Java implements file change monitoring

一. spring配置文件：

application.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop"xmlns:context="http://www.springframework.org/schema/context" xmlns:dwr="http://www.directwebremoting.org/schema/spring-dwr"xmlns:jaxrs="http://cxf.apache.org/jaxrs"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsdhttp://www.directwebremoting.org/schema/spring-dwr http://www.directwebremoting.org/schema/spring-dwr-3.0.xsdhttp://cxf.apache.org/jaxrs http://cxf.apache.org/schemas/jaxrs.xsd"><!-- 文件监测器 --> <bean id="monitor"class="com.interfaces.file.monitor.FileMonitorImpl"><constructor-arg index="0" value="10000" /> <!-- 监测时间间隔，单位：毫秒 --><constructor-arg index="1" ref="observer" /> <!-- 文件观察器 --></bean> <!-- 文件观察器 --> <bean id="observer"class="com.interfaces.file.monitor.FileObserverImpl"><constructor-arg index="0" value="D://UploadDir"/> <!-- 观察的目录 --><constructor-arg index="1" ref="filter"/> <!-- 文件过滤器--><constructor-arg index="2" ref="listener"/> <!-- 文件监听器 --></bean><!-- 文件监听器 --> <bean id="listener"class="com.interfaces.file.monitor.FileListener"/><!-- 文件过滤器 --> <bean id="filter"class="com.interfaces.file.monitor.FileFilterImpl"> <!-- 指定文件扩展名，只有指定的扩展名文件会被处理。不同的扩展名间以 "," 间隔，如：xml,txt,bak --><constructor-arg index="0" value="xml"/> </bean></beans>

二. spring上下文加载监听器：

SpringContextLoaderListener.class

import javax.servlet.ServletContextEvent;import org.springframework.web.context.ContextLoaderListener;public class SpringContextLoaderListener extends ContextLoaderListener{@Overridepublic void contextInitialized(ServletContextEvent event) {super.contextInitialized(event);FileMonitor scanner = getScanner();// 启动目录扫描器scanner.start();}@Overridepublic void contextDestroyed(ServletContextEvent event) {FileMonitor scanner = getScanner();// 关闭目录扫描器scanner.stop();super.contextDestroyed(event);}/*** 获取目录扫描器* @return*/private FileMonitor getScanner() {return getCurrentWebApplicationContext().getBean(FileMonitor.class);}}

三. web工程配置文件：

web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:web="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_4.xsd http://xmlns.jcp.org/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.4"><context-param><param-name>contextConfigLocation</param-name><param-value>classpath:application.xml</param-value></context-param><listener><listener-class>com.web.SpringContextLoaderListener</listener-class></listener></web-app>

四. 文件监测器

1. 接口：FileMonitor.class

import org.apache.commons.io.monitor.FileAlterationObserver;/*** 文件监测器角色*/public interface FileMonitor {/*** 注册观察器* @param observer 观察器*/void addObserver(FileAlterationObserver observer);/*** 删除观察器* @param observer 观察器*/void removeObserver(FileAlterationObserver observer); /*** 获取注册的所有观察器* @return 观察器集合*/Iterable<FileAlterationObserver> getObservers(); /*** 启动监测器*/void start(); /*** 停止监测器*/void stop(); /*** 获取监测间隔时间* @return 间隔时间（单位：毫秒）*/long getInterval(); }

2. 实现类：FileMonitorImpl.class

import java.util.concurrent.ThreadFactory;import org.apache.commons.io.monitor.FileAlterationMonitor;import org.apache.commons.io.monitor.FileAlterationObserver;import org.apache.commons.lang3.concurrent.BasicThreadFactory;/*** 监测器，监测时间间隔，设置文件观察器*/public class FileMonitorImpl implements FileMonitor{private final FileAlterationMonitor monitor;/*** 监测器线程名称*/private static final String MONITOR_THREAD_NAME = "File MONITOR Daemon";/*** 监测器线程Daemon标记*/private static final boolean DAEMON = false;/*** 定义监测时间间隔、文件观察器* @param interval 监测时间间隔* @param observer 文件观察者*/FileMonitorImpl(int interval, final FileAlterationObserver observer) {this(interval, observer, new BasicThreadFactory.Builder().namingPattern(MONITOR_THREAD_NAME).daemon(DAEMON).build()); } /*** 定义监测时间间隔、文件观察器和线程工厂* @param interval 监测时间间隔* @param observer 文件观察器* @param factory 线程工厂*/FileMonitorImpl(int interval, final FileAlterationObserver observer, final ThreadFactory factory) { this.monitor = new FileAlterationMonitor(interval, new FileAlterationObserver[] { observer });monitor.setThreadFactory(factory); } /*** 添加文件观察器* @param observer*/@Overridepublic void addObserver(FileAlterationObserver observer) {monitor.addObserver(observer);}/*** 删除文件观察器 * @param observer*/@Overridepublic void removeObserver(FileAlterationObserver observer) {monitor.removeObserver(observer);}/*** 获取注册的所有观察器* @return*/@Overridepublic Iterable<FileAlterationObserver> getObservers() {return monitor.getObservers();}/*** 启动监测器*/@Overridepublic void start() {try {monitor.start();} catch (Exception e) {e.printStackTrace();}}/*** 停止监测器*/@Overridepublic void stop() {try {monitor.stop();} catch (Exception e) {e.printStackTrace();}}/*** 获取监测时间间隔*/@Overridepublic long getInterval() {return monitor.getInterval(); }} 

