jsp:forward servlet link Tomcat 8 个错误

Question

我正在开发基于 JSP 的 Web 应用程序并尝试使用 [=44= 连接到 Servlet ] 8. 显然我的所有代码都是正确的，我已经在 google 中进行了搜索，但是没有任何好的结果与我添加到我的代码中的部分相同。

拜托，我需要帮助，因为我看不出错误在哪里。谢谢！

我的Index.jsp页面：

<%@ page import="java.util.ArrayList"%>
<%@ page import="app.negocio.GestionLibreria"%>
<%@ page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
         pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <link rel="stylesheet" type="text/css" href="styles/miestilo.css">
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
        <script type="text/javascript">


        </script>        
    </head>
    <body>
        <div id="header">
            <div id="header-inner">
                <div id="logo">
                    <a href="/" class>
                        <img src="http://image.casadellibro.com/t1/i/logo-img.png" id="logo-img"
                    </a>
                    <a href="/" class>
                        <img src="http://image.casadellibro.com/t1/i/logo-txt.png" id="logo-txt"
                    </a>
                </div>
                <div id="nav-a">
                    <div id="datos-registro">


                    </div>
                </div>
                <div id="nav-b">
                    <div id="nav-b-inner">
                        <ul id="nav03" class="delayed-hover">
                            <li class="dropdown" id="item01"><a href="controlador?" title="Libros">Libros</li>
                            <li class="dropdown" id="item02"><a href="/editoriales" title="Ebooks">Editoriales</li>     
                        </ul>  
                    </div>
                </div>
                <div id="header sub">
                </div>
            </div>
        </div>
        <div id="body">
            <jsp:forward page="/Servlet?">
                <jsp:param name="option" value="1"/>
            </jsp:forward>
            <% List<String> lista = new ArrayList<>();
                lista = (List<String>) request.getAttribute("list2");%>


            <div id="div-table">
                <table id="gridLibros-table">
                    <tr>
                        <td><%= lista.size()%></td>
                        <td>Jackson</td>        
                        <td>94</td>
                        <td>94</td>
                    </tr>
                    <tr>
                        <td>Eve</td>
                        <td>Jackson</td>        
                        <td>94</td>
                        <td>94</td>
                    </tr>
                    <tr>
                        <td>John</td>
                        <td>Doe</td>        
                        <td>80</td>
                        <td>94</td>
                    </tr>
                </table>
            </div>
        </div>
    </body>
</html>

Servlet.java

package app.web;

        import java.io.IOException;
        import java.util.ArrayList;
        import java.util.List;
        import javax.servlet.RequestDispatcher;
        import javax.servlet.ServletException;
        import javax.servlet.annotation.WebServlet;
        import javax.servlet.http.HttpServlet;
        import javax.servlet.http.HttpServletRequest;


    import javax.servlet.http.HttpServletResponse;



        public class Servlet extends HttpServlet {

        public Servlet() {
            super();
            // TODO Auto-generated constructor stub
        }

        private void procesar(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

            String op = request.getParameter("option");

            if ("1".equals(op)) {

                List<String> lista = new ArrayList<>();
                lista.add("number1");
                lista.add("number2");

                request.setAttribute("todos", list);

                RequestDispatcher rd = request.getRequestDispatcher("/index.jsp");
                rd.forward(request, response);
            }

        }

        /**
         * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
         * response)
         */
        protected void doGet(HttpServletRequest request,
                HttpServletResponse response) throws ServletException, IOException {
            procesar(request, response);
        }

        /**
         * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
         * response)
         */
        protected void doPost(HttpServletRequest request,
                HttpServletResponse response) throws ServletException, IOException {
            procesar(request, response);
        }

    }

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" 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">
    <display-name>Web_project3</display-name>
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
    </welcome-file-list>
    <servlet>
        <servlet-name>Servlet</servlet-name>
        <servlet-class>app.web.Servlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Servlet</servlet-name>
        <url-pattern>/Servlet</url-pattern>
    </servlet-mapping>
      <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
</web-app>

错误响应页面：

Estado HTTP 500 - Ha sucedido una excepción al procesar la página JSP /index.jsp en línea 49


type Informe de Excepción

mensaje Ha sucedido una excepción al procesar la página JSP /index.jsp en línea 49

descripción El servidor encontró un error interno que hizo que no pudiera rellenar este requerimiento.

excepción
org.apache.jasper.JasperException: Ha sucedido una excepción al procesar la página JSP /index.jsp en línea 49

