我正在开发一个java项目。我的导师希望我们严格使用apache ant进行编译。我一无所知,也不知道阿帕奇蚂蚁。我已经生成了一个ant buildfile并对目标“run”进行了编辑,因此该程序将在ant run命令之后运行。
我收到了以下错误,
Exception in thread "main" java.lang.NoClassDefFoundError: src/Client
[java] Caused by: java.lang.ClassNotFoundException: src.Client
[java] at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
[java] at java.security.AccessController.doPrivileged(Native Method)
[java] at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
[java] at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
[java] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
[java] at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
[java] Could not find the main class: src.Client. Program will exit.
我想我已经解决了所有目标依赖项。但是这个错误仍然存在。
有人能帮助我吗?这是我的ant build.xml
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!-- WARNING: Eclipse auto-generated file.
Any modifications will be overwritten.
To include a user specific buildfile here, simply create one in the same
directory with the processing instruction <?eclipse.ant.import?>
as the first entry and export the buildfile again. -->
<project basedir="." default="build" name="client">
<property environment="env"/>
<property name="ECLIPSE_HOME" value="../../../../usr/lib/eclipse"/>
<property name="debuglevel" value="source,lines,vars"/>
<property name="target" value="1.6"/>
<property name="source" value="1.6"/>
<path id="client.classpath">
<pathelement location="bin"/>
<pathelement location="libthrift-1.0.0-javadoc.jar"/>
<pathelement location="libthrift-1.0.0.jar"/>
<pathelement location="log4j-1.2.14.jar"/>
<pathelement location="slf4j-api-1.5.8.jar"/>
<pathelement location="slf4j-log4j12-1.5.8.jar"/>
</path>
<target name="init">
<mkdir dir="bin"/>
<mkdir dir="build"/>
<copy includeemptydirs="false" todir="bin">
<fileset dir="src">
<exclude name="**/*.java"/>
</fileset>
</copy>
</target>
<target name="clean">
<delete dir="bin"/>
</target>
<target depends="clean" name="cleanall"/>
<target depends="build-subprojects,build-project" name="build"/>
<target name="build-subprojects"/>
<target depends="init" name="build-project">
<echo message="${ant.project.name}: ${ant.file}"/>
<javac debug="true" debuglevel="${debuglevel}" destdir="bin" source="${source}" target="${target}">
<src path="src"/>
<classpath refid="client.classpath"/>
</javac>
</target>
<target name="jar" depends="init">
<mkdir dir="build/jar" />
<jar destfile="client.jar" basedir="bin">
<manifest>
<attribute name="Main-Class" value="src.Client" />
</manifest>
</jar>
</target>
<target description="Build all projects which reference this project. Useful to propagate changes." name="build-refprojects"/>
<target description="copy Eclipse compiler jars to ant lib directory" name="init-eclipse-compiler">
<copy todir="${ant.library.dir}">
<fileset dir="${ECLIPSE_HOME}/plugins" includes="org.eclipse.jdt.core_*.jar"/>
</copy>
<unzip dest="${ant.library.dir}">
<patternset includes="jdtCompilerAdapter.jar"/>
<fileset dir="${ECLIPSE_HOME}/plugins" includes="org.eclipse.jdt.core_*.jar"/>
</unzip>
</target>
<target description="compile project with Eclipse compiler" name="build-eclipse-compiler">
<property name="build.compiler" value="org.eclipse.jdt.core.JDTCompilerAdapter"/>
<antcall target="build"/>
</target>
<target name="Client">
<java classname="Client" failonerror="true" fork="yes">
<classpath refid="client.classpath"/>
</java>
</target>
<target name="run" depends="jar">
<java jar="client.jar" fork="true">
</java>
</target>
</project>
有人可以为我发现错误吗?
答案 0 :(得分:2)
Exception java.lang.NoClassDefFoundError
发生在您的代码所依赖的某个类,您的或库中时,尝试使用尚未加载的符号。类加载器使用java路径package_aa.package_bb.SomeClass
作为它知道的一组类的键,由-classpath或-cp指定。在您的情况下,这个“存储库是bin, libthrift-1.0.0-javadoc.jar, libthrift-1.0.0.jar, log4j-1.2.14.jar, slf4j-api-1.5.8.jar, slf4j-log4j12-1.5.8.jar
。
在你的上下文中,当要加载类p1.p2.Client时,类加载器会查找bin / p1 / p2 / Client.class,在每个jar中查找/p1/p2/Client.class以及何时所有搜索路径都已耗尽,抛出异常。
在build.xml的这一部分:
<target name="jar" depends="init">
<mkdir dir="build/jar" />
<jar destfile="client.jar" basedir="bin">
<manifest>
<attribute name="Main-Class" value="src.Client" />
</manifest>
</jar>
</target>
value="src.Client"
是错误的,它应该是逻辑java路径,即包+类名。 src是一个目录而不是包。如果你没有任何包,它只是classname。
我认为
<attribute name="Main-Class" value="Client" />
这应该可以解决问题。
参考:
首次调试后,编辑,出现第二个错误:
<target name="run" depends="jar">
<java jar="client.jar" fork="true">
</java>
</target>
因为Client.jar不是自治的,所以无法工作,它需要大量的depndencies,这里没有指定。您应该使用在build.xml之上定义的类路径ref。
可能写成:
<target name="run" depends="jar">
<java classpathref="client.classpath" fork="true" classname="Client" />
</target>