图片验证码

1.今天从网上找了一个图片验证码的例子，很好，看代码

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package com.zhao.util;   import java.awt.Color; import java.awt.Font; import java.awt.Graphics; 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 AuthImg extends HttpServlet {     private Font mFont = new Font("Arial Black", Font.BOLD, 16);//字体，风格，字号     public void init() throws ServletException     {         super.init();//applet初始化，在applet首次创建时执行     }     Color getRandColor(int fc,int bc)//随机产生r,g,b均在fc和bc之间的一种颜色     {         Random random = new Random();         if(fc>255) fc=255;         if(bc>255) bc=255;         int r=fc+random.nextInt(bc-fc);         int g=fc+random.nextInt(bc-fc);         int b=fc+random.nextInt(bc-fc);         return new Color(r,g,b);     }       public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException     {         response.setHeader("Pragma","No-cache");         response.setHeader("Cache-Control","no-cache");         response.setDateHeader("Expires", 0);         response.setContentType("image/jpeg");                   int width=100, height=150;         BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_4BYTE_ABGR);                   Graphics g = image.getGraphics();         Random random = new Random();         g.setColor(getRandColor(200,250));         g.fillRect(1, 1, width-1, height-1);         g.setColor(new Color(102,102,102));         g.drawRect(0, 0, width-1, height-1);//画矩形。左角坐标，宽，高         g.setFont(mFont);           g.setColor(getRandColor(160,200));         for (int i=0;i<155;i++)         {             int x = random.nextInt(width - 1);             int y = random.nextInt(height - 1);             int xl = random.nextInt(6) + 1;             int yl = random.nextInt(12) + 1;             g.drawLine(x,y,x + xl,y + yl);//画直线起点坐标、终点坐标         }         for (int i = 0;i < 70;i++)         {             int x = random.nextInt(width - 1);             int y = random.nextInt(height - 1);             int xl = random.nextInt(12) + 1;             int yl = random.nextInt(6) + 1;             g.drawLine(x,y,x - xl,y - yl);         }           String sRand="";         for (int i=0;i<6;i++)         {             String tmp = getRandomChar();             sRand += tmp;             g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));             g.drawString(tmp,15*i+10,15);//写文本tmp         }           HttpSession session = request.getSession(true);         session.setAttribute("rand",sRand);         g.dispose();         ImageIO.write(image, "JPEG", response.getOutputStream());     }     private String getRandomChar()//产生文本     {         int rand = (int)Math.round(Math.random() * 2);         long itmp = 0;         char ctmp = '\u0000';         switch (rand)         {             case 1:                 itmp = Math.round(Math.random() * 25 + 65);                 ctmp = (char)itmp;                 return String.valueOf(ctmp);             case 2:                 itmp = Math.round(Math.random() * 25 + 97);                 ctmp = (char)itmp;                 return String.valueOf(ctmp);             default :                 itmp = Math.round(Math.random() * 9);                 return String.valueOf(itmp);         }     } }

2.原作者给的步骤

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1.建立一个AuthImg类，用来生成验证码 2.在web中配置AuthImg   <servlet>     <servlet-name>img</servlet-name>     <servlet-class>com.zhao.util.AuthImg</class-class>   </servlet>   <servlet-mapping>     <servlet-name>img</servlet-name>     <url-pattern>/authImg</url-pattern>   </servlet-mapping> 3.页面上：  验证码如图：<img src="authImg" id="authImg"/>看不清？<a href="#" onClick="refresh()">单击此处刷新</a> <SCRIPT type="text/javascript" >             function refresh(){                 document.getElementById("authImg").src='authImg?now='+new Date();             }         </SCRIPT> 4.AuthImg.java

3.截图（框框改的有点大）