GDPU JavaWeb Servlet实现

踏入mvc的Controller层，实现servlet配置。

登录页面

1.参考课堂例子，客户端通过login.jsp发出登录请求，请求提交到loginServlet处理。如果用户名和密码相同则视为登录成功，跳转到loginSuccess.jsp页面，显示“欢迎你”+用户名；否则跳转到loginFail.jsp页面，显示“登录失败”，通过超链接返回login.jsp。

loginServlet

import javax.servlet.RequestDispatcher;
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 java.io.IOException;


@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 获取提交的用户名和密码
        response.setContentType("text/html;charset=utf-8");
        String username = request.getParameter("username");
        String password = request.getParameter("password");


        // 这里简单比较用户名和密码是否相同，实际项目中应该从数据库中验证
        if (username != null && password != null && username.equals(password)) {
            // 登录成功，重定向到登录成功页面
//            response.sendRedirect("loginSuccess.jsp?username=" + username);
            RequestDispatcher dispatcher = request.getRequestDispatcher("loginSuccess.jsp?" );
            dispatcher.forward(request, response);
        } else {
            // 登录失败，重定向到登录失败页面
//            response.sendRedirect("loginFail.jsp");
            RequestDispatcher dispatcher = request.getRequestDispatcher("loginFail.jsp");
            dispatcher.forward(request, response);

        }
    }
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // GET 请求时直接调用 doPost 方法处理
            doGet(request, response);
        }

}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    <title>Login</title>
</head>
<body>
<h2>Login</h2>
<form action="loginServlet" method="post">
    <label for="username">Username:</label>
    <input type="text" id="username" name="username" required><br><br>

    <label for="password">Password:</label>
    <input type="password" id="password" name="password" required><br><br>

    <button type="submit">Login</button>
</form>
</body>
</html>

loginSuccess.jsp

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    <title>Login Success</title>
</head>
<body>
<h2>Login Success</h2>
<p>欢迎你，<%= request.getParameter("username") %>!</p>
</body>
</html>

loginFail.jsp

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    <title>Login Fail</title>
</head>
<body>
<h2>Login Fail</h2>
<p>登录失败，请<a href="login.jsp">返回重试</a>。</p>
</body>
</html>

Servlet中读取参数

2.参考提供的“在Servlet中读取参数”内容，使用ServletConfig检索Servlet的初始化参数，请补充填写以下①-⑥空，并运行ConfigDemoServlet程序，将运行结果截图。

【步骤1】编写ConfigDemoServlet程序，内容如下：

package Servlet;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class ConfigDemoServlet extends HttpServlet{
String servletName=null;
ServletConfig config=null;
String email=null;
String telephone=null;

public void init() {
config =__getServletConfig()_________;
servletName = config.getServletName();
email=_config.getInitParameter("email"); ___;
telephone=__config.getInitParameter("telephone") __;
}

public void service(HttpServletRequest request, HttpServletResponse response)
             throws ServletException,IOException{  
  response.setContentType("text/html;charset=gb2312");
  PrintWriter out = response.getWriter();
  out.println("<html><body>");
    out.println("Servlet名称："+servletName+"<br>");
    out.println("Email地址："+email+"<br>");	
    out.println("电话："+telephone);
    out.println("</body></html>");
}
}

【步骤2】修改web.xml文件，在其中添加下面Servlet定义和初始化参数定义

<servlet>
    <servlet-name>  ConfigDemoServlet  </servlet-name>
    <servlet-class>Servlet.ConfigDemoServlet </servlet-class>
    <init-param>
      <param-name>email</param-name>
      <param-value>hacker@163.com</param-value>
    </init-param>
    <init-param>
      <param-name>telephone</param-name>
      <param-value>8899123</param-value>
    </init-param>
    
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
     <servlet-name>ConfigDemoServlet  </servlet-name>
     <url-pattern>  /configDemo       </url-pattern>
  </servlet-mapping>

【步骤3】在浏览器的地址栏中输入下面URL访问该Servlet并截图显示结果：