使用Ant执行Java类报错：找不到trackdeployment.DeploymentTracker类求助

目录结构 #

• 根目录：ci
• 构建文件路径：ci/scripts/applications/deploy-bpm.daa.xml
• Java类：ci/trackdeployment/DeploymentTracker.class（代码包含package trackdeployment;声明）
• 依赖包：ci/lib/ojdbc8.jar

出错的Ant Target #

<target name="update-deployment-details-in-db" description="Insert new or update existing entry in DB">
    <property file="${basedir}/../../target/artifact/${bpm.app.name}.properties"/>
    <propertyfile file="${basedir}/../../target/artifact/${bpm.app.name}.properties" comment="properties file for @{bpm-app-name} application">
        <entry key="Environment" value="${application.target.environment}"/>
    </propertyfile>
    <javac srcdir="${basedir}/../../trackdeployment" destdir="${basedir}/../../trackdeployment" classpath="${basedir}/../../lib/*.jar" debug="on" source="1.8" includeAntRuntime="false"/>
    <java classname="trackdeployment.DeploymentTracker">
        <arg value="${bpm.app.name}"/>
        <classpath>
            <pathelement location="${basedir}/../../lib/ojdbc8.jar"/>
            <pathelement path="${java.class.path}"/>
        </classpath>
    </java>
</target>

错误输出 #

C:\code\myappv>ant -f ci/scripts/applications/deploy-bpm-daa.xml -Dapplication.target.environment=DEV -Dbpm.environment.name=BPMEnvironment -Dbpm.app.name=notifications update-deployment-details-in-db
Buildfile: C:\code\myappv\ci\scripts\applications\deploy-bpm-daa.xml

update-deployment-details-in-db:
[propertyfile] 更新属性文件：C:\code\myappv\ci\target\artifact\notifications.properties
    [javac] 编译1个源文件至C:\code\myappv\ci\trackdeployment
     [java] 找不到trackdeployment.DeploymentTracker，请确保已将其加入类路径
     [java]     at org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:141)
     [java]     at org.apache.tools.ant.taskdefs.Java.run(Java.java:891)
     [java]     at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:231)
     [java]     at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:135)
     [java]     at org.apache.tools.ant.taskdefs.Java.execute(Java.java:108)
     [java]     at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:299)
     [java]     at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
     [java]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
     [java]     at java.lang.reflect.Method.invoke(Method.java:498)
     [java]     at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:99)
     [java]     at org.apache.tools.ant.Task.perform(Task.java:350)
     [java]     at org.apache.tools.ant.Target.execute(Target.java:449)
     [java]     at org.apache.tools.ant.Target.performTasks(Target.java:470)
     [java]     at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1401)
     [java]     at org.apache.tools.ant.Project.executeTarget(Project.java:1374)
     [java]     at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
     [java]     at org.apache.tools.ant.Project.executeTargets(Project.java:1264)
     [java]     at org.apache.tools.ant.Main.runBuild(Main.java:818)
     [java]     at org.apache.tools.ant.Main.startAnt(Main.java:223)
     [java]     at org.apache.tools.ant.launch.Launcher.run(Launcher.java:284)
     [java]     at org.apache.tools.ant.launch.Launcher.main(Launcher.java:101)
     [java] Java Result: -1

BUILD SUCCESSFUL
Total time: 3 seconds

C:\code\myappv>

当前类路径输出 #

[echo] 类路径为：C:\apps\apache\ant\lib\ant-launcher.jar;C:\apps\apache\ant\lib\ant-antlr.jar;C:\apps\apache\ant\lib\ant-apache-bcel.jar;C:\apps\apache\ant\lib\ant-apache-bsf.jar;C:\apps\apache\ant\lib\ant-apache-log4j.jar;C:\apps\apache\ant\lib\ant-apache-oro.jar;C:\apps\apache\ant\lib\ant-apache-regexp.jar;C:\apps\apache\ant\lib\ant-apache-resolver.jar;C:\apps\apache\ant\lib\ant-apache-xalan2.jar;C:\apps\apache\ant\lib\ant-commons-logging.jar;C:\apps\apache\ant\lib\ant-commons-net.jar;C:\apps\apache\ant\lib\ant-imageio.jar;C:\apps\apache\ant\lib\ant-jai.jar;C:\apps\apache\ant\lib\ant-javamail.jar;C:\apps\apache\ant\lib\ant-jdepend.jar;C:\apps\apache\ant\lib\ant-jmf.jar;C:\apps\apache\ant\lib\ant-jsch.jar;C:\apps\apache\ant\lib\ant-junit.jar;C:\apps\apache\ant\lib\ant-junit4.jar;C:\apps\apache\ant\lib\ant-junitlauncher.jar;C:\apps\apache\ant\lib\ant-launcher.jar;C:\apps\apache\ant\lib\ant-netrexx.jar;C:\apps\apache\ant\lib\ant-swing.jar;C:\apps\apache\ant\lib\ant-testutil.jar;C:\apps\apache\ant\lib\ant-xz.jar;C:\apps\apache\ant\lib\ant.jar;C:\Program Files\Java\jdk1.8.0_202\lib\tools.jar

解决方案 #

问题核心：Java任务的类路径未包含编译后class文件所在的包根目录。你的类属于trackdeployment包，JVM需要在类路径中找到包含trackdeployment文件夹的根目录（即ci目录）才能加载该类。

方案1：直接添加包根目录到类路径 #

修改<java>任务的classpath，加入ci目录的路径：

<java classname="trackdeployment.DeploymentTracker">
    <arg value="${bpm.app.name}"/>
    <classpath>
        <pathelement location="${basedir}/../../lib/ojdbc8.jar"/>
        <pathelement location="${basedir}/../../"/> <!-- 加入ci目录，即包结构的根目录 -->
        <pathelement path="${java.class.path}"/>
    </classpath>
</java>

方案2：规范分离源文件与编译文件（推荐） #

将编译后的class文件输出到单独的目录，避免与源文件混放：

1. 修改<javac>任务的destdir为单独的classes目录：

<javac srcdir="${basedir}/../../trackdeployment" destdir="${basedir}/../../classes" classpath="${basedir}/../../lib/*.jar" debug="on" source="1.8" includeAntRuntime="false"/>

2. 修改<java>任务的classpath，加入这个classes目录：

<java classname="trackdeployment.DeploymentTracker">
    <arg value="${bpm.app.name}"/>
    <classpath>
        <pathelement location="${basedir}/../../lib/ojdbc8.jar"/>
        <pathelement location="${basedir}/../../classes"/>
        <pathelement path="${java.class.path}"/>
    </classpath>
</java>

内容的提问来源于stack exchange，提问作者Ranjeet