RecyclerView 边框线设置

   本人新手，写这个博客主要给自己看，有什么错误的地方 ，还望指正，不喜勿喷。

import android.graphics.Canvas;import android.graphics.Paint;import android.support.v7.widget.RecyclerView;import android.view.View;public class MyItemDecoration extends RecyclerView.ItemDecoration {    @Override    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {        //先初始化一个Paint来简单指定一下Canvas的颜色，就黑的吧！  这个地方我们可以设置 paint 的 颜色大小        Paint paint = new Paint();        paint.setStrokeWidth(20);        paint.setColor(parent.getContext().getResources().getColor(R.color.hongse));        // 获得RecyclerView中总条目数量        int childCount = parent.getChildCount();        //遍历一下        for (int i = 0; i < childCount; i++) {            if (i == 0) {                //如果是第一个条目，那么我们就不画边框了                continue;            }                // 获得子View，也就是一个条目的View，准备给他画上边框                View childView = parent.getChildAt(i);                //先获得子View的长宽，以及在屏幕上的位置，方便我们得到边框的具体坐标                float x = childView.getX();                float y = childView.getY();                int width = childView.getWidth();                int height = childView.getHeight();                //根据这些点画条目的四周的线                c.drawLine(x, y, x + width, y, paint);                c.drawLine(x, y, x, y + height, paint);                c.drawLine(x + width, y, x + width, y + height, paint);                c.drawLine(x, y + height, x + width, y + height, paint);                //当然了，这里大家肯定是要根据自己不同的设计稿进行画线，或者画一些其他的东西，都可以在这里搞，非常方便            }            super.onDraw(c, parent, state);        }}

第二种也是找 别人的

import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.DashPathEffect;import android.graphics.NinePatch;import android.graphics.Paint;import android.graphics.Path;import android.graphics.PathEffect;import android.graphics.Rect;import android.support.v7.widget.GridLayoutManager;import android.support.v7.widget.RecyclerView;import android.view.View;import java.util.regex.Pattern;public class RecyclerViewItemDecoration extends RecyclerView.ItemDecoration {    /**mode for direction*/    public static final int MODE_HORIZONTAL = 0;    public static final int MODE_VERTICAL = 1;    public static final int MODE_GRID = 2;    /**default decoration thick size */    private final int DEFAULT_SIZE = 1;    /**default decoration color*/    private final String DEFAULT_COLOR = "#bdbdbd";    /**image resource id for R.java*/    private int drawableRid = 0;    /**decoration color*/    private int color = Color.parseColor(DEFAULT_COLOR);    /**decoration thick size*/    private int thick;    /**decoration dash with*/    private int dashWidth = 0;    /**decoration dash gap*/    private int dashGap = 0;    /**direction mode for decoration*/    private int recyclerviewMode;    private Paint paint;    private Bitmap bmp;    private NinePatch ninePatch;    /**sign for if the resource image is a ninepatch image*/    private Boolean hasNinePatch = false;    public RecyclerViewItemDecoration(int recyclerviewMode, Context context, int drawableRid){        this.recyclerviewMode = recyclerviewMode;        this.drawableRid = drawableRid;        this.bmp = BitmapFactory.decodeResource(context.getResources(), drawableRid);        if(bmp.getNinePatchChunk()!=null){            hasNinePatch = true;            ninePatch = new NinePatch(bmp, bmp.getNinePatchChunk(), null);        }        initPaint();    }    public RecyclerViewItemDecoration(int recyclerviewMode, int color, int thick, int dashWidth, int dashGap){        this.recyclerviewMode = recyclerviewMode;        this.color = color;        this.thick = thick;        this.dashWidth = dashWidth;        this.dashGap = dashGap;        initPaint();    }    public RecyclerViewItemDecoration(int recyclerviewMode, String color, int thick, int dashWidth, int dashGap){        this.recyclerviewMode = recyclerviewMode;        if(isColorString(color)){            this.color = Color.parseColor(color);        }else{            this.color = Color.parseColor(DEFAULT_COLOR);        }        this.thick = thick;        this.dashWidth = dashWidth;        this.dashGap = dashGap;        initPaint();    }    private void initPaint(){        paint = new Paint();        paint.setColor(color);        paint.setStyle(Paint.Style.STROKE);        paint.setStrokeWidth(thick);    }    @Override    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {        paint.setColor(color);        if(recyclerviewMode == MODE_HORIZONTAL){            drawHorinzonal(c,parent);        }else if(recyclerviewMode == MODE_VERTICAL){            drawVertical(c,parent);        }else if(recyclerviewMode == MODE_GRID){            drawGrid(c,parent);        }    }    @Override    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {        if(recyclerviewMode == MODE_HORIZONTAL                && parent.getChildLayoutPosition(view)!=parent.getAdapter().getItemCount()-1){            if(drawableRid!=0){                outRect.set(0,0,0,bmp.getHeight());            }else{                outRect.set(0,0,0,thick);            }        }else if(recyclerviewMode == MODE_VERTICAL                && parent.getChildLayoutPosition(view)!=parent.getAdapter().getItemCount()-1){            if(drawableRid!