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ServletContextListener实现全局配置装载入内存

2015-02-05 16:31 239 查看

(2011-03-27 19:34:06)

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杂谈

分类： java和数据库

1.定义ServletContextListener

public class ApplicationLoader implements ServletContextListener{

private String ip;

private String port;

private String username;

private String password;

private String server;

public void contextInitialized(ServletContextEvent arg0) {

//装载配置文件

this.loadXmlConfig();

// 将配置文件里的值装入context属性,这样可以在JSP,SERVLET里调用

ServletContext context = arg0.getServletContext();

context.setAttribute("ip", this.ip);

context.setAttribute("port", this.port);

context.setAttribute("username", this.username);

context.setAttribute("password", this.password);

context.setAttribute("server", this.server);

}

public void loadXmlConfig() {

//获取配置文件路径, 定义在系统环境变量中

String xmlFile = System.getenv(Constants.ENVNAME);

//Dom4J方式获取XML文件的节点值

List<String> retList = null;

retList = Dom4JParser.readNodeText(new File(

xmlFile+"/ibiconfig/xml/amconfig.xml"),"//host/ip");

if(null != retList){

for(String temp:retList){

this.ip = temp;

}

}

//Dom4J方式获取XML文件的节点值

retList = Dom4JParser.readNodeText(new File(

xmlFile+"/ibiconfig/xml/amconfig.xml"),"//host/port");

if(null != retList){

for(String temp:retList){

this.port = temp;

}

}

//Dom4J方式获取XML文件的节点值

retList = Dom4JParser.readNodeText(new File(

xmlFile+"/ibiconfig/xml/amconfig.xml"),"//host/authentication/username");

if(null != retList){

for(String temp:retList){

this.username = temp;

}

}

//Dom4J方式获取XML文件的节点值

retList = Dom4JParser.readNodeText(new File(

xmlFile+"/ibiconfig/xml/amconfig.xml"),"//host//authentication/password");

if(null != retList){

for(String temp:retList){

this.password = temp;

}

}

//Dom4J方式获取XML文件的节点值

retList = Dom4JParser.readNodeText(new File(

xmlFile+"/ibiconfig/xml/amconfig.xml"),"//host//authentication/server");

if(null != retList){

for(String temp:retList){

this.server = temp;

}

}

}

2.修改WEB-INF/web.xml, 启用前面定义的listener

<listener>

<listener-class>com.machome.system.ApplicationLoader</listener-class>

</listener>

3.在JSP页面里可以调用listener装入的变量值

<%@ page language="java" contentType="text/html; charset=UTF-8"

pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

<br />

<%=getServletContext().getAttribute("ip")%> <br />

<%=getServletContext().getAttribute("username")%> <br />

<%=getServletContext().getAttribute("password")%> <br />

</body>

</html>

4.自定义XML配置文件

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



<root>

<host>

<ip>192.168.0.101</ip>

<port>8080</port>

<authentication>

<username>macg</username>

<password>008421</password>

<server>EDASERVE</server>

</authentication>

</host>

</root>

前面采用的是读取环境变量获取XML文件路径,我们应该把这个配置文件的路径设到环境变量中.这里不赘述.

你也可以直接采用文件物理路径,访问更简单些,但路径做死在程序里,不好修改.

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ServletContextListener实现全局配置装载入内存

侦听器

全局变量

xml

杂谈