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この例ではIvyを使用する最も簡単な方法を示す。 特別な設定無しに、IvyはIvyファイル中に記述された依存をMaven 2のリポジトリを使って解決する。 以下に見てみよう。

このチュートリアルのソースはivyディストリビューションの src/example/hello-ivyディレクトリにおかれている。

ivy.xmlファイル

このファイルにはプロジェクトが他のライブラリに依存することを記述する。以下に例を示す。

<ivy-module version="2.0">
    <info organisation="apache" module="hello-ivy"/>
    <dependencies>
        <dependency org="commons-lang" name="commons-lang" rev="2.0"/>
        <dependency org="commons-cli" name="commons-cli" rev="1.0"/>
    </dependencies>
</ivy-module>

このファイルのフォーマットは極めて理解しやすいだろうが、以下に説明する。 まず最初にルート要素のivy-moduleである。ここにはバージョンアトリビュートがあり、どのバージョンのIvyを使用するかを示す。

次にinfoタグがある。これは我々が依存関係を定義しようとするモジュールについての情報を示すものである。 ここではorganizationとモジュール名のみを示している。 ここには何を書いても良いが、ただし空白は避けることが望ましい。

最後に依存関係を定義するdependenciesセクションがある。 このモジュールはcommons-lang, commons-cliという二つのライブラリに依存している。 見ての通りorgとnameは我々が必要とする依存のorganizationとモジュール名である。 rev属性は依存するモジュールのリビジョンを示す。

これらの属性を記述するためには、依存するものの正確な情報を得なければならない。 IvyはデフォルトでMaven 2のリポジトリを使用する。 したがって、欲しいモジュールをさがすには、mvnrepository.comを使用することを推奨する。 それが見つかればmaven POMの依存を宣言する方法を得ることになる。例えば、

<dependency>
    <groupId>commons-lang</groupId>
    <artifactId>commons-lang</artifactId>
    <version>2.0</version>
</dependency>

これをIvy依存宣言に変換するには、単にgroupIdをorganizationとし、artifactIdをモジュール名とし、そしてversionをリビジョンとすればよい。これは我々がこのチュートリアルで行ったことである。つまり、commons-langとcommons-cliである。

• Note that having commons-lang and commons-cli as organization is not the best example of what the organization should be. It would be better to use org.apache, org.apache.commons or org.apache.commons.lang. However, this is how these modules are identified in the maven 2 repository, so the simplest way to get them is to use the details as is (you will see in Building a repository that you can use namespaces to redefine these names if you want something cleaner).

If you want more details on what you can do in Ivy files, you can have a look at the Ivy files reference documentation. The build.xml file The corresponding build file contains a set of targets, allowing to resolve dependencies declared in the Ivy file, to compile and run the sample code, produce a report of dependency resolution, and clean the cache or the project. You can use the standard "ant -p" to get the list of available targets. Feel free to have a look at the whole file, but here is the part relevant to dependency resolution:

<project xmlns:ivy="antlib:org.apache.ivy.ant" name="hello-ivy" default="run">
    
    ...
    
    <!-- ================================= 
          target: resolve              
         ================================= -->
    <target name="resolve" description="--> retrieve dependencies with ivy">
        <ivy:retrieve />
    </target>
</project>

As you can see, it's very easy to call Ivy to resolve and retrieve dependencies: all you need if Ivy is properly installed is to define an XML namespace in your Ant file (xmlns:ivy="antlib:org.apache.ivy.ant"). Then all the Ivy ant tasks will be available in this namespace.

Here we use only one task: the retrieve task. With no attributes, it will use default settings and look for a file named ivy.xml for dependency definition. That's exactly what we want, so we need nothing more than that.

Note that in this case we define a "resolve" target and call the retrieve task. This may sound confusing, actually the retrieve task performs a resolve (which resolves dependencies and downloads them to a cache) followed by a retrieve (a copy of those file in a local project directory). Check the How does it work ? page for details about that. Running the project Ok, now that we have seen the files involved, let's run the sample to see what happens. Open a shell (or command line) window, and enter the hello-ivy example directory. Then, at the command prompt, run 'ant':

