Android开发中自定义View实现RecyclerView下划线

本篇文章主要讲解的是有关RecyclerView下划线的使用，主要有几个方法，具体如下：

第一种方式：网格分割线

public class GridDivider extends RecyclerView.ItemDecoration {

       private Drawable mDividerDarwable;
       private int mDividerHight = 1;
       private Paint mColorPaint;

public final int[] ATRRS = new int[]{android.R.attr.listDivider};

       public GridDivider(Context context) {
           final TypedArray ta = context.obtainStyledAttributes(ATRRS);
           this.mDividerDarwable = ta.getDrawable(0);
           ta.recycle();
       }

       /*
       int dividerHight 分割线的线宽
       int dividerColor 分割线的颜色
       */
       public GridDivider(Context context, int dividerHight, int dividerColor) {
           this(context);
           mDividerHight = dividerHight;
           mColorPaint = new Paint();
           mColorPaint.setColor(dividerColor);
       }

       /*
       int dividerHight 分割线的线宽
       Drawable dividerDrawable 图片分割线
       */
       public GridDivider(Context context, int dividerHight, Drawable dividerDrawable) {
           this(context);
           mDividerHight = dividerHight;
           mDividerDarwable = dividerDrawable;
       }

       @Override
       public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
           super.onDraw(c, parent, state);
           //画水平和垂直分割线
           drawHorizontalDivider(c, parent);
           drawVerticalDivider(c, parent);
       }

       public void drawVerticalDivider(Canvas c, RecyclerView parent) {
           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.getTop() - params.topMargin;
final int bottom = child.getBottom() + params.bottomMargin;

int left = 0;
int right = 0;

               //左边第一列
               if ((i % 3) == 0) {
                   //item左边分割线
                   left = child.getLeft();
                   right = left + mDividerHight;
                   mDividerDarwable.setBounds(left, top, right, bottom);
                   mDividerDarwable.draw(c);
                   if (mColorPaint != null) {
                       c.drawRect(left, top, right, bottom, mColorPaint);
                   }
                   //item右边分割线
                   left = child.getRight() + params.rightMargin - mDividerHight;
                   right = left + mDividerHight;
               } else {
                   //非左边第一列
                   left = child.getRight() + params.rightMargin - mDividerHight;
                   right = left + mDividerHight;
               }
               //画分割线
               mDividerDarwable.setBounds(left, top, right, bottom);
               mDividerDarwable.draw(c);
               if (mColorPaint != null) {
                   c.drawRect(left, top, right, bottom, mColorPaint);
               }

}
}

public void drawHorizontalDivider(Canvas c, RecyclerView parent) {

           final int childCount = parent.getChildCount();
           for (int i = 0; i < childCount; i++) {
               final View child = parent.getChildAt(i);
               RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();

               final int left = child.getLeft() - params.leftMargin - mDividerHight;
               final int right = child.getRight() + params.rightMargin;
               int top = 0;
               int bottom = 0;

               // 最上面一行
               if ((i / 3) == 0) {
                   //当前item最上面的分割线
                   top = child.getTop();
                   //当前item下面的分割线
                   bottom = top + mDividerHight;
                   mDividerDarwable.setBounds(left, top, right, bottom);
                   mDividerDarwable.draw(c);
                   if (mColorPaint != null) {
                       c.drawRect(left, top, right, bottom, mColorPaint);
                   }
                   top = child.getBottom() + params.bottomMargin;
                   bottom = top + mDividerHight;
               } else {
                   top = child.getBottom() + params.bottomMargin;
                   bottom = top + mDividerHight;
               }
               //画分割线
               mDividerDarwable.setBounds(left, top, right, bottom);
               mDividerDarwable.draw(c);
               if (mColorPaint != null) {
                   c.drawRect(left, top, right, bottom, mColorPaint);
               }
           }
       }
   }

第二种方式，水平下划线

第一种：

public class GridDivider extends RecyclerView.ItemDecoration {

       private Drawable mDividerDarwable;
       private int mDividerHight = 1;
       private Paint mColorPaint;

public final int[] ATRRS = new int[]{android.R.attr.listDivider};

       public GridDivider(Context context) {
           final TypedArray ta = context.obtainStyledAttributes(ATRRS);
           this.mDividerDarwable = ta.getDrawable(0);
           ta.recycle();
       }

final int top = child.getTop() - params.topMargin;
final int bottom = child.getBottom() + params.bottomMargin;

int left = 0;
int right = 0;

}
}

public void drawHorizontalDivider(Canvas c, RecyclerView parent) {

第二种：

public class GridDivider extends RecyclerView.ItemDecoration {

       private Drawable mDividerDarwable;
       private int mDividerHight = 1;
       private Paint mColorPaint;

public final int[] ATRRS = new int[]{android.R.attr.listDivider};

       public GridDivider(Context context) {
           final TypedArray ta = context.obtainStyledAttributes(ATRRS);
           this.mDividerDarwable = ta.getDrawable(0);
           ta.recycle();
       }