[FIXED] Error HTTP 500 Error instantiating servlet class

Issue

What I'm trying to do is making a simple web app where a teacher may take students' scores from excel files to the database

I have tried cleaning and rebuilding the project, cleaning tomcat workpath but none seemed to work

Here is my code of the servlet that is triggering the error

@WebServlet(name = "NhapFileExcelServlet", urlPatterns = {"/nhapFileExcelServlet"})
public class NhapFileExcelServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
 * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
 * methods.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException, ParseException {
    Part filePart = request.getPart("excel");
    InputStream inputStream = filePart.getInputStream();
    String fileName = filePart.getSubmittedFileName();
    if(fileName.endsWith(".xls") || fileName.endsWith(".xlsx")) {
        // Lấy file excel upload về server
        String uploadFileDirectory = "\\Users\\thanhhieu\\Desktop\\test" + fileName;
        File fileToSave = new File(uploadFileDirectory);
        Files.copy(inputStream, fileToSave.toPath(), StandardCopyOption.REPLACE_EXISTING);
        request.setAttribute("isValid", Boolean.TRUE);
        ExcelController excelController = new ExcelController(uploadFileDirectory);
        excelController.readExcel();
        ArrayList<SinhVien> dsSinhVien = excelController.getDsSinhVien();
        ArrayList<Diem> dsDiem = excelController.getDsDiem();
        request.setAttribute("dsSinhVien", dsSinhVien);
        request.setAttribute("dsDiem", dsDiem);
    }
    else {
        request.setAttribute("isValid", Boolean.FALSE);
    }
    
    //Chuyển request và response sang GDdiem.jsp
    String url = "/GDdiem.jsp";
    RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(url);
    System.out.println("Ma lop gui sang servlet: " + request.getParameter("maLop"));
    dispatcher.forward(request, response);
}

// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/**
 * Handles the HTTP <code>GET</code> method.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException, FileNotFoundException {
    try {
        processRequest(request, response);
    } catch (ParseException ex) {
        Logger.getLogger(NhapFileExcelServlet.class.getName()).log(Level.SEVERE, null, ex);
    }
}

/**
 * Handles the HTTP <code>POST</code> method.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException, FileNotFoundException {
    try {
        processRequest(request, response);
    } catch (ParseException ex) {
        Logger.getLogger(NhapFileExcelServlet.class.getName()).log(Level.SEVERE, null, ex);
    }
}

/**
 * Returns a short description of the servlet.
 *
 * @return a String containing servlet description
 */
@Override
public String getServletInfo() {
    return "Short description";
}// </editor-fold>
}

The part that would call the servlet

<div style = "margin: auto">
            <form action="nhapFileExcelServlet" method = "post" enctype="multipart/form-data">
                <input type="hidden" id="lopID" name="maLop" value= <%= maLop %> />
                <input type="hidden" id="monID" name="maMon" value= <%= maMon %> />
                <label for="fileID">Chọn file Excel danh sách điểm:</label>
                <input type="file" id="fileID" accept=".xls, .xlsx" name="excel"><br>
                <button type="submit">Nhập</button>
            </form>
        </div>

My xml file

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">
    <servlet>
        <servlet-name>NhapFileExcelServlet</servlet-name>
        <servlet-class>servlet.NhapFileExcelServlet</servlet-class>
        <multipart-config/>
    </servlet>
    <servlet>
        <servlet-name>TinhDiemServlet</servlet-name>
        <servlet-class>servlet.TinhDiemServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>LuuDiemLopServlet</servlet-name>
        <servlet-class>servlet.LuuDiemLopServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>NhapFileExcelServlet</servlet-name>
        <url-pattern>/nhapFileExcelServlet</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>TinhDiemServlet</servlet-name>
        <url-pattern>/tinhDiemServlet</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>LuuDiemLopServlet</servlet-name>
        <url-pattern>/luuDiemLopServlet</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
    <jsp-config>
        <jsp-property-group>
            <url-pattern>*.jsp</url-pattern>
            <page-encoding>UTF-8</page-encoding>
        </jsp-property-group>
    </jsp-config>
</web-app>

And my project structure

This is the stacktrace

jakarta.servlet.ServletException: Error instantiating servlet class [servlet.NhapFileExcelServlet]
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:353)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:870)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1696)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.base/java.lang.Thread.run(Thread.java:835)
cause mère

java.lang.NoClassDefFoundError: javax/servlet/http/HttpServlet
    java.base/java.lang.ClassLoader.defineClass1(Native Method)
    java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
    java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151)
    org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2470)
    org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:866)
    org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1370)
    org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1224)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:353)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:870)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1696)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.base/java.lang.Thread.run(Thread.java:835)
cause mère

java.lang.ClassNotFoundException: javax.servlet.http.HttpServlet
    org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1401)
    org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1224)
    java.base/java.lang.ClassLoader.defineClass1(Native Method)
    java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
    java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151)
    org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2470)
    org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:866)
    org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1370)
    org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1224)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:353)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:870)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1696)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.base/java.lang.Thread.run(Thread.java:835)

Any tip is appreciated

Solution

NVM I got it going

Turns out, not only importing the jar files but I also need to specify the dependency in pom.xml because the IDE doesn't do it automatically

Answered By - Long Doan
Answer Checked By - Gilberto Lyons (JavaFixing Admin)