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<html>
<head>
<link rel="stylesheet" type="text/css" href="stylesheets/style.css">
<title>Tutorial: Tasks using Properties, Filesets &amp; Paths</title>
</head>
<body>
<h1>Tutorial: Tasks using Properties, Filesets &amp; Paths</h1>
<p>After reading the tutorial about <a href="tutorial-writing-tasks.html">writing
tasks [1]</a> this tutorial explains how to get and set properties and how to use
nested filesets and paths. Finally it explains how to contribute tasks to Apache Ant.</p>
<h2>Content</h2>
<p><ul>
<li><a href="#goal">The goal</a></li>
<li><a href="#buildenvironment">Build environment</a></li>
<li><a href="#propertyaccess">Property access</a></li>
<li><a href="#filesets">Using filesets</a></li>
<li><a href="#path">Using nested paths</a></li>
<li><a href="#returning-list">Returning a list</a></li>
<li><a href="#documentation">Documentation</a></li>
<li><a href="#contribute">Contribute the new task</a></li>
<li><a href="#resources">Resources</a></li>
</ul></p>
<h2><a name="goal">The goal</a></h2>
<p>The goal is to write a task, which searchs in a path for a file and saves the
location of that file in a property.</p>
<h2><a name="buildenvironment">Build environment</a></h2>
<p>We can use the buildfile from the other tutorial and modify it a little bit.
That's the advantage of using properties - we can reuse nearly the whole script. :-)</p>
<pre class="code">
&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
&lt;project name="<b>FindTask</b>" basedir="." default="test"&gt;
...
&lt;target name="use.init" description="Taskdef's the <b>Find</b>-Task" depends="jar"&gt;
&lt;taskdef name="<b>find</b>" classname="<b>Find</b>" classpath="${ant.project.name}.jar"/&gt;
&lt;/target&gt;
<b>&lt;!-- the other use.* targets are deleted --&gt;</b>
...
&lt;/project&gt;
</pre>
<p>The buildfile is in the archive <a href="tutorial-tasks-filesets-properties.zip">
tutorial-tasks-filesets-properties.zip [2]</a> in <tt>/build.xml.01-propertyaccess</tt>
(future version saved as *.02..., final version as build.xml; same for sources).</p>
<h2><a name="propertyaccess">Property access</a></h2>
<p>Our first step is to set a property to a value and print the value of that property.
So our scenario would be
<pre class="code">
&lt;find property="test" value="test-value"/&gt;
&lt;find print="test"/&gt;
</pre>
ok, can be rewritten with the core tasks
<pre class="code">
&lt;property name="test" value="test-value"/&gt;
&lt;echo message="${test}"/&gt;
</pre>
but I have to start on known ground :-)</p>
<p>So what to do? Handling three attributes (property, value, print) and an execute method.
Because this is only an introduction example I don't do much checking:
<pre class="code">
import org.apache.tools.ant.BuildException;
public class Find extends Task {
private String property;
private String value;
private String print;
public void setProperty(String property) {
this.property = property;
}
// setter for value and print
public void execute() {
if (print != null) {
String propValue = <b>getProject().getProperty(print)</b>;
log(propValue);
} else {
if (property == null) throw new BuildException("property not set");
if (value == null) throw new BuildException("value not set");
<b>getProject().setNewProperty(property, value)</b>;
}
}
}
</pre>
As said in the other tutorial, the property access is done via Project instance.
We get this instance via the public <tt>getProject()</tt> method which we inherit from
<tt>Task</tt> (more precise from ProjectComponent). Reading a property is done via
<tt>getProperty(<i>propertyname</i>)</tt> (very simple, isn't it?). This property returns
the value as String or <i>null</i> if not set.<br>
Setting a property is ... not really difficult, but there is more than one setter. You can
use the <tt>setProperty()</tt> method which will do the job like expected. But there is
a golden rule in Ant: <i>properties are immutable</i>. And this method sets the property
to the specified value - whether it has a value before that or not. So we use another
way. <tt>setNewProperty()</tt> sets the property only if there is no property with that
name. Otherwise a message is logged.</p>
<p><i>(by the way: a short word to ants "namespaces" (don't
be confused with xml namespaces:
an <code>&lt;antcall&gt;</code> creates a new space for property names. All properties from the caller
are passed to the callee, but the callee can set its own properties without notice by the
caller.)</i></p>
<p>There are some other setter, too (but I haven't used them, so I can't say something
to them, sorry :-)</p>
<p>After putting our two line example from above into a target names <tt>use.simple</tt>
we can call that from our testcase:
<pre class="code">
import org.junit.Rule;
import org.junit.Test;
import org.junit.Before;
import org.junit.Assert;
import org.apache.tools.ant.BuildFileRule;
public class FindTest {
@Rule
public final BuildFileRule buildRule = new BuildFileRule();
@Before
public void setUp() {
configureProject("build.xml");
}
@Test
public void testSimple() {
buildRule.executeTarget("useSimgle");
<b>Assert.assertEquals("test-value", buildRule.getLog());</b>
}
}
</pre>
and all works fine.</p>
<h2><a name="filesets">Using filesets</a></h2>
<p>Ant provides a common way of bundling files: the fileset. Because you are reading
this tutorial I think you know them and I don't have to spend more explanations about
their usage in buildfiles. Our goal is to search a file in path. And on this step the
path is simply a fileset (or more precise: a collection of filesets). So our usage
would be
<pre class="code">
&lt;find file="ant.jar" location="location.ant-jar"&gt;
&lt;fileset dir="${ant.home}" includes="**/*.jar"/&gt;
&lt;/find&gt;
</pre>
</p>
<p>What do we need? A task with two attributes (file, location) and nested
filesets. Because we had attribute handling already explained in the example above and the
handling of nested elements is described in the other tutorial the code should be very easy:
<pre class="code">
public class Find extends Task {
private String file;
private String location;
private Vector filesets = new Vector();
public void setFile(String file) {
this.file = file;
}
public void setLocation(String location) {
this.location = location;
}
public void addFileset(FileSet fileset) {
filesets.add(fileset);
}
public void execute() {
}
}
</pre>
Ok - that task wouldn't do very much, but we can use it in the described manner without
failure. On next step we have to implement the execute method. And before that we will
implement the appropriate testcases (TDD - test driven development).</p>
<p>In the other tutorial we have reused the already written targets of our buildfile.
