现在基本上很多APP会用到圆形头像，而关于这方面也有很多的示例。
今天我也把我的分享一下给大家，也是新手一枚，不好的地方请多多指教。

package com.example.administrator.myapplication;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.NinePatchDrawable;
import android.util.AttributeSet;
import android.widget.ImageView;

/**
* Created by Administrator on 2016/9/7.
*/
public class YuanImageView extends ImageView{
   private int mBorderThickness = 0;
   private Context mContext;
   private int defaultColor = 0xFFFFFFFF;
   // 如果只有其中一个有值，则只画一个圆形边框
   private int mBorderOutsideColor = 0;
   private int mBorderInsideColor = 0;
   // 控件默认长、宽
   private int defaultWidth = 0;
   private int defaultHeight = 0;

   public YUANImageView(Context context) {
       super(context);
       mContext = context;
   }

   public YUANImageView(Context context, AttributeSet attrs) {
       super(context, attrs);
       mContext = context;
       setCustomAttributes(attrs);
   }

   public YUANImageView(Context context, AttributeSet attrs, int defStyle) {
       super(context, attrs, defStyle);
       mContext = context;
       setCustomAttributes(attrs);
   }

   private void setCustomAttributes(AttributeSet attrs) {
       TypedArray a = mContext.obtainStyledAttributes(attrs,
               R.styleable.shapeimageview);
       mBorderThickness = a.getDimensionPixelSize(
               R.styleable.shapeimageview_border_size, 0);
       mBorderOutsideColor = a
               .getColor(R.styleable.shapeimageview_in_border_color,
                       defaultColor);
       mBorderInsideColor = a.getColor(
               R.styleable.shapeimageview_out_border_color, defaultColor);
   }

   @Override
   protected void onDraw(Canvas canvas) {
       Drawable drawable = getDrawable();
       if (drawable == null) {
           return;
       }

       if (getWidth() == 0 || getHeight() == 0) {
           return;
       }
       this.measure(0, 0);
       if (drawable.getClass() == NinePatchDrawable.class)
           return;
       Bitmap b = ((BitmapDrawable) drawable).getBitmap();
       Bitmap bitmap = b.copy(Bitmap.Config.ARGB_8888, true);
       if (defaultWidth == 0) {
           defaultWidth = getWidth();

       }
       if (defaultHeight == 0) {
           defaultHeight = getHeight();
       }
       // 保证重新读取图片后不会因为图片大小而改变控件宽、高的大小（针对宽、高为wrap_content布局的imageview，但会导致margin无效）
       // if (defaultWidth != 0 && defaultHeight != 0) {
       // LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
       // defaultWidth, defaultHeight);
       // setLayoutParams(params);
       // }
       int radius = 0;
       if (mBorderInsideColor != defaultColor
               && mBorderOutsideColor != defaultColor) {// 定义画两个边框，分别为外圆边框和内圆边框
           radius = (defaultWidth < defaultHeight ? defaultWidth
                   : defaultHeight) / 2 - 2 * mBorderThickness;
           // 画内圆
           drawCircleBorder(canvas, radius + mBorderThickness / 2,
                   mBorderInsideColor);
           // 画外圆
           drawCircleBorder(canvas, radius + mBorderThickness
                   + mBorderThickness / 2, mBorderOutsideColor);
       } else if (mBorderInsideColor != defaultColor
               && mBorderOutsideColor == defaultColor) {// 定义画一个边框
           radius = (defaultWidth < defaultHeight ? defaultWidth
                   : defaultHeight) / 2 - mBorderThickness;
           drawCircleBorder(canvas, radius + mBorderThickness / 2,
                   mBorderInsideColor);
       } else if (mBorderInsideColor == defaultColor
               && mBorderOutsideColor != defaultColor) {// 定义画一个边框
           radius = (defaultWidth < defaultHeight ? defaultWidth
                   : defaultHeight) / 2 - mBorderThickness;
           drawCircleBorder(canvas, radius + mBorderThickness / 2,
                   mBorderOutsideColor);
       } else {// 没有边框
           radius = (defaultWidth < defaultHeight ? defaultWidth
                   : defaultHeight) / 2;
       }
       Bitmap roundBitmap = getCroppedRoundBitmap(bitmap, radius);
       canvas.drawBitmap(roundBitmap, defaultWidth / 2 - radius, defaultHeight
               / 2 - radius, null);
   }

