Download jars from nexus using ant build tool as done automatically in Maven

I have a build.xml(ant based) which requires some jar from nexus to get copied in existing lib folder. i.e when it builds it should copy the jar from n开发者_如何学JAVAexus with some version defined & then copy in lib & do compilation. like happen in maven we define the artifact & its version . If changed will automatically download it from maven repo. how can i do this in ant based builds?

experts pls advice.

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I have taken the example listed in this thread one step further and created a macrodef to clean things up a bit for re-use. See below for downloading two artifacts from nexus (one snapshot, one release).

<project>
<target name="get-all">
    <mkdir dir="lib" />
    <nexus-get 
        groupId="foo.bar" 
        artifactId="some-artifact"
        version="1.0.28"
        repo="releases"
        extension="jar" 
        dest="lib" 
    />

    <nexus-get 
        groupId="foo.bar" 
        artifactId="another-artifact"
        version="1.0.0-SNAPSHOT"
        repo="snapshots"
        extension="jar" 
        dest="lib" 
    />
</target>

<macrodef name="nexus-get">
    <attribute name="groupId"/>
    <attribute name="artifactId"/>
    <attribute name="version"/>
    <attribute name="repo"/>
    <attribute name="extension"/>
    <attribute name="dest"/>

    <sequential>
        <get src="http://my-nexus:9999/nexus/service/local/artifact/maven/redirect?r=@{repo}&amp;g=@{groupId}&amp;a=@{artifactId}&amp;v=@{version}&amp;e=@{extension}" dest="@{dest}/@{artifactId}.@{extension}" usetimestamp="true" />
    </sequential>
</macrodef>

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You would probably be interested in Ivy. It is a sub-project of Ant for dependency management. It is perfect for your situation because it can read Maven repositories and provides Ant tasks for downloading the published artifacts, constructing class paths from them, etc. It supports your use case of getting the most recent version of a dependency if you configure it to ask for the "latest.release" revision of the module.

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Although there are surely specific ways to combine ant and maven the simplest thing (if you know the nexus URL and your artifact parameters to construct the download URL) would be just to use the ant Get task.

<project name="MyProject" default="resolveDependencies" basedir=".">
  <target name="resolveDependencies">
   <mkdir dir="lib" />
   <get src="http://search.maven.org/remotecontent?filepath=log4j/log4j/1.2.9/log4j-1.2.9.jar" dest="lib/log4j-1.2.9.jar" usetimestamp="true" />
  </target>
</project>

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Perhaps use the Maven Ant Tasks.

As shown on http://maven.apache.org/ant-tasks/examples/dependencies.html Can list dependencies in ant, and also do things like copy them

I think the section Using FileSets and the Version Mapper covers your need

You can use is filesetId, which will give you a fileset reference that can be used to copy files into a particular location. For example, to populate WEB-INF/lib with your dependencies you could use the following:

<artifact:dependencies filesetId="dependency.fileset" useScope="runtime">
  <dependency groupId="junit" artifactId="junit" version="3.8.2" scope="test"/>
</artifact:dependencies>
<copy todir="${webapp.output}/WEB-INF/lib">
  <fileset refid="dependency.fileset" />
  <!-- This mapper strips off all leading directory information -->
  <mapper type="flatten" />
</copy>