Now we will configure most of the testcases via java code (sometimes it's much easier
to write a target than doing it via java coding). What can be tested?<ul>
<li>not valid configured task (missing file, missing location, missing fileset)</li>
<li>don't find a present file</li>
<li>behaviour if file can't be found</li>
</ul>
Maybe you find some more testcases. But this is enough for now.<br>
For each of these points we create a <tt>testXX</tt> method.</p>
<pre class="code">
public class FindTest {
@Rule
public final BuildFileRule buildRule = new BuildFileRule();
... // constructor, setUp as above
@Test
public void testMissingFile() {
<b>Find find = new Find();</b>
try {
<b>find.execute();</b>
fail("No 'no-file'-exception thrown.");
} catch (Exception e) {
// exception expected
String expected = "file not set";
assertEquals("Wrong exception message.", expected, e.getMessage());
}
}
@Test
public void testMissingLocation() {
Find find = new Find();
<b>find.setFile("ant.jar");</b>
try {
find.execute();
fail("No 'no-location'-exception thrown.");
} catch (Exception e) {
... // similar to testMissingFile()
}
}
@Test
public void testMissingFileset() {
Find find = new Find();
find.setFile("ant.jar");
find.setLocation("location.ant-jar");
try {
find.execute();
fail("No 'no-fileset'-exception thrown.");
} catch (Exception e) {
... // similar to testMissingFile()
}
}
@Test
public void testFileNotPresent() {
buildRule.executeTarget("testFileNotPresent");
String result = buildRule.getProject().getProperty("location.ant-jar");
assertNull("Property set to wrong value.", result);
}
@Test
public void testFilePresent() {
buildRule.executeTarget("testFilePresent");
String result = buildRule.getProject().getProperty("location.ant-jar");
assertNotNull("Property not set.", result);
assertTrue("Wrong file found.", result.endsWith("ant.jar"));
}
}
</pre>
<p>If we run this test class all test cases (except <i>testFileNotPresent</i>) fail. Now we
can implement our task, so that these test cases will pass.</p>
<pre class="code">
protected void validate() {
if (file==null) throw new BuildException("file not set");
if (location==null) throw new BuildException("location not set");
if (filesets.size()&lt;1) throw new BuildException("fileset not set");
}
public void execute() {
validate(); // 1
String foundLocation = null;
for(Iterator itFSets = filesets.iterator(); itFSets.hasNext(); ) { // 2
FileSet fs = (FileSet)itFSets.next();
DirectoryScanner ds = fs.getDirectoryScanner(getProject()); // 3
String[] includedFiles = ds.getIncludedFiles();
for(int i=0; i&lt;includedFiles.length; i++) {
String filename = includedFiles[i].replace('\\','/'); // 4
filename = filename.substring(filename.lastIndexOf("/")+1);
if (foundLocation==null &amp;&amp; file.equals(filename)) {
File base = ds.getBasedir(); // 5
File found = new File(base, includedFiles[i]);
foundLocation = found.getAbsolutePath();
}
}
}
if (foundLocation!=null) // 6
getProject().setNewProperty(location, foundLocation);
}
</pre>
<p>On <b>//1</b> we check the prerequisites for our task. Doing that in a <tt>validate</tt>-method
is a common way, because we separate the prerequisites from the real work. On <b>//2</b> we iterate
over all nested filesets. If we don't want to handle multiple filesets, the <tt>addFileset()</tt>
method has to reject the further calls. We can get the result of a fileset via its DirectoryScanner
like done in <b>//3</b>. After that we create a platform independent String representation of
the file path (<b>//4</b>, can be done in other ways of course). We have to do the <tt>replace()</tt>,
because we work with a simple string comparison. Ant itself is platform independent and can
therefore run on filesystems with slash (/, e.g. Linux) or backslash (\, e.g. Windows) as
path separator. Therefore we have to unify that. If we found our file we create an absolute
path representation on <b>//5</b>, so that we can use that information without knowing the basedir.
(This is very important on use with multiple filesets, because they can have different basedirs
and the return value of the directory scanner is relative to its basedir.) Finally we store the
location of the file as property, if we had found one (<b>//6</b>).</p>
<p>Ok, much more easier in this simple case would be to add the <i>file</i> as additional
<i>include</i> element to all filesets. But I wanted to show how to handle complex situations
without being complex :-)</p>
<p>The test case uses the ant property <i>ant.home</i> as reference. This property is set by the
<tt>Launcher</tt> class which starts ant. We can use that property in our buildfiles as a
<a href="properties.html#built-in-props">build-in property [3]</a>. But if we create a new ant
environment we have to set that value for our own. And we use the <code>&lt;junit&gt;</code> task in fork-mode.
Therefore we have do modify our buildfile:
<pre class="code">
&lt;target name="junit" description="Runs the unit tests" depends="jar"&gt;
&lt;delete dir="${junit.out.dir.xml}"/&gt;
&lt;mkdir dir="${junit.out.dir.xml}"/&gt;
&lt;junit printsummary="yes" haltonfailure="no"&gt;
&lt;classpath refid="classpath.test"/&gt;
<b>&lt;sysproperty key="ant.home" value="${ant.home}"/&gt;</b>
&lt;formatter type="xml"/&gt;
&lt;batchtest fork="yes" todir="${junit.out.dir.xml}"&gt;
&lt;fileset dir="${src.dir}" includes="**/*Test.java"/&gt;
&lt;/batchtest&gt;
&lt;/junit&gt;
&lt;/target&gt;
</pre>
<h2><a name="path">Using nested paths</a></h2>
<p>A task providing support for filesets is a very comfortable one. But there is another
possibility of bundling files: the <code>&lt;path&gt;</code>. Fileset are easy if the files are all under
a common base directory. But if this is not the case you have a problem. Another disadvantage
is its speed: if you have only a few files in a huge directory structure, why not use a
<code>&lt;filelist&gt;</code> instead? <code>&lt;path&gt;</code>s combines these datatypes in that way that a path contains
other paths, filesets, dirsets and filelists. This is why <a href="http://ant-contrib.sourceforge.net/">
Ant-Contribs [4]</a> <code>&lt;foreach&gt;</code> task is modified to support paths instead of filesets. So we want that,
too.</p>
<p>Changing from fileset to path support is very easy:</p>
<pre class="code">
<i><b>Change java code from:</b></i>
private Vector filesets = new Vector();
public void addFileset(FileSet fileset) {
filesets.add(fileset);
}
<i><b>to:</b></i>
private Vector paths = new Vector(); *1
public void add<b>Path</b>(<b>Path</b> path) { *2
paths.add(path);
}
<i><b>and build file from:</b></i>
&lt;find file="ant.jar" location="location.ant-jar"&gt;
&lt;fileset dir="${ant.home}" includes="**/*.jar"/&gt;
&lt;/find&gt;
<i><b>to:</b></i>
&lt;find file="ant.jar" location="location.ant-jar"&gt;
<b>&lt;path&gt;</b> *3
&lt;fileset dir="${ant.home}" includes="**/*.jar"/&gt;
&lt;/path&gt;
&lt;/find&gt;
</pre>
<p>On <b>*1</b> we rename only the vector. It�s just for better reading the source. On <b>*2</b>
we have to provide the right method: an add<i>Name</i>(<i>Type</i> t). Therefore replace the
fileset with path here. Finally we have to modify our buildfile on <b>*3</b> because our task
doesn�t support nested filesets any longer. So we wrap the fileset inside a path.</p>
<p>And now we modify the testcase. Oh, not very much to do :-) Renaming the <tt>testMissingFileset()</tt>
(not really a <i>must-be</i> but better it�s named like the think it does) and update the
<i>expected</i>-String in that method (now a <tt>path not set</tt> message is expected). The more complex
test cases base on the buildscript. So the targets <tt>testFileNotPresent</tt> and <tt>testFilePresent</tt> have to be
modified in the manner described above.</p>
<p>The test are finished. Now we have to adapt the task implementation. The easiest modification is
in the <tt>validate()</tt> method where we change le last line to <tt>if (paths.size()&lt;1) throw new
BuildException("path not set");</tt>. In the <tt>execute()</tt> method we have a little more work.
... mmmh ... in reality it's lesser work, because the Path class does the whole DirectoryScanner-handling
and creating-absolute-paths stuff for us. So the execute method is just:</p>
<pre class="code">
public void execute() {
validate();
String foundLocation = null;
for(Iterator itPaths = paths.iterator(); itPaths.hasNext(); ) {
Path path = (<b>Path</b>)itPaths.next(); // 1
String[] includedFiles = <b>path.list()</b>; // 2
for(int i=0; i&lt;includedFiles.length; i++) {
String filename = includedFiles[i].replace('\\','/');
filename = filename.substring(filename.lastIndexOf("/")+1);
if (foundLocation==null &amp;&amp; file.equals(filename)) {
<b>foundLocation = includedFiles[i];</b> // 3
}
}
}
if (foundLocation!=null)
getProject().setNewProperty(location, foundLocation);
}
</pre>
<p>Of course we have to do the typecase to Path on <b>//1</b>. On <b>//2</b> and <b>//3</b>
we see that the Path class does the work for us: no DirectoryScanner (was at 2) and no
creating of the absolute path (was at 3).</p>
<h2><a name="returning-list">Returning a list</a></h2>
<p>So far so good. But could a file be on more than one place in the path? - Of course.<br>
And would it be good to get all of them? - It depends on ...<p>
<p>In this section we will extend that task to support returning a list of all files.
Lists as property values are not supported by Ant natively. So we have to see how other
tasks use lists. The most famous task using lists is Ant-Contribs <code>&lt;foreach&gt;</code>. All list
elements are concatenated and separated with a customizable separator (default ',').</p>
<p>So we do the following:</p>
<pre class="code">
&lt;find ... <b>delimiter=""</b>/&gt; ... &lt;/find&gt;
</pre>
<p>If the delimiter is set we will return all found files as list with that delimiter.</p>
<p>Therefore we have to<ul>
<li>provide a new attribute</li>
<li>collect more than the first file</li>
<li>delete duplicates</li>
<li>create the list if necessary</li>
<li>return that list</li>
</ul></p>
<p>So we add as testcase:</p>
<pre class="code">
<b><i>in the buildfile:</i></b>
&lt;target name="test.init"&gt;
&lt;mkdir dir="test1/dir11/dir111"/&gt; *1
&lt;mkdir dir="test1/dir11/dir112"/&gt;
...
&lt;touch file="test1/dir11/dir111/test"/&gt;
&lt;touch file="test1/dir11/dir111/not"/&gt;
...
&lt;touch file="test1/dir13/dir131/not2"/&gt;
&lt;touch file="test1/dir13/dir132/test"/&gt;
&lt;touch file="test1/dir13/dir132/not"/&gt;
&lt;touch file="test1/dir13/dir132/not2"/&gt;
&lt;mkdir dir="test2"/&gt;
&lt;copy todir="test2"&gt; *2
&lt;fileset dir="test1"/&gt;
&lt;/copy&gt;
&lt;/target&gt;
&lt;target name="testMultipleFiles" depends="use.init,<b>test.init</b>"&gt; *3
&lt;find file="test" location="location.test" <b>delimiter=";"</b>&gt;
&lt;path&gt;
&lt;fileset dir="test1"/&gt;
&lt;fileset dir="test2"/&gt;
&lt;/path&gt;
&lt;/find&gt;
&lt;delete&gt; *4
&lt;fileset dir="test1"/&gt;
&lt;fileset dir="test2"/&gt;
&lt;/delete&gt;
&lt;/target&gt;
<b><i>in the test class:</i></b>
public void testMultipleFiles() {
executeTarget("testMultipleFiles");
String result = getProject().getProperty("location.test");
assertNotNull("Property not set.", result);
assertTrue("Only one file found.", result.indexOf(";") &gt; -1);
}
</pre>
<p>Now we need a directory structure where we CAN find files with the same
name in different directories. Because we can't sure to have one we create
one on <b>*1</b> and <b>*2</b>. And of course we clean up that on <b>*4</b>. The creation
can be done inside our test target or in a separate one, which will be better
for reuse later (<b>*3</b>).
<p>The task implementation is modified as followed:</p>
<pre class="code">
private Vector foundFiles = new Vector();
...
private String delimiter = null;
...
public void setDelimiter(String delim) {
delimiter = delim;
}
...
public void execute() {
validate();
// find all files
for(Iterator itPaths = paths.iterator(); itPaths.hasNext(); ) {
Path path = (Path)itPaths.next();
String[] includedFiles = path.list();
for(int i=0; i&lt;includedFiles.length; i++) {
String filename = includedFiles[i].replace('\\','/');
filename = filename.substring(filename.lastIndexOf("/")+1);
if (file.equals(filename) &amp;&amp; <b>!foundFiles.contains(includedFiles[i]</b>)) { // 1
foundFiles.add(includedFiles[i]);
}
}
}
// create the return value (list/single)
String rv = null;
if (foundFiles.size() &gt; 0) { // 2
if (delimiter==null) {
// only the first
rv = (String)foundFiles.elementAt(0);
} else {
// create list
StringBuffer list = new StringBuffer();
for(Iterator it=foundFiles.iterator(); it.hasNext(); ) { // 3
list.append(it.next());
if (<b>it.hasNext()</b>) list.append(delimiter); // 4
}
rv = list.toString();
}
}
// create the property
if (rv!=null)
getProject().setNewProperty(location, rv);
}
</pre>
<p>The algorithm does: finding all files, creating the return value depending on the users
wish, returning the value as property. On <b>//1</b> we eliminates the duplicates. <b>//2</b>
ensures that we create the return value only if we have found one file. On <b>//3</b> we
iterate over all found files and <b>//4</b> ensures that the last entry has no trailing
delimiter.</p>
<p>Ok, first searching for all files and then returning only the first one ... You can
tune the performance of your own :-)</p>
<h2><a name="documentation">Documentation</a></h2>
<p>A task is useless if the only who is able to code the buildfile is the task developer
(and he only the next few weeks :-). So documentation is also very important. In which
form you do that depends on your favourite. But inside Ant there is a common format and
it has advantages if you use that: all task users know that form, this form is requested if
you decide to contribute your task. So we will doc our task in that form.</p>