=0){                outRect.set(0,0,bmp.getWidth(),0);            }else{                outRect.set(0,0,thick,0);            }        }else if(recyclerviewMode == MODE_GRID){            int columnSize = ((GridLayoutManager)parent.getLayoutManager()).getSpanCount();            int itemSzie = parent.getAdapter().getItemCount();            if(drawableRid!=0){                if(isLastRowGrid(parent.getChildLayoutPosition(view),itemSzie,columnSize)                        && isLastGridColumn(parent.getChildLayoutPosition(view),columnSize)){                    outRect.set(0,0,0,0);                }else if(isLastRowGrid(parent.getChildLayoutPosition(view),itemSzie,columnSize)){                    outRect.set(0,0,bmp.getWidth(),0);                }else if((parent.getChildLayoutPosition(view)+1)%columnSize!=0){                    outRect.set(0,0,bmp.getWidth(),bmp.getHeight());                }else {                    outRect.set(0, 0, 0, bmp.getHeight());                }            }else{                if(isLastRowGrid(parent.getChildLayoutPosition(view),itemSzie,columnSize)                        && isLastGridColumn(parent.getChildLayoutPosition(view),columnSize)){                    outRect.set(0,0,0,0);                }else if(isLastRowGrid(parent.getChildLayoutPosition(view),itemSzie,columnSize)){                    outRect.set(0,0,thick,0);                }else if((parent.getChildLayoutPosition(view)+1)%columnSize!=0){                    outRect.set(0,0,thick,thick);                }else{                    outRect.set(0,0,0,thick);                }            }        }    }    /**     * judge is a color string like #xxxxxx or #xxxxxxxx     * @param colorStr     * @return     */    private boolean isColorString(String colorStr){        return Pattern.matches("^#([0-9a-fA-F]{6}||[0-9a-fA-F]{8})$",colorStr);    }    /**     * draw horizonal decoration     * @param c     * @param parent     */    private void drawHorinzonal(Canvas c,RecyclerView parent){        int childrentCount = parent.getChildCount();        if(drawableRid!=0){            if(hasNinePatch) {                for(int i=0;i<childrentCount;i++) {                    if (i != childrentCount - 1) {                        View childView = parent.getChildAt(i);                        int myY = childView.getBottom();                        Rect rect = new Rect(0, myY, parent.getWidth(), myY+bmp.getHeight());                        ninePatch.draw(c, rect);                    }                }            }else {                for(int i=0;i<childrentCount;i++) {                    if (i != childrentCount - 1) {                        View childView = parent.getChildAt(i);                        int myY = childView.getBottom();                        c.drawBitmap(bmp,0,myY,paint);                    }                }            }        }else if(dashWidth ==0 && dashGap==0){            for(int i=0;i<childrentCount;i++) {                if (i != childrentCount - 1) {                    View childView = parent.getChildAt(i);                    int myY = childView.getBottom() + thick / 2;                    c.drawLine(0,myY,parent.getWidth(),myY,paint);                }            }        }else{            PathEffect effects = new DashPathEffect(new float[]{0,0,dashWidth,thick},dashGap);            paint.setPathEffect(effects);            for(int i=0;i<childrentCount;i++) {                if (i != childrentCount - 1) {                    View childView = parent.getChildAt(i);                    int myY = childView.getBottom() + thick / 2;                    Path path = new Path();                    path.moveTo(0, myY);                    path.lineTo(parent.getWidth(),myY);                    c.drawPath(path, paint);                }            }        }    }    /**     * draw vertival decoration     * @param c     * @param parent     */    private void drawVertical(Canvas c,RecyclerView parent){        int childrentCount = parent.getChildCount();        if(drawableRid!=0){            if(hasNinePatch){                for(int i=0;i<childrentCount;i++) {                    if (i != childrentCount-1) {                        View childView = parent.getChildAt(i);                        int myX = childView.getRight();                        Rect rect = new Rect(myX, 0, myX+bmp.getWidth(), parent.getHeight());                        ninePatch.draw(c, rect);                    }                }            }else{                for(int i=0;i<childrentCount;i++) {                    if (i != childrentCount-1) {                        View childView = parent.getChildAt(i);                        int myX = childView.getRight();                        c.drawBitmap(bmp,myX,0,paint);                    }                }            }        } else if(dashWidth ==0 && dashGap==0){            for(int i=0;i<childrentCount;i++) {                if (i != childrentCount-1) {                    View childView = parent.getChildAt(i);                    int myX = childView.getRight()+thick/2;                    c.drawLine(myX,0,myX,parent.getHeight(),paint);                }            }        }else{            PathEffect effects = new DashPathEffect(new float[]{0,0,dashWidth,thick},dashGap);            paint.setPathEffect(effects);            for(int i=0;i<childrentCount;i++) {                if (i != childrentCount-1) {                    View childView = parent.getChildAt(i);                    int myX = childView.getRight()+thick/2;                    Path path = new Path();                    path.moveTo(myX, 0);                    path.lineTo(myX,parent.getHeight());                    c.drawPath(path, paint);                }            }        }    }    /**     * 鐢荤綉鏍煎垎鍓茬嚎     * @param c     * @param parent     */    private void drawGrid(Canvas c,RecyclerView parent){        int childrentCount = parent.getChildCount();        int columnSize = ((GridLayoutManager)parent.getLayoutManager()).getSpanCount();        int adapterChildrenCount = parent.getAdapter().getItemCount();        if(drawableRid!