原图

 

 修改后

 

方法一

//文件路径
File imageFile = new File(path);

 

 public  BufferedImage changeImages(File imageFile) {
	        BufferedImage  avatarImage = null;
	        try {
	        	avatarImage = ImageIO.read(imageFile);
avatarImage = scaleByPercentage(avatarImage, avatarImage.getWidth(),  avatarImage.getWidth());
 int width = avatarImage.getWidth();
	        	 
	            // 透明底的图片  
	            BufferedImage formatAvatarImage = new BufferedImage(avatarImage.getWidth(), avatarImage.getHeight(), BufferedImage.TYPE_4BYTE_ABGR);
	            Graphics2D graphics = formatAvatarImage.createGraphics();
	            //把图片切成一个园
	            graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
	            //留一个像素的空白区域，这个很重要，画圆的时候把这个覆盖
	            int border = 1;
	          //图片是一个圆型
	            Ellipse2D.Double shape = new Ellipse2D.Double(border, border, width - border * 2, width - border * 2);
	          //需要保留的区域
	            graphics.setClip(shape);
	            graphics.drawImage(avatarImage, border, border, width - border * 2, width - border * 2, null);
	            //在圆图外面再画一个圆
	            //新创建一个graphics，这样画的圆不会有锯齿
//	            graphics = formatAvatarImage.createGraphics();
//	            graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
//	            int border1 = 3;
//	            //画笔是4.5个像素，BasicStroke的使用可以查看下面的参考文档
//	            //使画笔时基本会像外延伸一定像素，具体可以自己使用的时候测试
//	            Stroke s = new BasicStroke(5F, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND);
//	            graphics.setStroke(s);
//	            graphics.setColor(Color.WHITE);
//	            graphics.drawOval(border1, border1, width - border1 * 2, width - border1 * 2);
//	            graphics.dispose();
//	          
	            return formatAvatarImage;
	        } catch (Exception e) {
	            e.printStackTrace();
	        }
	        return null;
	    }

/**
     * 缩小Image，此方法返回源图像按给定宽度、高度限制下缩放后的图像
     *
     * @param inputImage
     *            ：压缩后宽度
     *            ：压缩后高度
     * @throws java.io.IOException
     *             return
     */
    public BufferedImage scaleByPercentage(BufferedImage inputImage, int newWidth, int newHeight){
        // 获取原始图像透明度类型
        try {
            int type = inputImage.getColorModel().getTransparency();
            int width = inputImage.getWidth();
            int height = inputImage.getHeight();
            // 开启抗锯齿
            RenderingHints renderingHints = new RenderingHints(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            // 使用高质量压缩
            renderingHints.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
            BufferedImage img = new BufferedImage(newWidth, newHeight, type);
            Graphics2D graphics2d = img.createGraphics();
            graphics2d.setRenderingHints(renderingHints);
            graphics2d.drawImage(inputImage, 0, 0, newWidth, newHeight, 0, 0, width, height, null);
            graphics2d.dispose();
            return img;
 
        }catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

方法二

String url = "https://www.pngall.com/wp-content/uploads/13/Christmas-Golden-Bell-PNG-Photo.png";
		BufferedImage avatarImage = ImageIO.read(new URL(url));
//		 avatarImage = scaleByPercentage(avatarImage, avatarImage.getWidth(),  avatarImage.getWidth());
         int width = 120;
		// 透明底的图片
		BufferedImage formatAvatarImage = new BufferedImage(width, width, BufferedImage.TYPE_4BYTE_ABGR);
		Graphics2D graphics = formatAvatarImage.createGraphics();
		// 把图片切成一个圓
		{
			graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
			// 留一个像素的空白区域，这个很重要，画圆的时候把这个覆盖
			int border = 1;
			// 图片是一个圆型
			Ellipse2D.Double shape = new Ellipse2D.Double(border, border, width - border * 2, width - border * 2);
			// 需要保留的区域
			graphics.setClip(shape);
			graphics.drawImage(avatarImage, border, border, width - border * 2, width - border * 2, null);
			graphics.dispose();
		}
		// 在圆图外面再画一个圆
		{
			// 新创建一个graphics，这样画的圆不会有锯齿
			graphics = formatAvatarImage.createGraphics();
			graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
			int border = 3;
			// 画笔是4.5个像素，BasicStroke的使用可以查看下面的参考文档
			// 使画笔时基本会像外延伸一定像素，具体可以自己使用的时候测试
			Stroke s = new BasicStroke(4.5F, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND);
			graphics.setStroke(s);
			graphics.setColor(Color.WHITE);
			graphics.drawOval(border, border, width - border * 2, width - border * 2);
			graphics.dispose();
		}
		try (OutputStream os = new FileOutputStream("d:/temp-avatar.png")) {
			ImageIO.write(formatAvatarImage, "PNG", os);
		}
		{
			url = "https://img-blog.csdn.net/20180529213113521";
			BufferedImage srcImg = ImageIO.read(new URL(url));
			// scrImg加载完之后没有任何颜色
			BufferedImage blankImage = new BufferedImage(srcImg.getWidth(), srcImg.getHeight(),
					BufferedImage.TYPE_INT_RGB);
			graphics = blankImage.createGraphics();
			graphics.drawImage(srcImg, 0, 0, null);

			int x = (blankImage.getWidth() - width) / 2;
			int y = (blankImage.getHeight() - width) / 2;
			graphics.drawImage(formatAvatarImage, x, y, width, width, null);
			try (OutputStream os = new FileOutputStream("d:/temp-avatar.png")) {
				ImageIO.write(blankImage, "PNG", os);
			}
		}