JAVA生成缩略图

来源: http://wing929.javaeye.com/blog/185508

方法1：[第一种方法比后一种生成的缩略图要清晰]

importjavax.imageio.ImageIO;
 importjava.awt.image.BufferedImage;
 importjava.awt.image.ColorModel;
 importjava.awt.image.WritableRaster;
 importjava.awt.*;
 importjava.awt.geom.AffineTransform;
 importjava.io.InputStream;
 importjava.io.File;
 importjava.io.FileOutputStream;

 publicclassTest{
 publicstaticBufferedImageresize(BufferedImagesource,inttargetW,inttargetH){
 //targetW，targetH分别表示目标长和宽
 inttype=source.getType();
 BufferedImagetarget=null;
 doublesx=(double)targetW/source.getWidth();
 doublesy=(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ifelse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
ColorModelcm=source.getColorModel();
WritableRasterraster=cm.createCompatibleWritableRaster(targetW,targetH);
 booleanalphaPremultiplied=cm.isAlphaPremultiplied();
 target=newBufferedImage(cm,raster,alphaPremultiplied,null);
 }else
 target=newBufferedImage(targetW,targetH,type);
Graphics2Dg=target.createGraphics();
 //smootherthanexlax:
g.setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);
g.drawRenderedImage(source,AffineTransform.getScaleInstance(sx,sy));
g.dispose();
 returntarget;
}
 publicstaticvoidsaveImageAsJpg(StringfromFileStr,StringsaveToFileStr,intwidth,inthight)
 throwsException{
BufferedImagesrcImage;
 //Stringex=fromFileStr.substring(fromFileStr.indexOf("."),fromFileStr.length());
 StringimgType="JPEG";
 if(fromFileStr.toLowerCase().endsWith(".png")){
 imgType="PNG";
}
 //System.out.println(ex);
 FilesaveFile=newFile(saveToFileStr);
 FilefromFile=newFile(fromFileStr);
srcImage=ImageIO.read(fromFile);
 if(width>0||hight>0)
{
srcImage=resize(srcImage,width,hight);
}
ImageIO.write(srcImage,imgType,saveFile);

}

 publicstaticvoidmain(Stringargv[]){
 try{
 //参数1(from),参数2(to),参数3(宽),参数4(高)
 Test.saveImageAsJpg("E:/Document/MyPictures/3.gif","c:/6.gif",50,50);
 }catch(Exceptione)
{
e.printStackTrace();
}

}
}

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.WritableRaster;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.io.InputStream;
import java.io.File;
import java.io.FileOutputStream;

public class Test {
 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 void saveImageAsJpg (String fromFileStr,String saveToFileStr,int width,int hight)
 throws Exception {
 BufferedImage srcImage;
// String ex = fromFileStr.substring(fromFileStr.indexOf("."),fromFileStr.length());
 String imgType = "JPEG";
 if (fromFileStr.toLowerCase().endsWith(".png")) {
 imgType = "PNG";
 }
// System.out.println(ex);
 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);

 }
 
 public static void main (String argv[]) {
 try{
 //参数1(from),参数2(to),参数3(宽),参数4(高)
 Test.saveImageAsJpg("E:/Document/My Pictures/3.gif","c:/6.gif",50,50);
 } catch(Exception e)
 {
 e.printStackTrace();
 }

 }
}

方法2：

importjava.io.*;
 importjava.util.*;
 importcom.sun.image.codec.jpeg.*;
 importjava.awt.image.*;
 importjava.awt.*;
 importjava.net.*;
 importjava.applet.*;
 importjava.sql.*;

 //缩略图类，
 //本java类能将jpg图片文件，进行等比或非等比的大小转换。
 //具体使用方法
 //s_pic(大图片路径,生成小图片路径,大图片文件名,生成小图片文名,生成小图片宽度,生成小图片高度,是否等比缩放(默认为true))
 publicclassTes{
 StringInputDir;//输入图路径
 StringOutputDir;//输出图路径
 StringInputFileName;//输入图文件名
 StringOutputFileName;//输出图文件名
 intOutputWidth=80;//默认输出图片宽
 intOutputHeight=80;//默认输出图片高
 intrate=0;
 booleanproportion=true;//是否等比缩放标记(默认为等比缩放)

