content: package com.share.jack.customviewpath.util;
  
  import android.content.Context;
  import android.content.res.TypedArray;
  import android.graphics.Canvas;
  import android.graphics.Rect;
  import android.graphics.drawable.Drawable;
  import android.support.v4.content.ContextCompat;
  import android.support.v7.widget.GridLayoutManager;
  import android.support.v7.widget.RecyclerView;
  import android.support.v7.widget.StaggeredGridLayoutManager;
  import android.view.View;
  
  import com.share.jack.customviewpath.R;
  
  
  /**
   *
   */
  public class RecyclerViewDivider extends RecyclerView.ItemDecoration {
      private static final int[] ATTRS = new int[]{android.R.attr.listDivider};
      private Drawable mDivider;
  
      public RecyclerViewDivider(Context context, int drawableRes) {
          if (drawableRes == 0) {
              drawableRes = R.drawable.shape_divider;
          }
          final TypedArray a = context.obtainStyledAttributes(ATTRS);
          mDivider = ContextCompat.getDrawable(context, drawableRes);
          a.recycle();
  
      }
  
      public RecyclerViewDivider(Context context) {
          this(context, R.drawable.shape_divider);
  
      }
  
      @Override
      public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
  
          drawHorizontal(c, parent);
          drawVertical(c, parent);
  
      }
  
      private int getSpanCount(RecyclerView parent) {
          // 列数
          int spanCount = -1;
          RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
          if (layoutManager instanceof GridLayoutManager) {
  
              spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
          } else if (layoutManager instanceof StaggeredGridLayoutManager) {
              spanCount = ((StaggeredGridLayoutManager) layoutManager)
                      .getSpanCount();
          }
          return spanCount;
      }
  
      public void drawHorizontal(Canvas c, RecyclerView parent) {
          int childCount = parent.getChildCount();
          for (int i = 0; i < childCount; i++) {
              final View child = parent.getChildAt(i);
              final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                      .getLayoutParams();
              final int left = child.getLeft() - params.leftMargin;
              final int right = child.getRight() + params.rightMargin
                      + mDivider.getIntrinsicWidth();
              final int top = child.getBottom() + params.bottomMargin;
              final int bottom = top + mDivider.getIntrinsicHeight();
              mDivider.setBounds(left, top, right, bottom);
              mDivider.draw(c);
          }
      }
  
      public void drawVertical(Canvas c, RecyclerView parent) {
          final int childCount = parent.getChildCount();
          for (int i = 0; i < childCount; i++) {
              final View child = parent.getChildAt(i);
  
              final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                      .getLayoutParams();
              final int top = child.getTop() - params.topMargin;
              final int bottom = child.getBottom() + params.bottomMargin;
              final int left = child.getRight() + params.rightMargin;
              final int right = left + mDivider.getIntrinsicWidth();
  
              mDivider.setBounds(left, top, right, bottom);
              mDivider.draw(c);
          }
      }
  
      private boolean isLastColum(RecyclerView parent, int pos, int spanCount,
                                  int childCount) {
          RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
          if (layoutManager instanceof GridLayoutManager) {
              if ((pos + 1) % spanCount == 0)// 如果是最后一列，则不需要绘制右边
              {
                  return true;
              }
          } else if (layoutManager instanceof StaggeredGridLayoutManager) {
              int orientation = ((StaggeredGridLayoutManager) layoutManager)
                      .getOrientation();
              if (orientation == StaggeredGridLayoutManager.VERTICAL) {
                  if ((pos + 1) % spanCount == 0)// 如果是最后一列，则不需要绘制右边
                  {
                      return true;
                  }
              } else {
                  childCount = childCount - childCount % spanCount;
                  if (pos >= childCount)// 如果是最后一列，则不需要绘制右边
                      return true;
              }
          }
          return false;
      }
  
      private boolean isLastRaw(RecyclerView parent, int pos, int spanCount,
                                int childCount) {
          RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
          if (layoutManager instanceof GridLayoutManager) {
              childCount = childCount - childCount % spanCount;
              if (pos >= childCount)// 如果是最后一行，则不需要绘制底部
                  return true;
          } else if (layoutManager instanceof StaggeredGridLayoutManager) {
              int orientation = ((StaggeredGridLayoutManager) layoutManager)
                      .getOrientation();
              // StaggeredGridLayoutManager 且纵向滚动
              if (orientation == StaggeredGridLayoutManager.VERTICAL) {
                  childCount = childCount - childCount % spanCount;
                  // 如果是最后一行，则不需要绘制底部
                  if (pos >= childCount)
                      return true;
              } else
              // StaggeredGridLayoutManager 且横向滚动
              {
                  // 如果是最后一行，则不需要绘制底部
                  if ((pos + 1) % spanCount == 0) {
                      return true;
                  }
              }
          }
          return false;
      }
  
      @Override
      public void getItemOffsets(Rect outRect, int itemPosition,
                                 RecyclerView parent) {
          int spanCount = getSpanCount(parent);
          int childCount = parent.getAdapter().getItemCount();
          if (isLastRaw(parent, itemPosition, spanCount, childCount))// 如果是最后一行，则不需要绘制底部
          {
              outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
          } else if (isLastColum(parent, itemPosition, spanCount, childCount))// 如果是最后一列，则不需要绘制右边
          {
              outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
          } else {
              outRect.set(0, 0, mDivider.getIntrinsicWidth(),
                      mDivider.getIntrinsicHeight());
          }
      }
  }
  