<p>If you have a look at the manual page of the <a href="Tasks/java.html">Java task [5]</a>
you will see that it:<ul>
<li>is plain html</li>
<li>starts with the name</li>
<li>has sections: description, parameters, nested elements, (maybe return codes) and (most
important :-) examples</li>
<li>parameters are listed in a table with columns for attribute name, its description and whether
it's required (if you add a feature after an Ant release, provide a <tt>since Ant xx</tt>
statement when it's introduced)</li>
<li>describe the nested elements (since-statement if necessary)</li>
<li>provide one or more useful examples; first code, then description.</li>
</ul>
As a template we have:
<pre class="code">
&lt;html&gt;
&lt;head&gt;
&lt;meta http-equiv="Content-Language" content="en-us"&gt;
&lt;title&gt;<b>Taskname</b> Task&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;h2&gt;&lt;a name="<b>taskname</b>"&gt;<b>Taskname</b>&lt;/a&gt;&lt;/h2&gt;
&lt;h3&gt;Description&lt;/h3&gt;
&lt;p&gt; <b>Describe the task.</b>&lt;/p&gt;
&lt;h3&gt;Parameters&lt;/h3&gt;
&lt;table border="1" cellpadding="2" cellspacing="0"&gt;
&lt;tr&gt;
&lt;td valign="top"&gt;&lt;b&gt;Attribute&lt;/b&gt;&lt;/td&gt;
&lt;td valign="top"&gt;&lt;b&gt;Description&lt;/b&gt;&lt;/td&gt;
&lt;td align="center" valign="top"&gt;&lt;b&gt;Required&lt;/b&gt;&lt;/td&gt;
&lt;/tr&gt;
<b>do this html row for each attribute (including inherited attributes)</b>
&lt;tr&gt;
&lt;td valign="top"&gt;classname&lt;/td&gt;
&lt;td valign="top"&gt;the Java class to execute.&lt;/td&gt;
&lt;td align="center" valign="top"&gt;Either jar or classname&lt;/td&gt;
&lt;/tr&gt;
&lt;/table&gt;
&lt;h3&gt;Parameters specified as nested elements&lt;/h3&gt;
<b>Describe each nested element (including inherited)</b>
&lt;h4&gt;<b>your nested element</b>&lt;/h4&gt;
&lt;p&gt;<b>description</b>&lt;/p&gt;
&lt;p&gt;&lt;em&gt;since Ant 1.6&lt;/em&gt;.&lt;/p&gt;
&lt;h3&gt;Examples&lt;/h3&gt;
&lt;pre&gt;
<b>A code sample; don't forget to escape the &lt; of the tags with &amp;lt;</b>
&lt;/pre&gt;
<b>What should that example do?</b>
&lt;/body&gt;
&lt;/html&gt;
</pre>
<p>Here is an example documentation page for our task:</p>
<pre class="code">
&lt;html&gt;
&lt;head&gt;
&lt;meta http-equiv="Content-Language" content="en-us"&gt;
&lt;title&gt;Find Task&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;h2&gt;&lt;a name="find"&gt;Find&lt;/a&gt;&lt;/h2&gt;
&lt;h3&gt;Description&lt;/h3&gt;
&lt;p&gt;Searchs in a given path for a file and returns the absolute to it as property.
If delimiter is set this task returns all found locations.&lt;/p&gt;
&lt;h3&gt;Parameters&lt;/h3&gt;
&lt;table border="1" cellpadding="2" cellspacing="0"&gt;
&lt;tr&gt;
&lt;td valign="top"&gt;&lt;b&gt;Attribute&lt;/b&gt;&lt;/td&gt;
&lt;td valign="top"&gt;&lt;b&gt;Description&lt;/b&gt;&lt;/td&gt;
&lt;td align="center" valign="top"&gt;&lt;b&gt;Required&lt;/b&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td valign="top"&gt;file&lt;/td&gt;
&lt;td valign="top"&gt;The name of the file to search.&lt;/td&gt;
&lt;td align="center" valign="top"&gt;yes&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td valign="top"&gt;location&lt;/td&gt;
&lt;td valign="top"&gt;The name of the property where to store the location&lt;/td&gt;
&lt;td align="center" valign="top"&gt;yes&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td valign="top"&gt;delimiter&lt;/td&gt;
&lt;td valign="top"&gt;A delimiter to use when returning the list&lt;/td&gt;
&lt;td align="center" valign="top"&gt;only if the list is required&lt;/td&gt;
&lt;/tr&gt;
&lt;/table&gt;
&lt;h3&gt;Parameters specified as nested elements&lt;/h3&gt;
&lt;h4&gt;path&lt;/h4&gt;
&lt;p&gt;The path where to search the file.&lt;/p&gt;
&lt;h3&gt;Examples&lt;/h3&gt;
&lt;pre&gt;
&lt;find file="ant.jar" location="loc"&gt;
&lt;path&gt;
&lt;fileset dir="${ant.home}"/&gt;
&lt;path&gt;
&lt;/find&gt;
&lt;/pre&gt;
Searches in Ants home directory for a file &lt;i&gt;ant.jar&lt;/i&gt; and stores its location in
property &lt;i&gt;loc&lt;/i&gt; (should be ANT_HOME/bin/ant.jar).
&lt;pre&gt;
&lt;find file="ant.jar" location="loc" delimiter=";"&gt;
&lt;path&gt;
&lt;fileset dir="C:/"/&gt;
&lt;path&gt;
&lt;/find&gt;
&lt;echo&gt;ant.jar found in: ${loc}&lt;/echo&gt;
&lt;/pre&gt;
Searches in Windows C: drive for all &lt;i&gt;ant.jar&lt;/i&gt; and stores their locations in
property &lt;i&gt;loc&lt;/i&gt; delimited with &lt;i&gt;';'&lt;/i&gt;. (should need a long time :-)
After that it prints out the result (e.g. C:/ant-1.5.4/bin/ant.jar;C:/ant-1.6/bin/ant.jar).
