.setOnClickListener(new OnClickListener() {
+                    @Override
+                    public void onClick(View v) {
+                        pagerChangedListener.onPageClick(pagerView, position, dataList.get(position));
+                    }
+                });
+            }
+
+            return pagerView;
+        }
+
+        @Override
+        public void destroyItem(@NonNull final ViewGroup container, final int position, @NonNull Object object) {
+            ImageView removePager = null;
+            for (ImageView pager : viewList) {
+                if (pager.getTag() != null == pager.getTag() instanceof Integer) {
+                    if ((int) pager.getTag() == position) {
+                        removePager = pager;
+                    }
+                }
+            }
+            if (removePager != null) {
+                container.removeView(removePager);
+                viewList.remove(removePager);
+            }
+        }
+
+        @Override
+        public boolean isViewFromObject(@NonNull View view, @NonNull Object o) {
+            return view == o;
+        }
+
+        public boolean isLoopping() {
+            //如果只有一个item，则循环不可用
+            if (dataList.size() < 2) {
+                return true;
+            }
+            return isLoopping;
+        }
+    }
+}