ANT: Force error on missing resource?

Question

I've inherited an Ant build system that contains many resource set definitions like this:

<files id="app1.lib.jars">
  <include name="${java}/jre/lib/jsse.jar"/>
  <include name="${work.lib}/jtidy.jar"/>
  ...
</files>

<files id="app2.lib.jars">
  <include name="${work.lib}/itext.jar"/>
  <include name="${work.lib}/commons-httpclient.jar"/>
  ...
</files>

<files id="app3.lib.jars">
  <include name="${work.lib}/jdom.jar"/>
  <include name="${ant.lib}/ant.jar"/>
  ...
</files>

There are perhaps a dozen of these, and each can contain anywhere from 5 to 50 files. The problem is that I'm reworking this system to use Ivy for dependency management, and in the process some of the references now point to non-existent files. Unfortunately, Ant does not provide any help finding these bad pointers. When these resource collections are used to define a classpath any <include...> tags pointing to missing files are silently ignored.

I thought I could force an error by using the collections as the source of a <copy...>, but even with failonerror="true" it just ignored the bad references.

The command-line -v (verbose) and -d (debug) option didn't help either. The output acknowledged that some were missing but didn't actually show them

 [echo] app1.lib.jars
 [copy] C:\dev\src\tomcat6\work\java\jre\lib\jsse.jar omitted as C:\dev\src\tomcat6\work\verify\jsse.jar is up to date.
 [copy] C:\dev\src\tomcat6\work\lib\axis-ant.jar omitted as C:\dev\src\tomcat6\work\verify\axis-ant.jar is up to date.
 ...
 [copy] No sources found.
 [echo] app2.lib.jars
 ...

For a one-time solution I extracted all the filenames from the resource sets in the Ant file and compared that to a directory listing of the result of copying all the files (in Ant) into a temporary directory, after appropriate sorting.

Question: Is there a way to get Ant to tell me when a resource points to a missing file, preferably at the time the resource is defined?

Answer 1

Here's an illustration of one method. Key points

• Convert your files to filelists
• Use a restrict to check for existence
• Use a fail to error when something is missing

You'll need to add the "antlib:org.apache.tools.ant.types.resources.selectors" namespace to the project to use the resource selectors shown below. You'll hit snags with ant versions older than 1.7.0.

<project name="so" default="checkfiles" basedir="."
xmlns:rsel="antlib:org.apache.tools.ant.types.resources.selectors">

<filelist id="app1.lib.jars">
  <file name="${java}/jre/lib/jsse.jar"/>
  <file name="${work.lib}/jtidy.jar"/>
  ...
</filelist>

<restrict id="missing.app1.lib.jars">
  <filelist refid="app1.lib.jars"/>
  <rsel:not>
    <rsel:exists/>
  </rsel:not>
</restrict>

<property name="missing.files" refid="missing.app1.lib.jars" />
<fail message="These files are missing: ${missing.files}">
  <condition>
    <length string="${missing.files}" when="greater" length="0" />
  </condition>
</fail>
<pathconvert property="found.files" refid="app1.lib.jars" />
<echo message="Found files ${found.files}" />