RecyclerView设置分隔线的三种方法

一.在item.xml文件中在最下方指定一条分割线，例如：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <ImageView
            android:id="@+id/image_view"
            android:layout_gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
        <TextView
            android:id="@+id/text_view"
            android:layout_gravity="center"
            android:gravity="left"
            android:layout_marginTop="10dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </LinearLayout>
    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:layout_marginTop="10dp"
        android:background="@color/colorPrimary"/>
</LinearLayout>

二.可以指定宽度颜色的模板（成品模板）

1.添加默认分割线：高度为2px，颜色为灰色

mRecyclerView.addItemDecoration(new RecycleViewDivider(mContext, LinearLayoutManager.VERTICAL));

2.添加自定义分割线：可自定义分割线drawable

mRecyclerView.addItemDecoration(new RecycleViewDivider(
    mContext, LinearLayoutManager.VERTICAL, R.drawable.divider_mileage));

3.添加自定义分割线：可自定义分割线高度和颜色

mRecyclerView.addItemDecoration(new RecycleViewDivider(
    mContext, LinearLayoutManager.VERTICAL, 10, getResources().getColor(R.color.divide_gray_color)));

三.万能分割线

package hwp.com.recyclerviewdemo;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.annotation.NonNull;
import android.support.v4.content.ContextCompat;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;

/**
 * Created by hwp on 2018/12/29
 */
class MyItemDecoration extends RecyclerView.ItemDecoration{
    private final int mOrientation;
    private final Context mContext;
    private final int[] attrs=new int[]{android.R.attr.listDivider};
    private  int mDividerHeight;
    private  Paint mPaint;
    private Drawable mDivider;
    /**
     * 默认分割线：高度为2px，颜色为灰色
     *
     * @param context
     * @param orientation 列表方向
     */
    public  MyItemDecoration(Context context, int orientation){
        if(orientation!= LinearLayoutManager.VERTICAL&&orientation!=LinearLayoutManager.HORIZONTAL)throw  new IllegalArgumentException("请输入正确参数");
        this.mContext=context;
        this.mOrientation=orientation;
        TypedArray a = context.obtainStyledAttributes(attrs);
        mDivider=a.getDrawable(0);
        a.recycle();
    }
    /**
     * 自定义分割线
     *
     * @param context
     * @param orientation 列表方向
     * @param drawableId  分割线图片
     */

    public  MyItemDecoration(Context context,int orientation,int drawableId){
        this(context,orientation);
        mDivider= ContextCompat.getDrawable(context,drawableId);
        mDividerHeight =mDivider.getIntrinsicHeight();

    }

    /**
     *
     * @param context
     * @param orientation 列表方向
     * @param mDividerHeight 分割线高度
     * @param mDividerColor 分割线颜色
     */
    public  MyItemDecoration(Context context,int orientation,int mDividerHeight,int mDividerColor){
        this(context,orientation);
        this.mDividerHeight=mDividerHeight;
        mPaint=new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setColor(mDividerColor);
        mPaint.setStyle(Paint.Style.FILL);
    }
    //绘制分割线
    @Override
    public void onDraw(@NonNull Canvas c, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {
        super.onDraw(c, parent, state);
        if(mOrientation==LinearLayoutManager.VERTICAL){
            drawVertical(c,parent);
        }else{
            drawHorizontal(c,parent);
        }
    }
    //绘制横向 item 分割线
    private void drawHorizontal(Canvas canvas, RecyclerView parent) {
        final int left = parent.getPaddingLeft();
        final int right = parent.getMeasuredWidth() - parent.getPaddingRight();
        final int childSize = parent.getChildCount();
        for (int i = 0; i < childSize; i++) {
            final View child = parent.getChildAt(i);
            RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int top = child.getBottom() + layoutParams.bottomMargin;
            final int bottom = top + mDividerHeight;
            if (mDivider != null) {
                mDivider.setBounds(left, top, right, bottom);
                mDivider.draw(canvas);
            }
            if (mPaint != null) {
                canvas.drawRect(left, top, right, bottom, mPaint);
            }
        }

    }
    //绘制纵向 item 分割线
    private void drawVertical(Canvas canvas, RecyclerView parent) {
        final int top = parent.getPaddingTop();
        final int bottom = parent.getMeasuredHeight() - parent.getPaddingBottom();
        final int childSize = parent.getChildCount();
        for (int i = 0; i < childSize; i++) {
            final View child = parent.getChildAt(i);
            RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int left = child.getRight() + layoutParams.rightMargin;
            final int right = left + mDividerHeight;
            if (mDivider != null) {
                mDivider.setBounds(left, top, right, bottom);
                mDivider.draw(canvas);
            }
            if (mPaint != null) {
                canvas.drawRect(left, top, right, bottom, mPaint);
            }
        }


    }

    @Override
    public void getItemOffsets(@NonNull Rect outRect, @NonNull View view, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        outRect.set(0,0,0,mDividerHeight);
    }
}