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Headless Build for Beginners - Part II

· Java Zone

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 Plug-ins are rarely required to be built in isolation. The nicer way of building them is through features. Of course, features are more useful from distribution and deployment point of view. A feature is build the same way as a plug-in. Include the required plug-ins in the feature.xml and generate the build.xml from build.properties file (right-click and choose PDE Tools). Now launch the feature build.

java -jar <eclipse-installation-path>\plugins\org.eclipse.equinox.launcher_<version><qualifier>.jar -application org.eclipse.ant.core.antRunner -buildfile <eclipse-workspace-path>\<feature-project-path>\<build-xml-path> 

java -jar C:\eclipse\plugins\org.eclipse.equinox.launcher_1.1.0.v20100507.jar 
-application org.eclipse.ant.core.antRunner
-buildfile C:\workspace\com.example.helloworld.feature\build.xml

Note that build will fail if the included plug-ins do not have the build.xml generated for them. This is not a likely scenario and definitely not the way it is done. But let it be for time being. Generate the build.xml for all the plug-ins for build to succeed. Later on we will see how it can be done without it.

Passing parameters to AntRunner from command line

The build generated by the above command will leave the feature jar inside the feature project and the plug-in jar inside the plug-in project folder. Of course they shouldn't scattered all around. They need to be collected to one place.

Open the build.xml for the plug-in project and inside the 'init' target there is one property called 'plugin.destination'. It is this location where the jar is finally created by the 'build.update.jar' target.

<property name="plugin.destination" value="${basedir}"/>

Change the value of this property to "${buildDirectory}". Make the similar change for the 'feature.destination' property in the build.xml for the feature project.

If the build is triggered now, it will fail because it can not find the value for the 'buildDirectory'. The value can be provided through command line using -D option.

java -jar <eclipse-installation-path>\plugins\org.eclipse.equinox.launcher_<version><qualifier>.jar -application org.eclipse.ant.core.antRunner -buildfile <eclipse-workspace-path>\<feature-project-path>\<build-xml-path> -DbuildDirectory=<build-storage-location> 

java -jar C:\eclipse\plugins\org.eclipse.equinox.launcher_1.1.0.v20100507.jar 
-application org.eclipse.ant.core.antRunner
-buildfile C:\workspace\com.example.helloworld.feature\build.xml
-DbuildDirectory=c:\build\buildOutput

When the build is run, ${buildDirectory} will be replaced by the value(location) provided and jars will get created there.

More parameters can be supplied using -D<variable-name>=<value> from the command line.

Ant properties file

Passing parameters from the command line is not very scalable or maintainable. A better way is to pass the parameters using a properties file.

Create a properties file, say, 'custom_build.properties' inside a folder, say, 'buildConfiguration'. The name 'custom_build.properties' have been chosen to distinguish it from 'build.properties'. Carefully note that though both are name=value kind properties file, it is common(rather better) practice to not mix them. Since 'build.properties' has a special meaning in context of PDE, it is recommended that a different name is used to avoid any confusion.

Store the property and its value in the properties file.

buildDirectory=c:/build/buildConfiguration 

Note the forward slashes instead of backslash. The backslashes will work too but needs to be escaped.

Now open the build.xml for the feature project and add the 'loadproperties' entry under the 'project' tag

<project name="com.example.helloworld.feature" default="build.update.jar" basedir=".">
<loadproperties srcfile="../../buildConfiguration/build.properties" />
...

This entry needs to be made only in feature project's build.xml and is not required for the plug-in projects' build.xml. They still can use the same variable name and will get the value from the properties file.

Note that the value for the 'srcfile' is a relative path and the ../../ (grand-parent directory) indicates that the properties file has been kept in one folder outside the folder (or workspace) containing the projects.

From http://blog.ankursharma.org/2010/06/headless-build-for-beginners-part-ii.html

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