import java.awt.Dimension;

import java.awt.Image;

import java.awt.image.BufferedImage;

import java.io.FileOutputStream;

import java.io.IOException;

import com.sun.image.codec.jpeg.JPEGCodec;

import com.sun.image.codec.jpeg.JPEGEncodeParam;

import com.sun.image.codec.jpeg.JPEGImageEncoder;

import java.io.File;

import javax.imageio.ImageIO;

/**

 * JPG图片压缩工具

 * @author clj

 *

 */

public class ImageUtil {

    /**

     * 将原图src压缩后存入des中

     * @param src   原图片文件

     * @param des  压缩后的存储文件

     * @param imgSize  图片缩放的最大尺寸

     * @param quality   图片质量0~1

     */

    public  static void compress(File src,File des, int imgSize,float quality) {

        FileOutputStream out = null;

        try {

            //读取源图片到内存中

            Image image = ImageIO.read(src);

            //获得压缩尺寸

            Dimension dim = getRectangle(image.getWidth(null), image.getHeight(null),imgSize);

            //在内存中创建压缩图片的缓冲区

            BufferedImage tmpImg=new BufferedImage(dim.width,dim.height ,BufferedImage.TYPE_3BYTE_BGR);

            //在缓冲区按缩放后的大小绘制压缩图片

            tmpImg.getGraphics().drawImage(image.getScaledInstance(dim.width,dim.height,Image.SCALE_SMOOTH), 0, 0, null);

            //设置图片质量，

            JPEGEncodeParam jep =   JPEGCodec.getDefaultJPEGEncodeParam(tmpImg);

            jep.setQuality(quality, true);

            //保存压缩图片

            //输出图片存在则先删除

            if(des.exists()){

                des.delete();

            }

            //获得输出流

            out = new FileOutputStream(des);

            JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);

            encoder.encode(tmpImg);

        } catch (Exception ex) {

            ex.printStackTrace();

        }finally{

            try {

                out.close();

            } catch (IOException e) {

                e.printStackTrace();

            }

        }

    }

    /**

     * 获得压缩图片尺寸

     * 最长边压缩为size px，短边按比例变化

     * @param width

     * @param height

     * @return

     */

    private static Dimension getRectangle( int width, int height, int size){

        Dimension dim = new Dimension();

        double w = width+0.0;

        double h = height + 0.0;

        double rate = w/h;

        //宽或高大于size时,将较大者缩小为size,较小者则按比例变化

        if(w > h && w > size){

            w = size;

            h = w / rate;

        }else if(h > w && h > size){

            h = size;

            w = h*rate;

        }

        width = (int)w;

        height = (int)h;

        dim.width = width;

        dim.height = height;

        return dim;

    }

    public static void main(String args[]){

        ImageUtil.compress(new File("D:/test/img/src.jpg"), new File("D:/test/img/out.jpg"),600,1f);

    }

}