Question

我正在尝试使用servlet在jsp之间发送变量，但是我得到了这个错误，我仍然无法弄清楚为什么。它不断发送HTTP状态500错误。

这是jsp：

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <title> 
        Fuzzy Topsis Supplier Selection
    </title>

    <!-- Normalize -->
    <link href="assets/css/normalize.css" rel="stylesheet">

    <!-- Bootstrap -->
    <link href="assets/css/bootstrap.min.css" rel="stylesheet">

    <!-- Bootstrap -->
    <link href="assets/css/custom_style_00.css" rel="stylesheet">

    <!-- Font -->
    <link href="assets/css/font.css" rel="stylesheet">
</head>

<!-- BODY STARTS HERE -->
<body>
    <section class="main_wrapper">
        <%
            request.getSession().invalidate();
        %>
        <!-- FORM STARTS HERE -->
        <div class="form_wrapper">
            <form action="./Page_One_Controller">
                <div class="sub_form_wrapper">
                    <span>
                        Input jumlah supplier : 
                    </span>

                    <div class="sub_form_input">
                        <input type="text" class="form-control" name="sNum">
                    </div>
                </div>

                <div class="sub_form_wrapper">
                    <span>
                        Input jumlah pengambil keputusan : 
                    </span>

                    <div class="sub_form_input">
                        <input type="text" class="form-control" name="dNum">
                    </div>
                </div>

                <div class="sub_form_wrapper">
                    <span>
                        Input jumlah kriteria : 
                    </span>

                    <div class="sub_form_input">
                        <input type="text" class="form-control" name="cNum">
                    </div>
                </div>

                <div class="sub_form_wrapper">
                    <div class="sub_form_input">
                        <input class="btn btn-default btn-lg" type="submit" value="Submit" name="submit">
                    </div>
                </div>
            </form>
        </div>
    </section>     
</body>

这是servlet：

package Controller;

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

@WebServlet(name = "Page_One_Controller", urlPatterns =           {"/Page_One_Controller"})
public class Page_One_Controller extends HttpServlet {

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");

    int sNum = (Integer)request.getSession().getAttribute("sNum");
    int dNum = (Integer)request.getSession().getAttribute("dNum");
    int cNum = (Integer)request.getSession().getAttribute("cNum");

    request.getSession().setAttribute("sNum", sNum);
    request.getSession().setAttribute("dNum", dNum);
    request.getSession().setAttribute("cNum", cNum);

    request.getRequestDispatcher("page_two.jsp").forward(request, response);
}
}

对于这篇长篇文章感到抱歉，如果有人能说清楚，那就太好了。

感谢。

Answer 1

您收到500错误的原因在于此行：

request.getSession().setAttribute("sNum", sNum);

在这里，您尝试将会话属性设置为未初始化的原始数据类型。

要解决这个问题，应该从请求对象获取值，而不是从session：

获取

int sNum = Integer.parseInt(request.getParameter("sNum"));

所以你的servlet代码应该是这样的：

int sNum = Integer.parseInt(request.getParameter("sNum"));
int dNum = Integer.parseInt(request.getParameter("dNum"));
int cNum = Integer.parseInt(request.getParameter("cNum"));

request.getSession().setAttribute("sNum", sNum);
request.getSession().setAttribute("dNum", dNum);
request.getSession().setAttribute("cNum", cNum);

request.getRequestDispatcher("page_two.jsp").forward(request, response);

Answer 2

    **Demo.java**
    
    package com;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    import javax.servlet.ServletContext;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    
    @WebServlet("/Demo")
    public class Demo extends HttpServlet {
        private static final long serialVersionUID = 1L;
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            response.setContentType("text/html;charset=UTF-8");
            PrintWriter out = response.getWriter();
            ServletContext sc = getServletContext();
            out.println("<h1>"+sc.getInitParameter("driverName")+"</h1>");
        }
    
    }
**web.xml**
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
  <display-name>ServletContext</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>
  <context-param>
  <param-name>driverName</param-name>
  <param-value>sun.jdbc.jdbcOdbcDriver</param-value>
  </context-param>  
  <servlet>
  <servlet-name>MyDemo</servlet-name>
  <servlet-class>com.Demo</servlet-class>
  </servlet>
  <servlet-mapping>
  <servlet-name>MyDemo</servlet-name>
  <url-pattern>/MyDemo</url-pattern>
  </servlet-mapping>
</web-app>

如何修复“HTTP状态500 - 内部服务器错误”

2 个答案: