apache common io包基本使用（包括文件的监听，过来，比较等）
原文参考http://www.javacodegeeks.com/2014/10/apache-commons-io-tutorial.html
Apache Commons IO 包绝对是好东西，地址在http://commons.apache.org/proper/commons-io/，下面用例子分别介绍：
1） 工具类
2） 输入
3） 输出
4） filters过滤
5） Comparators
6） 文件监控
总的入口例子为：
Java代码
[*]public class ApacheCommonsExampleMain {
[*]
[*] public static void main(String[] args) {
[*] UtilityExample.runExample();
[*]
[*] FileMonitorExample.runExample();
[*]
[*] FiltersExample.runExample();
[*]
[*] InputExample.runExample();
[*]
[*] OutputExample.runExample();
[*]
[*] ComparatorExample.runExample();
[*] }
[*]}
一 工具类包UtilityExample代码：
这个工具类包分如下几个主要工具类：
1） FilenameUtils:主要处理各种操作系统下对文件名的操作
2) FileUtils:处理文件的打开，移动，读取和判断文件是否存在
3） IOCASE：字符串的比较
4） FileSystemUtils:返回磁盘的空间大小
Java代码
[*]import java.io.File;
[*]import java.io.IOException;
[*]
[*]import org.apache.commons.io.FileSystemUtils;
[*]import org.apache.commons.io.FileUtils;
[*]import org.apache.commons.io.FilenameUtils;
[*]import org.apache.commons.io.LineIterator;
[*]import org.apache.commons.io.IOCase;
[*]
[*]public final class UtilityExample {
[*]
[*] // We are using the file exampleTxt.txt in the folder ExampleFolder,
[*] // and we need to provide the full path to the Utility classes.
[*] private static final String EXAMPLE_TXT_PATH =
[*] "C:\\Users\\Lilykos\\workspace\\ApacheCommonsExample\\ExampleFolder\\exampleTxt.txt";
[*]
[*] private static final String PARENT_DIR =
[*] "C:\\Users\\Lilykos\\workspace\\ApacheCommonsExample";
[*]
[*] public static void runExample() throws IOException {
[*] System.out.println("Utility Classes example...");
[*]
[*]
[*] // FilenameUtils
[*]
[*] System.out.println("Full path of exampleTxt: " +
[*] FilenameUtils.getFullPath(EXAMPLE_TXT_PATH));
[*]
[*] System.out.println("Full name of exampleTxt: " +
[*] FilenameUtils.getName(EXAMPLE_TXT_PATH));
[*]
[*] System.out.println("Extension of exampleTxt: " +
[*] FilenameUtils.getExtension(EXAMPLE_TXT_PATH));
[*]
[*] System.out.println("Base name of exampleTxt: " +
[*] FilenameUtils.getBaseName(EXAMPLE_TXT_PATH));
[*]
[*]
[*] // FileUtils
[*]
[*] // We can create a new File object using FileUtils.getFile(String)
[*] // and then use this object to get information from the file.
[*] File exampleFile = FileUtils.getFile(EXAMPLE_TXT_PATH);
[*] LineIterator iter = FileUtils.lineIterator(exampleFile);
[*]
[*] System.out.println("Contents of exampleTxt...");
[*] while (iter.hasNext()) {
[*] System.out.println("\t" + iter.next());
[*] }
[*] iter.close();
[*]
[*] // We can check if a file exists somewhere inside a certain directory.
[*] File parent = FileUtils.getFile(PARENT_DIR);
[*] System.out.println("Parent directory contains exampleTxt file: " +
[*] FileUtils.directoryContains(parent, exampleFile));
[*]
[*]
[*] // IOCase
[*]
[*] String str1 = "This is a new String.";
[*] String str2 = "This is another new String, yes!";
[*]
[*] System.out.println("Ends with string (case sensitive): " +
[*] IOCase.SENSITIVE.checkEndsWith(str1, "string."));
[*] System.out.println("Ends with string (case insensitive): " +
[*] IOCase.INSENSITIVE.checkEndsWith(str1, "string."));
[*]
[*] System.out.println("String equality: " +
[*] IOCase.SENSITIVE.checkEquals(str1, str2));
[*]
[*]
[*] // FileSystemUtils
[*] System.out.println("Free disk space (in KB): " + FileSystemUtils.freeSpaceKb("C:"));
[*] System.out.println("Free disk space (in MB): " + FileSystemUtils.freeSpaceKb("C:") / 1024);
[*] }
[*]}
输出：
Java代码
[*]Utility Classes example...
