上传图片的缩放处理 - 非常实用！（感谢loveyourvv兄弟）
类别: JAVA教程 
import java.io.File;
import java.awt.image.BufferedImage;
import java.awt.Image;
import java.awt.image.AffineTransformOp;
import javax.imageio.ImageIO;
import java.awt.geom.AffineTransform;
public class UploadImg {
String fromdir; // fromdir 图片的原始目录
String todir; // todir 处理后的图片存放目录
String imgfile; // imgfile 原始图片
String sysimgfile; // sysimgfile 处理后的图片文件名前缀
UploadImg( String fromdirNow, String todirNow, String imgfileNow, String sysimgfileNow ){
fromdir = fromdirNow;
todir = todirNow;
imgfile = imgfileNow;
sysimgfile = sysimgfileNow;
}
public boolean CreateThumbnail() throws Exception
{
// fileExtNmae是图片的格式 gif JPG 或png
// String fileExtNmae="";
double Ratio = 0.0;
File F = new File(fromdir,imgfile);
if ( !F.isFile() )
throw new Exception(F+" is not image file error in CreateThumbnail!");
//首先判断上传的图片是gif还是JPG ImageIO只能将gif转换为png
// if (isJpg(imgfile)){
// fileExtNmae="jpg";
// }
//else{
// fileExtNmae="png";
// }
File ThF = new File( todir, sysimgfile + ".jpg" );
BufferedImage Bi = ImageIO.read(F);
//假设图片宽 高 最大为120 120
Image Itemp = Bi.getScaledInstance (120,120,Bi.SCALE_SMOOTH);
if ((Bi.getHeight()>120) || (Bi.getWidth()>120)){
if (Bi.getHeight()>Bi.getWidth())
Ratio = 120.0/Bi.getHeight();
else
Ratio = 120.0/Bi.getWidth();
}
AffineTransformOp op = new AffineTransformOp(AffineTransform.getScaleInstance(Ratio, Ratio), null);
Itemp = op.filter(Bi, null);
try {
ImageIO.write((BufferedImage)Itemp, "jpg", ThF);
}
catch (Exception ex) {
throw new Exception(" ImageIo.write error in CreatThum.: "+ex.getMessage());
}
return (true);
}
public static void main(String[] args)
{
UploadImg UI;
boolean ss = false;
try{
UI = new UploadImg( "d://javalearn", "d://javalearn", "ps_high.jpg", "ps_low" );
ss = UI.CreateThumbnail();
if ( ss ) {
System.out.println( "Success" );
}
else{
System.out.println( "Error" );
}
}
catch(Exception e){
System.out.print(e.toString());
}
}
}
import java.awt.image.BufferedImage;
import java.awt.Image;
import java.awt.image.AffineTransformOp;
import javax.imageio.ImageIO;
import java.awt.geom.AffineTransform;
public class UploadImg {
String fromdir; // fromdir 图片的原始目录
String todir; // todir 处理后的图片存放目录
String imgfile; // imgfile 原始图片
String sysimgfile; // sysimgfile 处理后的图片文件名前缀
UploadImg( String fromdirNow, String todirNow, String imgfileNow, String sysimgfileNow ){
fromdir = fromdirNow;
todir = todirNow;
imgfile = imgfileNow;
sysimgfile = sysimgfileNow;
}
public boolean CreateThumbnail() throws Exception
{
// fileExtNmae是图片的格式 gif JPG 或png
// String fileExtNmae="";
double Ratio = 0.0;
File F = new File(fromdir,imgfile);
if ( !F.isFile() )
throw new Exception(F+" is not image file error in CreateThumbnail!");
//首先判断上传的图片是gif还是JPG ImageIO只能将gif转换为png
// if (isJpg(imgfile)){
// fileExtNmae="jpg";
// }
//else{
// fileExtNmae="png";
// }
File ThF = new File( todir, sysimgfile + ".jpg" );
BufferedImage Bi = ImageIO.read(F);
//假设图片宽 高 最大为120 120
Image Itemp = Bi.getScaledInstance (120,120,Bi.SCALE_SMOOTH);
if ((Bi.getHeight()>120) || (Bi.getWidth()>120)){
if (Bi.getHeight()>Bi.getWidth())
Ratio = 120.0/Bi.getHeight();
else
Ratio = 120.0/Bi.getWidth();
}
AffineTransformOp op = new AffineTransformOp(AffineTransform.getScaleInstance(Ratio, Ratio), null);
Itemp = op.filter(Bi, null);
try {
ImageIO.write((BufferedImage)Itemp, "jpg", ThF);
}
catch (Exception ex) {
throw new Exception(" ImageIo.write error in CreatThum.: "+ex.getMessage());
}
return (true);
}
public static void main(String[] args)
{
UploadImg UI;
boolean ss = false;
try{
UI = new UploadImg( "d://javalearn", "d://javalearn", "ps_high.jpg", "ps_low" );
ss = UI.CreateThumbnail();
if ( ss ) {
System.out.println( "Success" );
}
else{
System.out.println( "Error" );
}
}
catch(Exception e){
System.out.print(e.toString());
}
}
}