   /**
    * 获取裁剪后的圆形图片
    *
    * @param radius
    *            半径
    */
   public Bitmap getCroppedRoundBitmap(Bitmap bmp, int radius) {
       Bitmap scaledSrcBmp;
       int diameter = radius * 2;

       // 为了防止宽高不相等，造成圆形图片变形，因此截取长方形中处于中间位置最大的正方形图片
       int bmpWidth = bmp.getWidth();
       int bmpHeight = bmp.getHeight();
       int squareWidth = 0, squareHeight = 0;
       int x = 0, y = 0;
       Bitmap squareBitmap;
       if (bmpHeight > bmpWidth) {// 高大于宽
           squareWidth = squareHeight = bmpWidth;
           x = 0;
           y = (bmpHeight - bmpWidth) / 2;
           // 截取正方形图片
           squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth,
                   squareHeight);
       } else if (bmpHeight < bmpWidth) {// 宽大于高
           squareWidth = squareHeight = bmpHeight;
           x = (bmpWidth - bmpHeight) / 2;
           y = 0;
           squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth,
                   squareHeight);
       } else {
           squareBitmap = bmp;
       }

       if (squareBitmap.getWidth() != diameter
               || squareBitmap.getHeight() != diameter) {
           scaledSrcBmp = Bitmap.createScaledBitmap(squareBitmap, diameter,
                   diameter, true);

       } else {
           scaledSrcBmp = squareBitmap;
       }
       Bitmap output = Bitmap.createBitmap(scaledSrcBmp.getWidth(),
               scaledSrcBmp.getHeight(), Bitmap.Config.ARGB_8888);
       Canvas canvas = new Canvas(output);

       Paint paint = new Paint();
       Rect rect = new Rect(0, 0, scaledSrcBmp.getWidth(),
               scaledSrcBmp.getHeight());

       paint.setAntiAlias(true);
       paint.setFilterBitmap(true);
       paint.setDither(true);
       canvas.drawARGB(0, 0, 0, 0);
       canvas.drawCircle(scaledSrcBmp.getWidth() / 2,
               scaledSrcBmp.getHeight() / 2, scaledSrcBmp.getWidth() / 2,
               paint);
       paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
       canvas.drawBitmap(scaledSrcBmp, rect, rect, paint);
       // bitmap回收(recycle导致在布局文件XML看不到效果)
       // bmp.recycle();
       // squareBitmap.recycle();
       // scaledSrcBmp.recycle();
       bmp = null;
       squareBitmap = null;
       scaledSrcBmp = null;
       return output;
   }

   /**
    * 边缘画圆
    */
   private void drawCircleBorder(Canvas canvas, int radius, int color) {
       Paint paint = new Paint();
       /* 去锯齿 */
       paint.setAntiAlias(true);
       paint.setFilterBitmap(true);
       paint.setDither(true);
       paint.setColor(color);
       /* 设置paint的　style　为STROKE：空心 */
       paint.setStyle(Paint.Style.STROKE);
       /* 设置paint的外框宽度 */
       paint.setStrokeWidth(mBorderThickness);
       canvas.drawCircle(defaultWidth / 2, defaultHeight / 2, radius, paint);
   }

}

使用的时候直接在xml布局文件中引用就行

如：

<com.example.administrator.myapplication.WoDe.YUANImageView
            android:id="@+id/wode_photo"
            android:layout_width="40dp"
            android:layout_height="40dp"
            android:layout_centerVertical="true"
            android:src="@drawable/news_img"/>