[*]Full path of exampleTxt: C:\Users\Lilykos\workspace\ApacheCommonsExample\ExampleFolder\
[*]Full name of exampleTxt: exampleTxt.txt
[*]Extension of exampleTxt: txt
[*]Base name of exampleTxt: exampleTxt
[*]Contents of exampleTxt...
[*] This is an example text file.
[*] We will use it for experimenting with Apache Commons IO.
[*]Parent directory contains exampleTxt file: true
[*]Ends with string (case sensitive): false
[*]Ends with string (case insensitive): true
[*]String equality: false
[*]Free disk space (in KB): 32149292
[*]Free disk space (in MB): 31395
二 FileMonitor工具类包
这个org.apache.commons.io.monitor 包中的工具类可以监视文件或者目录的变化，获得指定文件或者目录的相关信息，下面看例子：
Java代码
[*]import java.io.File;
[*]import java.io.IOException;
[*]
[*]import org.apache.commons.io.FileDeleteStrategy;
[*]import org.apache.commons.io.FileUtils;
[*]import org.apache.commons.io.monitor.FileAlterationListenerAdaptor;
[*]import org.apache.commons.io.monitor.FileAlterationMonitor;
[*]import org.apache.commons.io.monitor.FileAlterationObserver;
[*]import org.apache.commons.io.monitor.FileEntry;
[*]
[*]
[*]public final class FileMonitorExample {
[*]
[*] private static final String EXAMPLE_PATH =
[*] "C:\\Users\\Lilykos\\workspace\\ApacheCommonsExample\\ExampleFolder\\exampleFileEntry.txt";
[*]
[*] private static final String PARENT_DIR =
[*] "C:\\Users\\Lilykos\\workspace\\ApacheCommonsExample\\ExampleFolder";
[*]
[*] private static final String NEW_DIR =
[*] "C:\\Users\\Lilykos\\workspace\\ApacheCommonsExample\\ExampleFolder\\newDir";
[*]
[*] private static final String NEW_FILE =
[*] "C:\\Users\\Lilykos\\workspace\\ApacheCommonsExample\\ExampleFolder\\newFile.txt";
[*]
[*] public static void runExample() {
[*] System.out.println("File Monitor example...");
[*]
[*]
[*] // FileEntry
[*]
[*] // We can monitor changes and get information about files
[*] // using the methods of this class.
[*] FileEntry entry = new FileEntry(FileUtils.getFile(EXAMPLE_PATH));
[*]
[*] System.out.println("File monitored: " + entry.getFile());
[*] System.out.println("File name: " + entry.getName());
[*] System.out.println("Is the file a directory?: " + entry.isDirectory());
[*]
[*]
[*] // File Monitoring
[*]
[*] // Create a new observer for the folder and add a listener
[*] // that will handle the events in a specific directory and take action.
[*] File parentDir = FileUtils.getFile(PARENT_DIR);
[*]
[*] FileAlterationObserver observer = new FileAlterationObserver(parentDir);
[*] observer.addListener(new FileAlterationListenerAdaptor() {
[*]
[*] @Override
[*] public void onFileCreate(File file) {
[*] System.out.println("File created: " + file.getName());
[*] }
[*]
[*] @Override
[*] public void onFileDelete(File file) {
[*] System.out.println("File deleted: " + file.getName());
[*] }
[*]
[*] @Override
[*] public void onDirectoryCreate(File dir) {
[*] System.out.println("Directory created: " + dir.getName());
[*] }
[*]
[*] @Override
[*] public void onDirectoryDelete(File dir) {
[*] System.out.println("Directory deleted: " + dir.getName());
[*] }
[*] });
[*]
[*] // Add a monior that will check for events every x ms,
[*] // and attach all the different observers that we want.
[*] FileAlterationMonitor monitor = new FileAlterationMonitor(500, observer);
[*] try {
[*] monitor.start();
[*]
[*] // After we attached the monitor, we can create some files and directories
[*] // and see what happens!
[*] File newDir = new File(NEW_DIR);
[*] File newFile = new File(NEW_FILE);
[*]
[*] newDir.mkdirs();
[*] newFile.createNewFile();
[*]
[*] Thread.sleep(1000);
[*]
[*] FileDeleteStrategy.NORMAL.delete(newDir);
[*] FileDeleteStrategy.NORMAL.delete(newFile);
[*]
[*] Thread.sleep(1000);
[*]
[*] monitor.stop();
[*] } catch (IOException e) {
[*] e.printStackTrace();
[*] } catch (InterruptedException e) {
[*] e.printStackTrace();
[*] } catch (Exception e) {
[*] e.printStackTrace();
[*] }
[*] }
[*]}
输出如下：
Java代码
[*]File Monitor example...
[*]File monitored: C:\Users\Lilykos\workspace\ApacheCommonsExample\ExampleFolder\exampleFileEntry.txt
[*]File name: exampleFileEntry.txt
[*]Is the file a directory?: false
[*]Directory created: newDir
[*]File created: newFile.txt
[*]Directory deleted: newDir
[*]File deleted: newFile.txt
上面的特性的确很赞！分析下，这个工具类包下的工具类，可以允许我们创建跟踪文件或目录变化的监听句柄，当文件目录等发生任何变化，都可以用“观察者”的身份进行观察，
其步骤如下：
1） 创建要监听的文件对象
2） 创建FileAlterationObserver 监听对象，在上面的例子中，
File parentDir = FileUtils.getFile(PARENT_DIR);
FileAlterationObserver observer = new FileAlterationObserver(parentDir);
创建的是监视parentDir目录的变化，
3） 为观察器创建FileAlterationListenerAdaptor的内部匿名类，增加对文件及目录的增加删除的监听
4） 创建FileAlterationMonitor监听类，每隔500ms监听目录下的变化，其中开启监视是用monitor的start方法即可。
三 过滤器 filters
先看例子：
Java代码
[*]import java.io.File;
[*]
[*]import org.apache.commons.io.FileUtils;
[*]import org.apache.commons.io.IOCase;
[*]import org.apache.commons.io.filefilter.AndFileFilter;
[*]import org.apache.commons.io.filefilter.NameFileFilter;
[*]import org.apache.commons.io.filefilter.NotFileFilter;
[*]import org.apache.commons.io.filefilter.OrFileFilter;
[*]import org.apache.commons.io.filefilter.PrefixFileFilter;
[*]import org.apache.commons.io.filefilter.SuffixFileFilter;
[*]import org.apache.commons.io.filefilter.WildcardFileFilter;
[*]
[*]public final class FiltersExample {
[*]
[*] private static final String PARENT_DIR =
[*] "C:\\Users\\Lilykos\\workspace\\ApacheCommonsExample\\ExampleFolder";
[*]
[*] public static void runExample() {
[*] System.out.println("File Filter example...");
[*]
[*]
[*] // NameFileFilter
[*] // Right now, in the parent directory we have 3 files:
[*] // directory example
[*] // file exampleEntry.txt
[*] // file exampleTxt.txt
[*]
[*] // Get all the files in the specified directory
[*] // that are named "example".
[*] File dir = FileUtils.getFile(PARENT_DIR);
[*] String[] acceptedNames = {"example", "exampleTxt.txt"};
[*] for (String file: dir.list(new NameFileFilter(acceptedNames, IOCase.INSENSITIVE))) {
[*] System.out.println("File found, named: " + file);
[*] }
[*]
[*]
[*] //WildcardFileFilter
[*] // We can use wildcards in order to get less specific results
[*] // ? used for 1 missing char
[*] // * used for multiple missing chars
[*] for (String file: dir.list(new WildcardFileFilter("*ample*"))) {
[*] System.out.println("Wildcard file found, named: " + file);
[*] }
[*]
[*]
[*] // PrefixFileFilter
[*] // We can also use the equivalent of startsWith
[*] // for filtering files.
[*] for (String file: dir.list(new PrefixFileFilter("example"))) {
[*] System.out.println("Prefix file found, named: " + file);
[*] }
[*]
[*]
[*] // SuffixFileFilter
[*] // We can also use the equivalent of endsWith
[*] // for filtering files.
[*] for (String file: dir.list(new SuffixFileFilter(".txt"))) {
[*] System.out.println("Suffix file found, named: " + file);
[*] }
[*]
[*]
[*] // OrFileFilter
[*] // We can use some filters of filters.
[*] // in this case, we use a filter to apply a logical
[*] // or between our filters.
[*] for (String file: dir.list(new OrFileFilter(
[*] new WildcardFileFilter("*ample*"), new SuffixFileFilter(".txt")))) {
[*] System.out.println("Or file found, named: " + file);
[*] }
[*]
[*] // And this can become very detailed.
[*] // Eg, get all the files that have "ample" in their name
[*] // but they are not text files (so they have no ".txt" extension.
[*] for (String file: dir.list(new AndFileFilter( // we will match 2 filters...
[*] new WildcardFileFilter("*ample*"), // ...the 1st is a wildcard...
[*] new NotFileFilter(new SuffixFileFilter(".txt"))))) { // ...and the 2nd is NOT .txt.
[*] System.out.println("And/Not file found, named: " + file);
[*] }
[*] }
[*]}
可以看清晰看到，使用过滤器，可以分别在指定的目录下，寻找符合条件
的文件，比如以什么开头的文件名，支持通配符，甚至支持多个过滤器进行或的操作！
输出如下：
Java代码
[*]File Filter example...
[*]File found, named: example
[*]File found, named: exampleTxt.txt
[*]Wildcard file found, named: example
[*]Wildcard file found, named: exampleFileEntry.txt
[*]Wildcard file found, named: exampleTxt.txt
[*]Prefix file found, named: example
[*]Prefix file found, named: exampleFileEntry.txt
[*]Prefix file found, named: exampleTxt.txt
[*]Suffix file found, named: exampleFileEntry.txt
[*]Suffix file found, named: exampleTxt.txt
[*]Or file found, named: example
[*]Or file found, named: exampleFileEntry.txt
[*]Or file found, named: exampleTxt.txt
[*]And/Not file found, named: example
四 Comparators比较器
org.apache.commons.io.comparator包下的工具类，可以方便进行文件的比较：
Java代码
[*]import java.io.File;
[*]import java.util.Date;
[*]
[*]import org.apache.commons.io.FileUtils;
[*]import org.apache.commons.io.IOCase;
[*]import org.apache.commons.io.comparator.LastModifiedFileComparator;
[*]import org.apache.commons.io.comparator.NameFileComparator;
[*]import org.apache.commons.io.comparator.SizeFileComparator;
[*]
[*]public final class ComparatorExample {
[*]
[*] private static final String PARENT_DIR =
[*] "C:\\Users\\Lilykos\\workspace\\ApacheCommonsExample\\ExampleFolder";
[*]
[*] private static final String FILE_1 =
[*] "C:\\Users\\Lilykos\\workspace\\ApacheCommonsExample\\ExampleFolder\\example";
[*]
[*] private static final String FILE_2 =
[*] "C:\\Users\\Lilykos\\workspace\\ApacheCommonsExample\\ExampleFolder\\exampleTxt.txt";
[*]
[*] public static void runExample() {
[*] System.out.println("Comparator example...");
[*]
[*] //NameFileComparator
[*]
[*] // Let's get a directory as a File object
[*] // and sort all its files.
[*] File parentDir = FileUtils.getFile(PARENT_DIR);
[*] NameFileComparator comparator = new NameFileComparator(IOCase.SENSITIVE);
[*] File[] sortedFiles = comparator.sort(parentDir.listFiles());
[*]
[*] System.out.println("Sorted by name files in parent directory: ");
[*] for (File file: sortedFiles) {
[*] System.out.println("\t"+ file.getAbsolutePath());
[*] }
[*]
[*]
[*] // SizeFileComparator
[*]
[*] // We can compare files based on their size.
[*] // The boolean in the constructor is about the directories.
[*] // true: directory's contents count to the size.
[*] // false: directory is considered zero size.
[*] SizeFileComparator sizeComparator = new SizeFileComparator(true);
[*] File[] sizeFiles = sizeComparator.sort(parentDir.listFiles());
[*]
[*] System.out.println("Sorted by size files in parent directory: ");
[*] for (File file: sizeFiles) {
[*] System.out.println("\t"+ file.getName() + " with size (kb): " + file.length());
[*] }
[*]
[*]
[*] // LastModifiedFileComparator
[*]
[*] // We can use this class to find which file was more recently modified.
[*] LastModifiedFileComparator lastModified = new LastModifiedFileComparator();
[*] File[] lastModifiedFiles = lastModified.sort(parentDir.listFiles());
[*]
[*] System.out.println("Sorted by last modified files in parent directory: ");
[*] for (File file: lastModifiedFiles) {
[*] Date modified = new Date(file.lastModified());
[*] System.out.println("\t"+ file.getName() + " last modified on: " + modified);
[*] }
[*]
[*] // Or, we can also compare 2 specific files and find which one was last modified.
[*] // returns > 0 if the first file was last modified.
[*] // returns 0)
[*] System.out.println("File " + file1.getName() + " was modified last because...");
[*] else
[*] System.out.println("File " + file2.getName() + "was modified last because...");
[*]
[*] System.out.println("\t"+ file1.getName() + " last modified on: " +
[*] new Date(file1.lastModified()));
[*] System.out.println("\t"+ file2.getName() + " last modified on: " +
[*] new Date(file2.lastModified()));
[*] }
[*]}
输出如下：
Java代码
[*]Comparator example...
[*]Sorted by name files in parent directory:
[*] C:\Users\Lilykos\workspace\ApacheCommonsExample\ExampleFolder\comparator1.txt
[*] C:\Users\Lilykos\workspace\ApacheCommonsExample\ExampleFolder\comperator2.txt
[*] C:\Users\Lilykos\workspace\ApacheCommonsExample\ExampleFolder\example
[*] C:\Users\Lilykos\workspace\ApacheCommonsExample\ExampleFolder\exampleFileEntry.txt
[*] C:\Users\Lilykos\workspace\ApacheCommonsExample\ExampleFolder\exampleTxt.txt
[*]Sorted by size files in parent directory:
[*] example with size (kb): 0
[*] exampleTxt.txt with size (kb): 87
[*] exampleFileEntry.txt with size (kb): 503
[*] comperator2.txt with size (kb): 1458
[*] comparator1.txt with size (kb): 4436
[*]Sorted by last modified files in parent directory:
[*] exampleTxt.txt last modified on: Sun Oct 26 14:02:22 EET 2014
[*] example last modified on: Sun Oct 26 23:42:55 EET 2014
[*] comparator1.txt last modified on: Tue Oct 28 14:48:28 EET 2014
[*] comperator2.txt last modified on: Tue Oct 28 14:48:52 EET 2014
[*] exampleFileEntry.txt last modified on: Tue Oct 28 14:53:50 EET 2014
[*]File example was modified last because...
[*] example last modified on: Sun Oct 26 23:42:55 EET 2014
[*] exampleTxt.txt last modified on: Sun Oct 26 14:02:22 EET 2014
可以看到，在上面的代码中
NameFileComparator: 文件名的比较器，可以进行文件名称排序；
SizeFileComparator: 按照文件大小比较
LastModifiedFileComparator: 根据最新修改日期比较
五 input包
在 common io的org.apache.commons.io.input 包中，有各种对InputStream的实现类：
我们看下其中的TeeInputStream, ，它接受InputStream和Outputstream参数，例子如下：
Java代码
[*]import java.io.ByteArrayInputStream;
[*]import java.io.ByteArrayOutputStream;
[*]import java.io.File;
[*]import java.io.IOException;
[*]
[*]import org.apache.commons.io.FileUtils;
[*]import org.apache.commons.io.input.TeeInputStream;
[*]import org.apache.commons.io.input.XmlStreamReader;
[*]
[*]
[*]public final class InputExample {
[*]
[*] private static final String XML_PATH =
[*] "C:\\Users\\Lilykos\\workspace\\ApacheCommonsExample\\InputOutputExampleFolder\\web.xml";
[*]
[*] private static final String INPUT = "This should go to the output.";
[*]
[*] public static void runExample() {
[*] System.out.println("Input example...");
[*] XmlStreamReader xmlReader = null;
[*] TeeInputStream tee = null;
[*]
[*] try {
[*]
[*] // XmlStreamReader
[*]
[*] // We can read an xml file and get its encoding.
