Android RecyclerView 间距全适配

原文链接：https://segmentfault.com/a/1190000006858824

LinearLayoutManager spacing

import android.graphics.Rect;
import android.support.v7.widget.RecyclerView;
import android.view.View;

/**
 * Created by anonymous on 2016/9/9 0009.
 * 

 * SpacesItemDecoration
 * 

 * mRecyclerView.addItemDecoration(new SpacesItemDecoration(5));
 */
public class SpacesItemDecoration extends RecyclerView.ItemDecoration {

    private int space;

    public SpacesItemDecoration(int space) {
        this.space = space;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        outRect.left = space;
        outRect.right = space;
        outRect.bottom = space;

        // Add top margin only for the first item to avoid double space between items
        if (parent.getChildLayoutPosition(view) == 0) {
            outRect.top = space;
        } else {
            outRect.top = 0;
        }
    }
}

使用方法很简单，上面注释中也已经给出：

mRecyclerView.addItemDecoration(new SpacesItemDecoration(5));

GridLayoutManager or StaggeredGridLayoutManager spacing

import android.graphics.Rect;
import android.support.v7.widget.RecyclerView;
import android.view.View;

/**
 * Created by anonymous on 2016/9/9 0009.
 * 

 * GridSpacingItemDecoration
 * 

 * int spanCount = 3; // 3 columns
 * int spacing = 50; // 50px
 * boolean includeEdge = false;
 * recyclerView.addItemDecoration(new GridSpacingItemDecoration(spanCount, spacing, includeEdge));
 */
public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {

    private int spanCount;
    private int spacing;
    private boolean includeEdge;

    public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge) {
        this.spanCount = spanCount;
        this.spacing = spacing;
        this.includeEdge = includeEdge;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int position = parent.getChildAdapterPosition(view); // item position
        int column = position % spanCount; // item column

        if (includeEdge) {
            outRect.left = spacing - column * spacing / spanCount; // spacing - column * ((1f / spanCount) * spacing)
            outRect.right = (column + 1) * spacing / spanCount; // (column + 1) * ((1f / spanCount) * spacing)

            if (position < spanCount) { // top edge
                outRect.top = spacing;
            }
            outRect.bottom = spacing; // item bottom
        } else {
            outRect.left = column * spacing / spanCount; // column * ((1f / spanCount) * spacing)
            outRect.right = spacing - (column + 1) * spacing / spanCount; // spacing - (column + 1) * ((1f /    spanCount) * spacing)
            if (position >= spanCount) {
                outRect.top = spacing; // item top
            }
        }
    }
}

此处不仅对间距进行了处理，而且对spanCount也进行了处理，使用方法：

int spanCount = 3; // 3 columns
int spacing = 50; // 50px
boolean includeEdge = false;
mRecyclerView.addItemDecoration(new GridSpacingItemDecoration(spanCount, spacing, includeEdge));