Commons IO example source code file (description.xml)
The Commons IO description.xml source code
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<document>
<properties>
<title>User guide
<author email="dev@commons.apache.org">Commons Documentation Team
</properties>
<body>
<section name="User guide">
<p>
Commons-IO contains
<a href="#Utility classes">utility classes,
<a href="#Endian classes">endian classes,
<a href="#Line iterator">line iterator,
<a href="#File filters">file filters,
<a href="#File comparators">file comparators and
<a href="#Streams">stream implementations.
</p>
<p>
For a more detailed descriptions, take a look at the
<a href="api-release/index.html">javadocs.
</p>
</section>
<section name="Utility classes">
<subsection name="IOUtils">
<p>
<a href="api-release/index.html?org/apache/commons/io/IOUtils.html">IOUtils
contains utility methods dealing with reading, writing and copying.
The methods work on InputStream, OutputStream, Reader and Writer.
</p>
<p>
As an example, consider the task of reading bytes
from a URL, and printing them. This would typically done like this:
</p>
<source>
InputStream in = new URL( "http://jakarta.apache.org" ).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();
}</source>
<p>
With the IOUtils class, that could be done with:
</p>
<source>
InputStream in = new URL( "http://jakarta.apache.org" ).openStream();
try {
System.out.println( IOUtils.toString( in ) );
} finally {
IOUtils.closeQuietly(in);
}</source>
<p>
In certain application domains, such IO operations are
common, and this class can save a great deal of time. And you can
rely on well-tested code.
</p>
<p>
For utility code such as this, flexibility and speed are of primary importance.
However you should also understand the limitations of this approach.
Using the above technique to read a 1GB file would result in an
attempt to create a 1GB String object!
</p>
</subsection>
<subsection name="FileUtils">
<p>
The <a href="api-release/index.html?org/apache/commons/io/FileUtils.html">FileUtils
class contains utility methods for working with File objects.
These include reading, writing, copying and comparing files.
</p>
<p>
For example to read an entire file line by line you could use:
</p>
<source>
File file = new File("/commons/io/project.properties");
List lines = FileUtils.readLines(file, "UTF-8");</source>
</subsection>
<subsection name="FilenameUtils">
<p>
The <a href="api-release/index.html?org/apache/commons/io/FilenameUtils.html">FilenameUtils
class contains utility methods for working with filenames <i>without
using File objects. The class aims to be consistent
between Unix and Windows, to aid transitions between these
environments (such as moving from development to production).
</p>
<p>
For example to normalize a filename removing double dot segments:
</p>
<source>
String filename = "C:/commons/io/../lang/project.xml";
String normalized = FilenameUtils.normalize(filename);
// result is "C:/commons/lang/project.xml"</source>
</subsection>
<subsection name="FileSystemUtils">
<p>
The <a href="api-release/index.html?org/apache/commons/io/FileSystemUtils.html">FileSystemUtils
class contains
utility methods for working with the file system
to access functionality not supported by the JDK.
Currently, the only method is to get the free space on a drive.
Note that this uses the command line, not native code.
</p>
<p>
For example to find the free space on a drive:
</p>
<source>
long freeSpace = FileSystemUtils.freeSpace("C:/");</source>
</subsection>
</section>
<section name="Endian classes">
<p>
Different computer architectures adopt different
conventions for byte ordering. In so-called
"Little Endian" architectures (eg Intel), the low-order
byte is stored in memory at the lowest address, and
subsequent bytes at higher addresses. For "Big Endian"
architectures (eg Motorola), the situation is reversed.
</p>
<p>
There are two classes in this package of relevance:
</p>
<ul>
<li>
The <a href="api-release/index.html?org/apache/commons/io/EndianUtils.html">EndianUtils
class contains static methods for swapping the Endian-ness
of Java primitives and streams.
</li>
<li>
The <a href="api-release/index.html?org/apache/commons/io/input/SwappedDataInputStream.html">SwappedDataInputStream
class is an implementation of the <code>DataInput interface. With
this, one can read data from files of non-native Endian-ness.
</li>
</ul>
<p>
For more information, see
<a
href="http://www.cs.umass.edu/~verts/cs32/endian.html">http://www.cs.umass.edu/~verts/cs32/endian.html</a>
</p>
</section>
<section name="Line iterator">
<p>
The <code>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
<code>FileUtils or
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