 publicTes(){
 //初始化变量
 InputDir="";
 OutputDir="";
 InputFileName="";
 OutputFileName="";
 OutputWidth=80;
 OutputHeight=80;
 rate=0;
}

 publicvoidsetInputDir(StringInputDir){
 this.InputDir=InputDir;
}

 publicvoidsetOutputDir(StringOutputDir){
 this.OutputDir=OutputDir;
}

 publicvoidsetInputFileName(StringInputFileName){
 this.InputFileName=InputFileName;
}

 publicvoidsetOutputFileName(StringOutputFileName){
 this.OutputFileName=OutputFileName;
}

 publicvoidsetOutputWidth(intOutputWidth){
 this.OutputWidth=OutputWidth;
}

 publicvoidsetOutputHeight(intOutputHeight){
 this.OutputHeight=OutputHeight;
}

 publicvoidsetW_H(intwidth,intheight){
 this.OutputWidth=width;
 this.OutputHeight=height;
}

 publicStrings_pic(){
BufferedImageimage;
StringNewFileName;
 //建立输出文件对象
 Filefile=newFile(OutputDir+OutputFileName);
 FileOutputStreamtempout=null;
 try{
 tempout=newFileOutputStream(file);
 }catch(Exceptionex){
System.out.println(ex.toString());
}
 Imageimg=null;
Toolkittk=Toolkit.getDefaultToolkit();
 Appletapp=newApplet();
 MediaTrackermt=newMediaTracker(app);
 try{
img=tk.getImage(InputDir+InputFileName);
 mt.addImage(img,0);
 mt.waitForID(0);
 }catch(Exceptione){
e.printStackTrace();
}

 if(img.getWidth(null)==-1){
 System.out.println("can'tread,retry!"+"<BR>");
 return"no";
 }else{
 intnew_w;
 intnew_h;
 if(this.proportion==true){//判断是否是等比缩放.
 //为等比缩放计算输出的图片宽度及高度
 doublerate1=((double)img.getWidth(null))/
 (double)OutputWidth+0.1;
 doublerate2=((double)img.getHeight(null))/
 (double)OutputHeight+0.1;
 doublerate=rate1>rate2?rate1:rate2;
 new_w=(int)(((double)img.getWidth(null))/rate);
 new_h=(int)(((double)img.getHeight(null))/rate);
 }else{
 new_w=OutputWidth;//输出的图片宽度
 new_h=OutputHeight;//输出的图片高度
}
 BufferedImagebuffImg=newBufferedImage(new_w,new_h,
BufferedImage.TYPE_INT_RGB);

Graphicsg=buffImg.createGraphics();

g.setColor(Color.white);
 g.fillRect(0,0,new_w,new_h);

 g.drawImage(img,0,0,new_w,new_h,null);
g.dispose();

JPEGImageEncoderencoder=JPEGCodec.createJPEGEncoder(tempout);
 try{
encoder.encode(buffImg);
tempout.close();
 }catch(IOExceptionex){
System.out.println(ex.toString());
}
}
 return"ok";
}

 publicStrings_pic(StringInputDir,StringOutputDir,StringInputFileName,
StringOutputFileName){
 //输入图路径
 this.InputDir=InputDir;
 //输出图路径
 this.OutputDir=OutputDir;
 //输入图文件名
 this.InputFileName=InputFileName;
 //输出图文件名
 this.OutputFileName=OutputFileName;
 returns_pic();
}

 publicStrings_pic(StringInputDir,StringOutputDir,StringInputFileName,
 StringOutputFileName,intwidth,intheight,
 booleangp){
 //输入图路径
 this.InputDir=InputDir;
 //输出图路径
 this.OutputDir=OutputDir;
 //输入图文件名
 this.InputFileName=InputFileName;
 //输出图文件名
 this.OutputFileName=OutputFileName;
 //设置图片长宽
setW_H(width,height);
 //是否是等比缩放标记
 this.proportion=gp;
 returns_pic();
}

 publicstaticvoidmain(String[]a){
 //s_pic(大图片路径,生成小图片路径,大图片文件名,生成小图片文名,生成小图片宽度,生成小图片高度)
 Tesmypic=newTes();
System.out.println(
 mypic.s_pic("E:\Document\MyPictures\",
 "E:\Document\MyPictures\",
 "topbg-3.gif","3.gif",400,400,true)
);

}
}