多模块构建很困难，因为没有标准，每个构建作者都有自己的方法来解决这个问题。
我个人的偏好是模仿 Maven 的做法。每个模块创建一个 jar 文件并将其发布到“本地”存储库。然后，此 jar 文件是使用其类的其他模块的依赖项。这种方法在模块之间创建了清晰的分离，意味着您在处理一个子模块时不需要构建整个项目。
那么这是如何使用 ANT 完成的呢？那么你需要接受另一个 Maven 概念，依赖管理。 ivy plugin 为 ANT 提供了此功能。
示例
我的虚拟项目。一个名为“app”的模块，它是“server”模块的依赖项
├── build.xml <-- Builds all modules in correct order
├── app
│ ├── build.xml
│ ├── ivy.xml <-- Describes module dependencies
│ └── src
| ..
└── server
├── build.xml
├── ivy.xml <-- Dependency on the "app" module
└── src
..
除非您自定义位置，否则 ivy 使用以下目录来存储文件：
~/.ivy2/cache <-- Downloaded 3rd party dependencies go here
~/.ivy2/local <-- Repository which is private to the user.
创建替代存储位置和利用 Maven 存储库管理器超出了此问题的范围。
通过构建运行此示例后，会生成以下显式版本文件：
~/.ivy2/local/com.myspotontheweb/demo-app/1.0.0/jars/demo-app.jar
~/.ivy2/local/com.myspotontheweb/demo-server/1.0.0/wars/demo-server.war
build.xml
以正确的顺序构建所有模块。这是由每个模块的 ivy.xml 文件中记录的模块依赖关系决定的（参见 ivy buildlist 任务）。当您有大量相互依赖的模块时，这是一个非常有用的功能。
<project name="demo" default="build" xmlns:ivy="antlib:org.apache.ivy.ant">
<available classname="org.apache.ivy.Main" property="ivy.installed"/>
<target name="install-ivy" unless="ivy.installed">
<mkdir dir="${user.home}/.ant/lib"/>
<get dest="${user.home}/.ant/lib/ivy.jar" src="http://search.maven.org/remotecontent?filepath=org/apache/ivy/ivy/2.3.0/ivy-2.3.0.jar"/>
<fail message="Ivy has been installed. Run the build again"/>
</target>
<target name="build-list" depends="install-ivy">
<ivy:buildlist reference="build-path">
<fileset dir="." includes="**/build.xml" excludes="build.xml"/>
</ivy:buildlist>
</target>
<target name="build" depends="build-list">
<subant buildpathref="build-path">
<target name="clean"/>
<target name="publish"/>
</subant>
</target>
<target name="clean" depends="build-list">
<subant buildpathref="build-path">
<target name="clean"/>
</subant>
</target>
<target name="clean-all" depends="clean">
<ivy:cleancache/>
</target>
</project>
注意事项：
- 包含确保 ivy jar 依赖项在缺失时安装的逻辑
- Ivy 将缓存下载的第 3 方依赖项。 “clean-all”任务对于确保构建干净整洁很有用:-)
app/ivy.xml
列出模块具有的第 3 方依赖项。这是一个非常有用的 Maven 特性。依赖项会从 Maven Central 自动下载。无需将它们提交到您的源代码存储库中。
<ivy-module version="2.0">
<info organisation="com.myspotontheweb" module="demo-app"/>
<configurations>
<conf name="compile" description="Required to compile application"/>
<conf name="runtime" description="Additional run-time dependencies" extends="compile"/>
<conf name="test" description="Required for test only" extends="runtime"/>
</configurations>
<publications>
<artifact name="demo-app"/>
</publications>
<dependencies>
<!-- compile dependencies -->
<dependency org="org.slf4j" name="slf4j-api" rev="1.7.5" conf="compile->default"/>
<!-- runtime dependencies -->
<dependency org="org.slf4j" name="slf4j-log4j12" rev="1.7.5" conf="runtime->default"/>
<!-- test dependencies -->
<dependency org="junit" name="junit" rev="4.11" conf="test->default"/>
</dependencies>
</ivy-module>
注意：
- Ivy 配置用于对依赖项进行分类和分组。稍后用于填充类路径
app/build.xml
相当标准的构建过程。代码经过编译测试和打包。请注意如何使用 ivy 配置来控制类路径。
“发布”目标值得特别注意，它将构建的 jar 推送到 local location 中，其他模块构建可以获取它。
<project name="demo-app" default="build" xmlns:ivy="antlib:org.apache.ivy.ant">
<!--
================
Build properties
================
-->
<property name="src.dir" location="src/main/java"/>
<property name="resources.dir" location="src/main/resources"/>
<property name="test.src.dir" location="src/test/java"/>
<property name="build.dir" location="target"/>
<property name="dist.dir" location="${build.dir}/dist"/>
<property name="jar.main.class" value="org.demo.App"/>
<property name="jar.file" value="${dist.dir}/${ant.project.name}.jar"/>
<property name="pub.revision" value="1.0"/>
<property name="pub.resolver" value="local"/>
<!--
===========
Build setup
===========
-->
<target name="resolve" description="Use ivy to resolve classpaths">
<ivy:resolve/>
<ivy:report todir='${build.dir}/ivy-reports' graph='false' xml='false'/>
<ivy:cachepath pathid="compile.path" conf="compile"/>
<ivy:cachepath pathid="test.path" conf="test"/>
</target>
<!--
===============
Compile targets
===============
-->
<target name="resources" description="Copy resources into classpath">
<copy todir="${build.dir}/classes">
<fileset dir="${resources.dir}"/>
</copy>
</target>
<target name="compile" depends="resolve,resources" description="Compile code">
<mkdir dir="${build.dir}/classes"/>
<javac srcdir="${src.dir}" destdir="${build.dir}/classes" includeantruntime="false" debug="true" classpathref="compile.path"/>
</target>
