注册登陆页面使用 JSP + Servlet

整体目录结构如下：编写Bean，和Servletpackage com.ht.servlet;public class AccountBean {private String username;private String password;/*** @return the username*/public String getUsername() {return username;}..

沙漠一只雕得儿得儿

1563人浏览 · 2021-11-28 21:08:24

沙漠一只雕得儿得儿 · 2021-11-28 21:08:24 发布

整体目录结构如下：

编写Bean，和Servlet

package com.ht.servlet;

public class AccountBean {
    private String username;
    private String password;
    /**
     * @return the username
     */
    public String getUsername() {
        return username;
    }
    /**
     * @param username the username to set
     */
    public void setUsername(String username) {
        this.username = username;
    }
    /**
     * @return the password
     */
    public String getPassword() {
        return password;
    }
    /**
     * @param password the password to set
     */
    public void setPassword(String password) {
        this.password = password;
    }
}

package com.ht.servlet;

import java.io.IOException;

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;

/**
 * Servlet implementation class AccountBean
 */
@WebServlet("/CheckAccount")
public class CheckAccount extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public CheckAccount() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession sessionzxl = request.getSession();
        AccountBean account = new AccountBean();
        String username = request.getParameter("username");
        String pwd = request.getParameter("pwd");
        account.setPassword(pwd);
        account.setUsername(username);
        System.out.println("username :"+ username + " password :" + pwd);
        if((username != null)&&(username.trim().equals("jspp"))) {
            System.out.println("username is right!");
               if((pwd != null)&&(pwd.trim().equals("1"))) {
                   System.out.println("success");
                   sessionzxl.setAttribute("account", account);
                   String login_suc = "success.jsp";
                   response.sendRedirect(login_suc);
                   return;
               }
        }
        System.out.println("fail!");
        String login_fail = "fail.jsp";
        response.sendRedirect(login_fail);
        return;
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        doGet(request, response);
    }

}

登录的jsp页面如下Login.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<html>
<head>
<base href="<%=basePath%>">
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>My JSP 'login.jsp' starting page</title>
</head>
<body>
    This is my JSP page. <br>
    <form action="login">
    username:<input type="text" name="username"><br>
    password:<input type="password" name="pwd"><br>
    <input type="submit" value="Submit">
    </form>
</body>
</html>

登录成功界面如下success.jsp：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@ page import="com.ht.servlet.AccountBean"%>

<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<html>
<head>
<base href="<%=basePath%>">
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>My JSP 'success.jsp' starting page</title>
</head>
<body>
<%AccountBean account = (AccountBean)session.getAttribute("account");%>
username:<%= account.getUsername()%> <br>
password:<%= account.getPassword() %> <br>
basePath: <%=basePath%><br>
path:<%=path%><br>
</body>
</html>

登录失败的jsp页面如下：fail.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<html>
<head>
<base href="<%=basePath%>">
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>My JSP 'fail.jsp' starting page</title>
</head>
<body>
    Login Failed! <br>
    basePath: <%=basePath%><br>
    path:<%=path%><br>
</body>
</html>

web.xml配置如下：

<?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_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>ServletTest</display-name>
  <welcome-file-list>
    <welcome-file>Login.jsp</welcome-file>
  </welcome-file-list>

  <servlet>
       <description>This is the description of my J2EE component</description>
       <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>CheckAccount</servlet-name>
    <servlet-class>com.ht.servlet.CheckAccount</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>CheckAccount</servlet-name>
    <url-pattern>/login</url-pattern>
  </servlet-mapping>
</web-app>

描述一下上面运行过程：

在浏览器输入：http://localhost:8080/ServletTest/ 会通过欢迎页面welcome-file-list找到登录页面Login.jsp, 界面显示如下：

在登录页面输入用户名和密码，点击登录，找到对应的action, 会去运行/login其对应的servlet, 找到doGet()方法，判断用户名和密码

如果用户名密码不是jspp和1，就会跳转到失败页面fail.jsp

如果用户名等于jspp和1，则跳转到成功页面success.jsp

上面就是一个最简单的JSP和servlet例子。在运行上面例子中，有一个概念session.

在checkAccount.java中，直接通过request获取session

HttpSession sessionzxl = request.getSession();

后面将定义的变量存储到session中：sessionzxl.setAttribute("account", account);

在jsp中怎么获取session？

在success.jsp中，有这么一行<%AccountBean account = (AccountBean)session.getAttribute("account");%>，那么session来至于哪儿？

查看资料后得知，session是jsp隐式对象。

JSP隐式对象是JSP容器为每个页面提供的Java对象，开发者可以直接使用它们而不用显式声明。JSP隐式对象也被称为预定义变量。

JSP所支持的九大隐式对象：

对象	描述
request	HttpServletRequest 接口的实例
response	HttpServletResponse 接口的实例
out	JspWriter类的实例，用于把结果输出至网页上
session	HttpSession类的实例
application	ServletContext类的实例，与应用上下文有关
config	ServletConfig类的实例
pageContext	PageContext类的实例，提供对JSP页面所有对象以及命名空间的访问
page	类似于Java类中的this关键字
Exception	Exception类的对象，代表发生错误的JSP页面中对应的异常对象

  session是jsp的内置对象，所以你可以直接写在jsp的  
    <%  
    session.setAttribute("a",  b);  //把b放到session里，命名为a，  
    String M = session.getAttribute(“a”).toString(); //从session里把a拿出来，并赋值给M  
    %>

https://www.cnblogs.com/beilou310/p/10471836.html