Android RecyclerView添加分隔线 DividerItemDecoration

原文地址：http://blog.csdn.net/jjwwmlp456/article/details/51105287

 

RecyclerView的分隔线需要自定义设置

DividerItemDecoration 是一个官方的例子中的

mRecyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.HORIZONTAL_LIST));

mRecyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST));

import android.content.Context;  
import android.content.res.TypedArray;  
import android.graphics.Canvas;  
import android.graphics.Rect;  
import android.graphics.drawable.Drawable;  
import android.support.v7.widget.LinearLayoutManager;  
import android.support.v7.widget.RecyclerView;  
import android.view.View;  
  
/* 
这个是v7 中的一个sample中的 
 */  
public class DividerItemDecoration extends RecyclerView.ItemDecoration{  
  
    private static final int[] ATTRS = new int[]{  
            android.R.attr.listDivider  
    };  
  
    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;  
  
    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;  
  
    private Drawable mDivider;  
  
    private int mOrientation;  
  
    public DividerItemDecoration(Context context, int orientation) {  
        final TypedArray a = context.obtainStyledAttributes(ATTRS);  
        mDivider = a.getDrawable(0);//系统属性中获取  
        a.recycle();  
        setOrientation(orientation);  
    }  
  
    public void setOrientation(int orientation) {  
        if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {  
            throw new IllegalArgumentException("invalid orientation");  
        }  
        mOrientation = orientation;  
    }  
  
    @Override //在RecyclerView的onDraw中执行  
    public void onDraw(Canvas c, RecyclerView parent) {  
        if (mOrientation == VERTICAL_LIST) {  
            drawVertical(c, parent);  
        } else {  
            drawHorizontal(c, parent);  
        }  
    }  
  
    /** 
     * 绘制纵向列表时的分隔线  这时分隔线是横着的 
     * 每次 left相同，top根据child变化，right相同，bottom也变化 
     * @param c 
     * @param parent 
     */  
    public void drawVertical(Canvas c, RecyclerView parent) {  
        final int left = parent.getPaddingLeft();  
        final int right = parent.getWidth() - parent.getPaddingRight();  
  
        final int childCount = parent.getChildCount();  
        for (int i = 0; i < childCount; i++) {  
            final View child = parent.getChildAt(i);  
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child  
                    .getLayoutParams();  
            final int top = child.getBottom() + params.bottomMargin;  
            final int bottom = top + mDivider.getIntrinsicHeight();  
            mDivider.setBounds(left, top, right, bottom);  
            mDivider.draw(c);  
        }  
    }  
  
    /** 
     * 绘制横向列表时的分隔线  这时分隔线是竖着的 
     * l、r 变化； t、b 不变 
     * @param c 
     * @param parent 
     */  
    public void drawHorizontal(Canvas c, RecyclerView parent) {  
        final int top = parent.getPaddingTop();  
        final int bottom = parent.getHeight() - parent.getPaddingBottom();  
  
        final int childCount = parent.getChildCount();  
        for (int i = 0; i < childCount; i++) {  
            final View child = parent.getChildAt(i);  
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child  
                    .getLayoutParams();  
            final int left = child.getRight() + params.rightMargin;  
            final int right = left + mDivider.getIntrinsicHeight();  
            mDivider.setBounds(left, top, right, bottom);  
            mDivider.draw(c);  
        }  
    }  
  
    @Override  //预留item间隙  
    public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {  
        if (mOrientation == VERTICAL_LIST) {  
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());  
        } else {  
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);  
        }  
    }  
} 

参考官方DividerItemDecoration自定义的分割线
http://blog.csdn.net/dodod2012/article/details/79030559