图片压缩操作工具类

package com.ljq.durian.test;

import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.math.BigDecimal;
import java.math.MathContext;
import java.util.ArrayList;

import javax.imageio.ImageIO;

import org.apache.log4j.Logger;

/**
 * 图片压缩操作工具类
 * 
 * @author jqlin
 *
 */
public class ImageHelper {
    private static Logger log = Logger.getLogger(ImageHelper.class);
    
    public static void main(String[] args) {
        ImageHelper.scaleImage("C:/Users/ASUS/Desktop/0000.jpg", "C:/Users/ASUS/Desktop/1111.jpg", 1.8, "jpg");
        ImageHelper.scaleImageWithParams("C:/Users/ASUS/Desktop/0000.jpg", "C:/Users/ASUS/Desktop/2222.jpg", 200, 150, true, "jpg");
    }

    /***
     * 按指定的比例缩放图片
     * 
     * @param sourceImage 源图片，如：C:/test.jpg
     * @param destImage 目标图片，即压缩后的图片，如：C:/new_test.jpg
     * @param scale 缩放比例，如1.2
     * @param format 图片后缀名
     */
    public static void scaleImage(String sourceImage, String destImage, double scale, String format) {

        File file = new File(sourceImage);
        BufferedImage bufferedImage;
        try {
            bufferedImage = ImageIO.read(file);
            int width = bufferedImage.getWidth();
            int height = bufferedImage.getHeight();

            width = parseDoubleToInt(width * scale);
            height = parseDoubleToInt(height * scale);

            Image image = bufferedImage.getScaledInstance(width, height, Image.SCALE_SMOOTH);
            BufferedImage outputImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            Graphics graphics = outputImage.getGraphics();
            graphics.drawImage(image, 0, 0, null);
            graphics.dispose();

            ImageIO.write(outputImage, format, new File(destImage));
        } catch (IOException e) {
            log.error("按指定的比例缩放图片出错了", e);
        }

    }

    /***
     * 将图片缩放到指定的高度或者宽度
     * 
     * @param sourceImage 图片源地址
     * @param destImage 压缩完图片的地址
     * @param width 缩放后的宽度
     * @param height 缩放后的高度
     * @param auto 是否自动保持图片的原高宽比例
     * @param format 图片格式，如：jpg
     */
    public static void scaleImageWithParams(String sourceImage, String destImage, 
            int width, int height, boolean auto, String format) {

        try {
            File file = new File(sourceImage);
            BufferedImage bufferedImage = null;
            bufferedImage = ImageIO.read(file);
            if (auto) {
                ArrayList<Integer> paramsArrayList = getAutoWidthAndHeight(bufferedImage, width, height);
                width = paramsArrayList.get(0);
                height = paramsArrayList.get(1);
                log.info("自动调整比例，width=" + width + " height=" + height);
            }

            Image image = bufferedImage.getScaledInstance(width, height, Image.SCALE_DEFAULT);
            BufferedImage outputImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            Graphics graphics = outputImage.getGraphics();
            graphics.drawImage(image, 0, 0, null);
            graphics.dispose();
            ImageIO.write(outputImage, format, new File(destImage));
        } catch (Exception e) {
            log.error("将图片缩放到指定的高度或者宽度出错了", e);
        }

    }

    /**
     * 将double类型的数据转换为int，四舍五入原则
     * 
     * @param sourceDouble
     * @return
     */
    private static int parseDoubleToInt(double sourceDouble) {
        int result = 0;
        result = (int) sourceDouble;
        return result;
    }

    /***
     * 
     * @param bufferedImage
     *            要缩放的图片对象
     * @param width_scale
     *            要缩放到的宽度
     * @param height_scale
     *            要缩放到的高度
     * @return 一个集合，第一个元素为宽度，第二个元素为高度
     */
    private static ArrayList<Integer> getAutoWidthAndHeight(BufferedImage bufferedImage, int width_scale,
            int height_scale) {
        ArrayList<Integer> arrayList = new ArrayList<Integer>();
        int width = bufferedImage.getWidth();
        int height = bufferedImage.getHeight();
        double scale_w = getDot2Decimal(width_scale, width);

        System.out.println("getAutoWidthAndHeight width=" + width + "scale_w=" + scale_w);
        double scale_h = getDot2Decimal(height_scale, height);
        if (scale_w < scale_h) {
            arrayList.add(parseDoubleToInt(scale_w * width));
            arrayList.add(parseDoubleToInt(scale_w * height));
        } else {
            arrayList.add(parseDoubleToInt(scale_h * width));
            arrayList.add(parseDoubleToInt(scale_h * height));
        }
        return arrayList;

    }

    /***
     * 返回两个数a/b的小数点后三位的表示
     * 
     * @param a
     * @param b
     * @return
     */
    private static double getDot2Decimal(int a, int b) {

        BigDecimal bigDecimal_1 = new BigDecimal(a);
        BigDecimal bigDecimal_2 = new BigDecimal(b);
        BigDecimal bigDecimal_result = bigDecimal_1.divide(bigDecimal_2, new MathContext(4));
        Double double1 = new Double(bigDecimal_result.toString());
        return double1;
    }
}