JSP编写验证码

骑猪看日落 2022-05-19 13:09 230阅读 0赞

index.html

<%@ page language="java" contentType="text/html; charset=utf-8"
        pageEncoding="utf-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
    <title>Insert title here</title>
    <script type="text/javascript">
                 function reloadCode(){
                        var time = new Date().getTime();//根据时间的不同来刷新
                        document.getElementById("imagecode").src="<%=request.getContextPath() %>/servlet/ImageServlet?d="+time;
                 }
           </script>
    </head>
    <body>
    <form action="<%=request.getContextPath() %>/servlet/LoginServlet" method="get">
        验证码：<input type="text" name="checkcode"/>
        <img alt="验证码" id="imagecode" src="<%=request.getContextPath() %>/servlet/ImageServlet"/>
        <a href="javascript: reloadCode();">看不清楚</a><br>
        <input type="submit" value="提交">
        </form>
    </body>
    </html>

ImageServlet.java

import java.awt.Color;
    import java.awt.Graphics;
    import java.awt.Image;
    import java.awt.image.BufferedImage;
    import java.io.IOException;
    import java.util.Random;
    import javax.imageio.ImageIO;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    public class ImageServlet extends HttpServlet{
           public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException{
                 BufferedImage bi=new BufferedImage(68, 22, BufferedImage.TYPE_INT_RGB);
                 Graphics g=bi.getGraphics();//获取画笔
                 Color c=new Color(200,150,255);//颜色
                 g.setColor(c);
                 g.fillRect(0, 0, 68, 22);//框
                 
                 char[] ch="QWERTYUIOPASDFGHJKLZXCVBNM1234567890".toCharArray();
                 //获取四个字符
                 Random r=new Random();
                 int len=ch.length,index;//设置范围
                 StringBuffer sb=new StringBuffer();
                 for (int i = 0; i <4; i++) {
                        index=r.nextInt(len);
                        g.setColor(new Color(r.nextInt(88),r.nextInt(188),r.nextInt(255)));//有字符后放在颜色上
                        g.drawString(ch[index]+"",(i*15)+3,18);//字符转字符串  画字符
                        sb.append(ch[index]);
                 }//循环四次保存四次
                 request.getSession().setAttribute("piccode", sb.toString());///字符保存到session里，要进行验证
                 ImageIO.write(bi, "JPG",response.getOutputStream());
           }
    }

LoginServlet.java

import java.io.IOException;
    import java.io.PrintWriter;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class LoginServlet extends HttpServlet{
         public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException {
             String piccod=(String)request.getSession().getAttribute("piccode");//获得到原来的验证码信息
             String checkcode=request.getParameter("checkcode");//获取前台用户输入的数
             response.setContentType("text/html;charset=gbk");//防止乱码
             PrintWriter out=response.getWriter();//获得输出流
             if(piccod.equals(checkcode)){
                 out.print("输入正确！");
             }else{
                 out.print("输入错误！");
             }
             out.flush();//刷新
             out.close();
        }
    }

web.xml

<servlet>
           <servlet-name>ImageServlet</servlet-name>
           <servlet-class>com.moke.ImageServlet</servlet-class>
      </servlet>
      <servlet>
           <servlet-name>LoginServlet</servlet-name>
           <servlet-class>com.moke.LoginServlet</servlet-class>
      </servlet>
     
      
      <servlet-mapping>
           <servlet-name>ImageServlet</servlet-name>
           <url-pattern>/servlet/ImageServlet</url-pattern>
      </servlet-mapping>
      <servlet-mapping>
           <servlet-name>LoginServlet</servlet-name>
           <url-pattern>/servlet/LoginServlet</url-pattern>
      </servlet-mapping>

运行结果图：

![70][]

ps:更新了web.xml记得从新启动服务器。

[70]: /images/20220519/0069827fe3a04b89a5502d27e38fe834.png