&lt;/body&gt;
&lt;/html&gt;
</pre>
<h2><a name="contribute">Contribute the new task</a></h2>
If we decide to contribute our task, we should do some things:<ul>
<li>is our task welcome? :-) Simply ask on the user list</li>
<li>is the right package used? </li>
<li>does the code conform to the styleguide?</li>
<li>do all tests pass? </li>
<li>does the code compile on JDK 1.2 (and passes all tests there)?</li>
<li>code under Apache license</li>
<li>create a patch file</li>
<li>publishing that patch file</li>
</ul>
The <a href="http://ant.apache.org/ant_task_guidelines.html">Ant Task Guidelines [6]</a> support additional
information on that.</p>
<p>Now we will check the "Checklist before submitting a new task" described in that guideline.
<ul>
<li>Java file begins with Apache license statement. <b><i>must do that</i></b></li>
<li>Task does not depend on GPL or LGPL code. <b><i>ok</i></b></li>
<li>Source code complies with style guidelines <b><i>have to check (checkstyle)</i></b></li>
<li>Code compiles and runs on Java1.2 <b><i>have to try</i></b></li>
<li>Member variables are private, and provide public accessor methods
if access is actually needed. <b><i>have to check (checkstyle)</i></b></li>
<li><i>Maybe</i> Task has failonerror attribute to control failure behaviour <b><i>hasn't</i></b></li>
<li>New test cases written and succeed <b><i>passed on JDK 1.4, have to try on JDK 1.2</i></b></li>
<li>Documentation page written <b><i>ok</i></b></li>
<li>Example task declarations in the documentation tested. <b><i>ok (used in tests)</i></b></li>
<li>Patch files generated using cvs diff -u <b><i>to do</i></b></li>
<li>patch files include a patch to defaults.properties to register the
tasks <b><i>to do</i></b></li>
<li>patch files include a patch to tasklist.html to link to the new task page <b><i>to do</i></b></li>
<li>Message to dev contains [SUBMIT] and task name in subject <b><i>to do</i></b></li>
<li>Message body contains a rationale for the task <b><i>to do</i></b></li>
<li>Message attachments contain the required files -source, documentation,
test and patches zipped up to escape the HTML filter. <b><i>to do</i></b></li>
</ul>
<h3>Package / Directories</h3>
<p>This task does not depend on any external library. Therefore we can use this as
a core task. This task contains only one class. So we can use the standard package
for core tasks: <tt>org.apache.tools.ant.taskdefs</tt>. Implementations are in the
directory <tt>src/main</tt>, tests in <tt>src/testcases</tt> and buildfiles for
tests in <tt>src/etc/testcases</tt>.</p>
<p>Now we integrate our work into Ants distribution. So first we do an update of our
cvs tree. If not done yet, you have to checkout the ant module from Apaches cvs server
as described in <a href="http://ant.apache.org/cvs.html">Access the Source Tree (AnonCVS)
[7]</a> (password is <i>anoncvs</i>):<pre class="output">
cvs -d :pserver:anoncvs@cvs.apache.org:/home/cvspublic login //1
cvs -d :pserver:anoncvs@cvs.apache.org:/home/cvspublic checkout ant //2
</pre>
If you have a local copy of Ants sources just do an update
<pre class="output">
cvs -d :pserver:anoncvs@cvs.apache.org:/home/cvspublic login
cd ant //3
cvs -d :pserver:anoncvs@cvs.apache.org:/home/cvspublic update //4
</pre></p>
<p>We use the <i>-d</i> flag on <b>//1</b> to specify the cvs directory. You can
specify the environment variable CVSROOT with that value and after that you haven�t
to use that flag any more. On <b>//2</b> we get the whole cvs tree of ant. (Sorry,
but that uses a lot of time ... 10 up to 30 minutes are not unusual ... but this has
to be done only once :-). A cvs update doesn't use a modulename but you have to be
inside the directory. Therefore we go into that on <b>//3</b> and do the update
on <b>//4</b>.</p>
<p>Now we will build our Ant distribution and do a test. So we can see if there
are any tests failing on our machine. (We can ignore these failing tests on later
steps; windows syntax used here- translate to xNIX if needed):
<pre class="output">
ANTHOME&gt; build // 1
ANTHOME&gt; set ANT_HOME=%CD%\dist // 2
ANTHOME&gt; ant test -Dtest.haltonfailure=false // 3
</pre>
First we have to build our Ant distribution (<b>//1</b>). On <b>//2</b> we set the ANT_HOME
environment variable to the directory where the new created distribution is stored
(%CD% is expanded to the current directory on Windows 2000 and XP, on 9x and NT
write it out). On <b>//3</b> we let Ant do all the tests (which enforced a compile
of all tests) without stopping on first failure.</p>
<p>Next we apply our work onto Ants sources. Because we haven't modified any, this is
a relative simple step. <i>(Because I have a local copy of Ant and usually contribute my
work, I work on the local copy just from the beginning. The advantage: this step isn't
necessary and saves a lot of work if you modify existing source :-)</i>.
