Unable to instantiate a servlet, getting class not found exception

Question

I have created a sample maven project using the following command:

mvn archetype:generate -DgroupId=com.rohit -DartifactId=RohitLoginApp -DarchetypeArtifactId=maven-archetype-webapp -DinteractiveMode=false

Below is the image link of the project structure in eclipse:

Maven project structure in eclipse

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.rohit</groupId>
  <artifactId>RohitLoginApp</artifactId>
  <packaging>war</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>RohitLoginApp Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.0.1</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>   
  </dependencies>
  <build>
    <finalName>RohitLoginApp</finalName>
  </build>
</project>

web.xml:

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
  <servlet>
    <servlet-name>RohitTestServlet</servlet-name>
    <display-name>RohitTestServlet</display-name>
    <description></description>
    <servlet-class>com.company.rohit.RohitTestServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>RohitTestServlet</servlet-name>
    <url-pattern>/RohitTestServlet</url-pattern>
  </servlet-mapping>
</web-app>

RohitTestServlet.java

package com.company.rohit;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class RohitTestServlet
 */
public class RohitTestServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public RohitTestServlet() {
        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
        String userId = request.getParametker("userName");
        String pwd = request.getParametker("psw");
        response.getWriter().write("User ID and password are received");
    }

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

}

Index.jsp

<html>
<body>
<h2>Login Page</h2>
<form action="RohitTestServlet">
  User Name<br>
  <input type="text" name="userName">
  <br>
  Password<br>
  <input type="password" name="psw">
  <br><br>
  <input type="submit" value="Submit">
</form>
</body>
</html>

When I deploy this app on tomcat, it first loads the welcome screen where I enter the userID and password and click on submit button. Then it redirects to servlet url i.e. http://localhost:8080/RohitLoginApp/RohitTestServlet?userName="xyz"&psw="www". However its unable to hit the servlet and get the response. Below is the error:

SEVERE: Allocate exception for servlet RohitTestServlet java.lang.ClassNotFoundException: com.company.rohit.RohitTestServlet at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1856) at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1705) at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:506) at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:488) at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:115) 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:505) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)

It is unable to load the class. I had done clean build lot of times but still its unable to load the servlet.

Have you tried right click on project in Package Explorer and select Maven -> Update Project (Alt + F5) ? Then go to Servers tab, unfold Tomcat instance and delete your project from there. After that hit Run as.. -> Run on server — Krzysiek

GameSalutes GameSalutes · Accepted Answer · 2016-11-22T22:08:13

It looks like your class is not being compiled into the war file. You need to make sure your servlet class is defined in src/main/java with the appropriate package subfolders. You can verify this by going to webapps directory and looking in the "classes" folder to see if your class is there.

Unable to instantiate a servlet, getting class not found exception

1 Answers