JAVA生成验证码

<img border="0"
src="ValidateCode"
id='code' width="64" height="30"
style="vertical-align: top; cursor: pointer;"
title="点击刷新验证码" />

JAVA代码：

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.geom.Line2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class ValidateCode extends HttpServlet {

private static final long serialVersionUID = 1L;

private Random rand=new Random();

/**
* 生成随机颜色
*
* @param start [int]
* @param end [int]
* @return Color [object]
*/
public Color getRandColor(int start,int end){
int randNum;
if(start>255) start=255;
if(end>255) end=255;
if(start>end) randNum=start-end;
else randNum=end-start;
int r=start+rand.nextInt(randNum);
int g=start+rand.nextInt(randNum);
int b=start+rand.nextInt(randNum);
return new Color(r,g,b);
}

/**
* 着色\旋转\缩放
*
* @param word 文字
* @param g 图片对象
*/
public void coloredAndRotation(String word,int i,Graphics g){
/**着色**/
g.setColor(new Color(20+rand.nextInt(110),20+rand.nextInt(110),20+rand.nextInt(110)));
/**旋转**/
Graphics2D g2d=(Graphics2D)g;
AffineTransform trans=new AffineTransform();
trans.rotate(rand.nextInt(45)*3.14/180,15*i+8,7);
/**缩放**/
float scaleSize=rand.nextFloat()+0.8f;
if(scaleSize>1f) scaleSize=1f;
trans.scale(scaleSize, scaleSize);
g2d.setTransform(trans);
g.drawString(word,15*i+20,20);
}

/**
* 生成100条干扰线
*
* @param g2d
* @param width
* @param height
*/
public void getRandLine(Graphics2D g2d,int width,int height){
for(int i=0;i<100;i++){
int x=rand.nextInt(width-1);
int y=rand.nextInt(height-1);
int z=rand.nextInt(6)+1;
int w=rand.nextInt(12)+1;

BasicStroke bs=new BasicStroke(2f,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);
Line2D line=new Line2D.Double(x,y,x+z,y+w);
g2d.setStroke(bs);
g2d.draw(line);
}
}

/**
* 获取随机文字
* @param length [int] 验证码长度
* @param g [Graphics] 图片对象
* @return String
* @case1:A-Z
* @case2:chinese
* @default:0-9
*/
@SuppressWarnings("unused")
public String getRandWord(int length,Graphics g){
String finalWord="",firstWord="";
int tempInt=0;
String[] array={
"0","1","2","3",
"4","5","6","7",
"8","9","a","b",
"c","d","e","f"};

for(int i=0;i<length;i++){
switch(rand.nextInt(2)){
//英文数字混合
/* case 1:
tempInt=rand.nextInt(26)+65;
firstWord=String.valueOf((char)tempInt);
break;*/
//纯数字
case 2:
int r1,r2,r3,r4;
String strH,strL;//high&low
r1=rand.nextInt(3)+11; //前闭后开[11,14)
if(r1==13){
r2=rand.nextInt(7);
}else{
r2=rand.nextInt(16);
}

r3=rand.nextInt(6)+10;
if(r3==10){
r4=rand.nextInt(15)+1;
}else if(r3==15){
r4=rand.nextInt(15);
}else{
r4=rand.nextInt(16);
}

strH=array[r1]+array[r2];
strL=array[r3]+array[r4];

byte[] bytes=new byte[2];
bytes[0]=(byte)(Integer.parseInt(strH,16));
bytes[1]=(byte)(Integer.parseInt(strL,16));

firstWord=new String(bytes);
break;
default:
tempInt=rand.nextInt(10)+48;
firstWord=String.valueOf((char)tempInt);
break;
}
finalWord+=firstWord;
this.coloredAndRotation(firstWord,i, g);
}

return finalWord;
}

protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

//设制不缓存图片
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","No-cache");
response.setDateHeader("Expires",0);

//生成图片
response.setContentType("image/jpeg");
int width=80;
int height=30;
BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);

Graphics g=image.getGraphics();
Graphics2D g2d=(Graphics2D)g;
Font mFont=new Font("宋体",Font.BOLD,22);
g.setColor(this.getRandColor(200,250));
g.fillRect(0, 0, width, height);
g.setFont(mFont);
g.setColor(this.getRandColor(180,200));

this.getRandLine(g2d, width, height);

String randCode=this.getRandWord(4, g);

HttpSession session=request.getSession();
session.setAttribute("randCode",randCode);

g.dispose();

ImageIO.write(image,"JPEG",response.getOutputStream());

}
}