JAVA轻量级文件监控

Bertha 。 2022-08-23 14:50 173阅读 0赞

介绍

本文主要介绍一种轻量级的文件监控方式，对文件的Create & Change & Delete，都有一个对应的Event方法来进行处理。对于核心的File Monitor Class，我们继承一个监听适配器类FileAlterationListenerAdaptor，这样会更方便，就不用再去重写每个Event方法。

File Generator Class

package shuai.study.file.generator;
    
    import java.io.IOException;
    import java.nio.file.Files;
    import java.nio.file.Paths;
    import java.util.Date;
    
    import org.apache.log4j.Logger;
    
    import shuai.study.file.tooler.CommonTooler;
    
    /**
     * @author shengshu
     * 
     */
    public class FileGenerator implements Runnable {
    	private static final Logger LOG = Logger.getLogger(FileGenerator.class);
    
    	private String directory = null;
    
    	private static Date date = new Date();
    
    	public FileGenerator(String directory) {
    		this.directory = directory;
    	}
    
    	private void generator(String directory) {
    		for (int i = 0; i < 10; i++) {
    			String fileName = CommonTooler.getDateTimeFormat(date) + "-" + Thread.currentThread().getId() + i + ".pm";
    
    			LOG.info("[Path]: " + directory + "/" + fileName);
    
    			try {
    				// Create file (path: directory/fileName)
    				Files.createFile(Paths.get(directory, fileName));
    			} catch (IOException ioe) {
    				ioe.printStackTrace();
    			}
    		}
    	}
    
    	@Override
    	public void run() {
    		this.generator(directory);
    	}
    }

File Monitor Class

package shuai.study.file.monitor;
    
    import java.io.File;
    import java.io.IOException;
    
    import org.apache.commons.io.FileUtils;
    import org.apache.commons.io.FilenameUtils;
    import org.apache.commons.io.filefilter.FileFilterUtils;
    import org.apache.commons.io.monitor.FileAlterationListenerAdaptor;
    import org.apache.commons.io.monitor.FileAlterationMonitor;
    import org.apache.commons.io.monitor.FileAlterationObserver;
    import org.apache.log4j.Logger;
    
    import shuai.study.file.tooler.CommonTooler;
    
    /**
     * @author shengshu
     * 
     */
    public class FileMonitor extends FileAlterationListenerAdaptor {
    	private static final Logger LOG = Logger.getLogger(FileMonitor.class);
    
    	private static FileMonitor fileMonitor;
    
    	private static int pageNumber = 0;
    
    	private FileMonitor() {
    
    	}
    
    	// Get singleton object instance
    	public static FileMonitor getFileMonitor() {
    		if (fileMonitor == null) {
    			synchronized (FileMonitor.class) {
    				if (fileMonitor == null) {
    					fileMonitor = new FileMonitor();
    				}
    			}
    		}
    
    		return fileMonitor;
    	}
    
    	// Create file event
    	@Override
    	public void onFileCreate(File file) {
    		LOG.info("[Create]: " + file.getAbsolutePath());
    
    		String fileAbsolutePath = file.getAbsolutePath();
    		String fileAbsoluteParentPath = file.getParent();
    		String fileBaseName = FilenameUtils.getBaseName(fileAbsolutePath);
    
    		File destFile = new File(fileAbsoluteParentPath + File.separator + fileBaseName + "-" + CommonTooler.pagingFormat(pageNumber) + ".xml");
    
    		try {
    			FileUtils.moveFile(file, destFile);
    		} catch (IOException ioe) {
    			ioe.printStackTrace();
    		}
    
    		pageNumber++;
    	}
    
    	// Change file event
    	@Override
    	public void onFileChange(File file) {
    		LOG.info("[Change]: " + file.getAbsolutePath());
    	}
    
    	// Delete file event
    	@Override
    	public void onFileDelete(File file) {
    		LOG.info("[Delete]: " + file.getAbsolutePath());
    	}
    
    	public void monitor(String directory, int interval) {
    		// Observer file whose suffix is pm 
    		FileAlterationObserver fileAlterationObserver = new FileAlterationObserver(directory, FileFilterUtils.and(FileFilterUtils.fileFileFilter(),
    				FileFilterUtils.suffixFileFilter(".pm")), null);
    
    		// Add listener for event (file create & change & delete)
    		fileAlterationObserver.addListener(this);
    
    		// Monitor per interval
    		FileAlterationMonitor fileAlterationMonitor = new FileAlterationMonitor(interval, fileAlterationObserver);
    
    		try {
    			// Start to monitor
    			fileAlterationMonitor.start();
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    }

File Tester Class

package shuai.study.file.tester;
    
    import java.io.IOException;
    import java.nio.file.Files;
    import java.nio.file.Paths;
    
    import org.apache.log4j.Logger;
    
    import shuai.study.file.generator.FileGenerator;
    import shuai.study.file.monitor.FileMonitor;
    
    /**
     * @author shengshu
     * 
     */
    public class FileTester {
    	private static final Logger LOG = Logger.getLogger(FileTester.class);
    
    	private static String directory = "/home/omc/tmp";
    
    	public static void main(String[] args) {
    		// Create directory if it does not exist 
    		try {
    			Files.createDirectory(Paths.get(directory));
    		} catch (IOException ioe) {
    			ioe.printStackTrace();
    		}
    
    		LOG.info("File Monitor...");
    		// Start to monitor file event per 500 milliseconds
    		FileMonitor.getFileMonitor().monitor(directory, 500);
    
    		LOG.info("File Generater...");
    		// New runnable instance
    		FileGenerator fileGeneratorRunnable = new FileGenerator(directory);
    
    		// Start to multi-thread for generating file
    		for (int i = 0; i < 10; i++) {
    			Thread fileGeneratorThread = new Thread(fileGeneratorRunnable);
    			fileGeneratorThread.start();
    		}
    	}
    
    }

Common Tool Class

package shuai.study.file.tooler;
    
    import java.text.SimpleDateFormat;
    import java.util.Date;
    
    /**
     * @author shengshu
     * 
     */
    public class CommonTooler {
    
    	// Date time format
    	public static String getDateTimeFormat(Date date) {
    		SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyyMMdd-HHmm");
    		String dateTime = simpleDateFormat.format(date);
    
    		return dateTime;
    	}
    
    	// Page format
    	public static String pagingFormat(int pageNumber) {
    		String pageNumberStr = "P00";
    
    		if (pageNumber < 0) {
    			throw new NumberFormatException("The page number should not be negative");
    		}
    
    		if (pageNumber < 10) {
    			pageNumberStr = String.format("P0%d", pageNumber);
    		} else {
    			pageNumberStr = String.format("P%d", pageNumber);
    		}
    
    		return pageNumberStr;
    	}
    
    }