最近做專案需要用到圖片壓縮技術，在這裡整理下做個分享。

需要注意的是如果要壓縮的圖片太大，就需要修改JDK的預設記憶體了。廢話不多說，直接上程式碼。

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.image.ConvolveOp;
import java.awt.image.Kernel;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
 
import javax.swing.ImageIcon;
 
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGEncodeParam;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
 
/**
 * 
 * 圖片壓縮工具類
 * @author 李鋒鏑
 *
 */
public class ImageUtil {
     
    /**
     * 
     * @param originalFile  原檔案
     * @param resizedFile  壓縮目標檔案
     * @param newWidth  壓縮後的圖片寬度
     * @param quality  壓縮質量（0到1之間，越高質量越好）
     * @throws IOException
     */
    public static void resize(File originalFile, File resizedFile,  
            int newWidth, float quality) throws IOException {  
   
        if (quality > 1) {  
            throw new IllegalArgumentException(  
                    "Quality has to be between 0 and 1");  
        }  
   
        ImageIcon ii = new ImageIcon(originalFile.getCanonicalPath());  
        Image i = ii.getImage();  
        Image resizedImage = null;  
   
        int iWidth = i.getWidth(null);  
        System.out.println("iWidth:"+iWidth);
        int iHeight = i.getHeight(null);  
        System.out.println("iHeight:"+iHeight);
        if (iWidth > iHeight) {  
            resizedImage = i.getScaledInstance(newWidth, (newWidth * iHeight)  
                    / iWidth, Image.SCALE_SMOOTH);  
        } else {  
            resizedImage = i.getScaledInstance((newWidth * iWidth) / iHeight,  
                    newWidth, Image.SCALE_SMOOTH);  
        }  
   
        // 獲取圖片中的所有畫素
        Image temp = new ImageIcon(resizedImage).getImage();  
   
        // 建立緩衝
        BufferedImage bufferedImage = new BufferedImage(temp.getWidth(null),  
                temp.getHeight(null), BufferedImage.TYPE_INT_RGB);  
   
        // 複製圖片到緩衝流中
        Graphics g = bufferedImage.createGraphics();  
   
        // 清除背景並開始畫圖
        g.setColor(Color.white);  
        g.fillRect(0, 0, temp.getWidth(null), temp.getHeight(null));  
        g.drawImage(temp, 0, 0, null);  
        g.dispose();
   
        // 柔和圖片.  
        float softenFactor = 0.05f;  
        float[] softenArray = { 0, softenFactor, 0, softenFactor,  
                1 - (softenFactor * 4), softenFactor, 0, softenFactor, 0 };  
        Kernel kernel = new Kernel(3, 3, softenArray);  
        ConvolveOp cOp = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);  
        bufferedImage = cOp.filter(bufferedImage, null);  
   
        FileOutputStream out = new FileOutputStream(resizedFile);  
   
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);  
   
        JPEGEncodeParam param = encoder  
                .getDefaultJPEGEncodeParam(bufferedImage);  
   
        param.setQuality(quality, true);  
   
        encoder.setJPEGEncodeParam(param);  
        encoder.encode(bufferedImage);
        bufferedImage.flush();
        out.close();
    } 
   
    //測試
    public static void main(String[] args) throws IOException {  
         File originalImage = new File("H:\\000.jpg");  
         resize(originalImage, new File("H:\\1207-0.jpg"),500, 0.7f);  
         resize(originalImage, new File("H:\\1207-1.jpg"),500, 1f);  
    }  
}
 

最後，大家要注意一定要關閉檔案輸出流。