图片等比例缩放

http://my.oschina.net/vitoh/blog/491478

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;
 
/**
 * 图片等比例缩放工具
 * @Author vitoHuang
 * @Time 2015年8月12日
 * @Mark
 */
public class ImageUtil {
     
    /**
     * 
     * @param originalFile   原图片文件
     * @param resizedFile    缩放后文件
     * @throws IOException
     */
    public static void resize(File originalFile, File resizedFile)throws IOException {
        resize(originalFile,resizedFile,640);
    }
     
    /**
     * 
     * @param originalFile   原图片文件
     * @param resizedFile    缩放后文件
     * @param newWidth       缩放后宽度 单位：px
     * @throws IOException
     */
    public static void resize(File originalFile, File resizedFile,int newWidth)throws IOException {
        resize(originalFile, resizedFile, newWidth,1F);
    }
     
    /**
     * 
     * @param originalFile  原图片文件
     * @param resizedFile    缩放后文件
     * @param newWidth       缩放后宽度 单位：px
     * @param quality        质量 0-1之间
     * @throws IOException
     */
    public static void resize(File originalFile, File resizedFile,int newWidth, float quality) throws IOException {
         
        if (quality > 1)  throw new IllegalArgumentException("质量必须是0和1之间");  
         
        ImageIcon ii = new ImageIcon(originalFile.getCanonicalPath()); 
        Image i = ii.getImage();  
        Image resizedImage = null;  
         
        int iWidth = i.getWidth(null);  
        int iHeight = i.getHeight(null);  
         
        //根据提供的新图片宽度
        if (iWidth > iHeight) {  
            resizedImage = i.getScaledInstance(newWidth, (newWidth * iHeight) / iWidth, Image.SCALE_SMOOTH);  
        }else{  
            resizedImage = i.getScaledInstance((newWidth * iWidth) / iHeight,newWidth, Image.SCALE_SMOOTH);  
        }  
         
        //确保在加载图像中的所有像素
        Image temp = new ImageIcon(resizedImage).getImage();
         
        //创建图片缓存
        BufferedImage bufferedImage = new BufferedImage(temp.getWidth(null),temp.getHeight(null), BufferedImage.TYPE_INT_RGB); 
         
        //复制图像缓冲图像
        Graphics g = bufferedImage.createGraphics(); 
         
        g.setColor(Color.white);  
        g.fillRect(0, 0, temp.getWidth(null), temp.getHeight(null));  
        g.drawImage(temp, 0, 0, null);  
        g.dispose();  
         
        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);  
   
        // 编码图像作为JPEG数据流 
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);  
   
        JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bufferedImage);  
   
        param.setQuality(quality, true);  
   
        encoder.setJPEGEncodeParam(param);  
        encoder.encode(bufferedImage);  
    }
     
}