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- <html>
- <head>
- <title>Tutorial: Hello World with Apache Ant</title>
- <link rel="stylesheet" type="text/css" href="stylesheets/style.css">
- </head>
- <body>
- <h1>Tutorial: Hello World with Apache Ant</h1>
- <p>This document provides a step by step tutorial for starting java programming with Apache Ant.
- It does <b>not</b> contain deeper knowledge about Java or Ant. This tutorial has the goal
- to let you see, how to do the easiest steps in Ant.</p>
- <h2>Content</h2>
- <p><ul>
- <li><a href="#prepare">Preparing the project</a></li>
- <li><a href="#four-steps">Enhance the build file</a></li>
- <li><a href="#enhance">Enhance the build file</a></li>
- <li><a href="#ext-libs">Using external libraries</a></li>
- <li><a href="#resources">Resources</a></li>
- </ul></p>
- <a name="prepare"></a>
- <h2>Preparing the project</h2>
- <p>We want to separate the source from the generated files, so our java source files will
- be in <tt>src</tt> folder. All generated files should be under <tt>build</tt>, and there
- splitted into several subdirectories for the individual steps: <tt>classes</tt> for our compiled
- files and <tt>jar</tt> for our own JAR-file.</p>
- <p>We have to create only the <tt>src</tt> directory. (Because I am working on Windows, here is
- the win-syntax - translate to your shell):</p>
- <pre class="code">
- md src
- </pre>
- <p>The following simple Java class just prints a fixed message out to STDOUT,
- so just write this code into <tt>src\oata\HelloWorld.java</tt>.</p>
- <pre class="code">
- package oata;
- public class HelloWorld {
- public static void main(String[] args) {
- System.out.println("Hello World");
- }
- }
- </pre>
- <p>Now just try to compile and run that:
- <pre class="code">
- md build\classes
- javac -sourcepath src -d build\classes src\oata\HelloWorld.java
- java -cp build\classes oata.HelloWorld
- </pre>
- which will result in
- <pre class="output">
- Hello World
- </pre>
- </p>
- <p>Creating a jar-file is not very difficult. But creating a <i>startable</i> jar-file needs more steps: create a
- manifest-file containing the start class, creating the target directory and archiving the files.</p>
- <pre class="code">
- echo Main-Class: oata.HelloWorld>myManifest
- md build\jar
- jar cfm build\jar\HelloWorld.jar myManifest -C build\classes .
- java -jar build\jar\HelloWorld.jar
- </pre>
- <p><b>Note:</b> Do not have blanks around the >-sign in the <tt>echo Main-Class</tt> instruction because it would
- falsify it!</p>
- <a name="four-steps"></a>
- <h2>Four steps to a running application</h2>
- <p>After finishing the java-only step we have to think about our build process. We <i>have</i> to compile our code, otherwise we couldn't
- start the program. Oh - "start" - yes, we could provide a target for that. We <i>should</i> package our application.
- Now it's only one class - but if you want to provide a download, no one would download several hundreds files ...
- (think about a complex Swing GUI - so let us create a jar file. A startable jar file would be nice ... And it's a
- good practise to have a "clean" target, which deletes all the generated stuff. Many failures could be solved just
- by a "clean build".</p>
- <p>By default Ant uses <tt>build.xml</tt> as the name for a buildfile, so our <tt>.\build.xml</tt> would be:</p>
- <pre class="code">
- <project>
- <target name="clean">
- <delete dir="build"/>
- </target>
- <target name="compile">
- <mkdir dir="build/classes"/>
- <javac srcdir="src" destdir="build/classes"/>
- </target>
- <target name="jar">
- <mkdir dir="build/jar"/>
- <jar destfile="build/jar/HelloWorld.jar" basedir="build/classes">
- <manifest>
- <attribute name="Main-Class" value="oata.HelloWorld"/>
- </manifest>
- </jar>
- </target>
- <target name="run">
- <java jar="build/jar/HelloWorld.jar" fork="true"/>
- </target>
- </project>
- </pre>
- <p>Now you can compile, package and run the application via</p>
- <pre class="code">
- ant compile
- ant jar
- ant run
- </pre>
- <p>Or shorter with</p>
- <pre class="code">
- ant compile jar run
- </pre>
- <p>While having a look at the buildfile, we will see some similar steps between Ant and the java-only commands:
- <table>
- <tr>
- <th>java-only</th>
- <th>Ant</th>
- </tr>
- <tr>
- <td valign="top"><pre class="code">
- md build\classes
- javac
- -sourcepath src
- -d build\classes
- src\oata\HelloWorld.java
- echo Main-Class: oata.HelloWorld>mf
- md build\jar
- jar cfm
- build\jar\HelloWorld.jar
- mf
- -C build\classes
- .
