关于在jsp页面中取得request中的值并alert出来
如题，我在servlet中对于是否删除成功都进行了setAttribute并转发到jsp页面，在jsp页面中取出msg的值后如何将这个值alert出来呢？我自己尝试写了一下不成功，请老师指点一下。
package com.imooc.jdbc.servlet;
import com.imooc.jdbc.bean.Message;
import com.imooc.jdbc.bean.User;
import com.imooc.jdbc.service.MessageService;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;
import java.util.Objects;
public class MyMessageListServlet extends HttpServlet {
private MessageService messageService;
@Override
public void init() throws ServletException {
super.init();
messageService = new MessageService();
}
@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String pathName = request.getServletPath();
if(Objects.equals("/my/message/list.do",pathName)){
String pageStr = request.getParameter("page");//当前是第几页
User user = (User)request.getSession().getAttribute("user");
String username = user.getName();
int page = 1;//当拿不到数据时，默认值是1
//把当前页码赋值给page
if(null != pageStr && (!"".equals(pageStr))){
try {
page = Integer.parseInt(pageStr);
} catch (NumberFormatException e) {
//可能会出现问题，进行try／catch
//catch到异常了不管，默认第一页
e.printStackTrace();
}
}
List<Message> messages = messageService.getMyMessages(username,page,5 );//分页查询全部留言
int count = messageService.countMyMessages(username);
System.out.println(count);
//最后一页是第几页
int last = count % 5 == 0 ? (count/5) : ((count/5) + 1);
request.setAttribute("last",last);
request.setAttribute("messages",messages);
request.setAttribute("page",page);
request.getRequestDispatcher("/WEB-INF/views/biz/my_message_list.jsp").forward(request,response);
} else if(Objects.equals("/delete.do",pathName)) {
String id = request.getParameter("id");
int result = messageService.deleteMsgById(id);
if(result == 0){
request.setAttribute("msg","删除留言失败！");
request.getRequestDispatcher("/my/message/list.do").forward(request,response);
}else{
request.setAttribute("msg","删除留言成功！");
request.getRequestDispatcher("/my/message/list.do").forward(request,response);
}
}
}
}<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<html>
<head>
<meta charset="UTF-8">
<title>留言板</title>
<link rel="stylesheet" href="../../../css/index.css">
<script type="text/javascript">
function submitMessageForm(flag) {
if ('first' == flag) {
document.getElementById('page').value = 1;
} else if ('pre' == flag) {
var current = Number(document.getElementById('page').value);
if (current > 1) {
document.getElementById('page').value = current - 1;
}
} else if ('next' == flag) {
var current = Number(document.getElementById('page').value);
var last = Number(document.getElementById('last').value);
if (current < last) {
document.getElementById('page').value = current + 1;
}
} else if ('last' == flag) {
var last = Number(document.getElementById('last').value);
document.getElementById('page').value = last < 1 ? 1 : last;
}
document.getElementById('messageForm').submit();
}
</script>
</head>
<body>
<header>
<div class="container">
<%
if (null != request.getAttribute("msg")){
String msg = (String)request.getAttribute("msg");
%>
<script>
var msg = '<%=msg%>'
$(function () {
alert(msg);
})
</script>
<%
}
%>
<% if (null != request.getSession().getAttribute("user")) {%>
<nav>
<a href="/my/message/list.do">我的留言</a>
</nav>
<nav>
<a href="/userInfo.do">我的信息</a>
</nav>
<%} else { %>
<nav>
<a href="/login.do">登录</a>
<a href="/regPrompt.do">注册</a>
</nav>
<% } %>
</div>
</header>
<section class="banner">
<div class="container">
<div>
<h1>慕课网留言板</h1>
<p>慕课网是垂直的互联网IT技能免费学习网站。以独家视频教程、在线编程工具、学习计划、问答社区为核心特色。在这里，你可以找到最好的互联网技术牛人，也可以通过免费的在线公开视频课程学习国内领先的互联网IT技术。 </p>
</div>
</div>
</section>
<section class="main">
<div class="container">
<c:forEach items="${messages}" var="msg">
<div class="alt-item">
<div class="alt-head">
<div class="alt-info">
<span>作者：<a href="">${msg.username}</a></span>
<span>时间：<fmt:formatDate pattern="yyyy-MM-dd HH:mm:ss" value="${msg.createTime}"/></span>
</div>
</div>
<div class="alt-content">
<h3>${msg.title}</h3>
<p>${msg.content}</p>
</div>
<div id="update" >
<a href="#"><button>修改</button></a>
<a href="/delete.do?id=${msg.id}"><button>删除</button></a>
</div>
</div>
</c:forEach>
</div>
</section>
<section class="page">
<div class="container">
<% if (null != request.getSession().getAttribute("user")) {%>
<div id="fatie">
<a href="/addMessagePrompt.do"><button>点我留言</button></a>
</div>
<%} else { %>
<div id="fatie">
请<a href="/login.do"><button>登录</button></a>后留言
</div>
<% } %>
<div id="pagefy">
<ul>
<form id="messageForm" action="/my/message/list.do" method="post">
<input type="hidden" id="page" name="page" value="${page}">
<input type="hidden" id="last" name="last" value="${last}">
<li><a href="javascript:void(0)" onclick="submitMessageForm('first')">首页</a></li>
<li><a href="javascript:void(0)" onclick="submitMessageForm('pre')">上一页</a></li>
<li><a href="javascript:void(0)">当前第${page}页</a></li>
<li><a href="javascript:void(0)" onclick="submitMessageForm('next')">下一页</a></li>
<li><a href="javascript:void(0)" onclick="submitMessageForm('last')">尾页</a></li>
</form>
</ul>
</div>
</div>
</section>
<footer>
copy@慕课网
</footer>
</body>
</html>0
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2回答
慕数据7156690
2019-04-01 21:44:50
<%
if (null != request.getAttribute("msg")){
String msg = (String)request.getAttribute("msg");
%>
<script type="text/javascript" src="../../../js/jquery-3.3.1.js">
var msg = '<%=msg%>'
$(function () {
alert(msg);
})
</script>
<%
}
%>
js文件和src=""都加上了，不过还是无法成功alert，请老师看看。
src="../../../js/jquery-3.3.1.js" src="js/jquery-3.3.1.js" src="/js/jquery-3.3.1.js" 都试过，都没用。正确路径应该是怎么写？
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