如何使用 Ant 创建包含外部 jar 文件的 jar

Question

my build.XML下面给出。

<property name="src.dir"     value="src"/>
<property name="lib.dir"     value="lib"/>
<property name="build.dir"   value="build"/>
<property name="classes.dir" value="${build.dir}/classes"/>
<property name="jar.dir"     value="${build.dir}/jar"/>
<property name="main-class"  value="HighAvailablity"/>
<path id="classpath">
    <fileset dir="${lib.dir}" includes="**/*.jar"/>
</path>
<target name="clean">
    <delete dir="${build.dir}"/>
</target>
<target name="compile">
    <mkdir dir="${classes.dir}"/>
    <javac srcdir="${src.dir}" destdir="${classes.dir}" classpathref="classpath"/>
</target>
<target name="jar" depends="compile">
    <mkdir dir="${jar.dir}"/>
    <jar destfile="${jar.dir}/${ant.project.name}.jar" basedir="${classes.dir}">
        <manifest>
            <attribute name="Main-Class" value="${main-class}"/>
        </manifest>
    </jar>
</target>
<target name="run" depends="jar">
    <java fork="true" classname="${main-class}"/>
    <classpath>
        <path refid="classpath"/>
        <path location="${jar.dir}/${ant.project.name}.jar"/>
    </classpath>
</target>
<target name="clean-build" depends="clean,jar"/>
<target name="main" depends="clean,run"/>

使用 ant 命令运行时，出现以下错误。

Could not create task or type of type: classpath.
Ant could not find the task or a class this task relies upon.
This is common and has a number of causes; the usual
solutions are to read the manual pages then download and
install needed JAR files, or fix the build file:
 - You have misspelt 'classpath'.
   Fix: check your spelling.
 - The task needs an external JAR file to execute
     and this is not found at the right place in the classpath.
   Fix: check the documentation for dependencies.
   Fix: declare the task.
 - The task is an Ant optional task and the JAR file and/or libraries
     implementing the functionality were not found at the time you
     yourself built your installation of Ant from the Ant sources.
   Fix: Look in the ANT_HOME/lib for the 'ant-' JAR corresponding to the
     task and make sure it contains more than merely a META-INF/MANIFEST.MF.
     If all it contains is the manifest, then rebuild Ant with the needed
     libraries present in ${ant.home}/lib/optional/ , or alternatively,
     download a pre-built release version from apache.org
 - The build file was written for a later version of Ant
   Fix: upgrade to at least the latest release version of Ant
 - The task is not an Ant core or optional task
     and needs to be declared using <taskdef>.
 - You are attempting to use a task defined using
    <presetdef> or <macrodef> but have spelt wrong or not
   defined it at the point of use
Remember that for JAR files to be visible to Ant tasks implemented
in ANT_HOME/lib, the files must be in the same directory or on the
classpath
Please neither file bug reports on this problem, nor email the
Ant mailing lists, until all of these causes have been explored,
as this is not an Ant bug.
Total time: 2 seconds

如何解决此问题？

Answer 1

看起来像run目标中的一个小错误 - 类路径应该是java任务的子元素，如下所示：

<java fork="true" classname="${main-class}">
    <classpath>
        <path refid="classpath"/>
        <path location="${jar.dir}/${ant.project.name}.jar"/>
    </classpath>
</java>

否则，Ant 会将目标解释为 java 任务，后跟类路径任务 - 并且没有类路径任务。

顺便说一下，这是最臭名昭著的错误消息之一 - 在较新版本的 Ant 中，它被"缩短"了。