ImageIO.wtrie生成jpg图片质量损失方案：BufferedImage生成jpg图片文件流

　　　　 Iterator<ImageWriter> iterator = ImageIO.getImageWritersByFormatName("jpeg");
        ImageWriter imageWriter = iterator.next();
        ImageWriteParam imageWriteParam = imageWriter.getDefaultWriteParam();
        imageWriteParam.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
        imageWriteParam.setCompressionQuality(1);  

        imageWriter.setOutput(imageOutput);
        IIOImage iio_image = new IIOImage(image, null, null);
        imageWriter.write(null, iio_image, imageWriteParam);
        imageWriter.dispose();