Jakarta Commons Cookbook

Chapter 10. I/O and Networking

Introduction

If you’ve ever had to copy a File or copy the contents of an InputStream to an OutputStream, you’ve probably wondered why Java goes out of its way to make things difficult. Java I/O is not a terribly complex subject, but it does have a knack for turning simpler tasks into complex nests of heavily wrapped Readers and streams. Jakarta Commons IO fills a few gaps in Java’s I/O and networking capabilities by providing utilities and methods to copy streams, copy files, touch files, recursively delete directories, and safely close Readers and streams. If you are working with Reader, Writer, InputStream, or OutputStream, you should take a look at IOUtils and CopyUtils; they may save you a few lines of tedious code.

Commons IO also provides a set of simple FilenameFilter implementations, which can be used to selectively list files or directories. In addition to Commons IO’s FilenameFilter implementations, Jakarta ORO’s GlobFilenameFilter and Perl5FilenameFilter are presented to introduce you to more complex filters involving expressions. ORO is a subproject of Jakarta that provides support for Perl 5 regular expressions and glob expressions. A glob expression is commonly used when listing files in a directory; for example, the expression, *.xml, is a glob expression that matches every file that ends in .xml. While Java 1.4 provides support for regular expressions, there are subtle differences between the regular expression syntax supported by Java ...