[*] File xml = FileUtils.getFile(XML_PATH);
[*]
[*] xmlReader = new XmlStreamReader(xml);
[*] System.out.println("XML encoding: " + xmlReader.getEncoding());
[*]
[*]
[*] // TeeInputStream
[*]
[*] // This very useful class copies an input stream to an output stream
[*] // and closes both using only one close() method (by defining the 3rd
[*] // constructor parameter as true).
[*] ByteArrayInputStream in = new ByteArrayInputStream(INPUT.getBytes("US-ASCII"));
[*] ByteArrayOutputStream out = new ByteArrayOutputStream();
[*]
[*] tee = new TeeInputStream(in, out, true);
[*] tee.read(new byte);
[*]
[*] System.out.println("Output stream: " + out.toString());
[*] } catch (IOException e) {
[*] e.printStackTrace();
[*] } finally {
[*] try { xmlReader.close(); }
[*] catch (IOException e) { e.printStackTrace(); }
[*]
[*] try { tee.close(); }
[*] catch (IOException e) { e.printStackTrace(); }
[*] }
[*] }
[*]}
输出：
Java代码
[*]Input example...
[*]XML encoding: UTF-8
[*]Output stream: This should go to the output.
tee = new TeeInputStream(in, out, true);
中，分别三个参数，将输入流的内容输出到输出流，true参数为最后关闭流
六 output工具类包
其中的org.apache.commons.io.output 是实现了outputstream,其中好特别的是
TeeOutputStream能将一个输入流分别输出到两个输出流
Java代码
[*]import java.io.ByteArrayInputStream;
[*]import java.io.ByteArrayOutputStream;
[*]import java.io.IOException;
[*]
[*]import org.apache.commons.io.input.TeeInputStream;
[*]import org.apache.commons.io.output.TeeOutputStream;
[*]
[*]public final class OutputExample {
[*]
[*] private static final String INPUT = "This should go to the output.";
[*]
[*] public static void runExample() {
[*] System.out.println("Output example...");
[*] TeeInputStream teeIn = null;
[*] TeeOutputStream teeOut = null;
[*]
[*] try {
[*]
[*] // TeeOutputStream
[*]
[*] ByteArrayInputStream in = new ByteArrayInputStream(INPUT.getBytes("US-ASCII"));
[*] ByteArrayOutputStream out1 = new ByteArrayOutputStream();
[*] ByteArrayOutputStream out2 = new ByteArrayOutputStream();
[*]
[*] teeOut = new TeeOutputStream(out1, out2);
[*] teeIn = new TeeInputStream(in, teeOut, true);
[*] teeIn.read(new byte);
[*]
[*] System.out.println("Output stream 1: " + out1.toString());
[*] System.out.println("Output stream 2: " + out2.toString());
[*]
[*] } catch (IOException e) {
[*] e.printStackTrace();
[*] } finally {
[*] // No need to close teeOut. When teeIn closes, it will also close its
[*] // Output stream (which is teeOut), which will in turn close the 2
[*] // branches (out1, out2).
[*] try { teeIn.close(); }
[*] catch (IOException e) { e.printStackTrace(); }
[*] }
[*] }
[*]}
输出：
Java代码
[*]Output example...
[*]Output stream 1: This should go to the output.
[*]Output stream 2: This should go to the output.
完整代码下载：http://a3ab771892fd198a96736e50.javacodegeeks.netdna-cdn.com/wp-content/uploads/2014/10/ApacheCommonsIOExample.rar
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