请问老师这是怎么回事？
package com.imooc.total;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.http.HttpServletRequest;
public class RequestTotalListener implements ServletContextListener,ServletRequestListener{
@Override
public void requestDestroyed(ServletRequestEvent sre) {
// TODO Auto-generated method stub
}
@Override
public void requestInitialized(ServletRequestEvent sre) {
HttpServletRequest request=(HttpServletRequest)sre.getServletRequest();
String url=request.getRequestURL().toString();
if(url.endsWith("/rt")==true) {
return;
}
// TODO Auto-generated method stub
List<String> timeList=(List)sre.getServletContext().getAttribute("timList");
List<Integer> valueList=(List)sre.getServletContext().getAttribute("valueList");
Date date=new Date();
SimpleDateFormat sdf=new SimpleDateFormat("HH:mm");
String time=sdf.format(date);
if(timeList.indexOf(time) == -1) {
timeList.add(time);
valueList.add(1);
sre.getServletContext().setAttribute("timeList",timeList);
sre.getServletContext().setAttribute("valueList", valueList);
}else {
int index=timeList.indexOf(time);
int value=valueList.get(index);
valueList.set(index, value+1);
sre.getServletContext().setAttribute("valueList", valueList);
}
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
// TODO Auto-generated method stub
}
@Override
public void contextInitialized(ServletContextEvent sce) {
// TODO Auto-generated method stub
List timeList=new ArrayList();
List valueList=new ArrayList();
sce.getServletContext().setAttribute("timeList", timeList);
sce.getServletContext().setAttribute("valueList", valueList);
}
}package com.imooc.total;
import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
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 com.alibaba.fastjson.JSON;
/**
* Servlet implementation class RequestTotalServlet
*/
@WebServlet("/rt")
public class RequestTotalServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public RequestTotalServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
ServletContext context=request.getServletContext();
List<String> timeList=(List)context.getAttribute("timeList");
List<Integer> valueList=(List)context.getAttribute("valueList");
response.setContentType("text/html;charset=utf-8");
/*response.getWriter().println(timeList.toString());
response.getWriter().println("<br/>");
response.getWriter().println(valueList.toString());*/
Map result=new HashMap();
result.put("timeList",timeList);
result.put("valueList",valueList);
String json=JSON.toJSONString(result);
response.getWriter().println(json);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="js/echarts.min.js"></script>
<script type="text/javascript" src="js/jquery-3.5.1.min.js"></script>
</head>
<body>
<div id="main" style="width:600px;heigth:400px;"></div>
<script type="text/javascript">
function showChart(){
$.ajax({
url:"./rt",
type:"get",
datatype:"json";
success:function(json){
console.log(json.timeList);
console.log(json.valueList);
// 基于准备好的dom，初始化echarts实例
var myChart = echarts.init(document.getElementById('main'));
// 指定图表的配置项和数据
var option = {
title: {
text: '请求流量分析统计'
},
tooltip: {},
legend: {
data:['访问量']
},
xAxis: {
data: json.timeList
},
yAxis: {},
series: [{
name: '访问量',
type: 'bar',
data:json.valueList
}]
};
// 使用刚指定的配置项和数据显示图表。
myChart.setOption(option);
}
})
}
window.setInterval("showChart()",1000);
</script>
</body>
</html><!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>test page</title> </head> <body> <h1>I'm test page 1</h1> </body> </html>
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>test page</title> </head> <body> <h1>I'm test page 2</h1> </body> </html>
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>test page</title> </head> <body> <h1>I'm test page 3</h1> </body> </html>
源自：监听器
2-4 实现动态图表
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