java 改变图片的DPI

代码如下：

 

public class test01
{

    private static int DPI = 300;

    public static void main(String[] args)
    {
        String path = "E:\\002.jpg";
        File file = new File(path);
        handleDpi(file, DPI, DPI);
    }


    /**
     * 改变图片DPI
     * @param file
     * @param xDensity 水平分辨率
     * @param yDensity 垂直分辨率
     */
    public static void handleDpi(File file, int xDensity, int yDensity)
    {
        FileOutputStream fileOutputStream = null;
        try
        {
            BufferedImage image = ImageIO.read(file);
            fileOutputStream = new FileOutputStream(file);
            JPEGImageEncoder jpegEncoder = JPEGCodec.createJPEGEncoder(fileOutputStream);
            JPEGEncodeParam jpegEncodeParam = jpegEncoder.getDefaultJPEGEncodeParam(image);
            jpegEncodeParam.setDensityUnit(JPEGEncodeParam.DENSITY_UNIT_DOTS_INCH);
            jpegEncoder.setJPEGEncodeParam(jpegEncodeParam);
            jpegEncodeParam.setQuality(0.75f, false);
            jpegEncodeParam.setXDensity(xDensity);
            jpegEncodeParam.setYDensity(yDensity);
            jpegEncoder.encode(image, jpegEncodeParam);
            image.flush();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            //关流
            try
            {
                if(fileOutputStream!=null)
                {
                    fileOutputStream.close();
                }
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
        }
    }
}