前提

业务需要，得获取大图的缩略图

代码

controller

java
    @GetMapping("getThumbnail")
    @ApiOperation("获取缩略图")
    public void  getThumbnail(String url, HttpServletResponse response){
        try (OutputStream outputStream = response.getOutputStream()){
            // 设置响应类型为JPEG图片
            response.setContentType("image/jpeg");
            // 防止中文乱码以及图片在浏览器中显示问题
            response.setHeader("Content-Disposition", "inline; filename=image.jpg");

            // 写入图片数据到输出流
            ImageUtil.getImageStream(url,200,200).writeTo(outputStream);
            // 刷新缓冲区并结束响应
            outputStream.flush();
        }catch (IOException e){
            throw new SystemException(500,"获取缩略图失败");
        }
    }

ImageUtil

java

public static ByteArrayOutputStream getImageStream(String url,int width, int height) {
        ByteArrayOutputStream outputStream=null;
        // 打开URL连接
        try (InputStream in = new URL(url).openStream()) {
            // 从输入流中读取原始图片
            BufferedImage originalImage = ImageIO.read(in);
            // 创建一个新的缩放后的图片
            BufferedImage resizedImage = new BufferedImage(width, height, originalImage.getType());
            Graphics2D graphics2D = resizedImage.createGraphics();
            graphics2D.drawImage(originalImage, 0, 0, width, height, null);
            graphics2D.dispose();
            // 将缩放后的图片转换为字节数组
             outputStream = new ByteArrayOutputStream();
            ImageIO.write(resizedImage, "jpg", outputStream);
        } catch (Exception e) {
            e.printStackTrace();
            log.error("获取图片失败:"+e.getMessage());
            // 处理异常情况
        }
        return outputStream;
    }
``

使用

bash
http://localhost:8888/dictimg/getThumbnail?url=http://www.baidu.com/image1.jpg