servlet实现验证码登录

//用户登录HTML页面




    
    


    

        

            

            
登录界面

            

                用户名：
                        * 


                密    码：
                *


                
                
                换一张
                

                验证码：
                *


                登录

            

        
    





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//获取验证码的servlet页面

package com.westos.web01.servlet;

import org.apache.commons.lang3.RandomUtils;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

@WebServlet(name = "YzmServlet")
public class YzmServlet extends HttpServlet {
    String str="";
    private static final int WIDTH = 100;
    private static final int HEIGHT = 40;

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

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

        response.setContentType("image/jpg");

        //产生一张图片
        BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        Graphics g = image.getGraphics();
        //填充背景
        g.fillRect(0, 0, WIDTH, HEIGHT);

        //设置背景色
        g.setColor(Color.WHITE);

        //设置前景色
        g.setColor(Color.RED);

        //设置字体
        Font font = new Font("微软雅黑", Font.BOLD, 20);
        g.setFont(font);

        //获取随机字母
        str= genRandomString(4);

                //验证码传
        HttpSession session = request.getSession();
        session.setAttribute("d",str);


        //绘制验证码
        g.drawString(str, 10, 30);

        //绘制点
        for (int i = 0; i < 200; i++) {
            int x = RandomUtils.nextInt(0, WIDTH);
            int y = RandomUtils.nextInt(0, HEIGHT);
            Color color = new Color(RandomUtils.nextInt(0, 255), RandomUtils.nextInt(0, 255), RandomUtils.nextInt(0, 255));
            g.setColor(color);
            g.drawLine(x, y, x, y);
        }
        //绘制直线
        for (int i = 0; i < 15; i++) {
            int x1 = RandomUtils.nextInt(0, WIDTH);
            int x2 = RandomUtils.nextInt(0, WIDTH);
            int y1 = RandomUtils.nextInt(0, HEIGHT);
            int y2 = RandomUtils.nextInt(0, HEIGHT);
            Color color = new Color(RandomUtils.nextInt(0, 255), RandomUtils.nextInt(0, 255), RandomUtils.nextInt(0, 255));
            g.setColor(color);
            g.drawLine(x1, y1, x2, y2);
        }
        //输出图片
         ImageIO.write(image, "jpg", response.getOutputStream());

//        ImageIO.write(image,"jpg",new File("e:\\yzm.jpg"));


    }

    private String genRandomString(int len) {
        String result = "";
        //获取len个验证码字母
        for (int i = 0; i < len; i++) {
            char c = (char) RandomUtils.nextInt(65, 91);

            result = result + c ;

        }
        return result;
    }
}


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//判断用户信息输入是否正确


package com.westos.web01.servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

@WebServlet(name = "JudgeServlet")
public class JudgeServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        doGet(request,response);
    }

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

        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");

        //设置用户名和密码
        String myusername="用户";
        String mypassword="666";

        //获取输入框中的用户名、密码及验证码
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        String yzm=request.getParameter("yzm");

        //验证码接收
        HttpSession session = request.getSession();
        String s=(String) session.getAttribute("d");
        //判断登录是否正确
             if((myusername.equals(username))&&(mypassword.equals(password))&&(yzm.equalsIgnoreCase(s))&&(yzm!=null)&&(s!=null)){
                response.getWriter().println(" ");
                response.getWriter().println("
登录成功后的界面
");
            }else
                 if(username==""||password==""||yzm==""){
                     response.getWriter().println("  ");
                     response.getWriter().println("");
                 }else
                     if((myusername.equals(username))&&(mypassword.equals(password))&&(!yzm.equalsIgnoreCase(s))) {
                         response.getWriter().println(" ");
                     }
             else
                 response.getWriter().println(" ");

    }
}

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//配置servlet






        

    java web01

     java web01 


    
        YzmServlet
        com.westos.web01.servlet.YzmServlet
    
    
        YzmServlet
        /login
    


    JudgeServlet
    com.westos.web01.servlet.JudgeServlet


    JudgeServlet
    /judge