IO

Apache Commons IO

IO 相关操作实用工具类

Posted by John-zero on December 27, 2017

Apache Commons IO

官网主页
	http://commons.apache.org/proper/commons-io/
	
User guide
	http://commons.apache.org/proper/commons-io/description.html

项目引入

Maven
	<!-- https://mvnrepository.com/artifact/commons-io/commons-io -->
	<dependency>
		<groupId>commons-io</groupId>
		<artifactId>commons-io</artifactId>
		<version>2.6</version>
	</dependency>
	
Gradle 
	// https://mvnrepository.com/artifact/commons-io/commons-io
	compile group: 'commons-io', name: 'commons-io', version: '2.6'

主要涉及

  1. Utility classes (使用工具类)
  2. Input (输入)
  3. Output (输出)
  4. Filters (过滤器)
  5. Comparators (比较器)
  6. File Monitor (文件监控)

File Monitor


import org.apache.commons.io.monitor.FileAlterationListener;
import org.apache.commons.io.monitor.FileAlterationMonitor;
import org.apache.commons.io.monitor.FileAlterationObserver;
import org.slf4j.LoggerFactory;

import java.io.File;

/**
 * Created by John_zero on 2017/12/27.
 */
public final class FileUtils
{

    private static final org.slf4j.Logger logger = LoggerFactory.getLogger(FileUtils.class);

    /**
     * 文件夹监听 (默认开启) (底层用的是 Thread 运行, 所以不建议监听太多)
     * @param directoryName 文件夹路径
     * @param fileAlterationListener
     * @param monitoInterval
     * @return
     */
    public static FileAlterationMonitor directoryMonitor (String directoryName, FileAlterationListener fileAlterationListener, long monitoInterval)
    {
        if(directoryName == null)
            return null;

        if(fileAlterationListener == null)
            return null;

        if(monitoInterval <= 0)
            monitoInterval = 3;

        File monitorDirectoryFile = new File(directoryName);
        if(!monitorDirectoryFile.exists())
        {
            monitorDirectoryFile.mkdirs();
        }
        else if(monitorDirectoryFile.exists())
        {
            if(!monitorDirectoryFile.isDirectory())
                return null;
        }

        FileAlterationObserver fileAlterationObserver = new FileAlterationObserver(monitorDirectoryFile);

        fileAlterationObserver.addListener(fileAlterationListener);

        FileAlterationMonitor fileAlterationMonitor = new FileAlterationMonitor(monitoInterval, fileAlterationObserver);

        try
        {
            fileAlterationMonitor.start();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

        return fileAlterationMonitor;
    }

}

使用工具类:

String directoryPath = ""; // 监控的文件夹路径

FileAlterationMonitor fileAlterationMonitor = FileUtils.directoryMonitor(directoryPath, new FileAlterationListener() {
	@Override
	public void onStart(FileAlterationObserver fileAlterationObserver) { }

	@Override
	public void onStop(FileAlterationObserver fileAlterationObserver) { }

	@Override
	public void onDirectoryCreate(File file) { }

	@Override
	public void onDirectoryChange(File file) { }

	@Override
	public void onDirectoryDelete(File file) { }

	@Override
	public void onFileCreate(File file)
	{
		try
		{
			// TODO 
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
	}

	@Override
	public void onFileChange(File file)
	{
		try
		{
			// TODO 
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
	}

	@Override
	public void onFileDelete(File file)
	{
		try
		{
			// TODO 
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
	}

}, 2);

注意点:

  1. 在 FileAlterationListener 接口实现函数内必须使用 try-catch 捕获异常, 如果不然出现异常没有捕获会导致后续监听无效…

  2. 监听的文件夹或者文件路径如果是共享模式, 监听会失效, 对于共享模型下的文件夹或者文件请谨慎使用之…

扩展

文件操作监听工具: http://file-leak-detector.kohsuke.org

文件上传(阿里云 OSS SDK, 各种骚操作): https://github.com/aliyun/aliyun-oss-java-sdk

其他

其他几个相关领域的使用就比较简单, 就没贴代码了哈…

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