关于图表中的请求次数变动，每次刷新访问量会+2而不是+1
来源：2-4 实现动态图表
Ranron
2019-12-03 21:15:41
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;
public class RequestTotalListener implements ServletContextListener,ServletRequestListener{
@Override
public void requestDestroyed(ServletRequestEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public void requestInitialized(ServletRequestEvent arg0) {
List<String> timeList=(List<String>) arg0.getServletContext().getAttribute("timeList");
List<Integer> valueList=(List<Integer>)arg0.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);
arg0.getServletContext().setAttribute("timeList", timeList);
arg0.getServletContext().setAttribute("valueList", valueList);
}else {
int a = timeList.indexOf(time);
int value=valueList.get(a);
valueList.set(a, value+1);
arg0.getServletContext().setAttribute("valueList", valueList);
}
}
@Override
public void contextDestroyed(ServletContextEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public void contextInitialized(ServletContextEvent arg0) {
List timeList = new ArrayList();
List valueList = new ArrayList();
arg0.getServletContext().setAttribute("timeList",timeList);
arg0.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 com.alibaba.fastjson.JSON;
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;
/**
* 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<String>) context.getAttribute("timeList");
List<Integer> valueList = (List<Integer>) 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 map = new HashMap();
map.put("timeList", timeList);
map.put("valueList", valueList);
String json=JSON.toJSONString(map);
response.getWriter().println(json);
System.out.println("收到请求");
}
}<!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-3.4.1.min.js"></script>
</head>
<body>
<div id="main" style="width: 600px;height:400px;"></div>
<script type="text/javascript">
$.ajax({
"url":"./rt",
"type":"get",
"dataType":"json",
"success" : function(json){
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: 'line',
data: json.valueList
}]
};
// 使用刚指定的配置项和数据显示图表。
myChart.setOption(option);
}
})
// 基于准备好的dom，初始化echarts实例
</script>
</body>
</html>
2回答
-
同学你好，你的理解是正确的，这里ajax的请求也会被监听器所拦截到，所以访问量回家2，在本节的视频中16分钟左右。老师会讲到将ajax的请求的请求排出到请求范围外的方式。同学可以继续看一下视频的内容。
如果我的回答解决了你的疑惑，请采纳！祝学习愉快！
0 -
Ranron
提问者
2019-12-03
好像是因为页面本身的请求+ajax请求，所以一次+2.。
0
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