五. 文件观察器

　1. 接口：FileObserver.class

import java.io.File;import org.apache.commons.io.monitor.FileAlterationListener;/*** 文件观察器角色*/public interface FileObserver {/*** 添加监听器* @param listener*/void addListener(final FileAlterationListener listener);/*** 删除监听器* @param listener*/void removeListener(final FileAlterationListener listener);/*** 获取注册的监听器* @return*/Iterable<FileAlterationListener> getListeners(); /*** 初始化观察器* @throws Exception*/void initialize() throws Exception; /*** 销毁观察器* @throws Exception*/void destroy() throws Exception; /*** 获取观察的目录* @return*/File getDirectory();/*** 获取文件过滤器* * @return*/public FileFilter getFilter();} 

2. 实现类：FileObserverImpl.class

import java.io.File;import java.io.IOException;import org.apache.commons.io.FileUtils;import org.apache.commons.io.IOCase;import org.apache.commons.io.monitor.FileAlterationListener;import org.apache.commons.io.monitor.FileAlterationObserver;/*** 文件观察器* * 当有文件创建、删除、或变更动作时，则消息通知监听器*/public class FileObserverImpl extends FileAlterationObserver implements FileObserver{private static final long serialVersionUID = -7239227289538993830L;/*** 文件过滤器*/private final FileFilter filter;/*** 设置要监听观察的目录，并设置文件过滤器和监听器，用以观察指定具有指定扩展名的文件* @param dir 观察监听的目录* @param filter 文件过滤器* @param listener 文件监听器*/public FileObserverImpl(String dir, final FileFilter filter, FileAlterationListener listener) {super(dir, filter, (IOCase) null);addListener(listener); this.filter = filter;File directory = new File(dir);// 如果目录不存在if(!directory.exists()) {try {FileUtils.forceMkdir(directory);} catch (IOException e) {e.printStackTrace();}}// 如果存在的是文件else if(directory.exists() && directory.isFile()) {try {FileUtils.forceDelete(directory);FileUtils.forceMkdir(directory);} catch (IOException e) {e.printStackTrace();}}}/*** 添加监听器*/@Overridepublic void addListener(final FileAlterationListener listener) {super.addListener(listener);}/*** 移除监听器*/@Overridepublic void removeListener(final FileAlterationListener listener) {super.removeListener(listener);}/*** 获取观察者对象的所有监听器*/@Overridepublic Iterable<FileAlterationListener> getListeners() {return super.getListeners();}/*** 初始化文件观察者*/@Overridepublic void initialize() throws Exception {super.initialize();}/*** 销毁文件观察者*/@Overridepublic void destroy() throws Exception {super.destroy();}/*** 获取所观察的目录*/@Overridepublic File getDirectory() {return super.getDirectory();}/*** 获取文件过滤器* @return*/public FileFilter getFilter() {return filter;} }

六. 文件监听器：

FileListener.class

import java.io.File;import org.apache.commons.io.monitor.FileAlterationListenerAdaptor;import org.apache.commons.io.monitor.FileAlterationObserver;/*** 文件监听器*/public final class FileListener extends FileAlterationListenerAdaptor {/*** 文件创建时执行的动作*/@Overridepublic void onFileCreate(File file) {// To do something}/*** 文件删除（转移）时执行的动作*/@Overridepublic void onFileDelete(File file) {// To do something}/*** 文件内容改变时执行的动作*/@Overridepublic void onFileChange(File file) {// To do something}/*** 开始执行监听时执行的动作*/@Overridepublic void onStart(FileAlterationObserver observer) {// To do something}/*** 停止监听时执行的动作*/@Overridepublic void onStop(FileAlterationObserver observer) {// To do something}}

七. 文件过滤器

1. 接口：FileFilter.class

/*** 文件过滤器角色，扩展自java.io.FileFilter*/public interface FileFilter extends java.io.FileFilter {/*** 获取定义的扩展名* * @return*/String[] getExtensions();}

2. 实现类：

FileFilterImpl.class

import java.io.File;import org.apache.commons.io.FilenameUtils;/*** 文件过滤器*/public class FileFilterImpl implements FileFilter{private String[] extensions;public FileFilterImpl(String... extensions) {this.extensions = extensions;}/*** 是否接受该文件*/@Overridepublic boolean accept(File pathname) {return FilenameUtils.isExtension(pathname.getName(), extensions); }/*** 获取定义的扩展名* @return */@Overridepublic String[] getExtensions() {return extensions;}}

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