Java 如何将变量从Servlet输出到JSP？_Java_Jsp_Servlets

Java 如何将变量从Servlet输出到JSP？

java jsp servlets

Java 如何将变量从Servlet输出到JSP？,java,jsp,servlets,Java,Jsp,Servlets,我试图将Servlet中定义的变量输出到JSP，但我就是做不到这是我的密码： MainServlet: /* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */ package DAO

我试图将Servlet中定义的变量输出到JSP，但我就是做不到

这是我的密码：

MainServlet:

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package DAO;

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 = "MainServlet", urlPatterns = {"/MainServlet"})
public class MainServlet extends HttpServlet {

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

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");
        request.setAttribute("msg", "Bloody Hell"); // Here <<<<<<<<<<<<<<<
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    @Override
    public String getServletInfo() {
        return "Short description";
    }

}

index.jsp：

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>BlueBank</title>
    </head>
    <body>
        <h1>Whatever: ${msg}</h1>
    </body>
</html>

假设jsp位于根上下文中，则修改servlet

protected void doGet(HttpServletRequest request, HttpServletResponse response) 
        throws ServletException, IOException {
    // response.setContentType("text/html");
    request.setAttribute("msg", "Bloody Hell");
    request.getRequestDispatcher("/index.jsp").include(request, response);
}

然后访问servlet url，它将设置属性，然后包含索引jsp。

为什么会出现？你的servlet与你展示的JSP有什么关系？你需要使用原始servlet而不是像Spring MVC这样更易于管理的东西吗？我的WEB-INF是不正确的，我是在URL上以index.JSP而不是MainServlet访问的是的，很愚蠢，但现在可以了。谢谢你的帮助！