图片缩略 补白边 java实现

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.WritableRaster;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.JFileChooser;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;/*** @author hongliang* */
public class Grip {
	public static void main(String[] args) throws Throwable 
	{		

                createNewPic("F:\\img\\img2", "F:\\img\\back\\kong.png", "F:\\img\\tar\\");第一个参数是要处理图片所在的文件夹，第二个就是上面说的用ps搞的一张空白图，第三个参数是处理玩的图片放的文件夹。
		
	}
	
	
	public static BufferedImage resize(BufferedImage source, int targetW, int targetH) { 
        // targetW，targetH分别表示目标长和宽 
        int type = source.getType(); 
        BufferedImage target = null; 
        double sx = (double) targetW / source.getWidth(); 
        double sy = (double) targetH / source.getHeight(); 
        //这里想实现在targetW，targetH范围内实现等比缩放。如果不需要等比缩放 
        //则将下面的if else语句注释即可 
        if(sx>sy) 
        { 
            sx = sy; 
            targetW = (int)(sx * source.getWidth()); 
        }else{ 
            sy = sx; 
            targetH = (int)(sy * source.getHeight()); 
        } 
        if (type == BufferedImage.TYPE_CUSTOM) { //handmade 
            ColorModel cm = source.getColorModel(); 
            WritableRaster raster = cm.createCompatibleWritableRaster(targetW, targetH); 
            boolean alphaPremultiplied = cm.isAlphaPremultiplied(); 
            target = new BufferedImage(cm, raster, alphaPremultiplied, null); 
        } else 
            target = new BufferedImage(targetW, targetH, type); 
            Graphics2D g = target.createGraphics(); 
            //smoother than exlax: 
            g.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY ); 
            g.drawRenderedImage(source, AffineTransform.getScaleInstance(sx, sy)); 
            g.dispose(); 
            return target; 
        } 
	public static boolean isPic(File file){
		 String imgeArray []= {"bmp","dib","gif","jfif","jpe","jpeg","jpg","png","tif","tiff","ico"};
		 String fileName = file.getName();
		 fileName=fileName.substring(fileName.lastIndexOf(".")+1);
		 for(String suffix:imgeArray){
			 if(fileName.equals(suffix)){
				 return true;
			 }
		 }
		return false;
	}
	
	public static void createNewPic(String dir,String backGroundPicPath,String targetPicPath) throws IOException{
		File ML = new File(dir);
		File[] files = ML.listFiles();
		for(File f:files){
			if(f.isFile()){
				if(isPic(f)){
				File file = new File(backGroundPicPath);
				Image img = ImageIO.read(file);
				int width = img.getWidth(null);
				int height = img.getHeight(null);
				//create target image
				BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);//get a graphics pen
				Graphics g = image.createGraphics();//draw source image
				g.drawImage(img, 0, 0, width, height, null); 
				//draw target logo
				BufferedImage doPic = ImageIO.read(f);
				if(doPic.getWidth()>width||doPic.getHeight()>height){
					BufferedImage didPic=resize(doPic,width,height);
				}
				BufferedImage didPic=doPic;
				int lw = didPic.getWidth(null);
				int lh = didPic.getHeight(null);
				int px_x=(width-lw)/2;
				int px_y=(height-lh)/2;
				g.drawImage(didPic, px_x, px_y, lw, lh, null);
				//这里是添加水印文字//				 String str = "http://www.hongliang.net";
//				 g.setColor(Color.red);
//				 g.setFont(new Font("Courier", Font.PLAIN, 36));
				//水印文字对准//			    g.drawString(str, width-400, height-60);
				g.dispose();
				FileOutputStream os = new FileOutputStream(targetPicPath+f.getName());
				JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(os);
				encoder.encode(image);
				System.out.println("完成："+f.getName());
				}
			}
		}
	}
	
	}

 附件 放上一张kong。png图。 程序要运行只要建立好几个相应的文件夹就可以了。