- java -jar build\jar\HelloWorld.jar
- </pre></td>
- <td valign="top"><pre class="code">
- <mkdir dir="build/classes"/>
- <javac
- srcdir="src"
- destdir="build/classes"/>
- <i><!-- automatically detected --></i>
- <i><!-- obsolete; done via manifest tag --></i>
- <mkdir dir="build/jar"/>
- <jar
- destfile="build/jar/HelloWorld.jar"
- basedir="build/classes">
- <manifest>
- <attribute name="Main-Class" value="oata.HelloWorld"/>
- </manifest>
- </jar>
- <java jar="build/jar/HelloWorld.jar" fork="true"/>
- </pre></td>
- </tr></table>
- </p>
- <a name="enhance"></a>
- <h2>Enhance the build file</h2>
- <p>Now we have a working buildfile we could do some enhancements: many time you are referencing the
- same directories, main-class and jar-name are hard coded, and while invocation you have to remember
- the right order of build steps.</p>
- <p>The first and second point would be addressed with <i>properties</i>, the third with a special property - an attribute
- of the <project>-tag and the fourth problem can be solved using dependencies.</p>
- <pre class="code">
- <project name="HelloWorld" basedir="." default="main">
- <property name="src.dir" value="src"/>
- <property name="build.dir" value="build"/>
- <property name="classes.dir" value="${build.dir}/classes"/>
- <property name="jar.dir" value="${build.dir}/jar"/>
- <property name="main-class" value="oata.HelloWorld"/>
- <target name="clean">
- <delete dir="${build.dir}"/>
- </target>
- <target name="compile">
- <mkdir dir="${classes.dir}"/>
- <javac srcdir="${src.dir}" destdir="${classes.dir}"/>
- </target>
- <target name="jar" depends="compile">
- <mkdir dir="${jar.dir}"/>
- <jar destfile="${jar.dir}/${ant.project.name}.jar" basedir="${classes.dir}">
- <manifest>
- <attribute name="Main-Class" value="${main-class}"/>
- </manifest>
- </jar>
- </target>
- <target name="run" depends="jar">
- <java jar="${jar.dir}/${ant.project.name}.jar" fork="true"/>
- </target>
- <target name="clean-build" depends="clean,jar"/>
- <target name="main" depends="clean,run"/>
- </project>
- </pre>
- <p>Now it's easier, just do a <tt class="code">ant</tt> and you will get</p>
- <pre class="output">
- Buildfile: build.xml
- clean:
- compile:
- [mkdir] Created dir: C:\...\build\classes
- [javac] Compiling 1 source file to C:\...\build\classes
- jar:
- [mkdir] Created dir: C:\...\build\jar
- [jar] Building jar: C:\...\build\jar\HelloWorld.jar
- run:
- [java] Hello World
- main:
- BUILD SUCCESSFUL
- </pre>
- <a name="ext-libs"></a>
- <h2>Using external libraries</h2>
- <p>Somehow told us not to use syso-statements. For log-Statements we should use a Logging-API - customizable on a high
- degree (including switching off during usual life (= not development) execution). We use Log4J for that, because <ul>
- <li>it is not part of the JDK (1.4+) and we want to show how to use external libs</li>
- <li>it can run under JDK 1.2 (as Ant)</li>
- <li>it's highly configurable</li>
- <li>it's from Apache ;-)</li>
- </ul></p>
- <p>We store our external libraries in a new directory <tt>lib</tt>. Log4J can be
- <a href="http://www.apache.org/dist/logging/log4j/1.2.13/logging-log4j-1.2.13.zip">downloaded [1]</a> from Logging's Homepage.
- Create the <tt>lib</tt> directory and extract the log4j-1.2.9.jar into that lib-directory. After that we have to modify
- our java source to use that library and our buildfile so that this library could be accessed during compilation and run.
