ClassNotFoundException Occurs When Initializing a Servlet Class

Thank you for your help.

500 error when calling servlet from jsp.
ClassNotFoundException appears and
Is the web.xml configuration or jsp incorrectly specifying the URL in the form?
I thought it was the source that was able to call the servlet from jsp without any problems and
By comparison, there was no difference in the description of web.xml.

I would appreciate your advice.

Below are the source code and error messages.

index.jsp

<%@pagecontentType="text/html;charset=UTF-8"%>

<html>
<head>
<title>Pakutter</title>
</head>
<body>
    <h1>Welcome to Pakutter!!</h1>
    <form action="/pakutter/servlet/Login" method="Post">
    Username: <input type="text" name="name"><br>
    Password &nbsp;:<input type="text" name="pass"><br>
    <input type="submit" value="Login">
    </form>

</body>
</html>

package servlet;

import java.io.IOException;


import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import model.LoginLogic;
import model.User;


public class Login extensions HttpServlet {
    private static final long serialVersionUID = 1L;


    protected void doPost (HttpServletRequest request, HttpServletResponse response)
            US>throws ServletException, IOException {

        // Retrieving Request Parameters
        request.setCharacterEncoding("UTF-8");
        String name = request.getParameter("name");
        String pass = request.getParameter("pass");

        // Generating User Instances (User Information)
        User user = new User(name, pass);

        // login process
        LoginLogic loginLogic = new LoginLogic();
        boolean isLogin=loginLogic.execute(user);

        // Successful Login Action
        if(isLogin){

            // Save user information to session scope
            // Retrieving an HttpSession Instance
            HttpSession session=request.getSession();
            // Save instance to session scope
            session.setAttribute("loginUser", user);

        }

        // Forward to login results screen
        RequestDispatcher dispatcher=request.getRequestDispatcher("/WEB-INF/jsp/LoginResult.jsp");
        dispatcher.forward (request, response);

    }

}

/pakutter/WEB-INF/web.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/j2ee"xmlns:web="http://xmlns.jcp.org/xml/ns/javaee"
    xsi: schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
    version="2.4" >

    <servlet>
        <servlet-name>Login</servlet-name>
        <servlet-class>servlet.Login</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>Login</servlet-name>
        <url-pattern>
                /servlet/Login
            </url-pattern>
    </servlet-mapping>
</web-app>

Error Message

HTTP Status 500 - Internal Server Error

Type Exception Report

Error initializing message servlet class servlet.Login

Description The server encountered an unexpected condition that presented it from filling the request.

exception

javax.servlet.ServletException—Error initializing servlet class servlet.Login
    org.apache.catalina.authenticator.AuthenticatorBase.invoke (AuthenticatorBase.java:478)
    org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.java:80)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke (AbstractAccessLogValve.java:624)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:341)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:799)
    org.apache.coyote.AbstractProcessorLight.process (AbstractProcessorLight.java:66)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process (AbstractProtocol.java:861)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun (NioEndpoint.java:1455)
    org.apache.tomcat.util.net.SocketProcessorBase.run (SocketProcessorBase.java:49)
    java.util.current.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1142)
    java.util.current.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:617)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunable.run(TaskThread.java:61)
    java.lang.Thread.run (Thread.java:745)

cause

java.lang.ClassNotFoundException: servlet.Login
    org.apache.catalina.loader.WebappClassLoaderBase.loadClass (WebappClassLoaderBase.java:1285)
    org.apache.catalina.loader.WebappClassLoaderBase.loadClass (WebappClassLoaderBase.java:1119)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke (AuthenticatorBase.java:478)
    org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.java:80)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke (AbstractAccessLogValve.java:624)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:341)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:799)
    org.apache.coyote.AbstractProcessorLight.process (AbstractProcessorLight.java:66)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process (AbstractProtocol.java:861)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun (NioEndpoint.java:1455)
    org.apache.tomcat.util.net.SocketProcessorBase.run (SocketProcessorBase.java:49)
    java.util.current.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1142)
    java.util.current.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:617)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunable.run(TaskThread.java:61)
    java.lang.Thread.run (Thread.java:745)

Below is the code that worked properly.
The operation was to get the value entered in index.jsp on the servlet side of Result.java and perform the calculation, so there was no ClassNotFoundException and I was able to perform the process.

index.jsp

<%@pagelanguage="java" contentType="text/html;charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<metacharset=UTF-8">
<title>Movie Fee Calculation</title>
</head>

Result.java

package servlet;

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

// @WebServlet ("/Result")
public class Result extensions HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doPost (HttpServletRequest request, HttpServletResponse response)
            US>throws ServletException, IOException {
        intage=-1;

        // Get request parameters
        request.setCharacterEncoding("UTF-8");
        String gender = request.getParameter("gender");
        age = Integer.parseInt(request.getParameter("age"));
        String type = request.getParameter("type");

        // Generate an instance of a Calc class
        Calc calc = new Calc();

        // substitute calculation results
        int result=calc.movieFeeCalc(age,gender,type);

        request.setAttribute("result", result);

        getServletConfig().getServletContext().getRequestDispatcher("/WEB-INF/jsp/result.jsp").forward(request,
                response);

    }

}
    <body>
    <h1>Calculate movie rates!</h1>
    <form action="/movieFee/servlet/Result" method="Post">
    Gender: <br>
    Man <input type="radio" name="gender" value="0" required>
    Woman <input type="radio" name="gender" value="1">br>
    Age: <br>
    <input type="number" name="age" required><br>
    Type: <br>
    3D<input type="radio"name="type"value="0"required>
    2D<input type="radio"name="type"value"1">
    <input type="submit" value="To Calculate">
    </body>
    </html>

web.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/j2ee"xmlns:web="http://xmlns.jcp.org/xml/ns/javaee"
    xsi: schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
    version="2.4" >

    <servlet>
        <servlet-name>Result</servlet-name>
        <servlet-class>servlet.Result</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>Result</servlet-name>
        <url-pattern>
                /servlet/Result
            </url-pattern>
    </servlet-mapping>
</web-app>

java jsp servlet

2022-09-30 18:23

1 Answers

java.lang.ClassNotFoundException: servlet.Login

It is said that

/pakutter/WEB-INF/classes/servlet/Login.class

This is probably because the file is not located.What do you think?

2022-09-30 18:23

If you have any answers or tips

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