org.apache.commons.io

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Apache Commons包含了很多开源的工具，用于解决平时编程经常会遇到的问题，减少重复劳动。其中CommonsIO是Apache的一个开源的工具包，封装了IO操作的相关类，使用CommonsIO可以很方便的读写文件、URL代码等。Commons IO是JakartaCommons项目的一个子项目。用来帮助进行IO功能开发．它包含三个主要的领域:

Utility classes-提供一些静态方法来完成公共任务．
Filters-提供文件过滤器的各种实现．
Streams-提供实用的Stream，reader与 writer实现．

项目主页：http://commons.apache.org/io/

官网Commons IO的简介：

Commons IO is a library of utilities to assist with developingIO functionality.

There are six main areas included:

Utility classes - with static methods to perform commontasks
Input - useful Input Stream and Reader implementations
Output - useful Output Stream and Writer implementations
Filters - various implementations of file filters
Comparators - various implementations ofjava.util.Comparator for files
File Monitor - a component for monitoring file systemevents

Packages

org.apache.commons.io

This package defines utility classes for working with streams,readers, writers and files.

org.apache.commons.io.comparator

This package provides variousComparator implementations forFiles.

org.apache.commons.io.filefilter

This package defines an interface (IOFileFilter) that combines bothFileFilter and FilenameFilter.

org.apache.commons.io.input

This package provides implementations of input classes, suchasInputStreamand Reader.

org.apache.commons.io.output

This package provides implementations of output classes,such asOutputStream andWriter.

org.apache.commons.io.filefilter
filefilter包中包含了大量的文件过滤器，这些过滤器都继承或实现了java.io.FileFilter和java.io.FilenameFilter两个接口，如：HiddenFileFilter、SizeFileFilter，实现了对文件或目录的过滤。
例如，显示当前目录下的所有隐藏文件：

     File dir = new File(".");     String[] files = dir.list( HiddenFileFilter.HIDDEN );      for ( int i = 0; i < files.length; i++ )      {         System.out.println(files[i]);      }

类图

Apache <wbr>Commons <wbr>IO <wbr>(二) <wbr>- <wbr>FileFilter

过滤器

               功能
TrueFileFilter      不进行过滤
FalseFileFilter     过滤所有文件及目录

FileFileFilter      仅接受文件

DirectoryFilter 仅接受目录

PrefixFileFilter 基于前缀（不带路径的文件名)

SuffixFileFilter 基于后缀(不带路径的文件名)

NameFileFilter 基于文件名称(不带路径的文件名)

WildcardFileFilter 基于通配符(不带路径的文件名)
RegexFileFilter 基于正则表达式

AgeFileFilter 基于最后修改时间

SizeFileFilter      基于文件尺寸
MagicNumberFileFileter 基于Magic Number
EmptyFileFilter     基于文件或目录是否为空
HiddenFileFilter    基于文件或目录是否隐藏

CanReadFileFilter   基于是否可读
CanWriteFileFilter  基于是否可写入

DelegateFileFilter  将普通的FileFilter和FilenameFilter包装成IOFileFilter

复合过滤器            功能
AndFileFilter       基于AND逻辑运算
OrFileFilter        基于OR逻辑运算
NotFileFilter       基于NOT逻辑运算