- </p>
- <p>Working with Log4J is documented inside its manual. Here we use the <i>MyApp</i>-example from the
- <a href="http://logging.apache.org/log4j/docs/manual.html">Short Manual [2]</a>. First we have to modify the java source to
- use the logging framework:</p>
- <pre class="code">
- package oata;
- <b>import org.apache.log4j.Logger;</b>
- <b>import org.apache.log4j.BasicConfigurator;</b>
- public class HelloWorld {
- <b>static Logger logger = Logger.getLogger(HelloWorld.class);</b>
- public static void main(String[] args) {
- <b>BasicConfigurator.configure();</b>
- <font color="blue"><b>logger.info("Hello World");</b></font> // the old SysO-statement
- }
- }
- </pre>
- <p>Most of the modifications are "framework overhead" which has to be done once. The blue line is our "old System-out"
- statement.</p>
- <p>Don't try to run <tt>ant</tt> - you will only get lot of compiler errors. Log4J is not inside the classpath so we have
- to do a little work here. But do not change the CLASSPATH environment variable! This is only for this project and maybe
- you would break other environments (this is one of the most famous mistakes when working with Ant). We introduce Log4J
- (or to be more precise: all libraries (jar-files) which are somewhere under <tt>.\lib</tt>) into our buildfile:</p>
- <pre class="code">
- <project name="HelloWorld" basedir="." default="main">
- ...
- <b><property name="lib.dir" value="lib"/></b>
- <b><path id="classpath"></b>
- <b><fileset dir="${lib.dir}" includes="**/*.jar"/></b>
- <b></path></b>
- ...
- <target name="compile">
- <mkdir dir="${classes.dir}"/>
- <javac srcdir="${src.dir}" destdir="${classes.dir}" <b>classpathref="classpath"</b>/>
- </target>
- <target name="run" depends="jar">
- <java fork="true" <b>classname="${main-class}"</b>>
- <b><classpath></b>
- <b><path refid="classpath"/></b>
- <font color="red"><b><path location="${jar.dir}/${ant.project.name}.jar"/></b></font>
- <b></classpath></b>
- </java>
- </target>
- ...
- </project>
- </pre>
- <p>In this example we start our application not via its Main-Class manifest-attribute, because we could not provide
- a jarname <i>and</i> a classpath. So add our class in the red line to the already defined path and start as usual. Running
- <tt>ant</tt> would give (after the usual compile stuff):</p>
- <pre class="output">
- [java] 0 [main] INFO oata.HelloWorld - Hello World
- </pre>
- <p>What's that? <ul>
- <li><i>[java]</i> Ant task running at the moment</li>
- <li><i>0</i> <font size="-1">sorry don't know - some Log4J stuff</font></li>
- <li><i>[main]</i> the running thread from our application </li>
- <li><i>INFO</i> log level of that statement</i>
- <li><i>oata.HelloWorld</i> source of that statement</i>
- <li><i>-</i> separator</li>
- <li><i>Hello World</i> the message</li>
- </ul>
- For another layout ... have a look inside Log4J's documentation about using other PatternLayout's.</p>
- <a name="config-files">
- <h2>Configuration files</h2>
- <p>Why we have used Log4J? "It's highly configurable"? No - all is hard coded! But that is not the debt of Log4J - it's
- ours. We had coded <tt>BasicConfigurator.configure();</tt> which implies a simple, but hard coded configuration. More
- comfortable would be using a property file. In the java source delete the BasicConfiguration-line from the main() method
- (and the related import-statement). Log4J will search then for a configuration as described in it's manual. Then create
- a new file <tt>src/log4j.properties</tt>. That's the default name for Log4J's configuration and using that name would make
- life easier - not only the framework knows what is inside, you too!</p>
- <pre class="code">
- log4j.rootLogger=DEBUG, <b>stdout</b>
- log4j.appender.<b>stdout</b>=org.apache.log4j.ConsoleAppender
- log4j.appender.<b>stdout</b>.layout=org.apache.log4j.PatternLayout
- log4j.appender.<b>stdout</b>.layout.ConversionPattern=<font color="blue"><b>%m%n</b></font>
- </pre>
- <p>This configuration creates an output channel ("Appender") to console named as <tt>stdout</tt> which prints the
- message (%m) followed by a line feed (%n) - same as the earlier System.out.println() :-) Oooh kay - but we haven't
- finished yet. We should deliver the configuration file, too. So we change the buildfile:</p>
- <pre class="code">
- ...
- <target name="compile">
- <mkdir dir="${classes.dir}"/>
- <javac srcdir="${src.dir}" destdir="${classes.dir}" classpathref="classpath"/>
- <b><copy todir="${classes.dir}"></b>
- <b><fileset dir="${src.dir}" excludes="**/*.java"/></b>
- <b></copy></b>
- </target>
- ...
