java 图片压缩 javax.imageio

File file = new File(imgUrl); // 读取文件
FileInputStream in = new FileInputStream(file);// 流读取文件

ByteArrayOutputStream baos = new ByteArrayOutputStream(); // 定义输出字节流

BufferedImage bufferedImage= ImageIO.read(inputStream); // 文件缓存读取

ImageWriter imgWriter = ImageIO.getImageWritersByFormatName("jpg").next(); // 

 imgWriter.reset();

 ImageWriteParam imgWriteParams= new JPEGImageWriteParam(null);

 imgWriteParams.setCompressionMode(imgWriteParams.MODE_EXPLICIT);
            // 这里指定压缩的程度，参数qality是取值0~1范围内，
            imgWriteParams.setCompressionQuality(qality);

        // 要使用压缩，必须指定压缩方式为MODE_EXPLICIT
            imgWriteParams.setProgressiveMode(imgWriteParams.MODE_DISABLED);
            ColorModel colorModel = bufferedImage.getColorModel();// ColorModel.getRGBdefault();
imgWriteParams.setDestinationType(new ImageTypeSpecifier(colorModel,                 colorModel.createCompatibleSampleModel(32, 32)));

 // OutputStream构造
 imgWriter.setOutput(ImageIO.createImageOutputStream(baos));

imgWriter.write(null, new IIOImage(bufferedImage, null, null), imgWriteParams);

byte[] returnImage = baos.toByteArray(); 

 FileImageOutputStream fileOutputStream = new FileImageOutputStream(new File("c:\\images\\myimage22.png"));

 fileOutputStream.write(returnImage);