这是我的第一篇文章。我希望有人可以帮助我=） 通常，我会尝试自己寻找解决此类问题的方法。 但是这个问题让我头疼...
在下面的html代码中有action标签，我想启动Java servlet。 可悲的是，我总是收到HTTP 404-Not found错误。 我已经尝试写过/ Login，.. / Login，Login（大写和小写）等等。
这是我的目录结构：
.
├── ps_18_gruppe09
│ └── src
│ ├── main
│ │ └── com.food42.servlet
│ │ └── LoginServelet.java
│ WebContent
│ ├── html
│ │ └── login.jsp
│ └── WEB-INF
│ └── lib
│ └── web.xml
我已经尝试过在类似帖子中回答的解决方案，但可惜它们没有帮助。
在我的Java构建路径中，我安装了以下库： Apache Tomcat v8.5 JRE系统库[jre1.8.0_201a] Web应用程序库 MySQL JDBC驱动程序 EAR图书馆 JUnit5 log4j-1.2.17.jar
源文件夹为ps_18_gruppe09 / src / main
完整错误消息：
HTTP状态404 –找不到
类型状态报告
消息/ ps_18_gruppe09 /登录
说明原始服务器未找到当前表示 目标资源或不愿意透露其存在。
Apache Tomcat / 8.5.35
预先感谢您的帮助=）
<?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>ServletDBLog4j</display-name>
<welcome-file-list>
<welcome-file>login.jsp</welcome-file>
</welcome-file-list>
<context-param>
<param-name>dbUser</param-name>
<param-value>admin</param-value>
</context-param>
<context-param>
<param-name>dbPassword</param-name>
<param-value>Food42</param-value>
</context-param>
<context-param>
<param-name>dbURL</param-name>
<param-value>jdbc:mysql://localhost/</param-value>
</context-param>
<context-param>
<param-name>log4j-config</param-name>
<param-value>WEB-INF/lib/log4j.xml</param-value>
</context-param>
<error-page>
<error-code>404</error-code>
<location>/AppErrorHandler</location>
</error-page>
<error-page>
<exception-type>java.lang.Throwable</exception-type>
<location>/AppErrorHandler</location>
</error-page>
<filter>
<filter-name>AuthenticationFilter</filter-name>
<filter-class>com.food42.servlet.AuthenticationFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>AuthenticationFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
<%@ page contentType="text/html; charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport"
content="width=device-width, initial-scale=1, shrink-to-fit=no">
<meta name="description" content="">
<meta name="author" content="">
<title>Food42 Login Page</title>
<!-- Bootstrap core CSS -->
<link href="../vendor/bootstrap/css/bootstrap.css" rel="stylesheet">
<!-- Custom fonts for this template -->
<link href="../vendor/fontawesome-free/css/all.min.css" rel="stylesheet"
type="text/css">
<link href="https://fonts.googleapis.com/css?family=Montserrat:400,700"
rel="stylesheet" type="text/css">
<link
href="https://fonts.googleapis.com/css?family=Lato:400,700,400italic,700italic"
rel="stylesheet" type="text/css">
<!-- Plugin CSS -->
<link href="../vendor/magnific-popup/magnific-popup.css"
rel="stylesheet" type="text/css">
<!-- Custom styles for this template -->
<link href="../css/freelancer.css" rel="stylesheet">
</head>
<body id="page-top">
<!-- Navigation -->
<nav
class="navbar navbar-expand-lg bg-secondary fixed-top text-uppercase"
id="mainNav">
<div class="container">
<a class="navbar-brand js-scroll-trigger" href="startseite.html">Food42</a>
<button
class="navbar-toggler navbar-toggler-right text-uppercase bg-primary text-white rounded"
type="button" data-toggle="collapse" data-target="#navbarResponsive"
aria-controls="navbarResponsive" aria-expanded="false"
aria-label="Toggle navigation">
Menu <i class="fas fa-bars"></i>
</button>
<div class="topnav">
<input type="text" placeholder="Suchen...">
</div>
<form action="suchresultate.html">
<input type="submit" value="Suchen" class="searchButton" />
</form>
<div class="collapse navbar-collapse" id="navbarResponsive">
<ul class="navbar-nav ml-auto">
<li class="nav-item mx-0 mx-lg-1"><a
class="nav-link py-3 px-0 px-lg-3 rounded js-scroll-trigger"
href="register.html">Registrieren</a></li>
</ul>
</div>
</div>
</nav>
<!-- Header -->
