找不到HTTP 404（找不到Servlet）[重复]

Question

我是一名学习使用jsp和Servlet构建Web应用程序的学生。一个月以来，我的Web应用程序项目一直运行良好，但今天它的行为突然变得奇怪了。当我提交jsp页面时，它无法找到我的servlet。我已经使用servlet注释来映射请求。

以下是我的JSP：-

<form name=registration_form action="<%=application.getContextPath() %>/Registration" method="post">  
    First Name:</td><td><input type="text" name="firstName" required/></td></tr> 
    </form>

以下是我的servlet：-

package servlets;
    @WebServlet("/Registration")
    public class Registration extends HttpServlet {
        private static final long serialVersionUID = 1L;
        public Registration() {
            super();
        }

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

        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            String firstName=request.getParameter("firstName"); 
            System.out.println(firstName);
        }
    }

<?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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 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>Login</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

HTTP Status 404 - /Login/Registration
type Status report

message /Login/Registration

description The requested resource is not available.

Apache Tomcat/7.0.47 

以下是我的控制台日志：-

Mar 11, 2014 11:30:33 AM org.apache.catalina.core.AprLifecycleListener init
INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: C:\Program Files (x86)\Java\jre7\bin;C:\windows\Sun\Java\bin;C:\windows\system32;C:\windows;C:/Program Files (x86)/Java/jdk1.6.0_17/bin/../jre/bin/client;C:/Program Files (x86)/Java/jdk1.6.0_17/bin/../jre/bin;C:/Program Files (x86)/Java/jdk1.6.0_17/bin/../jre/lib/i386;C:\Program Files (x86)\PC Connectivity Solution\;C:\Program Files (x86)\Java\jdk1.6.0_17\bin;C:\Program Files\Common Files\Microsoft Shared\Windows Live;C:\Program Files (x86)\Common Files\Microsoft Shared\Windows Live;C:\windows\system32;C:\windows;C:\windows\System32\Wbem;C:\windows\System32\WindowsPowerShell\v1.0\;C:\Program Files\Intel\WiFi\bin\;C:\Program Files\Common Files\Intel\WirelessCommon\;c:\Program Files (x86)\Common Files\Roxio Shared\DLLShared\;c:\Program Files (x86)\Common Files\Roxio Shared\OEM\DLLShared\;c:\Program Files (x86)\Common Files\Roxio Shared\OEM\DLLShared\;c:\Program Files (x86)\Common Files\Roxio Shared\OEM\12.0\DLLShared\;c:\Program Files (x86)\Roxio\OEM\AudioCore\;C:\Program Files (x86)\Windows Live\Shared;C:\Program Files (x86)\Microsoft SQL Server\90\Tools\binn\;C:\Program Files (x86)\Android\android-sdk;C:\Program Files (x86)\Java\jdk1.6.0_17\bin;C:\Program Files (x86)\MySQL\MySQL Utilities 1.3.4\;C:\Program Files (x86)\Intel\OpenCL SDK\2.0\bin\x86;C:\Program Files (x86)\Intel\OpenCL SDK\2.0\bin\x64;D:\mongodb\bin;D:\development tools\apache-maven-3.1.1-bin\apache-maven-3.1.1\bin;C:\Program Files (x86)\Google\google_appengine\;D:\development tools\eclipse;;.
Mar 11, 2014 11:30:33 AM org.apache.tomcat.util.digester.SetPropertiesRule begin
WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:Login' did not find a matching property.
Mar 11, 2014 11:30:34 AM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["http-bio-8080"]
Mar 11, 2014 11:30:34 AM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["ajp-bio-8009"]
Mar 11, 2014 11:30:34 AM org.apache.catalina.startup.Catalina load
INFO: Initialization processed in 1071 ms
Mar 11, 2014 11:30:34 AM org.apache.catalina.core.StandardService startInternal
INFO: Starting service Catalina
Mar 11, 2014 11:30:34 AM org.apache.catalina.core.StandardEngine startInternal
INFO: Starting Servlet Engine: Apache Tomcat/7.0.47
Mar 11, 2014 11:30:35 AM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-bio-8080"]
Mar 11, 2014 11:30:35 AM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["ajp-bio-8009"]
Mar 11, 2014 11:30:35 AM org.apache.catalina.startup.Catalina start
INFO: Server startup in 1463 ms

Answer 1

我也遇到过这个问题。每当我们删除一个tomcat服务器，并在没有构建类路径的情况下在新的服务器中运行我们的项目，并且清理和构建该项目时，我们就会遇到这种类型的异常。

因此，构建项目类路径。然后选择=>java Build Path=>Order and export。选择所有类路径。