/*** Finds files within a given directory (and optionally its* subdirectories). All files found are filtered by an IOFileFilter.* <p>* If your search should recurse into subdirectories you can pass in* an IOFileFilter for directories. You don't need to bind a* DirectoryFileFilter (via logical AND) to this filter. This method does* that for you.* <p>* An example: If you want to search through all directories called* "temp" you pass in <code>FileFilterUtils.NameFileFilter("temp")</code>* <p>* Another common usage of this method is find files in a directory* tree but ignoring the directories generated CVS. You can simply pass* in <code>FileFilterUtils.makeCVSAware(null)</code>.** @param directory  the directory to search in* @param fileFilter filter to apply when finding files.* @param dirFilter  optional filter to apply when finding subdirectories.*                   If this parameter is {@code null}, subdirectories will not be included in the*                   search. Use TrueFileFilter.INSTANCE to match all directories.* @return an collection of java.io.File with the matching files* @see org.apache.commons.io.filefilter.FileFilterUtils* @see org.apache.commons.io.filefilter.NameFileFilter*/

在指定的目录中（可以指定到子目录）通过IOFileFilter过滤器查找文件。
比如:
如果你要在所有的名为"temp"的目录，你可以使用：FileFilterUtils.NameFileFilter("temp")

M:\FileTest
│      5.txt
├─001
│ │    1.txt
│ │    2.txt
│ │
│ └─011
│      bc.eddx
│      d.docx
│
└─0023.txt4.txt

        Collection<File> listFiles = FileUtils.listFiles(new File("M:/FileTest"), null, null);for (File file : listFiles) {System.out.println(file.getName());}

    private static void validateListFilesParameters(final File directory, final IOFileFilter fileFilter) {if (!directory.isDirectory()) {throw new IllegalArgumentException("Parameter 'directory' is not a directory: " + directory);}if (fileFilter == null) {throw new NullPointerException("Parameter 'fileFilter' is null");}}

    @Testpublic void test2(){Collection<File> listFiles = FileUtils.listFiles(new File("M:/FileTest"), FileFilterUtils.suffixFileFilter("txt"), null);showFiles(listFiles);}private void showFiles(Collection<File> listFiles) {if (listFiles==null) {return;}for (File file : listFiles) {System.out.println(file.getName());}}

5.txt

    @Testpublic void test3(){Collection<File> listFiles = FileUtils.listFiles(new File("M:/FileTest"), FileFilterUtils.suffixFileFilter("txt"), DirectoryFileFilter.INSTANCE);showFiles(listFiles);}

1.txt
2.txt
3.txt
4.txt
5.txt

    @Testpublic void test4(){Collection<File> listFiles = FileUtils.listFiles(new File("M:/FileTest"), new String[]{"txt"}, true);showFiles(listFiles);}

    @Testpublic void test5(){Collection<File> listFiles = FileUtils.listFiles(new File("M:/FileTest"), FileFilterUtils.and(EmptyFileFilter.NOT_EMPTY,new RegexFileFilter("^[0-9]+.[a-zA-z]+$")), DirectoryFileFilter.INSTANCE);showFiles(listFiles);}

FileFilterUtils.and(EmptyFileFilter.NOT_EMPTY,new RegexFileFilter("^[0-9]+.[a-zA-z]+$"))