=0){            if(hasNinePatch){                for(int i=0;i<childrentCount;i++) {                    View childView = parent.getChildAt(i);                    int myX = childView.getRight();                    int myY = childView.getBottom();                    //horizonal                    if(!isLastRowGrid(i,adapterChildrenCount,columnSize)){                        Rect rect = new Rect(0, myY, myX, myY+bmp.getHeight());                        ninePatch.draw(c, rect);                    }                    //vertical                    if(isLastRowGrid(i,adapterChildrenCount,columnSize)                            && !isLastGridColumn(i,columnSize)){                        Rect rect = new Rect(myX, childView.getTop(), myX+bmp.getWidth(), myY);                        ninePatch.draw(c, rect);                    }else if(!isLastGridColumn(i,columnSize)){                        Rect rect = new Rect(myX, childView.getTop(), myX+bmp.getWidth(), myY+bmp.getHeight());                        ninePatch.draw(c, rect);                    }                }            }else{                for(int i=0;i<childrentCount;i++) {                    View childView = parent.getChildAt(i);                    int myX = childView.getRight();                    int myY = childView.getBottom();                    //horizonal                    if(!isLastRowGrid(i,adapterChildrenCount,columnSize)){                        c.drawBitmap(bmp,childView.getLeft(),myY,paint);                    }                    //vertical                    if(!isLastGridColumn(i,columnSize)){                        c.drawBitmap(bmp,myX,childView.getTop(),paint);                    }                }            }        } else if(dashWidth ==0 && dashGap==0){            for(int i=0;i<childrentCount;i++) {                View childView = parent.getChildAt(i);                int myX = childView.getRight()+thick/2;                int myY = childView.getBottom() + thick / 2;                //horizonal                if(!isLastRowGrid(i,adapterChildrenCount,columnSize)){                    c.drawLine(childView.getLeft(),myY,childView.getRight()+thick,myY,paint);                }                //vertical                if(isLastRowGrid(i,adapterChildrenCount,columnSize)                        && !isLastGridColumn(i,columnSize)) {                    c.drawLine(myX, childView.getTop(), myX, childView.getBottom(), paint);                }else if(!isLastGridColumn(i,columnSize)){                    c.drawLine(myX,childView.getTop(),myX,myY,paint);                }            }        }else{            PathEffect effects = new DashPathEffect(new float[]{0,0,dashWidth,thick},dashGap);            paint.setPathEffect(effects);            for(int i=0;i<childrentCount;i++) {                View childView = parent.getChildAt(i);                int myX = childView.getRight()+thick/2;                int myY = childView.getBottom() + thick / 2;                //horizonal                if(!isLastRowGrid(i,adapterChildrenCount,columnSize)){                    Path path = new Path();                    path.moveTo(0, myY);                    path.lineTo(myX,myY);                    c.drawPath(path, paint);                }                //vertical                if(isLastRowGrid(i,adapterChildrenCount,columnSize)                        && !isLastGridColumn(i,columnSize)) {                    Path path = new Path();                    path.moveTo(myX, childView.getTop());                    path.lineTo(myX,childView.getBottom());                    c.drawPath(path, paint);                } else if(!isLastGridColumn(i,columnSize)){                    Path path = new Path();                    path.moveTo(myX, childView.getTop());                    path.lineTo(myX,childView.getBottom());                    c.drawPath(path, paint);                }            }        }    }    /**     * check if is one of the last columns     * @param position     * @param columnSize     * @return     */    private boolean isLastGridColumn(int position,int columnSize){        boolean isLast = false;        if((position+1)%columnSize==0){            isLast = true;        }        return isLast;    }    /**     * check if is the last row of the grid     * @param position     * @param itemSize     * @param columnSize     * @return     */    private boolean isLastRowGrid(int position,int itemSize,int columnSize){        return position/columnSize == (itemSize-1)/columnSize;    }}