<header class="masthead bg-primary text-white text-center"> </header>
<!-- Portfolio Grid Section -->
<section class="portfolio" id="portfolio">
<div class="container">
<h2 class="text-center text-uppercase text-secondary mb-0">Benutzer-Login</h2>
<hr class="star-dark mb-5">
<form action="${pageContext.request.contextPath}/Login" method="post">
<h3 class="text-center">Bitte geben Sie Ihre Login-Daten ein:</h3>
<fieldset class="container" style="width: 400px">
<table style="width: 400px">
<tr>
<th><label class="mt-2 mb-2" for="username">Username:</label></th>
<td><input type="text" id="username" name="username"
required autofocus /></td>
</tr>
<tr>
<th><label class="mt-2 mb-2" for="password">Password:</label></th>
<td><input type="password" id="password" name="password"
required /></td>
</tr>
<tr>
<th><label class="mt-2 mb-2" for="pwdconfirm">Bestätigen:</label></th>
<td><input type="password" id="pwdconfirm" name="pwdconfirm"
required /></td>
</tr>
<tr>
<th><label class="mt-4 mb-3 " for="submit"></label> <input
type="submit" id="submit" name="submit" value="Login" /></th>
</tr>
</table>
</fieldset>
</form>
</div>
</section>
<!-- Footer -->
<footer class="footer text-center">
<div class="container">
<div class="row">
<div class="col-md-4 mb-5 mb-lg-0">
<h4 class="text-uppercase mb-4">Location</h4>
<p class="lead mb-0">
ZHAW Winterthur <br>Technikum
</p>
</div>
<div class="col-md-4 mb-5 mb-lg-0">
<h4 class="text-uppercase mb-4">Around the Web</h4>
<ul class="list-inline mb-0">
<li class="list-inline-item"><a
class="btn btn-outline-light btn-social text-center rounded-circle"
href="https://www.facebook.com/Food42ch-954018978130563/?modal=admin_todo_tour">
<i class="fab fa-fw fa-facebook-f"></i>
</a></li>
<li class="list-inline-item"><a
class="btn btn-outline-light btn-social text-center rounded-circle"
href="https://twitter.com/Food42C?edit=true"> <i
class="fab fa-fw fa-twitter"></i>
</a></li>
<li class="list-inline-item"><a
class="btn btn-outline-light btn-social text-center rounded-circle"
href="https://www.linkedin.com/company/food42-ch/"> <i
class="fab fa-fw fa-linkedin-in"></i>
</a></li>
</ul>
</div>
<div class="col-md-4">
<h4 class="text-uppercase mb-4">Food42</h4>
<p class="lead mb-0">Share your food
</div>
</div>
</div>
</footer>
<div class="copyright py-4 text-center text-white">
<div class="container">
<small>Copyright © Food42 2018</small>
</div>
</div>
<!-- Scroll to Top Button (Only visible on small and extra-small screen sizes) -->
<div class="scroll-to-top d-lg-none position-fixed ">
<a class="js-scroll-trigger d-block text-center text-white rounded"
href="#page-top"> <i class="fa fa-chevron-up"></i>
</a>
</div>
<!-- Bootstrap core JavaScript -->
<script src="../vendor/jquery/jquery.min.js"></script>
<script src="../vendor/bootstrap/js/bootstrap.bundle.min.js"></script>
<!-- Plugin JavaScript -->
<script src="../vendor/jquery-easing/jquery.easing.min.js"></script>
<script src="../vendor/magnific-popup/jquery.magnific-popup.min.js"></script>
<!-- Contact Form JavaScript -->
<script src="../js/jqBootstrapValidation.js"></script>
<script src="../js/contact_me.js"></script>
<!-- Custom scripts for this template -->
<script src="../js/freelancer.min.js"></script>
</body>
</html>
package com.food42.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
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 javax.servlet.http.HttpSession;
import org.apache.log4j.Logger;
import com.food42.util.User;
@WebServlet(name = "Login", urlPatterns = {"/Login"})
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
static Logger logger = Logger.getLogger(LoginServlet.class);
@Override