<ul>
<li>move the Find.java to ANTHOME/src/main/org/apache/tools/ant/taskdefs/Find.java </li>
<li>move the FindTest.java to ANTHOME/src/testcases/org/apache/tools/ant/taskdefs/FindTest.java </li>
<li>move the build.xml to ANTHOME/src/etc/testcases/taskdefs/<b>find.xml</b> (!!! renamed !!!)</li>
<li>add a <tt>package org.apache.tools.ant.taskdefs;</tt> at the beginning of the two java files </li>
<li>delete all stuff from find.xml keeping the targets "testFileNotPresent", "testFilePresent",
"test.init" and "testMultipleFiles" </li>
<li>delete the dependency to "use.init" in the find.xml </li>
<li>in FindTest.java change the line <tt>configureProject("build.xml");</tt> to
<tt>configureProject("src/etc/testcases/taskdefs/find.xml");</tt> </li>
<li>move the find.html to ANTHOME/docs/manual/Tasks/find.html </li>
<li>add a <tt>&lt;a href="Tasks/find.html"&gt;Find&lt;/a&gt;&lt;br&gt;</tt>
in the ANTHOME/docs/manual/tasklist.html </li>
</ul>
Now our modifications are done and we will retest it:
<pre class="output">
ANTHOME&gt; build
ANTHOME&gt; ant run-single-test // 1
-Dtestcase=org.apache.tools.ant.taskdefs.FindTest // 2
-Dtest.haltonfailure=false
</pre>
Because we only want to test our new class, we use the target for single tests, specify
the test to use and configure not to halt on the first failure - we want to see all
failures of our own test (<b>//1 + 2</b>).</p>
<p>And ... oh, all tests fail: <i>Ant could not find the task or a class this task relies upon.</i></p>
<p>Ok: in the earlier steps we told Ant to use the Find class for the <code>&lt;find&gt;</code> task (remember the
<code>&lt;taskdef&gt;</code> statement in the "use.init" target). But now we want to introduce that task as
a core task. And nobody wants to taskdef the javac, echo, ... So what to do? The answer is the
src/main/.../taskdefs/default.properties. Here is the mapping between taskname and implementing
class done. So we add a <tt>find=org.apache.tools.ant.taskdefs.Find</tt> as the last core
task (just before the <tt># optional tasks</tt> line). Now a second try:
<pre class="output">
ANTHOME&gt; build // 1
ANTHOME&gt; ant run-single-test
-Dtestcase=org.apache.tools.ant.taskdefs.FindTest
-Dtest.haltonfailure=false
</pre>
We have to rebuild (<b>//1</b>) Ant because the test look in the %ANT_HOME%\lib\ant.jar
(more precise: on the classpath) for the properties file. And we have only modified it in the
source path. So we have to rebuild that jar. But now all tests pass and we check whether our class
breaks some other tests.
<pre class="output">
ANTHOME&gt; ant test -Dtest.haltonfailure=false
</pre>
Because there are a lot of tests this step requires a little bit of time. So use the <i>run-single-test</i>
during development and do the <i>test</i> only at the end (maybe sometimes during development too).
We use the <i>-Dtest.haltonfailure=false</i> here because there could be other tests fail and we have
to look into them.</p>
<p>This test run should show us two things: our test will run and the number of failing tests
is the same as directly after the cvs update (without our modifications).</p>
<h3>Apache license statement</h3>
<p>Simply copy the license text from one the other source from the Ant source tree.</p>
<h3>Test on JDK 1.2</h3>
<p>Until version 1.5 Ant must be able to run on a JDK 1.1. With version 1.6 this is not a
requisite any more. But JDK 1.2 is a must-to-work-with. So we have to test that. You can download older
JDKs from <a href="http://www.oracle.com/technetwork/java/archive-139210.html">Oracle [8]</a>.</p>
<p>Clean the ANT_HOME variable, delete the <i>build, bootstrap</i> and <i>dist</i> directory
and point JAVA_HOME to the JDK 1.2 home directory. Then do the <tt>build</tt>, set ANT_HOME
and run <tt>ant test</tt> (like above).</p>
<p>Our test should pass.</p>
<h3>Checkstyle</h3>
<p>There are many things we have to ensure. Indentation with 4 spaces, blanks here and there, ...
(all described in the <a href="http://ant.apache.org/ant_task_guidelines.html">Ant Task Guidelines [6]</a> which
includes the <a href="http://www.oracle.com/technetwork/java/codeconvtoc-136057.html">Sun code style
[9]</a>). Because there are so many things we would be happy to have a tool for do the checks.
There is one: checkstyle. Checkstyle is available at <a href="http://checkstyle.sourceforge.net/">
Sourceforge [10]</a> and Ant provides with the <tt>check.xml</tt> a buildfile which will do the job
for us.</p>
<p>Download it and put the checkstyle-*-all.jar into your %USERPROFILE%\.ant\lib directory.
All jar's stored there are available to Ant so you haven't to add it to you %ANT_HOME%\lib
directory (this feature was added with Ant 1.6).</p>
<p>So we will run the tests with
<pre class="output">
ANTHOME&gt; ant -f check.xml checkstyle htmlreport
</pre>
I prefer the HTML report because there are lots of messages and we can navigate faster.
Open the ANTHOME/build/reports/checkstyle/html/index.html and navigate to the Find.java. Now we
see that there are some errors: missing whitespaces, unused imports, missing javadocs. So we have
to do that.</p>
<p>Hint: start at the <b>buttom</b> of the file so the line numbers in the report will keep
up to date and you will find the next error place much more easier without redoing the checkstyle.</p>
<p>After cleaning up the code according to the messages we delete the reports directory and
do a second checkstyle run. Now our task isn't listed. That's fine :-)</p>
<!--
Couldnt create the diff that way for myself, but that should be documented.