- </pre>
- <p>This copies all resources (as long as they haven't the suffix ".java") to the build directory, so we could
- start the application from that directory and these files will included into the jar.</p>
- <a name="junit">
- <h2>Testing the class</h2>
- <p>In this step we will introduce the usage of the JUnit [3] testframework in combination with Ant. Because Ant
- has a built-in JUnit 3.8.2 you could start directly using it. Write a test class in <tt>src\HelloWorldTest.java</tt>: </p>
- <pre class="code">
- public class HelloWorldTest extends junit.framework.TestCase {
- public void testNothing() {
- }
-
- public void testWillAlwaysFail() {
- fail("An error message");
- }
-
- }</pre>
- <p>Because we dont have real business logic to test, this test class is very small: just show how to start. For
- further information see the JUnit documentation [3] and the manual of <a href="Tasks/junit.html">junit</a> task.
- Now we add a junit instruction to our buildfile:</p>
- <pre class="code">
- ...
- <path <b>id="application"</b> location="${jar.dir}/${ant.project.name}.jar"/>
- <target name="run" depends="jar">
- <java fork="true" classname="${main-class}">
- <classpath>
- <path refid="classpath"/>
- <b><path refid="application"/></b>
- </classpath>
- </java>
- </target>
-
- <b><target name="junit" depends="jar">
- <junit printsummary="yes">
- <classpath>
- <path refid="classpath"/>
- <path refid="application"/>
- </classpath>
-
- <batchtest fork="yes">
- <fileset dir="${src.dir}" includes="*Test.java"/>
- </batchtest>
- </junit>
- </target></b>
- ...
- </pre>
- <p>We reuse the path to our own jar file as defined in run-target by
- giving it an ID and making it globally available.
- The <tt>printsummary=yes</tt> lets us see more detailed information than just a "FAILED" or "PASSED" message.
- How much tests failed? Some errors? Printsummary lets us know. The classpath is set up to find our classes.
- To run tests the <tt>batchtest</tt> here is used, so you could easily add more test classes in the future just
- by naming them <tt>*Test.java</tt>. This is a common naming scheme.</p>
- <p>After a <tt class="code">ant junit</tt> you'll get:</p>
- <pre class="output">
- ...
- junit:
- [junit] Running HelloWorldTest
- [junit] Tests run: 2, Failures: 1, Errors: 0, Time elapsed: 0,01 sec
- [junit] Test HelloWorldTest FAILED
- BUILD SUCCESSFUL
- ...
- </pre>
- <p>We can also produce a report. Something that you (and other) could read after closing the shell ....
- There are two steps: 1. let <junit> log the information and 2. convert these to something readable (browsable).<p>
- <pre class="code">
- ...
- <b><property name="report.dir" value="${build.dir}/junitreport"/></b>
- ...
- <target name="junit" depends="jar">
- <b><mkdir dir="${report.dir}"/></b>
- <junit printsummary="yes">
- <classpath>
- <path refid="classpath"/>
- <path refid="application"/>
- </classpath>
-
- <b><formatter type="xml"/></b>
-
- <batchtest fork="yes" <b>todir="${report.dir}"</b>>
- <fileset dir="${src.dir}" includes="*Test.java"/>
- </batchtest>
- </junit>
- </target>
-
- <b><target name="junitreport">
- <junitreport todir="${report.dir}">
- <fileset dir="${report.dir}" includes="TEST-*.xml"/>
- <report todir="${report.dir}"/>
- </junitreport>
- </target></b>
- </pre>
- <p>Because we would produce a lot of files and these files would be written to the current directory by default,
- we define a report directory, create it before running the <tt>junit</tt> and redirect the logging to it. The log format
- is XML so <tt>junitreport</tt> could parse it. In a second target <tt>junitreport</tt> should create a browsable
- HTML-report for all generated xml-log files in the report directory. Now you can open the ${report.dir}\index.html and
- see the result (looks something like JavaDoc).<br>
- Personally I use two different targets for junit and junitreport. Generating the HTML report needs some time and you dont
- need the HTML report just for testing, e.g. if you are fixing an error or a integration server is doing a job.
- </p>
- <a name="resources"></a>
- <h2>Resources</h2>
- <pre>
- [1] <a href="http://www.apache.org/dist/logging/log4j/1.2.13/logging-log4j-1.2.13.zip">http://www.apache.org/dist/logging/log4j/1.2.13/logging-log4j-1.2.13.zip</a>
- [2] <a href="http://logging.apache.org/log4j/docs/manual.html">http://logging.apache.org/log4j/docs/manual.html</a>
- [3] <a href="http://www.junit.org/index.htm">http://www.junit.org/index.htm</a>
- </pre>
- </body>
- </html>