<target name="compile-tests" depends="compile" description="Compile tests">
<mkdir dir="${build.dir}/test-classes"/>
<javac srcdir="${test.src.dir}" destdir="${build.dir}/test-classes" includeantruntime="false" debug="true">
<classpath>
<path refid="test.path"/>
<pathelement path="${build.dir}/classes"/>
</classpath>
</javac>
</target>
<!--
============
Test targets
============
-->
<target name="test" depends="compile-tests" description="Run unit tests">
<mkdir dir="${build.dir}/test-reports"/>
<junit printsummary="yes" haltonfailure="yes">
<classpath>
<path refid="test.path"/>
<pathelement path="${build.dir}/classes"/>
<pathelement path="${build.dir}/test-classes"/>
</classpath>
<formatter type="xml"/>
<batchtest fork="yes" todir="${build.dir}/test-reports">
<fileset dir="${test.src.dir}">
<include name="**/*Test*.java"/>
<exclude name="**/AllTests.java"/>
</fileset>
</batchtest>
</junit>
</target>
<!--
=====================
Build project
=====================
-->
<target name="build" depends="test" description="Create executable jar archive">
<ivy:retrieve pattern="${dist.dir}/lib/[artifact]-[revision](-[classifier]).[ext]" conf="runtime"/>
<manifestclasspath property="jar.classpath" jarfile="${jar.file}">
<classpath>
<fileset dir="${dist.dir}/lib" includes="*.jar"/>
</classpath>
</manifestclasspath>
<jar destfile="${jar.file}" basedir="${build.dir}/classes">
<manifest>
<attribute name="Main-Class" value="${jar.main.class}" />
<attribute name="Class-Path" value="${jar.classpath}" />
</manifest>
</jar>
</target>
<!--
=====================
Publish project
=====================
-->
<target name="publish" depends="build" description="Publish artifacts to shared repo">
<ivy:buildnumber organisation="${ivy.organisation}" module="${ivy.module}" revision="${pub.revision}"/>
<ivy:publish resolver="${pub.resolver}" pubrevision="${ivy.new.revision}">
<artifacts pattern="${build.dir}/dist/[artifact].[ext]"/>
</ivy:publish>
</target>
<!--
=============
Clean project
=============
-->
<target name="clean" description="Cleanup build files">
<delete dir="${build.dir}"/>
</target>
</project>
注意事项：
服务器/ivy.xml
此模块仅依赖于最新版本的“app”模块。实际的修订号是在构建时根据本地存储库中存在的文件确定的。
<ivy-module version="2.0">
<info organisation="com.myspotontheweb" module="demo-server"/>
<configurations>
<conf name="compile" description="Required to compile application"/>
<conf name="runtime" description="Additional run-time dependencies" extends="compile"/>
<conf name="test" description="Required for test only" extends="runtime"/>
</configurations>
<publications>
<artifact name="demo-server" type="war"/>
</publications>
<dependencies>
<!-- runtime dependencies -->
<dependency org="com.myspotontheweb" name="demo-app" rev="latest.integration" conf="runtime"/>
</dependencies>
</ivy-module>
服务器/build.xml
这个构建只是将库打包到一个 WAR 文件中。值得注意的是它使用了 ivy retrieve 任务。它将拉取“app”模块依赖项及其所有传递依赖项。手动跟踪这些可能很困难。
<project name="demo-server" default="build" xmlns:ivy="antlib:org.apache.ivy.ant">
<!--
================
Build properties
================
-->
<property name="build.dir" location="target"/>
<property name="dist.dir" location="${build.dir}/dist"/>
<property name="war.file" value="${dist.dir}/${ant.project.name}.war"/>
<property name="pub.revision" value="1.0"/>
<property name="pub.resolver" value="local"/>
<!--
===========
Build setup
===========
-->
<target name="resolve" description="Use ivy to resolve classpaths">
<ivy:resolve/>
<ivy:report todir='${build.dir}/ivy-reports' graph='false' xml='false'/>
</target>
<!--
=====================
Build project
=====================
-->
<target name="build" depends="resolve" description="Create executable jar archive">
<ivy:retrieve pattern="${build.dir}/lib/[artifact]-[revision](-[classifier]).[ext]" conf="runtime"/>
<war destfile="${war.file}" webxml="src/resources/web.xml">
<lib dir="${build.dir}/lib"/>
</war>
</target>
<!--
=====================
Publish project
=====================
-->
<target name="publish" depends="build" description="Publish artifacts to shared repo">
<ivy:buildnumber organisation="${ivy.organisation}" module="${ivy.module}" revision="${pub.revision}"/>
<ivy:publish resolver="${pub.resolver}" pubrevision="${ivy.new.revision}">
<artifacts pattern="${build.dir}/dist/[artifact].[ext]"/>
</ivy:publish>
</target>
<!--
=============
Clean project
=============
-->
<target name="clean" description="Cleanup build files">
<delete dir="${build.dir}"/>
</target>
</project>