验证码的简易使用

Posted 2020-10-23 zhangzonghua

tags:

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1.设计web 页面

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <style type="text/css">
        .s1{
            cursor:pointer;
        }
    
    </style>


<title>验证码</title>
</head>
<body>
    
    <form action="code.action" method="post">

    验证码：<input type="text" name="vcode">
    <img src="validate.code" onclick="this.src=‘ValidateCode.code?‘+Math.random()"
        class="s1" title="点击刷新"> 

    <%        Object err=(request.getAttribute("code_err"));
        
    %>
    <span style="color:red"><%=err==null?"":err %></span>
    <input type="submit" value="确定">
</form>
    
</body>
</html>

2. 使用java代码画出验证码的图片

package day4;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
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;

import org.apache.catalina.connector.OutputBuffer;
import org.apache.catalina.tribes.membership.StaticMember;

/**
 * Servlet implementation class ValidateCode
 */
public class ValidateCode extends HttpServlet {
    Random r=new Random();
    protected void service(HttpServletRequest request, 
            HttpServletResponse response) throws ServletException, IOException {

        HttpSession session =request.getSession();
        BufferedImage image=new BufferedImage(100, 20, BufferedImage.TYPE_INT_RGB);
        Graphics g=image.getGraphics();
        g.setColor(new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));
        g.fillRect(0, 0, 100, 20);
        String content=getContent(3);
        g.setColor(new Color(0, 0, 0));
        g.setFont(new Font(null, Font.BOLD, 18));
        g.drawString(content, 30, 15);
        
        for (int i = 0; i < 5; i++) {
            g.drawLine(100, 20, r.nextInt(100), r.nextInt(20));
            
        }
        session.setAttribute("code", content);
        response.setContentType("text/html");
        OutputStream os=response.getOutputStream();
        ImageIO.write(image, "jpeg", os);
        os.close();
    }
        
    public String getContent(int size) {
        String str="ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        String content="";
        for (int i = 0; i < size; i++) {
            content+=str.charAt(r.nextInt(str.length()));
        }
        return content;
    }    
}

3. 服务端检验验证码是否相同

package day2;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;



/**
 * Servlet implementation class userAction
 */
public class userAction extends HttpServlet {

    protected void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        PrintWriter pw=response.getWriter();
            
            String code=(String) session.getAttribute("code");
            String vcode=request.getParameter("vcode");
            if(code.equals(vcode)) {
                pw.print(code+"<br><p>相等</p>");
            }else {
                request.setAttribute("code_err", "验证码错误");
                
    request.getRequestDispatcher("validate.jsp").forward(request, response);
            
        }
        
        
    }

    

}

end

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