另一种方法：
首先创建一个继承ImageView的抽象类MaskedImage。让他重写onDraw方法。代码如下

public abstract class MaskedImage extends ImageView {  
    private static final Xfermode MASK_XFERMODE;  
    private Bitmap mask;  
    private Paint paint;  
  
    static {  
        PorterDuff.Mode localMode = PorterDuff.Mode.DST_IN;  
        MASK_XFERMODE = new PorterDuffXfermode(localMode);  
    }  
  
    public MaskedImage(Context paramContext) {  
        super(paramContext);  
    }  
  
    public MaskedImage(Context paramContext, AttributeSet paramAttributeSet) {  
        super(paramContext, paramAttributeSet);  
    }  
  
    public MaskedImage(Context paramContext, AttributeSet paramAttributeSet, int paramInt) {  
        super(paramContext, paramAttributeSet, paramInt);  
    }  
  
    public abstract Bitmap createMask();  
  
    protected void onDraw(Canvas paramCanvas) {  
        Drawable localDrawable = getDrawable();  
        if (localDrawable == null)  
            return;  
        try {  
            if (this.paint == null) {  
                Paint localPaint1 = new Paint();  
                this.paint = localPaint1;  
                this.paint.setFilterBitmap(false);  
                Paint localPaint2 = this.paint;  
                Xfermode localXfermode1 = MASK_XFERMODE;  
                @SuppressWarnings("unused")  
                Xfermode localXfermode2 = localPaint2.setXfermode(localXfermode1);  
            }  
            float f1 = getWidth();  
            float f2 = getHeight();  
            int i = paramCanvas.saveLayer(0.0F, 0.0F, f1, f2, null, 31);  
            int j = getWidth();  
            int k = getHeight();  
            localDrawable.setBounds(0, 0, j, k);  
            localDrawable.draw(paramCanvas);  
            if ((this.mask == null) || (this.mask.isRecycled())) {  
                Bitmap localBitmap1 = createMask();  
                this.mask = localBitmap1;  
            }  
            Bitmap localBitmap2 = this.mask;  
            Paint localPaint3 = this.paint;  
            paramCanvas.drawBitmap(localBitmap2, 0.0F, 0.0F, localPaint3);  
            paramCanvas.restoreToCount(i);  
            return;  
        } catch (Exception localException) {  
            StringBuilder localStringBuilder = new StringBuilder()  
                    .append("Attempting to draw with recycled bitmap. View ID = ");  
            System.out.println("localStringBuilder=="+localStringBuilder);  
        }  
    }  
}  

然后新建一个类CircularImage继承MaskedImage。代码如下：

public class CircularImage extends MaskedImage {  
    public CircularImage(Context paramContext) {  
        super(paramContext);  
    }  
  
    public CircularImage(Context paramContext, AttributeSet paramAttributeSet) {  
        super(paramContext, paramAttributeSet);  
    }  
  
    public CircularImage(Context paramContext, AttributeSet paramAttributeSet, int paramInt) {  
        super(paramContext, paramAttributeSet, paramInt);  
    }  
  
    public Bitmap createMask() {  
        int i = getWidth();  
        int j = getHeight();  
        Bitmap.Config localConfig = Bitmap.Config.ARGB_8888;  
        Bitmap localBitmap = Bitmap.createBitmap(i, j, localConfig);  
        Canvas localCanvas = new Canvas(localBitmap);  
        Paint localPaint = new Paint(1);  
        localPaint.setColor(-16777216);  
        float f1 = getWidth();  
        float f2 = getHeight();  
        RectF localRectF = new RectF(0.0F, 0.0F, f1, f2);  
        localCanvas.drawOval(localRectF, localPaint);  
        return localBitmap;  
    }  
}

XML布局文件为:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    xmlns:tools="http://schemas.android.com/tools"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:gravity="center" >  
    <com.doublefi123.diary.widget.CircularImage  
        android:id="@+id/cover_user_photo"  
        android:layout_width="74.0dip"  
        android:layout_height="74.0dip"  
        android:layout_centerInParent="true" />  
</RelativeLayout>  

现在 Glide加载图片的时候可以直接支持圆形图片 , 方法 :

Glide.with(你的图片).transform(new GlideCircleTransform(this)).error(R.mipmap.r_moren).into(放图片的组件);