为图片文件生成缩略图

package ImageTest;import java.awt.Graphics2D;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.IOException;import javax.imageio.ImageIO;public class Test {/** * 为图片文件生成缩略图 * @param args */public static void main(String[] args) {try {//参数1（源图片路径），参数2 （缩略图路径），参数3（缩略图宽）参数4（缩略图高）Test.saveImageAsJpg("E:\\QQ20120612154244.gif", "E:\\test.jpg", 400, 400);} catch (IOException e) {e.printStackTrace();}}/** * 生成缩略图 * @param fromFileStr 源图片路径 * @param saveToFileStr 缩略图路径 * @param width 缩略图的宽 * @param hight 缩略图的高 * @throws IOException */public static void saveImageAsJpg(String fromFileStr,String saveToFileStr,int width,int hight) throws IOException{BufferedImage srcImage;String imgType="JPEG";if(fromFileStr.toLowerCase().endsWith(".png")){imgType="PNG";}File saveFile=new File(saveToFileStr);File fromFile=new File(fromFileStr);srcImage=ImageIO.read(fromFile);if(width>0||hight>0){srcImage=resize(srcImage,width,hight);}ImageIO.write(srcImage, imgType, saveFile);}/** * 将源图片的BufferedImage对象生成缩略图 * @param source 源图片的BufferedImage对象 * @param targetW 缩略图的宽 * @param targetH 缩略图的高 * @return */private static BufferedImage resize(BufferedImage source, int targetW,int targetH) {int type=source.getType();BufferedImage target=null;double sx=(double)targetW/source.getWidth();double sy=(double)targetH/source.getHeight();if(sx>sy){sx=sy;targetW=(int)(sx*source.getWidth());}else{sy=sx;targetH=(int)(sy*source.getHeight());}if(type==BufferedImage.TYPE_CUSTOM){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();g.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);g.drawRenderedImage(source, AffineTransform.getScaleInstance(sx, sy));g.dispose();return target;}}