Session实现一次性验证码(十)

最新推荐文章于 2021-09-21 09:36:34 发布

凯耐

最新推荐文章于 2021-09-21 09:36:34 发布

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分类专栏： Java Web 文章标签： session

本文链接：https://blog.youkuaiyun.com/weixin_36279318/article/details/78555736

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(一)创建登录界面

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>验证码演示W</title>
</head>
<body>
<form action="/Project01/LoginServlet"  method="post">

  用户名：<input  name="username" type="text"><br/>
  密      码：<input name="password" type="password"><br/>
  验证码 ：<input name="check_code"  type="text">
       <img  src="/Project01/CheckServlet">
 <input  type="submit"  value="提交">
</form>

</body>
</html>

(二)验证提交的表单数据

package com.Test;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//此类处理login.html表单提交
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;


    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8");
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        String checkcode=request.getParameter("check_code");
        String  saveCode=(String) request.getSession().getAttribute("check_code");
        PrintWriter out=response.getWriter();
        //1.把账号、密码分别设置为root、123
        if(username.equals("root")&&password.equals("123")&&checkcode.equals(saveCode)){
            //2.创建User对象保存账号、密码
            User user=new User();
            user.setUsername(username);
            user.setPassword(password);


            //3.创建Session对象保存User对象
            request.getSession().setAttribute("user", user);

            //4.登陆成功跳转指定页面
            response.sendRedirect("/Project01/IndexServlet");
        } 
        else if(checkcode.equals(saveCode)){
            out.println("账号或密码错误，请从新输入....");
        }else{
            out.println("验证码输入错误，请从新输入....");
        }
    }


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

        doGet(request, response);
    }

}

(三)跳转页面

package com.Test;
import java.io.IOException;
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;
//1.创建IndexServlet显示网站的首界面 
public class IndexServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //2.response解决乱码问题
        response.setContentType("text/html;charset=utf-8");
        //3.创建Session对象保存用户信息
        HttpSession session=request.getSession();
        //4.方法体中的参数要与setAttribute()键一致
        User user=(User) session.getAttribute("user");
        if(user==null){
            response.getWriter().print("您还未登陆，请<a href='/Project01/login.html'>登陆</a>");
        }else{
            response.getWriter().print("您已登陆，欢迎您 "+user.getUsername());
            response.getWriter().print("<a href='/Project01/LogoutServlet'>退出</a>");

            //5.创建Cookie对象用来保存Session的id
            Cookie cookie=new Cookie("JSESSIONID",session.getId());
            cookie.setMaxAge(30*60);
            cookie.setPath("/Project01");
            response.addCookie(cookie);
        }


    }


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

        doGet(request, response);
    }

}

(四)验证码生成

package com.Test;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class CheckServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private static int WIDTH = 60;// 验证码图片的宽度
    private static int HEIGHT = 20;// 验证码图片的高度

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        HttpSession session = request.getSession();
        // 1.设置响应消息体的类型
        response.setContentType("image/jpeg");
        // 2.创建ServletOutputStream打印图片
        ServletOutputStream sos = response.getOutputStream();

        // 3.告知浏览器不要缓存此图片
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "No-cache");
        response.setDateHeader("Expires", 0);

        // 4.创建内存图片并获得图像上下文
        BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        Graphics g = image.getGraphics();

        // 5.产生随机验证码
        char[] rands = generateCheckCode();

        // 6绘制图像
        drawBackground(g);
        drawRands(g, rands);

        // 7.绘制完毕，完成图像
        g.dispose();

        // 8.将图片打印到浏览器上
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        ImageIO.write(image, "JPEG", bos);
        byte[] buf = bos.toByteArray();
        response.setContentLength(buf.length);
        sos.write(buf);
        bos.close();
        sos.close();

        // 9.将验证码存入到Session中
        session.setAttribute("check_code", new String(rands));

    }

    private void drawRands(Graphics g, char[] rands) {
        g.setColor(Color.BLACK);
        g.setFont(new Font(null, Font.ITALIC | Font.BOLD, 18));
        // 10在不同高度上输入验证码的每一个字符
        g.drawString("" + rands[0], 1, 17);
        g.drawString("" + rands[1], 16, 15);
        g.drawString("" + rands[2], 31, 18);
        g.drawString("" + rands[3], 46, 16);

    }

    private void drawBackground(Graphics g) {
        // 11.绘制背景
        g.setColor(new Color(0xDCDCDC));
        g.fillRect(0, 0, WIDTH, HEIGHT);

        // 12.产生120个干扰点
        for (int i = 0; i < 120; i++) {
            int x = (int) (Math.random() * WIDTH);
            int y = (int) (Math.random() * HEIGHT);
            int red = (int) (Math.random() * 255);
            int blue = (int) (Math.random() * 255);
            int green = (int) (Math.random() * 255);
            g.setColor(new Color(red, green, blue));
            g.drawOval(x, y, 1, 0);

        }

    }

    private char[] generateCheckCode() {
        String chars = "0123456789abcdefghijklmnopqrstuvwxyz";
        char[] rands = new char[4];
        for (int i = 0; i < 4; i++) {
            int rand = (int) (Math.random() * 36);
            rands[i] = chars.charAt(rand);
        }
        return rands;
    }

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

        doGet(request, response);
    }

}

(五)用户实体类

package com.Test;

public class User {
    private String username;
    private String password;
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }


}

(六)配置Servlet

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>Project01</display-name>
  <welcome-file-list>
    <welcome-file>login.html</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>IndexServlet</display-name>
    <servlet-name>IndexServlet</servlet-name>
    <servlet-class>com.Test.IndexServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>IndexServlet</servlet-name>
    <url-pattern>/IndexServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <description></description>
    <display-name>LoginServlet</display-name>
    <servlet-name>LoginServlet</servlet-name>
    <servlet-class>com.Test.LoginServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/LoginServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <description></description>
    <display-name>LogoutServlet</display-name>
    <servlet-name>LogoutServlet</servlet-name>
    <servlet-class>com.Test.LogoutServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>LogoutServlet</servlet-name>
    <url-pattern>/LogoutServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <description></description>
    <display-name>CheckServlet</display-name>
    <servlet-name>CheckServlet</servlet-name>
    <servlet-class>com.Test.CheckServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>CheckServlet</servlet-name>
    <url-pattern>/CheckServlet</url-pattern>
  </servlet-mapping>
</web-app>

结果：

这里写图片描述