使用 HTTPServletRequest return 将参数从 servlet 传递到 jsp null

Question

我正在尝试使用 HTTPServletRequest 将参数从 servlet 传递到 JSP，但没有成功。有人可以解释我哪里错了吗？

这里是 servlet： HelloServlet

package net.codejava;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
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;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class HelloServlet
 */
public class HelloServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

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

        request.setAttribute("name", "name1");
        request.setAttribute("surname", "surname1");
        request.getRequestDispatcher("index.jsp").forward(request, response);

    }

}

这里是 JSP： JSP ("HelloServlet/index.jsp")

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>HelloWorld Index</title>
</head>
<body>
    Welcome <%= request.getAttribute("name") %>
</body>
</html>

和 web.xml： web.xml

<web-app xmlns="http://java.sun.com/xml/ns/javaee" version="2.5">
    <servlet>
        <servlet-name>helloservlet</servlet-name>
        <servlet-class>net.codejava.HelloServlet</servlet-class>
        <jsp-file>/HelloServlet/index.jsp</jsp-file>        
    </servlet>
    <servlet-mapping>
        <servlet-name>helloservlet</servlet-name>
        <url-pattern>/HelloServlet</url-pattern>
    </servlet-mapping>
</web-app>

结果

Welcome null

Answer 1

实际上你的动作永远不会被调用。尝试更改代码中的以下部分。

已更新 web.xml

<web-app xmlns="http://java.sun.com/xml/ns/javaee" version="2.5">
    <servlet>
        <servlet-name>helloservlet</servlet-name>
        <servlet-class>net.codejava.HelloServlet</servlet-class>
   </servlet>
    <servlet-mapping>
        <servlet-name>helloservlet</servlet-name>
        <url-pattern>*.htm</url-pattern>
    </servlet-mapping>
</web-app>

并通过

调用您的操作

http://localhost:8080/HelloServlet/index.htm

使用 HTTPServletRequest return 将参数从 servlet 传递到 jsp null

Pass parameters from servlet to jsp using HTTPServletRequest return null

java

jsp

web.xml

servlets