Jsp 没有连接到 servlet

Question

我在尝试调用新的 Servlet 时收到错误 404。

我认为，我已经在 servlet 上设置了 urlPatterns，并且我正在正确链接 JSP 文件。看看下面的档案。

小服务程序：

package controller;

import java.io.IOException;
import java.sql.SQLException;
import java.util.List;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import dao.DAOFactory;
import dao.DiagnosisDAO;
import model.Category;
import model.Diagnosis;

/**
 * Servlet implementation class DiagnosisController
 */
@MultipartConfig
@WebServlet(name = "/DiagnosisController", urlPatterns = {
        "/diagnosis",
        "/diagnosis/all"
})

public class DiagnosisController extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public DiagnosisController() {
        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
        RequestDispatcher dispatcher;


        switch(request.getServletPath()) {
        case "/diagnosis":
            DiagnosisDAO diagDao;
            try(DAOFactory daoFactory = new DAOFactory()){
                diagDao = daoFactory.getDiagnosisDAO();

                Diagnosis diag = diagDao.get_DMFSteam();
                request.setAttribute("DSteam", diag.getDMFSteamList());

            } catch (ClassNotFoundException e1) {
                request.getSession().setAttribute("error", e1.getMessage());
            } catch (SQLException e1) {
                request.getSession().setAttribute("error", e1.getMessage());
            } catch (Exception e1) {
                request.getSession().setAttribute("error", e1.getMessage());
            }
            dispatcher = request.getRequestDispatcher("/view/diagnosis/charts.jsp");
            dispatcher.forward(request, response);
            break;
        }
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }

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



        doGet(request, response);
    }

}

这就是 JSP：

<%-- 
    Document   : navbar
    Created on : 03/07/2018, 11:55:04
    Author     : dskaster
--%>

<%@page contentType="text/html" pageEncoding="UTF-8" %>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<div class="navbar navbar-default navbar-fixed-top">
    <div class="container">
        <div class="navbar-header">
            <button class="navbar-toggle" type="button" data-toggle="collapse" data-target=".navbar-collapse">
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </button>
            <span class="navbar-brand"><a href="${pageContext.servletContext.contextPath}/view/menuInicial.jsp">Banco de Dados</a></span>
        </div>
        <div class="navbar-collapse collapse">

                <ul class="nav navbar-nav">
                    <li>
                        <a href="${pageContext.servletContext.contextPath}/view/menuInicial.jsp">Home</a>
                    </li>

                    <li class="dropdown">
                        <a class="dropdown-toggle" href="javascript:void(0)" data-toggle="dropdown">
                            Jogos<span class="caret"></span>
                        </a>
                        <ul class="dropdown-menu">
                            <li><a href="${pageContext.servletContext.contextPath}/game">Listar jogos</a></li>
                            <li><a href="${pageContext.servletContext.contextPath}/game/create/first">Cadastrar jogo</a></li>
                        </ul>
                    </li>

                    <li>
                        <a href="${pageContext.servletContext.contextPath}/developer">Desenvolvedoras</a>
                    </li>

                    <li>
                        <a href="${pageContext.servletContext.contextPath}/publisher">Publicadoras</a>
                    </li>

                    <li>
                        <a href="${pageContext.servletContext.contextPath}/view/category/create.jsp">Nova Categoria</a>
                    </li>

                    <li>
                        <a href="${pageContext.servletContext.contextPath}/view/json/import.jsp">Upload Json</a>
                    </li>

                    <li>
                        <a class="btn btn-lg btn-warning" href="${pageContext.servletContext.contextPath}/diagnosis/all">Diagnósticos</a>
                    </li>
                </ul>


        </div>
    </div>
</div>

JSP 文件的最后一个“li”是“href="${pageContext.servletContext.contextPath}/diagnosis/all”，它应该调用上面的 Servlet，但不起作用. 我已经尝试创建一个新的 Controller 但仍然无法正常工作。

我真的需要这个问题的帮助，这个错误已经有很多时间了，我放弃了这个项目。

我将 Eclipse IDE Photon 与 apache tomcat 8.0 和 9.0 一起使用。

Answer 1

我在 Servlet 中发现了错误，我删除了标签“@MultipartConfig”，一切正常。 Servlet 是这样的：

package controller;

import java.io.IOException;
import java.sql.SQLException;
import java.util.List;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import dao.DAOFactory;
import dao.DiagnosisDAO;
import model.Category;
import model.Diagnosis;

/**
 * Servlet implementation class DiagnosisController
 */

@WebServlet(name = "/DiagnosisController", urlPatterns = {
        "/diagnosis",
        "/diagnosis/all"
})

public class DiagnosisController extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public DiagnosisController() {
        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
        RequestDispatcher dispatcher;


        switch(request.getServletPath()) {
        case "/diagnosis":
            DiagnosisDAO diagDao;
            try(DAOFactory daoFactory = new DAOFactory()){
                diagDao = daoFactory.getDiagnosisDAO();

                Diagnosis diag = diagDao.get_DMFSteam();
                request.setAttribute("DSteam", diag.getDMFSteamList());

            } catch (ClassNotFoundException e1) {
                request.getSession().setAttribute("error", e1.getMessage());
            } catch (SQLException e1) {
                request.getSession().setAttribute("error", e1.getMessage());
            } catch (Exception e1) {
                request.getSession().setAttribute("error", e1.getMessage());
            }
            dispatcher = request.getRequestDispatcher("/view/diagnosis/charts.jsp");
            dispatcher.forward(request, response);
            break;
        }
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }

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



        doGet(request, response);
    }

}

谢谢你们。