老是我这个一直报错500

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老是我这个一直报错500

来源：2-1 请求流量分析统计-开发监听器

weixin_慕设计3058955

2020-01-05 15:52:55

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 contextDestroyed(ServletContextEvent sce) {

// TODO Auto-generated method stub

}

@Override

public void contextInitialized(ServletContextEvent sce) {

// TODO Auto-generated method stub

List<String> timeList=new ArrayList<>();

List<Integer> valueList=new ArrayList<>();

sce.getServletContext().setAttribute("timeList", "timeList");

sce.getServletContext().setAttribute("valueList", "valueList");

}

@Override

public void requestDestroyed(ServletRequestEvent sre) {

// TODO Auto-generated method stub

}

@Override

public void requestInitialized(ServletRequestEvent sre) {

// TODO Auto-generated method stub

List<String> timeList=(List)sre.getServletContext().getAttribute("timeList");

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);

sre.getServletContext().setAttribute("valueList", "valueList");

}

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">

<display-name>requesttotal</display-name>

<welcome-file-list>

<welcome-file>index.html</welcome-file>

<welcome-file>index.htm</welcome-file>

<welcome-file>index.jsp</welcome-file>

<welcome-file>default.html</welcome-file>

<welcome-file>default.htm</welcome-file>

<welcome-file>default.jsp</welcome-file>

</welcome-file-list>

<listener-class>com.imooc.total.RequestTotalListener</listener-class>

</listener>

</web-app>

package com.imooc.total;

import java.io.IOException;

import java.util.List;

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 RequestTotalSerlvet

@WebServlet("/req")

public class RequestTotalSerlvet extends HttpServlet {

private static final long serialVersionUID = 1L;

/**

* @see HttpServlet#HttpServlet()

public RequestTotalSerlvet() {

super();

// TODO Auto-generated constructor stub

}

/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

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(valueList.toString());

}

<!DOCTYPE html>

<html>

<head>

<title>Insert title here</title>

</head>

<body>

</body>

</html>

<!DOCTYPE html>

<html>

<head>

<title>Insert title here</title>

</head>

<body>

</body>

</html>

写回答

1回答

好帮手慕酷酷

2020-01-05

同学你好，根据报错信息是类型转换的异常。不能将String类型转换为List。根据报错定位到RequestTotalListener类的39行代码。

如：

发现在设置值的时候设置的是String字符串而不是List集合。应该设置timeList和valueList集合，删除双引号。

具体如下：

修改后如下：

如果我的回答解决了你的疑惑，请采纳！祝学习愉快！

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