java实现图片压缩

package Test;

import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;

import javax.imageio.ImageIO;

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

public class ReduceImgTest {
    /**
     * 指定图片宽度和高度和压缩比例对图片进行压缩
     *
     * @param imgsrc
     *            源图片地址
     * @param imgdist
     *            目标图片地址
     * @param widthdist
     *            压缩后图片的宽度
     * @param heightdist
     *            压缩后图片的高度
     * @param rate
     *            压缩的比例
     */
    public static void reduceImg(String imgsrc, String imgdist, int widthdist, int heightdist, Float rate) {
        try {
            File srcfile = new File(imgsrc);
            // 检查图片是否存在
            if (!srcfile.exists()) {
                System.out.println("文件不存在");
            }
            // 如果比例不为空则说明是按比例压缩
            if (rate != null && rate > 0) {
                int[] results = getImgWidthHeight(srcfile);
                if (results == null || results[0] == 0 || results[1] == 0) {
                    return;
                } else {
                    widthdist = (int) (results[0] * rate);
                    heightdist = (int) (results[1] * rate);
                }
            }
            // 开始读取文件并进行压缩
            Image src = ImageIO.read(srcfile);
            BufferedImage tag = new BufferedImage((int) widthdist, (int) heightdist, BufferedImage.TYPE_INT_RGB);

            tag.getGraphics().drawImage(src.getScaledInstance(widthdist, heightdist, Image.SCALE_SMOOTH), 0, 0, null);

            FileOutputStream out = new FileOutputStream(imgdist);
            JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
            encoder.encode(tag);
            out.close();
        } catch (Exception ef) {
            ef.printStackTrace();
        }
    }

    /**
     * 获取图片宽度和高度
     *
     * @param 图片路径
     * @return 返回图片的宽度
     */
    public static int[] getImgWidthHeight(File file) {
        InputStream is = null;
        BufferedImage src = null;
        int result[] = { 0, 0 };
        try {
            // 获得文件输入流
            is = new FileInputStream(file);
            // 将图片写入缓冲图片区
            src = ImageIO.read(is);
            result[0] =src.getWidth(null); // 得到源图片宽
            result[1] =src.getHeight(null);// 得到源图片高
            is.close();
        } catch (Exception ef) {
            ef.printStackTrace();
        }

        return result;
    }

    public static void main(String[] args) {
        System.out.println("压缩图片开始");
        File srcfile = new File("d://bb//3.jpg");
        File distfile = new File("d://bb//31.jpg");
        System.out.println("压缩前图片大小：" + srcfile.length());
        reduceImg("d://bb//3.jpg", "d://bb//31.jpg", 500, 500, null);
        System.out.println("压缩后图片大小：" + distfile.length());

    }
}