If you are a platform-level system, you can consider message queue middleware, such as Alibaba's rocketmq, and use this for message subscription and distribution.
If you simply need to prompt to the web (jsp) page, you can use js to schedule ajax to access the background, and the background will determine whether there is data update, no matter where the data comes from.
Recommended course: Java Tutorial.
Here we use JS to implement the message pop-up box on the JSP page. The style can be modified according to the requirements. Here is just a simple demonstration example with two customized messages. , the pop-up effect is as follows:
The code implementation is not connected to the background:
<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>
<%@page import="java.util.*"%>
<html>
<head>
<style type="text/css">
#winpop { width:250px; height:0px; position:absolute; right:0; bottom:0; border:1px solid grey; margin:0; padding:1px; overflow:hidden; display:none; background:#FFFFFF}
#winpop .title { width:100%; height:20px; line-height:20px; background:#0AB0FF ; font-weight:bold; text-align:center; font-size:12px;color:white}
#winpop .con { width:100%; height:360px; line-height:80px; font-weight:bold; font-size:12px; color:#FF0000; text-decoration:underline; text-align:center}
.close { position:absolute; right:4px; top:-1px; color:#FFFFFF; cursor:pointer}
</style>
</head>
<%
//未读消息unreadList根据实际情况取
List<Map> unreadList = new ArrayList<Map>();
Map<String,String> map1=new HashMap<String,String>();
map1.put("msgId","1");
map1.put("msgContent","message111111");
unreadList.add(map1);
Map<String,String> map2=new HashMap<String,String>();
map2.put("msgId","2");
map2.put("msgContent","message222222");
unreadList.add(map2);
int num=unreadList.size();
%>
<body>
<script language="javascript" type="text/javascript">
window.onload = function tanchuang() { //加载
document.getElementById('winpop').style.height = '0px';//要初始化这个高度,虽然CSS里已经初始化了
setTimeout("tips_pop()",0); //调用tips_pop()这个函数
}
function tips_pop() {
var MsgPop = document.getElementById("winpop");//获取窗口这个对象,即ID为winpop的对象
var popH = parseInt(MsgPop.style.height);//用parseInt将对象的高度转化为数字,以方便下面比较
if (popH == 0) { //如果窗口的高度是0
MsgPop.style.display = "block";//那么将隐藏的窗口显示出来
show = setInterval("changeH('up')", 2);//开始以每0.002秒调用函数changeH("up"),即每0.002秒向上移动一次
} else { //否则
hide = setInterval("changeH('down')", 2);//开始以每0.002秒调用函数changeH("down"),即每0.002秒向下移动一次
}
}
function changeH(str) {
var MsgPop = document.getElementById("winpop");
var popH = parseInt(MsgPop.style.height);
if (str == "up") { //如果这个参数是UP
if (popH <= 100) { //如果转化为数值的高度小于等于100
MsgPop.style.height = (popH + 4).toString() + "px";//高度增加4个象素
} else {
clearInterval(show);//否则就取消这个函数调用,意思就是如果高度超过100象度了,就不再增长了
}
}
if (str == "down") {
if (popH >= 4) { //如果这个参数是down
MsgPop.style.height = (popH - 4).toString() + "px";//那么窗口的高度减少4个象素
} else { //否则
clearInterval(hide); //否则就取消这个函数调用,意思就是如果高度小于4个象度的时候,就不再减了
MsgPop.style.display = "none"; //因为窗口有边框,所以还是可以看见1~2象素没缩进去,这时候就把DIV隐藏掉
}
}
}
</script>
<%if(num>0){ %>
<div id="winpop">
<div class="title" >系统信息<br>
共有<font color="red"><big><%=num %></big></font>条未读消息
<span class="close" onclick="tips_pop()">X</span></div>
<%for(int i=0;i<num;i++) { %>
<!-- 点击信息标题链接到信息明细，传递信息编号参数 -->
<a href="/XXXAction.do?msgId=<%=unreadList.get(i).get("msgId") %>">
<%if(String.valueOf(unreadList.get(i).get("msgContent")).length()>16) {%>
<%=String.valueOf(unreadList.get(i).get("msgContent")).substring(0,16)+"..." %>
<%} else{ %>
<%=String.valueOf(unreadList.get(i).get("msgContent")) %>
<%} %>
</a><br>
<%
if(i>=1){//最多显示两条
break;
}
} %>
<center>
<!-- 点击查看更多未读消息 -->
<a href="/XXXAction.do %>"><font color="red">更多未读消息...</font></a></center>
</div>
<%} %>
</body>
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