在网上找了两个图片的缩放类，在这里分享一下：
1 package manager.util; 2 import java.util.Calendar; 3 import java.io.File; 4 import java.awt.image.BufferedImage; 5 import java.awt.Image; 6 import java.awt.image.AffineTransformOp; 7 import javax.imageio.ImageIO; 8 import java.awt.geom.AffineTransform; 9 public class UploadImg {10 String fromFileStr;11 String saveToFileStr;12 String sysimgfile;13 int width;14 int height;15 String suffix;16 /**17 * @param fromFileStr18 * 原始图片完整路径19 * @param saveToFileStr20 * 缩略图片保存路径21 * @param sysimgfilenNow22 * 处理后的图片文件名前缀23 * 24 */25 public UploadImg(String fromFileStr, String saveToFileStr, String sysimgfile,String suffix,int width,int height) {26 this.fromFileStr = fromFileStr;27 this.saveToFileStr = saveToFileStr;28 this.sysimgfile = sysimgfile;29 this.width=width;30 this.height=height;31 this.suffix=suffix;32 }33 public boolean createThumbnail() throws Exception {34 // fileExtNmae是图片的格式 gif JPG 或png35 // String fileExtNmae="";36 double Ratio = 0.0;37 File F = new File(fromFileStr);38 if (!F.isFile())39 throw new Exception(F40 + " is not image file error in CreateThumbnail!");41 File ThF = new File(saveToFileStr, sysimgfile +"."+suffix);42 BufferedImage Bi = ImageIO.read(F);43 Image Itemp = Bi.getScaledInstance(width, height, Bi.SCALE_SMOOTH);44 if ((Bi.getHeight() > width) || (Bi.getWidth() > height)) {45 if (Bi.getHeight() > Bi.getWidth())46 Ratio = (double)width / Bi.getHeight();47 else48 Ratio = (double)height / Bi.getWidth();49 }50 AffineTransformOp op = new AffineTransformOp(AffineTransform51 .getScaleInstance(Ratio, Ratio), null);52 Itemp = op.filter(Bi, null);53 try {54 ImageIO.write((BufferedImage) Itemp, suffix, ThF);55 } catch (Exception ex) {56 throw new Exception(" ImageIo.write error in CreatThum.: "57 + ex.getMessage());58 }59 return (true);60 }61 public static void main(String[] args) {62 UploadImg UI;63 boolean ss = false;64 try {65 UI = new UploadImg("d://FairyTaleVector040.png", "d://temp", "ps_low1","png",650,650);66 ss = UI.createThumbnail();67 if (ss) {68 System.out.println("Success");69 } else {70 System.out.println("Error");71 }72 } catch (Exception e) {73 System.out.print(e.toString());74 }75 }76 }
这个类，可以对jpg、png、gif三种图片缩放，缩放按等比例缩放
1 package manager.util; 2 import java.awt.Graphics2D; 3 import java.awt.RenderingHints; 4 import java.awt.geom.AffineTransform; 5 import java.awt.image.BufferedImage; 6 import java.awt.image.ColorModel; 7 import java.awt.image.WritableRaster; 8 import java.io.File; 9 import javax.imageio.ImageIO;10 public class Thumbnail {11 /**12 * 生成缩略图 13 * fromFileStr:原图片路径14 * saveToFileStr:缩略图路径 15 * width:缩略图的宽 16 * height:缩略图的高17 */18 public static void saveImageAsJpg(String fromFileStr, String saveToFileStr,19 int width, int height,boolean equalProportion) throws Exception {20 BufferedImage srcImage;21 String imgType="JPEG";22 if(fromFileStr.toLowerCase().endsWith(".png")){23 imgType="PNG";24 }25 File fromFile=new File(fromFileStr);26 File saveFile=new File(saveToFileStr);27 srcImage=ImageIO.read(fromFile);28 if(width>0||height>0){29 srcImage=resize(srcImage,width,height,equalProportion);30 }31 ImageIO.write(srcImage,imgType,saveFile);32 }33 34 /**35 * 将原图片的BufferedImage对象生成缩略图36 * source：原图片的BufferedImage对象37 * targetW:缩略图的宽38 * targetH:缩略图的高39 */40 public static BufferedImage resize(BufferedImage source,int targetW,int targetH,boolean equalProportion){41 int type=source.getType();42 BufferedImage target=null;43 double sx=(double)targetW/source.getWidth();44 double sy=(double)targetH/source.getHeight();45 //这里想实现在targetW，targetH范围内实现等比例的缩放46 //如果不需要等比例的缩放则下面的if else语句注释调即可47 if(equalProportion){48 if(sx>sy){49 sx=sy;50 targetW=(int)(sx*source.getWidth());51 }else{52 sy=sx;53 targetH=(int)(sx*source.getHeight());54 }55 }56 if(type==BufferedImage.TYPE_CUSTOM){57 ColorModel cm=source.getColorModel();58 WritableRaster raster=cm.createCompatibleWritableRaster(targetW,targetH);59 boolean alphaPremultiplied=cm.isAlphaPremultiplied();60 target=new BufferedImage(cm,raster,alphaPremultiplied,null);61 }else{62 target=new BufferedImage(targetW,targetH,type);63 Graphics2D g=target.createGraphics();64 g.setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);65 g.drawRenderedImage(source,AffineTransform.getScaleInstance(sx,sy));66 g.dispose();67 }68 return target;69 }70 71 public static void main(String[] args){72 try{73 Thumbnail.saveImageAsJpg("D://FairyTaleVector040.png", "D://temp//test.png", 480, 480,true);74 }catch(Exception e){75 e.printStackTrace();76 }77 }78 } 这个类只能对jpg图片缩放，但是提供了两种缩放方式：等比例和不等比例