java验证码/servlet

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项目结构如图一：

第一步，新建PictureCode.java：

package com.servlet;


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 PictureCode extends HttpServlet
{

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException
    {
        //设置不缓存
        resp.setHeader("pragma", "no-cache");
        resp.setHeader("cache-control", "no-cache");
        resp.setDateHeader("expires", 0);
        //指定生成的图片的格式
        resp.setContentType("image/jpeg");
        //验证码的张宽
        int width=80,height=30;
        //图片流
        BufferedImage image=new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);


        Graphics g=image.getGraphics();     //创建Graphics对象,其作用相当于画笔 
        Graphics2D g2d=(Graphics2D)g;       //创建Grapchics2D对象 
        Font mfont=new Font("楷体",Font.BOLD,16); //定义字体样式 
        g.setColor(getRandColor(200,250)); 
        g.fillRect(0, 0, width, height);    //绘制背景 
        g.setFont(mfont);                   //设置字体 
        g.setColor(getRandColor(180,200)); 

      //绘制100条颜色和位置全部为随机产生的线条,该线条为2f 
        Random random=new Random();
        for (int i = 0; i < 100; i++)
        {
            int x=random.nextInt(width-1);
            int y=random.nextInt(height-1);
            int x1=random.nextInt(6)+1;
            int y1=random.nextInt(12)+1;
            BasicStroke bs=new BasicStroke(2f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL);
            Line2D line2d=new Line2D.Double(x,y,x+x1,y+y1);
            g2d.setStroke(bs);
            g2d.draw(line2d);
        }


        //输出由英文，数字，和中文随机组成的验证文字，具体的组合方式根据生成随机数确定。 
        String sRand=""; 
        String ctmp=""; 
        int itmp=0; 
        //制定输出的验证码为四位 
        for(int i=0;i<4;i++){ 
            //random.nextInt(2)在0-2中间去随机，不包含2，这样是为了下面不去生成中文验证码，验证出现中文时，不好判断
            switch(random.nextInt(2)){ 
                case 1:     //生成A-Z的字母 
                     itmp=random.nextInt(26)+65; 
                     ctmp=String.valueOf((char)itmp); 
                     break; 
                default: 
                     itmp=random.nextInt(10)+48; 
                     ctmp=String.valueOf((char)itmp); 
                     break; 
            } 
            sRand+=ctmp;
            Color color=new Color(20+random.nextInt(110),20+random.nextInt(110),random.nextInt(110)); 
            g.setColor(color); 
            //将生成的随机数进行随机缩放并旋转制定角度 PS.建议不要对文字进行缩放与旋转,因为这样图片可能不正常显示 
            /*将文字旋转制定角度*/ 
            Graphics2D g2d_word=(Graphics2D)g; 
            AffineTransform trans=new AffineTransform(); 
            trans.rotate((45)*3.14/180,15*i+8,7); 
            /*缩放文字*/ 
            float scaleSize=random.nextFloat()+0.8f; 
            if(scaleSize>1f) scaleSize=1f; 
            trans.scale(scaleSize, scaleSize); 
            g2d_word.setTransform(trans); 
            g.drawString(ctmp, 15*i+18, 14); 
        } 


        //打开session，并放入验证图片
        HttpSession session=req.getSession(true);
        session.setAttribute("randCheckCode", sRand); 
        g.dispose();    //释放g所占用的系统资源 
        ImageIO.write(image,"JPEG",resp.getOutputStream()); //输出图片 
    }


    public PictureCode()
    {
        super();
    }

    public void destroy()
    {
        super.destroy(); // Just puts "destroy" string in log
        // Put your code here
    }

    public void init() throws ServletException
    {
        super.init();
    }
    /*该方法主要作用是获得随机生成的颜色*/  
    public Color getRandColor(int s,int e){ 
        Random random=new Random (); 
        if(s>255) s=255; 
        if(e>255) e=255; 
        int r,g,b; 
        r=s+random.nextInt(e-s);    //随机生成RGB颜色中的r值 
        g=s+random.nextInt(e-s);    //随机生成RGB颜色中的g值 
        b=s+random.nextInt(e-s);    //随机生成RGB颜色中的b值 
        return new Color(r,g,b); 
    } 
}

第二步，新建index.jsp和Check.jsp

index.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>

    <title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">   
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<script type="text/javascript">
function myReload() { 
    document.getElementById("PictureCode").src = document 
            .getElementById("PictureCode").src 
            + "?nocache=" + new Date().getTime(); 
} 
</script>
  </head>

  <body>
    <form action="Check.jsp" method="post">
            <input name="checkCode" type="text" id="checkCode"  
                size="8" ,maxlength="4" /> 
            <img src="PictureCode" id="PictureCode" align="middle"> 
            <a href="" onclick="myReload()">&nbsp;看不清,换一个</a> 
            <input type="submit" value="提交" /> 
    </form>
  </body>
</html>

Check.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">

    <title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">   
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
  </head>

  <body>
     <% 
        String checkcode=request.getParameter("checkCode"); 
        if(checkcode.equals("")||checkcode==null){ 
            out.print("<script>alert('请输入验证码');window.location.href('index.jsp')</script>"); 
        }else{ 
            if(!checkcode.equalsIgnoreCase((String)session.getAttribute("randCheckCode"))){ 
                out.print("<script>alert('验证码不正确,请重新输入');history.back(-1);</script>"); 
            }else{ 
                out.print("登录成功;<script>window.location.href('http://www.google.com')</script>"); 
            } 
        } 
     %> 
  </body>
</html>

第四步：配置web.xml中的servlet，部署运行：

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <servlet>
    <servlet-name>PictureCode</servlet-name>
    <servlet-class>com.servlet.PictureCode</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>PictureCode</servlet-name>
    <url-pattern>/PictureCode</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

在tomcat等服务器中部署后，打开浏览器键入：

http://localhost:8080/checkcode2/

即可查看到如图二，图三中，随机生成的验证码