怎么修改上传图片的大小

如何修改上传图片的大小
RT，主要是修改图片的长和宽。谢谢

[解决办法]
按原来的象素比修改长度和和宽度
[解决办法]
缩略图算法，网上有
[解决办法]
图片的长和宽和像素有关，要去下载专门的多媒体转换软件
[解决办法]
自己查一下资料，实现代码比较简单的
[解决办法]
给你一些代码啊
看看就明白了
package qx;
import java.io.*;
import java.awt.*;
import java.awt.image.*;
import com.sun.image.codec.jpeg.*;
import javax.imageio.ImageIO;

public class JpgTest {
public static void jpg_logo(String jpgName, String logoText) throws Exception {
File _file = new File(jpgName+ ".jpg "); //读入文件
Image src = ImageIO.read(_file); //构造Image对象
int w0 = src.getWidth(null); //得到源图宽
int h0 = src.getHeight(null); //得到源图长
int w2 = 800; //=w0/2
int h2 = 600; //=h0/2
int fontSize = 32;
//缩小一半为（800,600）
BufferedImage tag = null;
tag = new BufferedImage(w2, h2, BufferedImage.TYPE_INT_RGB);
tag.getGraphics().drawImage(src, 0, 0,w2, h2, null); //绘制缩小后的图
//标注水印
Graphics g = tag.getGraphics();
g.setColor(Color.RED); //以下设置前景色BLACK
// g.setXORMode(Color.RED);
g.setFont(new Font( "MyFont ", Font.BOLD, fontSize)); //PLAIN,BOLD,ITALIC
// g.drawString(logoText, 10, 10+fontSize);
g.drawString(logoText, w2-fontSize*(logoText.length()+3)/2, h2-10);
g.dispose();
//保存文件，输出到文件流
FileOutputStream out = new FileOutputStream(jpgName+ "_800.jpg ");
try {
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(tag); //近JPEG编码
//System.out.print(width+ "* "+h0);
}finally{
out.close();
}
}

public static void jpg_yasuo(String jpgName, String newname, int size) throws Exception {
try{

String f0 = jpgName;
File f = new File(f0); //读入文件
Image src = ImageIO.read(f); //构造Image对象
int w0 = src.getWidth(null); //得到源图宽
int h0 = src.getHeight(null); //得到源图长

String f2 = newname;
int w2 = w0 / size;
int h2 = h0 / size;
BufferedImage tag = new BufferedImage(w2, h2,BufferedImage.TYPE_INT_RGB);
tag.getGraphics().drawImage(src, 0, 0, w2, h2, null); //绘制缩小后的图
System.out.println(f0+ "( "+w0+ "* "+h0+ ") \t=> "+f2+ "( "+w2+ "* "+h2+ ") ");
//保存文件
FileOutputStream out = new FileOutputStream(f2); //输出到文件流
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(tag); //近JPEG编码
out.close();
}
catch(Exception e)
{
System.out.println( "进行压缩图片时出错----- ");
e.printStackTrace();
}
}

public static void jpg_logo() throws Exception {

File _file = new File( "test_old.jpg "); //读入文件
Image src = ImageIO.read(_file); //构造Image对象
int w0=src.getWidth(null); //得到源图宽
int h0=src.getHeight(null); //得到源图长
//缩小一半
BufferedImage tag = null;
tag = new BufferedImage(w0/2,h0/2,BufferedImage.TYPE_INT_RGB);
tag.getGraphics().drawImage(src,0,0,w0/2,h0/2,null); //绘制缩小后的图
//标注水印
Graphics g = tag.getGraphics();
//g.setColor(Color.BLACK); //以下设置前景色
g.setXORMode(Color.GREEN);
g.setFont(new Font( "MyFont ", Font.ITALIC, 24));
g.drawString( "www.Test.com ", w0/4, h0/4);
g.dispose();
//保存文件
FileOutputStream out = new FileOutputStream( "test_new.jpg "); //输出到文件流
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(tag); //近JPEG编码
//System.out.print(width+ "* "+h0);
out.close();
}
public static void jpg_mini(String fn, int factor) throws Exception {
String f0 = fn+ ".jpg ";
File f = new File(f0); //读入文件
Image src = ImageIO.read(f); //构造Image对象
int w0 = src.getWidth(null); //得到源图宽
int h0 = src.getHeight(null); //得到源图长
if (w0 <800) throw new Exception( "w0 <800 ");
//-------------------------
String f2 = fn+ "_.jpg ";
int w2 = w0 / factor;
int h2 = h0 / factor;
BufferedImage tag = new BufferedImage(w2, h2,BufferedImage.TYPE_INT_RGB);
tag.getGraphics().drawImage(src, 0, 0, w2, h2, null); //绘制缩小后的图
System.out.println(f0+ "( "+w0+ "* "+h0+ ") \t=> "+f2+ "( "+w2+ "* "+h2+ ") ");
//保存文件
FileOutputStream out = new FileOutputStream(f2); //输出到文件流
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(tag); //近JPEG编码
out.close();
}
public static void jpg_rename(String fn) throws Exception {
File f0 = new File(fn+ ".jpg ");
f0.delete();
File f2 = new File(fn+ "_.jpg ");
f2.renameTo(f0);
}
public static String zeroInt(int n, int len) {
String s = " "+n;
for(int i=s.length(); i <len; i++) {
s = '0 '+s;
}
return s;
}
public static void jpg_mini(int factor, String fx, int idx0, int idx2, int iLen) throws Exception {
//String fx = "D:/_拓展培训20060915/DSC_ ";
//int idx0 = 624;
//int idx2 = 656;
String fn = null;
for(int i=idx0; i <=idx2; i++) {
fn = fx + zeroInt(i, iLen); //长度4 如：DSC_0168.JPG
try {
jpg_mini(fn, factor);
jpg_rename(fn);
}catch(Exception e){
System.out.println(fn+ "... "+e);
}
}
}
public static void main(String args[]) throws Exception {
// jpg_logo();
// jpg_mini( "test_old ");
jpg_mini(4, "D:/_拓展培训20060915/DSC_ ", 1, 200, 4); //缩小4倍(0001-0200)
// jpg_logo( "P1010105 ", "2005-4-9 ");

// jpg_logo( "P1010086 ", "2005-4-9 ");
// jpg_logo( "P1010017 ", "2005-4-18 ");
// Font f1 = Font.decode( "宋体 "); //System.out.println(s);
// Font f2 = Font.getFont( "宋体 "); //System.out.println(s);
}
}

怎么修改上传图片的大小

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