自定义RecycleView分割线

1、自定义分割线
package com.example.xp.widget.divide;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.Log;
import android.view.View;
import android.widget.LinearLayout;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

public class LinearItemDecoration extends RecyclerView.ItemDecoration {
public static final int HORIZONTAL = LinearLayout.HORIZONTAL;
public static final int VERTICAL = LinearLayout.VERTICAL;

private static final int DEFAULT_MARGIN = 0;

private static final String TAG = "DividerItem";
private static final int[] ATTRS = new int[]{android.R.attr.listDivider};

private Drawable mDivider;
private int mWidthMargin;//宽度margin

/**
 * Current orientation. Either {@link #HORIZONTAL} or {@link #VERTICAL}.
 */
private int mOrientation;

private final Rect mBounds = new Rect();

/**
 * Creates a divider {@link RecyclerView.ItemDecoration} that can be used with a
 *
 * @param context     Current context, it will be used to access resources.
 * @param orientation Divider orientation. Should be {@link #HORIZONTAL} or {@link #VERTICAL}.
 */
public LinearItemDecoration(Context context, int orientation) {
    final TypedArray a = context.obtainStyledAttributes(ATTRS);
    mDivider = a.getDrawable(0);
    if (mDivider == null) {
        Log.w(TAG, "@android:attr/listDivider was not set in the theme used for this "
                + "DividerItemDecoration. Please set that attribute all call setDrawable()");
    }
    a.recycle();
    setOrientation(orientation);
}

/**
 * Sets the orientation for this divider. This should be called if
 * {@link RecyclerView.LayoutManager} changes orientation.
 *
 * @param orientation {@link #HORIZONTAL} or {@link #VERTICAL}
 */
public void setOrientation(int orientation) {
    if (orientation != HORIZONTAL && orientation != VERTICAL) {
        throw new IllegalArgumentException(
                "Invalid orientation. It should be either HORIZONTAL or VERTICAL");
    }
    mOrientation = orientation;
}

/**
 * Sets the {@link Drawable} for this divider.
 *
 * @param drawable Drawable that should be used as a divider.
 */
public void setDrawable(@NonNull Drawable drawable) {
    if (drawable == null) {
        throw new IllegalArgumentException("Drawable cannot be null.");
    }
    mDivider = drawable;
}

@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
    if (parent.getLayoutManager() == null || mDivider == null) {
        return;
    }
    if (mOrientation == VERTICAL) {
        drawVertical(c, parent);
    } else {
        drawHorizontal(c, parent);
    }
}

private void drawVertical(Canvas canvas, RecyclerView parent) {
    canvas.save();
    //设置分割线水平间距
    int horizontalMargin;
    if (mWidthMargin != 0) {
        horizontalMargin = mWidthMargin;
    } else {
        horizontalMargin = DEFAULT_MARGIN;
    }

    final int left;
    final int right;
    //noinspection AndroidLintNewApi - NewApi lint fails to handle overrides.
    if (parent.getClipToPadding()) {
        left = parent.getPaddingLeft() + horizontalMargin;
        right = parent.getWidth() - horizontalMargin;
        canvas.clipRect(left, parent.getPaddingTop(), right,
                parent.getHeight() - parent.getPaddingBottom());
    } else {
        left = horizontalMargin;
        right = parent.getWidth() - horizontalMargin;
    }

    final int childCount = parent.getChildCount();
    //默认为childCount，这里设置为childCount-1，这样最后一行末尾处就没有分割线
    for (int i = 0; i < childCount - 1; i++) {
        final View child = parent.getChildAt(i);
        parent.getDecoratedBoundsWithMargins(child, mBounds);
        final int bottom = mBounds.bottom + Math.round(child.getTranslationY());
        final int top = bottom - mDivider.getIntrinsicHeight();
        mDivider.setBounds(left, top, right, bottom);
        mDivider.draw(canvas);
    }
    canvas.restore();
}

private void drawHorizontal(Canvas canvas, RecyclerView parent) {
    canvas.save();
    final int top;
    final int bottom;
    //noinspection AndroidLintNewApi - NewApi lint fails to handle overrides.
    if (parent.getClipToPadding()) {
        top = parent.getPaddingTop();
        bottom = parent.getHeight() - parent.getPaddingBottom();
        canvas.clipRect(parent.getPaddingLeft(), top,
                parent.getWidth() - parent.getPaddingRight(), bottom);
    } else {
        top = 0;
        bottom = parent.getHeight();
    }

    final int childCount = parent.getChildCount();
    for (int i = 0; i < childCount; i++) {
        final View child = parent.getChildAt(i);
        parent.getLayoutManager().getDecoratedBoundsWithMargins(child, mBounds);
        final int right = mBounds.right + Math.round(child.getTranslationX());
        final int left = right - mDivider.getIntrinsicWidth();
        mDivider.setBounds(left, top, right, bottom);
        mDivider.draw(canvas);
    }
    canvas.restore();
}

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
    if (mDivider == null) {
        outRect.set(0, 0, 0, 0);
        return;
    }
    if (mOrientation == VERTICAL) {
        outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
    } else {
        outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
    }
}

public int getWidthMargin() {
    return mWidthMargin;
}

public void setWidthMargin(int widthMargin) {
    this.mWidthMargin = widthMargin;
}

}

2、使用
//添加Android自带的分割线
LinearItemDecoration linearItemDecoration = new LinearItemDecoration(getContext(), DividerItemDecoration.VERTICAL);
linearItemDecoration.setDrawable(getContext().getResources().getDrawable(R.drawable.bg_divider));

recyclerView.addItemDecoration(linearItemDecoration);

3、分割线布局
bg_divider.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#EDF6F8"/>
<size android:height="5dp"/>
</shape>