图片流压缩java实现

 @PostMapping("/download-image")
    public ResponseEntity<String> downloadImage(@RequestParam("imageUrl") String imageUrl) {
        try {
            URL url = new URL(imageUrl);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            connection.connect();

            // 检查响应码是否为200
            if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
                return ResponseEntity.badRequest().body("Failed to download image");
            }

            // 从输入流中读取数据
            InputStream inputStream = connection.getInputStream();
            ByteArrayOutputStream bao = new ByteArrayOutputStream();
            ImageStreamCompressorUtil.compressImage(inputStream, bao, 0.5f); // 压缩质量为50%

            // 将压缩后的图片转换为字节数组
            byte[] compressedImageBytes = bao.toByteArray();

            // 设置响应头
            HttpHeaders headers = new HttpHeaders();
            headers.add(HttpHeaders.CONTENT_TYPE, MediaType.IMAGE_JPEG_VALUE);

            // 返回压缩后的图片
//            return ResponseEntity.ok().headers(headers).body(compressedImageBytes);
            String encodedImage = Base64.getEncoder().encodeToString(compressedImageBytes);
            System.out.println("----------------"+encodedImage);
//            return encodedImage;
            // 返回成功响应
            return ResponseEntity.ok(encodedImage);
        } catch (IOException e) {
            e.printStackTrace();
            return ResponseEntity.internalServerError().body("Error downloading image");
        }
    }
public class ImageStreamCompressorUtil {
        public static void compressImage(InputStream inputStream, OutputStream outputStream, float quality) throws IOException {
            // 从输入流中读取图片
            BufferedImage inputImage = ImageIO.read(inputStream);

            // 确保图片是RGB格式
            BufferedImage rgbImage = new BufferedImage(inputImage.getWidth(), inputImage.getHeight(), BufferedImage.TYPE_INT_RGB);
            Graphics2D g = rgbImage.createGraphics();
            g.drawImage(inputImage, 0, 0, null);
            g.dispose();

            // 获取支持的图片写入器（例如JPEG）
            Iterator<ImageWriter> writers = ImageIO.getImageWritersByFormatName("jpeg");
            if (!writers.hasNext()) {
                throw new IllegalStateException("No writers found");
            }
            ImageWriter writer = writers.next();

            // 创建图片输出流
            ImageOutputStream ios = ImageIO.createImageOutputStream(outputStream);
            writer.setOutput(ios);

            // 获取默认的图片写入参数并设置压缩质量
            ImageWriteParam param = writer.getDefaultWriteParam();
            param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
            param.setCompressionQuality(quality);

            // 写入图片
            writer.write(null, new IIOImage(rgbImage, null, null), param);

            // 清理资源
            ios.flush();
            writer.dispose();
            ios.close();
        }
        }