404 错误 - 尝试访问我的 Servlet 时显示错误

Question

主页工作正常，但是，当我尝试访问我正在测试的两个 servlet 之一时，出现 404 错误。我正在使用 IDE intellij、tomcat 9、maven、servlet 版本 5，

HTTP Status 404 – Não Encontrado
Type Status Report

Description The origin server did not find a current representation for the target resource or is not willing to disclose that one exists.

Apache Tomcat/9.0.84

Servlet 1 :

package br.com.caelum.fj21agenda;

import java.io.*;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.*;
import jakarta.servlet.annotation.*;

@WebServlet("/servlet")
public class HelloServlet extends HttpServlet {

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


        PrintWriter out = response.getWriter();

        //Escreve o texto
        out.println("<html>");
        out.println("<body>");
        out.println("Primeira Servlet ^^ yay");
        out.println("</body>");
        out.println("</html>");

    }
}

servlet 2：

package br.com.caelum.fj21agenda;

import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import jakarta.servlet.annotation.WebServlet;

@WebServlet("/hello")
public class HelloServlet2 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Preprocess request: we actually don't need to do any business stuff, so just display JSP.
        request.getRequestDispatcher("/WEB-INF/hello.jsp").forward(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Postprocess request: gather and validate submitted data and display the result in the same JSP.

        // Prepare messages.
        Map<String, String> messages = new HashMap<>();
        request.setAttribute("messages", messages);

        // Get and validate name.
        String name = request.getParameter("name");
        if (name == null || name.trim().isEmpty()) {
            messages.put("name", "Please enter name");
        } else if (!name.matches("\\p{Alnum}+")) {
            messages.put("name", "Please enter alphanumeric characters only");
        }

        // Get and validate age.
        String age = request.getParameter("age");
        if (age == null || age.trim().isEmpty()) {
            messages.put("age", "Please enter age");
        } else if (!age.matches("\\d+")) {
            messages.put("age", "Please enter digits only");
        }

        // No validation errors? Do the business job!
        if (messages.isEmpty()) {
            messages.put("success", String.format("Hello, your name is %s and your age is %s!", name, age));
        }

        request.getRequestDispatcher("/WEB-INF/hello.jsp").forward(request, response);
    }

}

web.xml：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_5_0.xsd"
         version="5.0">

    <servlet>
        <servlet-name>HelloServlet</servlet-name>
        <servlet-class>br.com.caelum.fj21agenda.HelloServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>HelloServlet</servlet-name>
        <url-pattern>/servlet</url-pattern>
    </servlet-mapping>

</web-app>

index.html：

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Projeto Fj21-agenda </title>
    </head>
    <body>
        <h1>Primeira Pagina YAYY</h1>
    </body>
</html>

我正在测试两个 servlet，一个仅包含 @WebServlet 标记，该标记未映射到 xml 文件中，另一个具有该标记并已映射。没有一个有效

Answer 1

Tomcat 9 支持 Java Servlet，而不是 Jakarta Servlet。您需要针对 Tomcat 10 或更高版本运行您编写的内容。

404 错误 - 尝试访问我的 Servlet 时显示错误

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