图片压缩

1，调用java API按等比例缩放图片

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
import org.apache.commons.lang.StringUtils;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Date;

public class ImgCompress {
    private BufferedImage img;
    private int width;
    private int height;
    private String path;
    private String name;

    @SuppressWarnings("deprecation")
    public static void main(String[] args) throws Exception {
        System.out.println("开始：" + new Date().toLocaleString());
        ImgCompress imgCom = new ImgCompress("C:\Users\fly\Desktop\Picture\QQ.png");
        imgCom.resizeFix(1000, 1000);
        System.out.println("结束：" + new Date().toLocaleString());
    }

    /**
     * 图片压缩
     * @param file
     * @throws IOException
     */
    public static void drawImage(File file, int proportion) throws IOException {
        ImgCompress imgCom = new ImgCompress(file);
        imgCom.resizeFix(proportion, proportion);
    }

    /**
     * 图片压缩
     * @param path
     * @throws IOException
     */
    public static void drawImage(String path, String name) throws IOException {
        ImgCompress imgCom = new ImgCompress(path, name);
        imgCom.resizeFix(1000, 1000);
    }

    /**
     * 构造函数
     */
    public ImgCompress(String path, String name) throws IOException {
        File file = new File(path, name);// 读入文件
        this.path = path;
        this.name = name;
        img = ImageIO.read(file);      // 构造Image对象
        width = img.getWidth(null);    // 得到源图宽
        height = img.getHeight(null);  // 得到源图长
    }

    /**
     * 构造函数
     */
    public ImgCompress(String fileName) throws IOException {
        File file = new File(fileName);// 读入文件
        img = ImageIO.read(file);      // 构造Image对象
        width = img.getWidth(null);    // 得到源图宽
        height = img.getHeight(null);  // 得到源图长
    }

    /**
     * 构造函数
     */
    public ImgCompress(File file) throws IOException {
        this.path = file.getPath();
        img = ImageIO.read(file);      // 构造Image对象
        width = img.getWidth(null);    // 得到源图宽
        height = img.getHeight(null);  // 得到源图长
    }
    /**
     * 按照宽度还是高度进行压缩
     * @param w int 最大宽度
     * @param h int 最大高度
     */
    public void resizeFix(int w, int h) throws IOException {
        if (new Double(width) / height > new Double(w) / h) {
            resizeByWidth(w);
        } else {
            resizeByHeight(h);
        }
    }
    /**
     * 以宽度为基准，等比例放缩图片
     * @param w int 新宽度
     */
    public void resizeByWidth(int w) throws IOException {
        int h = (int) (height * w / width);
        resize(w, h);
    }
    /**
     * 以高度为基准，等比例缩放图片
     * @param h int 新高度
     */
    public void resizeByHeight(int h) throws IOException {
        int w = (int) (width * h / height);
        resize(w, h);
    }
    /**
     * 强制压缩/放大图片到固定的大小
     * @param w int 新宽度
     * @param h int 新高度
     */
    public void resize(int w, int h) throws IOException {
        // SCALE_SMOOTH 的缩略算法 生成缩略图片的平滑度的 优先级比速度高 生成的图片质量比较好 但速度慢
        BufferedImage image = new BufferedImage(w, h,BufferedImage.TYPE_INT_RGB );
        image.getGraphics().drawImage(img, 0, 0, w, h, null); // 绘制缩小后的图
        File destFile = null;
        if(StringUtils.isBlank(name)){
            destFile= new File(path);
        }else{
            destFile = new File(path, name);
        }
        FileOutputStream out = new FileOutputStream(destFile); // 输出到文件流
        // 可以正常实现bmp、png、gif转jpg
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
        encoder.encode(image); // JPEG编码
        out.close();
    }
}

2，调用google提供Thumbnails.jar图片处理API

import net.coobird.thumbnailator.Thumbnails;

public class ThumPic {

    public static void main(String[] args) throws IOException{
        System.out.println("开始：" + new Date().getTime());
        File fromPic = new File("C:\Users\fly\Desktop\img\2.jpg");
        File toPic = new File("C:\Users\fly\Desktop\img_1\2_1.jpg");
        File waterPic = new File("C:\Users\fly\Desktop\img\logo.png");

        //按指定大小把图片进行缩和放（会遵循原图高宽比例）
        //此处把图片压成400×500的缩略图
        Thumbnails.of(fromPic).size(1500,1500).toFile(toPic);//变为400*300,遵循原图比例缩或放到400*某个高度

        //按比例缩小，压缩到原图的0.2尺寸
        //Thumbnails.of(fromPic).scale(0.2f).toFile(toPic);
        //按比例放大，宽高*2
        //Thumbnails.of(fromPic).scale(2f).toFile(toPic);

        //图片尺寸不变，压缩图片文件大小outputQuality实现,参数1为最高质量
        //Thumbnails.of(fromPic).scale(1f).outputQuality(0.25f).toFile(toPic);

        //watermark(位置，水印图，透明度)
        //Thumbnails.of(fromPic).size(1280, 1024).watermark(Positions.BOTTOM_RIGHT, ImageIO.read(waterPic), 0.5f).outputQuality(0.8f).toFile(toPic);

        //图片中心400*400的区域
        //Thumbnails.of(fromPic).sourceRegion(Positions.CENTER, 400,400).size(200, 200).keepAspectRatio(false).toFile(toPic);

        System.out.println("结束：" + new Date().getTime());
    }