RecyclerView设置Item的边距

一，通过继承RecyclerView.ItemDecoration

RecyclerView有三种布局即：LinearLayoutManager 线性布局、StaggeredGridLayoutManager瀑布流布局、GridLayoutManager网格布局。LinearLayoutManager布局和其他两种布局实现设置RecyclerView的Item间距不太一样；以下分别给出实现方法；

1.1，LinearLayoutManager 布局

实现方式1：上下左右间距可以分开设置，也可以设置一样的参数

a，继承RecyclerView.ItemDecoration重写getItemOffsets方法

public class SpacesItemDecoration extends RecyclerView.ItemDecoration { private HashMap<String, Integer> spaceValue; public static final String TOP_SPACE = "top_space"; public static final String BOTTOM_SPACE = "bottom_space"; public static final String LEFT_SPACE = "left_space"; public static final String RIGHT_SPACE = "right_space"; public SpacesItemDecoration(HashMap spaceValue) { this.spaceValue = spaceValue; } @Override public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) { if (spaceValue.get(LEFT_SPACE) != null) outRect.left = spaceValue.get(LEFT_SPACE); if (spaceValue.get(RIGHT_SPACE) != null) outRect.right = spaceValue.get(RIGHT_SPACE); if (spaceValue.get(BOTTOM_SPACE) != null) outRect.bottom = spaceValue.get(BOTTOM_SPACE); if (spaceValue.get(TOP_SPACE) != null) outRect.top = spaceValue.get(TOP_SPACE); } }

b，设置item间距

HashMap<String, Integer> spacesVelue = new HashMap<>(); spacesVelue.put(SpacesItemDecoration.TOP_SPACE, 10); spacesVelue.put(SpacesItemDecoration.BOTTOM_SPACE, 20); spacesVelue.put(SpacesItemDecoration.LEFT_SPACE, 0); spacesVelue.put(SpacesItemDecoration.RIGHT_SPACE, 0); recyclerView.addItemDecoration(new SpacesItemDecoration(spacesVelue));

实现方式2：设置是否包含四周边距；上下左右间距可以分开设置，也可以设置一样的参数；

a，继承RecyclerView.ItemDecoration重写getItemOffsets方法

public class SpacesItemDecoration2 extends RecyclerView.ItemDecoration { private HashMap<String, Integer> spaceValue; //间隔 private boolean includeEdge; //是否包含四周边距 public static final String TOP_SPACE = "top_space"; public static final String BOTTOM_SPACE = "bottom_space"; public static final String LEFT_SPACE = "left_space"; public static final String RIGHT_SPACE = "right_space"; public SpacesItemDecoration2(HashMap spaceValue, boolean includeEdge) { this.spaceValue = spaceValue; this.includeEdge = includeEdge; } @Override public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) { LinearLayoutManager layoutManager = (LinearLayoutManager) parent.getLayoutManager(); if (includeEdge) { if (spaceValue.get(LEFT_SPACE) != null) outRect.left = spaceValue.get(LEFT_SPACE); if (spaceValue.get(RIGHT_SPACE) != null) outRect.right = spaceValue.get(RIGHT_SPACE); if (spaceValue.get(BOTTOM_SPACE) != null) outRect.bottom = spaceValue.get(BOTTOM_SPACE); if (spaceValue.get(TOP_SPACE) != null) outRect.top = spaceValue.get(TOP_SPACE); } else { if (layoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL) { if (parent.getChildAdapterPosition(view) == 0) outRect.left = 0; if (parent.getChildAdapterPosition(view) == layoutManager.getItemCount() - 1) outRect.right = 0; } if (layoutManager.getOrientation() == LinearLayoutManager.VERTICAL) { if (parent.getChildAdapterPosition(view) == 0) outRect.top = 0; if (parent.getChildAdapterPosition(view) == layoutManager.getItemCount() - 1) outRect.bottom = 0; } } } }

b,设置间距：

HashMap<String, Integer> spacesVelue = new HashMap<>(); spacesVelue.put(SpacesItemDecoration.TOP_SPACE, 10); //item上边距 spacesVelue.put(SpacesItemDecoration.BOTTOM_SPACE, 20); //item下边距 spacesVelue.put(SpacesItemDecoration.LEFT_SPACE, 0); //item左边距 spacesVelue.put(SpacesItemDecoration.RIGHT_SPACE, 0); //item 右边距 recyclerView.addItemDecoration(new SpacesItemDecoration(spacesVelue,true)); //true代表有边距，false表示没有边距

1.2，网格布局和瀑布流布局解决办法：

public class SpacesItemDecoration extends RecyclerView.ItemDecoration { private HashMap<String, Integer> spaceValue; //间隔 private boolean includeEdge; //是否包含四周边距 private int spanCount; //列数 public static final String TOP_SPACE = "top_space"; public static final String BOTTOM_SPACE = "bottom_space"; public static final String LEFT_SPACE = "left_space"; public static final String RIGHT_SPACE = "right_space"; public SpacesItemDecoration(int spanCount, HashMap<String, Integer> spaceValue, boolean includeEdge) { this.spanCount = spanCount; this.spaceValue = spaceValue; this.includeEdge = includeEdge; } @Override public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) { //这里是关键，需要根据你有几列来判断 int position = parent.getChildAdapterPosition(view); // item position int column = position % spanCount; // item column if (includeEdge) { outRect.left = spaceValue.get(LEFT_SPACE) - column * spaceValue.get(LEFT_SPACE) / spanCount; outRect.right = (column + 1) * spaceValue.get(RIGHT_SPACE) / spanCount; if (position < spanCount) { // top edge 判断是首行 outRect.top = spaceValue.get(TOP_SPACE); } outRect.bottom = spaceValue.get(BOTTOM_SPACE); // item bottom } else { outRect.left = column * spaceValue.get(LEFT_SPACE) / spanCount; outRect.right = spaceValue.get(RIGHT_SPACE) - (column + 1) * spaceValue.get(RIGHT_SPACE) / spanCount; if (position >= spanCount) {//不是首行 outRect.top = spaceValue.get(TOP_SPACE); // item top } //只有首行设置上边距 //if (position >= spanCount) {//不是首行 // outRect.top = spaceValue.get(TOP_SPACE); // item top //}else { // outRect.top = 20; //首行 //} //只有下边距 // if (position > (parent.getAdapter().getItemCount() - spanCount)-1) { // outRect.bottom = 100; // } } } }

设置item边距：

HashMap<String, Integer> spacesVelue = new HashMap<>(); spacesVelue.put(SpacesItemDecoration.TOP_SPACE, 10); spacesVelue.put(SpacesItemDecoration.BOTTOM_SPACE, 20); spacesVelue.put(SpacesItemDecoration.LEFT_SPACE, 0); spacesVelue.put(SpacesItemDecoration.RIGHT_SPACE, 0); recyclerView.addItemDecoration(new SpacesItemDecoration(2,spacesVelue, false));

本文参考：https://www.jianshu.com/p/e372cec819db