RecycleView设置item上下间距

使用方式：

RecyclerView rvParentCategory = (RecyclerView) view.findViewById(R.id.rv_parent_category);
        rvParentCategory.addItemDecoration(new SpaceItemDecoration(DensityUtils.dp2px(getActivity(),20)));

自定义间距类：

package com.onetoo.www.onetoo.config;

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

/**
 * Created by longShun on 2017/2/7.
 * desc
 */
public class SpaceItemDecoration extends RecyclerView.ItemDecoration {

private int space;

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

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {

if(parent.getChildPosition(view) != -1)
            outRect.top = space;
    }
}

工具类

package com.onetoo.www.onetoo.utils;

import android.content.Context;
import android.util.TypedValue;

/**
 * Created by longShun on 2016/10/20.
 *
 */
public class DensityUtils {
private DensityUtils() {
    }

/**
 * dp转px
 */
public static int dp2px(Context context, float dpVal) {
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
                dpVal, context.getResources().getDisplayMetrics());
    }

/**
 * sp转px
 */
public static int sp2px(Context context, float spVal) {
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,
                spVal, context.getResources().getDisplayMetrics());
    }

/**
 * px转dp
 */
public static float px2dp(Context context, float pxVal) {
final float scale = context.getResources().getDisplayMetrics().density;
return (pxVal / scale);
    }

/**
 * px转sp
 */
public static float px2sp(Context context, float pxVal) {
return (pxVal / context.getResources().getDisplayMetrics().scaledDensity);
    }
}