javascript - JSP Servlet 中的登录页面

问题描述

我正在尝试在 JSP 和 servlet 中实现一个简单的登录页面示例。以下是我的 servlet 代码；

package 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;

import model.UserBean;

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

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

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        super.doPost(request, response);

        System.out.println("in do post");

        String page = "";
        try {
            UserBean user = new UserBean();
            user.setUserName(request.getParameter("username"));
            user.setPassword(request.getParameter("password"));

            System.out.println(user.getUsername());
            System.out.println(user.getPassword());

            if (user.getUsername().equalsIgnoreCase("jsp") && user.getPassword().equalsIgnoreCase("1234")) {

//                  HttpSession session = request.getSession(true);
//                  session.setAttribute("currentSessionUser", user);
                page = "cashtransactions.jsp";

            } else {
                page = "invalidLogin.jsp"; // error page
            }
        } catch (Exception e) {
            System.out.println(e);
        }

        response.sendRedirect(page);
    }

}

以下是我的 JSP 代码；

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Welcome to Bank</title>
<link rel="stylesheet"
    href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css"
    integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T"
    crossorigin="anonymous">
</head>
<body>

    <div class="container col-md-4 col-md-offset-3 align-middle"
        style="overflow: auto; margin-top: 100px;">
        <h2>Bank</h2>
        <form action="<%=request.getContextPath()%>/login" method="post">
            <div class="form-group">
                <label for="uname">User Name:</label> <input type="text"
                    class="form-control" id="username" placeholder="User Name"
                    name="username" required>
            </div>

            <div class="form-group">
                <label for="uname">Password:</label> <input type="password"
                    class="form-control" id="password" placeholder="Password"
                    name="password" required>
            </div>


            <button type="submit" value="Login" class="btn btn-primary">Submit</button>
        </form>
    </div>
</body>
</html>

我收到以下错误；

INFO: Server startup in 653 ms
in do post
jsp
1234
Aug 24, 2020 9:39:52 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [servlet.LoginController] in context with path [/BankApplication] threw exception
java.lang.IllegalStateException: Cannot call sendRedirect() after the response has been committed
    at org.apache.catalina.connector.ResponseFacade.sendRedirect(ResponseFacade.java:483)
    at servlet.LoginController.doPost(LoginController.java:74)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

我能够从用户名和密码中检索值。我检查了此链接以供参考，但仍然没有运气。我在这里想念什么？

感谢帮助！

标签： javascriptjavajspservlets

javascript - JSP Servlet 中的登录页面

问题描述

解决方案

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