I:\hello-ivy>ant
Buildfile: src\example\hello-ivy\build.xml

resolve:
[ivy:retrieve] :: Ivy 2.0.0-beta1-local-20071104204849 - 20071104204849 :: http://ant.apache.org/ivy/ ::
[ivy:retrieve] No ivy:settings found for the default reference 'ivy.instance'.  A default instance will be used
[ivy:retrieve] no settings file found, using default...
[ivy:retrieve] :: loading settings :: url = jar:file:/c:/dev/data/opensource_workspace/ivy/build/artifact/ivy-core.jar!/org/apache/ivy/core/settings/ivysettings.xml
[ivy:retrieve] :: resolving dependencies :: [ org.apache | hello-ivy | working@BEN-ScokartG ]
[ivy:retrieve]  confs: [default]
[ivy:retrieve]  found [ commons-lang | commons-lang | 2.0 ] in public
[ivy:retrieve]  found [ commons-cli | commons-cli | 1.0 ] in public
[ivy:retrieve]  found [ commons-logging | commons-logging | 1.0 ] in public
[ivy:retrieve] downloading http://repo1.maven.org/maven2/commons-lang/commons-lang/2.0/commons-lang-2.0.jar ...
[ivy:retrieve] .......................................................................................
[ivy:retrieve] .............................. (165kB)
[ivy:retrieve] .. (0kB)
[ivy:retrieve]  [SUCCESSFUL ] [ commons-lang | commons-lang | 2.0 ]/commons-lang.jar[jar] (3335ms)
[ivy:retrieve] downloading http://repo1.maven.org/maven2/commons-cli/commons-cli/1.0/commons-cli-1.0.jar ...
[ivy:retrieve] ...................... (29kB)
[ivy:retrieve] .. (0kB)
[ivy:retrieve]  [SUCCESSFUL ] [ commons-cli | commons-cli | 1.0 ]/commons-cli.jar[jar] (2053ms)
[ivy:retrieve] downloading http://repo1.maven.org/maven2/commons-logging/commons-logging/1.0/commons-logging-1.0.jar ...
[ivy:retrieve] ................. (21kB)
[ivy:retrieve] .. (0kB)
[ivy:retrieve]  [SUCCESSFUL ] [ commons-logging | commons-logging | 1.0 ]/commons-logging.jar[jar] (1933ms)
[ivy:retrieve] :: resolution report ::
[ivy:retrieve]  :: evicted modules:
[ivy:retrieve]  [ commons-lang | commons-lang | 1.0 ] by [[ commons-lang | commons-lang | 2.0 ]] in [default]
        ---------------------------------------------------------------------
        |                  |            modules            ||   artifacts   |
        |       conf       | number| search|dwnlded|evicted|| number|dwnlded|
        ---------------------------------------------------------------------
        |      default     |   4   |   3   |   0   |   1   ||   3   |   3   |
        ---------------------------------------------------------------------
[ivy:retrieve] :: retrieving :: [ org.apache | hello-ivy ]
[ivy:retrieve]  confs: [default]
[ivy:retrieve]  3 artifacts copied, 0 already retrieved

run:
     [java] standard message : hello ivy !
     [java] capitalized by org.apache.commons.lang.WordUtils : Hello Ivy !

BUILD SUCCESSFUL
Total time: 14 seconds

What happened ? Without any settings, Ivy retrieves files from the maven 2 repository. That's what happened here. The resolve task has found the commons-lang and commons-cli modules in the maven 2 repository, identified that commons-cli depends on commons-logging and so resolved it as a transitive dependency. Then Ivy has downloaded all corresponding artifacts in its cache (by default in your user home, in a .ivy2/cache directory). Finally, the retrieve task copies the resolved jars from the ivy cache to the default library directory of the project: the lib dir (you can change this easily by setting the pattern attribute on the retrieve task).

You might say that the task took a long time just to write out a "Hello Ivy !" message. But remember that a lot of time was spent downloading the required files from the web. Let's try to run it again:

I:\hello-ivy>ant
Buildfile: src\example\hello-ivy\build.xml

resolve:
[ivy:retrieve] :: Ivy 2.0.0-beta1-local-20071104204849 - 20071104204849 :: http://ant.apache.org/ivy/ ::
[ivy:retrieve] No ivy:settings found for the default reference 'ivy.instance'.  A default instance will be used
[ivy:retrieve] no settings file found, using default...
[ivy:retrieve] :: loading settings :: url = jar:file:/c:/dev/data/opensource_workspace/ivy/build/artifact/ivy-core.jar!/org/apache/ivy/core/settings/ivysettings.xml
[ivy:retrieve] :: resolving dependencies :: [ org.apache | hello-ivy | working@BEN-ScokartG ]
[ivy:retrieve]  confs: [default]
[ivy:retrieve]  found [ commons-lang | commons-lang | 2.0 ] in public
[ivy:retrieve]  found [ commons-cli | commons-cli | 1.0 ] in public
[ivy:retrieve]  found [ commons-logging | commons-logging | 1.0 ] in public
[ivy:retrieve] :: resolution report ::
[ivy:retrieve]  :: evicted modules:
[ivy:retrieve]  [ commons-lang | commons-lang | 1.0 ] by [[ commons-lang | commons-lang | 2.0 ]] in [default]
        ---------------------------------------------------------------------
        |                  |            modules            ||   artifacts   |
        |       conf       | number| search|dwnlded|evicted|| number|dwnlded|
        ---------------------------------------------------------------------
        |      default     |   4   |   0   |   0   |   1   ||   3   |   0   |
        ---------------------------------------------------------------------
[ivy:retrieve] :: retrieving :: [ org.apache | hello-ivy ]
[ivy:retrieve]  confs: [default]
[ivy:retrieve]  0 artifacts copied, 3 already retrieved

run:
     [java] standard message : hello ivy !
     [java] capitalized by org.apache.commons.lang.WordUtils : Hello Ivy !

BUILD SUCCESSFUL
Total time: 3 seconds

Great! the cache was used, no download was needed and the build was instantaneous.

And now, if you want to generate a report detailing all the dependencies of your module, you can call the report target, and check the generated file in the build directory. You should obtain something looking like this.

As you can see, using Ivy to resolve dependencies stored in the maven 2 repository is extremely easy. Now you can go on with the next tutorials to learn more about how to use module configurations which is a very powerful Ivy specific feature. Other tutorials are also available where you will learn how to use Ivy settings to leverage a possibly complex enterprise repository. It may also be a good time to start reading the reference documentation, and especially the introduction material which gives a good overview of Ivy. The best practices page is also a must read to start thinking about how to use Ant+Ivy to build a clean and robust build system.