启动tomcat时加载配置文件信息

 1.创建一个class 需要 导入ServletContextListener

package com;

import java.io.IOException;
import java.util.Properties;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;


public class TestL implements ServletContextListener
{
	public static Properties p  = new Properties();; 
	@Override
	public void contextDestroyed(ServletContextEvent arg0)
	{
		//未知调用时刻
		System.out.println(111111);
		
	}
	@Override
	public void contextInitialized(ServletContextEvent event)
	{
		ServletContext servletContext = event.getServletContext();
		
		
		try {
			p.load(servletContext.getResourceAsStream("/WEB-INF/config/data.properties"));
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		// 在应用启动时候调用
		System.out.println(2222);
		
	}
	public static String getProValue(String key) { 
		 return p.getProperty(key);
	}
}

2. WEB-INF/config/data.properties 文件
内容：
WCITY.WEATHER.URL=http://218.207.217.158:8080/weather/QueryByCityNameAndReturnJson.do

3.web.xml 文件
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>Testxl</display-name>
 
  <listener>
  <listener-class>com.TestL</listener-class>
   </listener>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

 

 

4.测试类

 

package com;
public class Pcommon
{
 public void getI(String s)
 {
	 String ss = TestL.getProValue("WCITY.WEATHER.URL");
	 System.out.println(ss+"====ddd=="+s);
 }

}