java - 尝试从 JSP 页面调用 servlet 时出现严重的 : Allocate exception for servlet, 错误

Question

当我在 tomcat 服务器上运行 jsp 并且它运行正常，但是当我单击提交时它抛出以下错误，我已经检查了所有内容但我不确定从这里去哪里因为它看起来应该可以工作, 任何帮助将不胜感激，谢谢。

错误堆栈跟踪:

SEVERE: Allocate exception for servlet RegistrationServlet
java.lang.ClassNotFoundException: logon.RegistrationServlet.java
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:529)
at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:511)
at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:139)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1148)
at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:864)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:134)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:315)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

网络.xml

<?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" 
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns /javaee    /web-app_2_5.xsd" 
id="WebApp_ID" version="2.5">
<display-name>RegistrationTest</display-name>
 <servlet>
        <display-name>RegistrationServlet</display-name>
        <servlet-name>RegistrationServlet</servlet-name>
        <servlet-class>logon.RegistrationServlet</servlet-class>
 </servlet>
 <servlet-mapping>
     <servlet-name>RegistrationServlet</servlet-name>
     <url-pattern>/RegistrationServlet</url-pattern>
 </servlet-mapping>
</web-app>

JSP 页面:

<h2>Signup Details</h2>
        <form name="actionForm" action="RegistrationServlet" method ="post">
        <br/>Username:<input type="text" name="name">
        <br/>Password:<input type="password" name="password">
        <br/>Email:<input type="text" name="email">
        <br/><input type="submit" value="Submit">
        </form>

小服务程序:

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;

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

public RegistrationServlet() {
    super();

}


protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

}


protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    try{
        System.out.println("In the registration Servlet");
        User user = new User();
        user.setName(request.getParameter("name"));
        user.setPassword(request.getParameter("password"));
        user.setEmail(request.getParameter("email"));
        RegisterUser.addUser(user);
        //response.sendRedirect("welcome.jsp");        
    } catch (Throwable exc)
    {
        System.out.println(exc);
    }
}

}

Answer 1

对于将来遇到类似问题的任何人，清理项目后，确保在项目下拉菜单下选中自动构建框，因为清理后需要重建，我的由于某种原因默认未选中.

此外，我在代码中犯了一个小错误，我在我的 servlet 中使用了注释 (@webservlet)，我还将 servlet 添加到我的 web.xml 中，这导致了冲突。现在，这是通过注释自动完成的。