```
package main
.java
.com
.example;
import javax
.servlet
.*;
import javax
.servlet
.annotation
.WebServlet;
import javax
.servlet
.http
.*;
import java
.io
.IOException;
import java
.util
.HashMap;
import java
.util
.Map;
@WebServlet("/exampleServlet")
public class ExampleServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServlet
Request request, HttpServletResponse response) throws ServletException, IOException {
Map<String, String>
requestMap = new HashMap<>
();
requestMap
.put("key1", "value1");
requestMap
.put("key2", "value2");
request.setAttribute("
requestMap",
requestMap);
Map<String, String>
sessionMap = new HashMap<>
();
sessionMap
.put("key3", "value3");
sessionMap
.put("key4", "value4");
request.get
Session().setAttribute("
sessionMap",
sessionMap);
Map<String, String> contextMap = new HashMap<>
();
contextMap
.put("key5", "value5");
contextMap
.put("key6", "value6");
getServletContext
().setAttribute("contextMap", contextMap);
RequestDispatcher dispatcher =
request.get
RequestDispatcher("/example
.jsp");
dispatcher
.forward(
request, response);
}
protected void doPost(HttpServlet
Request request, HttpServletResponse response) throws ServletException, IOException {
doGet(
request, response);
}
}
<%@ page import="java
.util
.Map" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>EL Expression Example</title>
</head>
<body>
<h2>
Request Scope Map</h2>
<ul>
<c:forEach var="entry" items="${
requestScope
.requestMap}">
<li>${entry
.key} : ${entry
.value}</li>
</c:forEach>
</ul>
<h2>
Session Scope Map</h2>
<ul>
<c:forEach var="entry" items="${
sessionScope
.sessionMap}">
<li>${entry
.key} : ${entry
.value}</li>
</c:forEach>
</ul>
<h2>ServletContext Scope Map</h2>
<ul>
<c:forEach var="entry" items="${applicationScope
.contextMap}">
<li>${entry
.key} : ${entry
.value}</li>
</c:forEach>
</ul>
</body>
</html>```java代码为1-33行，
jsp页面代码为34-64行，我通过
IDEA运行tomcat9，
使用java-web框架运行后，遍历map集合一直无法实现效果，请问代码有什么问题吗
本文探讨了在JSP页面中使用session.setAttribute方法时遇到的常见错误，主要原因是未正确导入servlet-api资源包。文章深入解析了servlet-api的作用，以及如何在项目中正确配置和引用。
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