工具类：FileFilterUtils

提供一些工厂方法用于生成各类文件过滤器
提供一些静态方法用于对指定的File集合进行过滤

package simple.io;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;
import org.apache.commons.io.FileSystemUtils;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.FilenameUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.io.LineIterator;
import org.apache.commons.io.filefilter.AndFileFilter;
import org.apache.commons.io.filefilter.DirectoryFileFilter;
import org.apache.commons.io.filefilter.FileFilterUtils;
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.junit.Test;
public class ApacheIO {
/**
* 用普通的Java IO来解析HTML
*/
@Test
public void testReadURL1()throws MalformedURLException, IOException{
InputStream in = new URL( "http://www.blogjava.net/rongxh7" ).openStream();
try {
InputStreamReader inR = new InputStreamReader( in );
BufferedReader buf = new BufferedReader( inR );
String line;
while ( ( line = buf.readLine() ) !=null ) {
System.out.println( line );
}
} finally {
in.close();
}
}
/**
* 用Apache IO来解析HTML
* 学习要点:
* IOUtils contains utility methods dealing with reading, writing and copying.
* The methods work on InputStream, OutputStream, Reader and Writer.
*/
@Test
public void testReadURL2()throws MalformedURLException, IOException {
InputStream in = new URL("http://www.blogjava.net/rongxh7").openStream();
try {
System.out.println(IOUtils.toString(in));
} finally {
IOUtils.closeQuietly(in);
}
}
/**
* 用Apache IO来读文件
* 学习要点:
* The FileUtils class contains utility methods for working with File objects.
* These include reading, writing, copying and comparing files.
*/
@Test
public void testReadFile()throws IOException {
File file = new File("README");
List<String> lines = FileUtils.readLines(file, "GBK");
for(String line : lines){
System.out.println(line);
}
}
/**
* 用Apache IO来操作文件名
* The FilenameUtils class contains utility methods
* for working with filenames without using File objects.
*/
@Test
public void testFileName() {
String filename = "C:/a/b/ccc.txt";
String baseName = FilenameUtils.getBaseName(filename); //ccc
String extName = FilenameUtils.getExtension(filename); //txt
String fullPath = FilenameUtils.getFullPath(filename); //C:/a/b
String name = FilenameUtils.getName(filename); //ccc.txt
System.out.println(baseName);
System.out.println(extName);
System.out.println(fullPath);
System.out.println(name);
}
/**
* 用Apache IO查询磁盘空间
* The FileSystemUtils class contains utility methods
* for working with the file system to access functionality not supported by the JDK.
*/
@Test
public void testFindDrive()throws IOException{
long space = FileSystemUtils.freeSpaceKb("C:/");//查C盘还剩下多少可用空间
System.out.println("C盘可用空间为: " + space/1024 +" MB");
}
/**
* Line Iterator的用法
* The org.apache.commons.io.LineIterator class provides a flexible way
* for working with a line-based file. An instance can be created directly,
* or via factory methods on FileUtils or IOUtils.
*/
@Test
public void testLineIterater()throws IOException{
File file = new File("README");
LineIterator it = FileUtils.lineIterator(file, "GBK");
try{
while(it.hasNext()){
String line = it.nextLine();
System.out.println(line);
}
} finally {
LineIterator.closeQuietly(it);
}
}
/**
*
* 各种常用的FileFiter
*
* There are a number of 'primitive' filters:
*
* DirectoryFilter Only accept directories
* PrefixFileFilter Filter based on a prefix
* SuffixFileFilter Filter based on a suffix
* NameFileFilter Filter based on a filename
* WildcardFileFilter Filter based on wildcards
* AgeFileFilter Filter based on last modified time of file
* SizeFileFilter Filter based on file size
*
* And there are five 'boolean' filters:
*
* TrueFileFilter Accept all files
* FalseFileFilter Accept no files
* NotFileFilter Applies a logical NOT to an existing filter
* AndFileFilter Combines two filters using a logical AND
* OrFileFilter Combines two filter using a logical OR
*
*/
/**
* FileFilter的用法1
* 用 "new 子类" 的方式
*
*/
@Test
public void testFileFilter1(){
File dir = new File("data");//若表示本目录,则用"."
//Returns an array of strings naming the files and directories in the directory denoted by this abstract pathname that satisfy the specified filter.
String[] files = dir.list(
//Constructs a new file filter that ANDs the result of two other filters.
new AndFileFilter(
new AndFileFilter(
new PrefixFileFilter("t"),//Constructs a new Prefix file filter for a single prefix.
new OrFileFilter( //Constructs a new file filter that ORs the result of two other filters.
new SuffixFileFilter(".txt"),//Constructs a new Suffix file filter for a single extension.
new SuffixFileFilter(".dic")
)
),
//Constructs a new file filter that NOTs the result of another filters.
new NotFileFilter(
DirectoryFileFilter.INSTANCE //This filter accepts Files that are directories.
)
)
);
for ( int i=0; i<files.length; i++ ) {
System.out.println(files[i]);
}
}
/**
* FileFilter的用法2
* 用FileFilterUtils的方式
*/
@Test
public void testFileFilter2(){
File dir = new File("data");
String[] files = dir.list(
FileFilterUtils.andFileFilter(
FileFilterUtils.andFileFilter(
FileFilterUtils.prefixFileFilter("t"),
FileFilterUtils.orFileFilter(
FileFilterUtils.suffixFileFilter(".txt"),
FileFilterUtils.suffixFileFilter(".dic")
)
),
FileFilterUtils.notFileFilter(
FileFilterUtils.directoryFileFilter()
)
)
);
for ( int i=0; i<files.length; i++ ) {
System.out.println(files[i]);
}
}
}

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