java web配置文件修改监听

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工程的总体结构如下：

1. pom文件

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">  <modelVersion>4.0.0</modelVersion>  <groupId>com.johnfnash.learn</groupId>  <artifactId>config-listen</artifactId>  <packaging>war</packaging>  <version>0.0.1-SNAPSHOT</version>  <name>config-listen Maven Webapp</name>  <url>http://maven.apache.org</url>      <properties>  <springframework.version>4.1.4.RELEASE</springframework.version>  </properties>    <dependencies>  <!-- spring相关包-->  <dependency>  <groupId>org.springframework</groupId>  <artifactId>spring-core</artifactId>  <version>${springframework.version}</version>  </dependency>  <dependency>  <groupId>org.springframework</groupId>  <artifactId>spring-beans</artifactId>  <version>${springframework.version}</version>  </dependency>  <dependency>  <groupId>org.springframework</groupId>  <artifactId>spring-context</artifactId>  <version>${springframework.version}</version>  </dependency>  <dependency>  <groupId>org.springframework</groupId>  <artifactId>spring-web</artifactId>  <version>${springframework.version}</version>  </dependency>    <!-- servlet --><dependency><groupId>javax.servlet</groupId><artifactId>servlet-api</artifactId><version>2.5</version><scope>provided</scope></dependency><dependency><groupId>javax.servlet.jsp</groupId><artifactId>jsp-api</artifactId><version>2.0</version><scope>provided</scope></dependency>  </dependencies>    <build>    <finalName>config-listen</finalName>  </build></project>

2. 监听器类

继承自 Spring的 ContextLoaderListener

package com.johnfnash.learn.config.listener;import java.io.File;import java.util.Timer;import java.util.TimerTask;import javax.servlet.ServletContextEvent;import org.springframework.web.context.ContextLoaderListener;/** *配置文件更改listener */public class ConfigModifyListener extends ContextLoaderListener {/** 配置文件的相对路径 */private final static String FILE_NAME = "/configue.properties";/** 文件更改时间 */private long modifyTime = 0;/** 文件 */private File file;@Overridepublic void contextInitialized(ServletContextEvent event) {super.contextInitialized(event);    String rootPath = getClass().getResource("/").getFile().toString();      System.out.println("curr: " + rootPath);file = new File(rootPath + "/" + FILE_NAME);//启动定时任务new Timer().schedule(new CheckFileTask(), 10000, 20000);}/** * 检测文件更新任务  */class CheckFileTask extends TimerTask {public void run() {long time = file.lastModified();System.out.println("time: " + time);if(0 == modifyTime) {modifyTime = time;} else if(time != modifyTime) {//文件被改动,在此可以做出相应操作System.out.println("File has been changed!");modifyTime = time;}}}}

其中配置文件放在 src/main/resources下

3. web.xml

这里需要将新建的ConfigModifyListener随web项目一起启动

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" ><web-app>  <display-name>Archetype Created Web Application</display-name>    <!--加载spring配置文件 -->  <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:applicationContext-*.xml</param-value>  </context-param>    <!--设置一起动当前的Web应用，就加载Spring，让Spring管理Bean-->  <listener> <listener-class>com.johnfnash.learn.config.listener.ConfigModifyListener </listener-class>  </listener>  </web-app>

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