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username = request.getParameter("username");
String password = request.getParameter("password");
String errorMsg = null;
if(username == null || username.equals("")){
errorMsg ="Username can't be null or empty";
}
if(password == null || password.equals("")){
errorMsg = "Password can't be null or empty";
}
if(errorMsg != null){
RequestDispatcher rd = getServletContext().getRequestDispatcher("/login.jsp");
PrintWriter out= response.getWriter();
out.println("<font color=red>"+errorMsg+"</font>");
rd.include(request, response);
} else {
Connection con = (Connection) getServletContext().getAttribute("DBConnection");
PreparedStatement ps = null;
ResultSet rs = null;
try {
ps = con.prepareStatement("select id, title, prename, lastname, dateofbirth, mail, signupdate from user where username=? and password=? limit 1");
ps.setString(1, username);
ps.setString(2, password);
rs = ps.executeQuery();
if(rs != null && rs.next()){
User user = new User(rs.getString("lastName"), rs.getString("preName"), rs.getInt("id"), rs.getString("birthDate"), rs.getString("zip"), rs.getString("cityName"), rs.getString("street"), rs.getString("mail"), rs.getString("username"));
logger.info("User found with details = " + user);
HttpSession session = request.getSession();
session.setAttribute("User", user);
response.sendRedirect("/index.jsp");;
} else {
RequestDispatcher rd = getServletContext().getRequestDispatcher("/login.jsp");
PrintWriter out= response.getWriter();
logger.error("User not found with username = " + username);
out.println("<font color=red>No user found with given email id, please register first.</font>");
rd.include(request, response);
}
} catch (SQLException e) {
e.printStackTrace();
logger.error("Database connection problem");
throw new ServletException("Database Connection problem.");
}
finally{
try {
rs.close();
ps.close();
} catch (SQLException e) {
logger.error("SQLException in closing PreparedStatement or ResultSet");;
}
}
}
}
}
答案 0 :(得分：0)
在我拥有的类似项目中，我是这样做的，
1 -我没有在Servlet类中声明任何内容，只是有了它，
public class Margin extends HttpServlet { ... }
＆我在我的web.xml中进行所有Servlet声明，
<servlet>
<servlet-name>Margin</servlet-name>
<servlet-class>gr.thebexperts.servlets.Margin</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Margin</servlet-name>
<url-pattern>/Margin</url-pattern>
</servlet-mapping>
这可能与您的问题无关，但是您可以通过类似的方式尝试。
2 -可能引起问题的不同之处在于，您可以尝试将login.jsp页面放置在与WEB-INF相同的级别上，即直接位于/ WebContent下，可能有用。
希望有帮助！
答案 1 :(得分：0)
我设法解决了这个问题。 我将发布解决方案，也许它可以帮助遇到类似问题的人。
我必须更改项目目录结构。
我的问题是，我将Java软件包命名为com.example.test（在我的项目com.food42.servlet中），而不是为com创建目录，而在com目录中创建了名为example等的目录。
之前：
src ├── main │ ├── com.food42.database │ │ └── database.sql │ ├── com.food42.servlet │ │ ├── AuthenticationFilter.java │ │ ├── LoginServlet.java │ │ ├── LogoutServlet.java │ │ └── RegisterServlet.java │ ├── com.food42.servlet.errorhandler │ │ └── AppErrorHandler.java │ ├── com.food42.servlet.listeners │ │ └── AppContextListener.java │ └── com.food42.util │ ├── DBConnectionManager.java │ └── User.java └── test └── TestLoginFilter.java
之后：
src ├── main │ └── java │ └── com │ └── food42 │ ├── database │ │ └── database.sql │ ├── servlet │ │ ├── AuthenticationFilter.java │ │ ├── LoginServlet.java │ │ ├── LogoutServlet.java │ │ ├── RegisterServlet.java │ │ ├── errorhandler │ │ │ └── AppErrorHandler.java │ │ └── listeners │ │ └── AppContextListener.java │ └── util │ ├── DBConnectionManager.java │ └── User.java └── test └── TestLoginFilter.java
感谢我的教授，他帮助我找出了问题所在=）
一些图片可以更好地显示我的更改：
Changing the text color titlePositionAdjustment Directory structure Deployment_Assembly
