java - Ant 找不到主类错误

Question

这是我第一次使用 Ant，当它尝试运行时，我遇到了 java.lang.NoClassDefFoundError 异常。这是我的 Ant 构建脚本，

<project name="LearnKirtan" basedir="." default="main">

    <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" />

    <path id="classpath">
        <fileset dir="${lib.dir}" includes="**/*.jar" />
    </path>

    <property name="main-class" value="gsingh.learnkirtan.Main" />

    <target name="clean">
        <delete dir="${build.dir}" />
    </target>

    <target name="compile">
        <mkdir dir="${classes.dir}" />
        <javac srcdir="${src.dir}" destdir="${classes.dir}" includeantruntime="false" 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 classname="${main-class}" fork="true" />
        <classpath>
            <path refid="classpath" />
            <path location="${jar.dir}/${ant.project.name}.jar" />
        </classpath>
    </target>

    <target name="clean-build" depends="clean,jar" />

    <target name="main" depends="clean,run" />

</project>

构建没有错误。运行目标给出了异常。我检查了 jar 文件中生成的 list ，它看起来像这样，

Manifest-Version: 1.0
Ant-Version: Apache Ant 1.8.2
Created-By: 1.6.0_30-b12 (Sun Microsystems Inc.)
Main-Class: gsingh.learnkirtan.Main

Answer 1

你的运行目标看起来有点奇怪，<java classname="${main-class}" fork="true" />是自动关闭的，所以 classpath元素从未被使用过

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

可能适合你。