缺少依赖项而无法建立ANT

Question

I have come across the same issue as this Proper usage of Apache Commons Configuration ie Commons Lang is not included as a dependency.

Although eclipse and IDEA both pick it up, javac from ANT does not.

<javac debug="true" destdir="${build.classes.dir}" srcdir="${src.dir}" includeantruntime="false">
  <classpath refid="build.classpath"/>
</javac>

I want the build server to be able to pick up these dependency issues and fail the build if someone has missed them out.

Answer 1

Add a task as below

<fail  message="Missing the commons lang jar dependency.">
  <condition>
     <not>  
     <available file="common-lang.jar"/>
     </not>
  </condition>
</fail>

Ant fail task link: https://ant.apache.org/manual/Tasks/fail.html

Answer 2

Use ivy to manage your builds 3rd party dependencies.

<ivy:cachepath pathid="build.classpath">
    <dependency org="commons-lang" name="commons-lang" rev="2.6" conf="default"/>
</ivy:cachepath>

By default ivy will download (and cache) from the Maven Central repository and is aware of transitive dependencies (dependencies of dependencies).

Answer 3

Suresh Koya is close, but there's a couple of issues:

• Suresh's way will only work if commons-lang.jar is actually in the current directory.
• It also won't work if the jar is called something like commons-lang-2.6.jar .

The first can be fixed by adding a <filepath> sub-entity to <available> . This gives the <available> condition a directory path to search for the jar. However, it won't work if the user downloaded commons-lang with the version number on it (as you would from a Maven repository).

To get around this issue, you need to create a path resource using something like <fileset> and then checking to see if you picked up any version of the commons-lang jarfile. You can see below that I am looking for any file that begins with commons-lang and has a .jar suffix.

After I set my resource, I can use a <resoucecount> condition to see if I picked up any version of commons-lang :

<path id="commons-lang.path">
     <fileset dir="${lib.dir}">
         <incude name="commons-lang*.jar"/>
     </fileset>
</path>

<fail message="Missing commons-lang Jar">
    <condition>
        <resourcecount refid="commons-lang.path" 
             when="equals" count="0"/>
    </condition>

Now, if I know something about the commons-lang jar, I could have used the <available> condition to search for a particular class in my classpath:

<fail message="Can't find commons-lang Jar">
     <condition>
         <not>
            <available classname="org.apache.commons.lang.Entities">
                 <classpath refid="compile.classpath"/>
            </available>
         </not>
     </condition>
</fail>

This will find that commons-lang jar no matter what it's called.

If you're interested in Ivy, I have a project in GitHub that makes it pretty easy to add Ivy to an entire development site. Third party dependency management is the way to go. Using Ivy is great because it integrates with Ant. Maven and Gradle have their advantages, but you'll have to redo your whole build infrastructure in order to use them.