46:             </div>
47:         </div>
48:         <div id="body">
49:             <jsp:forward page="/ServletLibreria?">
50:                 <jsp:param name="option" value="1"/>
51:             </jsp:forward>
52:             <% List<String> lista = new ArrayList<>();


Stacktrace:
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:567)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:454)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)


causa raíz
org.apache.jasper.JasperException: Ha sucedido una excepción al procesar la página JSP /index.jsp en línea 49

46:             </div>
47:         </div>
48:         <div id="body">
49:             <jsp:forward page="/Servlet?">
50:                 <jsp:param name="option" value="1"/>
51:             </jsp:forward>
52:             <% List<String> lista = new ArrayList<>();


Stacktrace:
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:567)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:454)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    app.web.ServletLibreria.procesar(ServletLibreria.java:49)
    app.web.ServletLibreria.doGet(ServletLibreria.java:60)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:618)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.apache.jasper.runtime.PageContextImpl.doForward(PageContextImpl.java:741)
    org.apache.jasper.runtime.PageContextImpl.forward(PageContextImpl.java:711)
    org.apache.jsp.index_jsp._jspService(index_jsp.java:144)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:431)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

Answer 1

您的页面 index.jsp 将调用参数选项等于 1 的 servlet，并转发到 index.jsp。我认为您不应该在 index.jsp 中使用 jsp:forward，而应该使用简单的 link。试试这个代码：

<%@ page import="java.util.List" %>
<%@ page import="java.util.ArrayList" %>
<%@ page language="java" contentType="text/html; charset=UTF-8"
         pageEncoding="UTF-8" %>
<!DOCTYPE html>
<html>
<head>
    <link rel="stylesheet" type="text/css" href="styles/miestilo.css">
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>JSP Page</title>
    <script type="text/javascript">


    </script>
</head>
<body>
<div id="header">
    <div id="header-inner">
        <div id="logo">
            <a href="/" class>
                <img src="http://image.casadellibro.com/t1/i/logo-img.png" id="logo-img"
            </a>
            <a href="/" class>
                <img src="http://image.casadellibro.com/t1/i/logo-txt.png" id="logo-txt"
            </a>
        </div>
        <div id="nav-a">
            <div id="datos-registro">


            </div>
        </div>
        <div id="nav-b">
            <div id="nav-b-inner">
                <ul id="nav03" class="delayed-hover">
                    <li class="dropdown" id="item01"><a href="controlador?" title="Libros">Libros</li>
                    <li class="dropdown" id="item02"><a href="/editoriales" title="Ebooks">Editoriales</li>
                </ul>
            </div>
        </div>
        <div id="header sub">
        </div>
    </div>
</div>
<div id="body">
    <a href="Servlet?option=1">link to servlet with Option 1</a>
    <%--<jsp:forward page="/Servlet?">
        <jsp:param name="option" value="1"/>
    </jsp:forward>--%>
    <% List<String> lista = (List<String>) request.getAttribute("lista");
        if (lista == null) {
            lista = new ArrayList<String>();
        }
    %>


    <div id="div-table">
        <table id="gridLibros-table">
            <tr>
                <td><%= lista.size()%>
                </td>
                <td>Jackson</td>
                <td>94</td>
                <td>94</td>
            </tr>
            <tr>
                <td>Eve</td>
                <td>Jackson</td>
                <td>94</td>
                <td>94</td>
            </tr>
            <tr>
                <td>John</td>
                <td>Doe</td>
                <td>80</td>
                <td>94</td>
            </tr>
        </table>
    </div>
</div>
</body>
</html>

package app.web;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

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

public class Servlet extends HttpServlet {

    public Servlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    private void procesar(HttpServletRequest request, HttpServletResponse response) throws ServletException,
            IOException {

        String op = request.getParameter("option");

        if ("1".equals(op)) {
            List<String> lista = new ArrayList<String>();

            lista.add("number1");
            lista.add("number2");

            request.setAttribute("lista", lista);

            RequestDispatcher rd = request.getRequestDispatcher("/index.jsp");
            rd.forward(request, response);
        }

    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        procesar(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException,
            IOException {
        procesar(request, response);
    }

}

Answer 2

我终于解决了这个问题并真诚地没有明确的迹象表明它的主要原因是什么。我创建了一个新项目，并逐步小心地部署相同的代码。我正在使用 Netbeans 8.02 和 Tomcat 8.01.

非常感谢大家！！！

jsp:forward servlet link Tomcat 8 个错误

jsp:forward servlet link Tomcat 8 error

jsp

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