But on the other hand this tutorial should not be forgotten any longer so I
comment that out. JHM
<h3>Creating the diff</h3>
<p>Creating a diff for Ant is very easy: just start <tt>ant -f patch.xml</tt> and all is done
automatically. This step requires a cvs executable in your path and internet access (more precise:
cvs access). As a result we get a file <i> TODO </i>.</p>
-->
<h3>Publish the task</h3>
<p>Finally we publish that archive. As described in the <a href="http://ant.apache.org/ant_task_guidelines.html">
Ant Task Guidelines [7]</a> we can post it on the developer mailinglist or we create a BugZilla
entry. For both we need some information:</p>
<table border="1">
<tr>
<th>subject</th>
<td><i>short description</i></td>
<td>Task for finding files in a path</td>
</tr>
<tr>
<th>body</th>
<td><i>more details about the path</i></td>
<td>This new task looks inside a nested <code>&lt;path/&gt;</code> for occurrences of a file and stores
all locations as a property. See the included manual for details.</td>
</tr>
<tr>
<th>attachments</th>
<td><i>all files needed to apply the path</i></td>
<td>Archive containing a patch with the new and modified resources</td>
</tr>
</table>
<p>Sending an email with these information is very easy and I think I haven't to show that.
The other way - BugZilla - is slightly more difficult. But it has the advantage that entries
will not be forgotten (once per week a report is generated). So I will show this way.</p>
<p>You must have a BugZilla account for that. So open the <a href="http://issues.apache.org/bugzilla/">
BugZilla Main Page [11]</a> and follow the link
<a href="http://issues.apache.org/bugzilla/createaccount.cgi">Open a new Bugzilla account [12]</a>
and the steps described there if you haven't one.</p>
<ol>
<li>From the BugZilla main page choose <a href="http://issues.apache.org/bugzilla/enter_bug.cgi">Enter
a new bug report [13]</a></li>
<li>Choose "Ant" as product </li>
<li>Version is the last "Alpha (nightly)" (at this time 1.7)</li>
<li>Component is "Core tasks"</li>
<li>Platform and Severity are ok with "Other" and "Normal"</li>
<li>Initial State is ok with "New"</li>
<li>Same with the empty "Assigned to"</li>
<li>It is not required to add yourself as CC, because you are the reporter and therefore will be
informed on changes</li>
<li>URL: no url required</li>
<li>Summary: add the <i>subject</i> from the table</li>
<li>Description: add the <i>body</i> from the table</li>
<li>Then press "Commit"</li>
<li>After redirecting to the new created bug entry click "Create a New Attachment"</li>
<li>Enter the path to your local path file into "File" or choose it via the "File"'s
button.</li>
<li>Enter a short description into "Description", so that you could guess, what the
path file includes. Here we could add "Initial Patch".</li>
<li>The "Content Type" is "auto-detect". You could use the "patch" type, if you only
provide a single path file, but we want do upload more that one, included in our
patch.zip.</li>
<li>Then press "Commit"</li>
</ol>
Now the new task is uploaded into the bug database.
<h2><a name="resources">Resources</a></h2>
&nbsp;&nbsp;[1] <a href="tutorial-writing-tasks.html">tutorial-writing-tasks.html</a><br>
&nbsp;&nbsp;[2] <a href="tutorial-tasks-filesets-properties.zip">tutorial-tasks-filesets-properties.zip</a><br>
&nbsp;&nbsp;[3] <a href="properties.html#built-in-props">properties.html#built-in-props</a><br>
&nbsp;&nbsp;[4] <a href="http://ant-contrib.sourceforge.net/">http://ant-contrib.sourceforge.net/</a><br>
&nbsp;&nbsp;[5] <a href="Tasks/java.html">Tasks/java.html</a><br>
&nbsp;&nbsp;[6] <a href="http://ant.apache.org/ant_task_guidelines.html">http://ant.apache.org/ant_task_guidelines.html</a><br>
&nbsp;&nbsp;[7] <a href="http://ant.apache.org/cvs.html">http://ant.apache.org/cvs.html</a><br>
&nbsp;&nbsp;[8] <a href="http://www.oracle.com/technetwork/java/archive-139210.html">http://www.oracle.com/technetwork/java/archive-139210.html</a><br>
&nbsp;&nbsp;[9] <a href="http://www.oracle.com/technetwork/java/codeconvtoc-136057.html">http://www.oracle.com/technetwork/java/codeconvtoc-136057.html</a><br>
&nbsp;&nbsp;[10] <a href="http://checkstyle.sourceforge.net/">http://checkstyle.sourceforge.net/</a><br>
&nbsp;&nbsp;[11] <a href="http://issues.apache.org/bugzilla/">http://issues.apache.org/bugzilla/</a><br>
&nbsp;&nbsp;[12] <a href="http://issues.apache.org/bugzilla/createaccount.cgi">http://issues.apache.org/bugzilla/createaccount.cgi</a><br>
&nbsp;&nbsp;[13] <a href="http://issues.apache.org/bugzilla/enter_bug.cgi">http://issues.apache.org/bugzilla/enter_bug.cgi</a><br>
<!--
TODO:
- how to create a path (path.xml / command line)
-->
</body>
</html>