JAR文件NoClassDefFoundError

Question

我正在嘗試通過使用build.xml文件和提示代碼來構建項目的可運行JAR文件

    cd <the directory of you application>
    ant -f bin/build.xml jar

但是在運行JAR時會有例外，因為我無法添加外部JAR。

build.xml如下：

<?xml version="1.0" encoding="ISO-8859-1" ?>

<!--

                    This file was generated by Jason 1.3.9-alpha
                    http://jason.sf.net

                    Ocak 11, 2014 - 01:09:12
-->

<project name   ="virtualClassroom"
         basedir=".."
         default="run">

    <property name="mas2j.project.file" value="virtualClassroom.mas2j"/>
    <property name="debug" value=""/> <!-- use "-debug" to run in debug mode -->
    <property name="build.dir" value="${basedir}/bin/classes" />

    <property name="jasonJar" value="C:\Users\Emre\Desktop\MasterThesis-BDI\Jason-1.3.9\Jason-1.3.9\lib\jason.jar"/>
    <property name="JavaCsBridgeJar" value="C:\Users\Emre\Desktop\MasterThesis-BDI\virtualClassroom\lib\JavaCsBridge.jar"/>

    <path id="project.classpath">
        <pathelement location="${basedir}"/>
        <pathelement location="${build.dir}"/>
        <pathelement location="${JavaCsBridgeJar}"/>
        <pathelement location="${jasonJar}"/>
        <fileset dir="${basedir}/lib" >  <include name="*.jar" /> </fileset>
    </path>


    <!-- tasks the user can override in his/her c-build.xml script -->
    <target name="user-init">
    </target>
    <target name="user-end">
    </target>

    <target name="init">
        <mkdir dir="${build.dir}" />
        <antcall target="user-init" />
    </target>

    <target name="compile" depends="init">
        <condition property="srcdir" value="${basedir}/src/java" else="${basedir}" >
            <available file="${basedir}/src/java" />
        </condition>
        <javac srcdir="${srcdir}" destdir="${build.dir}" debug="true" optimize="true" includeantruntime="false" >
            <classpath refid="project.classpath"/>
        </javac>
    </target>

    <target name="jar" depends="compile">
        <delete file="${ant.project.name}.jar" />
        <copy file="${jasonJar}" tofile="${ant.project.name}.jar" />
        <copy file="${JavaCsBridge}" tofile="${ant.project.name}.jar" />
        <copy file="${mas2j.project.file}" tofile="default.mas2j" />
        <jar update="yes" jarfile="${ant.project.name}.jar" >
            <fileset dir="${basedir}">
                <include name="**/*.asl" />
                <include name="**/*.mas2j" />
            </fileset>
            <fileset dir="${build.dir}">
                <include name="**/*.class" />
            </fileset>
            <manifest>
                  <attribute name="Main-Class" value="jason.infra.centralised.RunCentralisedMAS"/>
            </manifest>
        </jar>
        <delete file="default.mas2j" />
    </target>


    <target name="jnlp" depends="jar" >
        <mkdir dir="${basedir}/${ant.project.name}-jws"/>
        <java classname="jason.infra.centralised.CreateJNLP"
              failonerror="true" fork="yes" dir="${basedir}/${ant.project.name}-jws" >
            <classpath refid="project.classpath"/>
            <arg line="${ant.project.name} ${mas2j.project.file}"/>
        </java>
        <copy todir="${basedir}/${ant.project.name}-jws" failonerror="no">
            <fileset dir="${basedir}/lib" includes="**/*.jar" />
            <fileset dir="${basedir}" includes="${ant.project.name}.jar" />
            <fileset dir="C:\Users\Emre\Desktop\MasterThesis-BDI\Jason-1.3.9\Jason-1.3.9/src/images" includes="Jason-GMoreau-Icon.jpg" />
        </copy>
        <signjar jar="${basedir}/${ant.project.name}-jws/${ant.project.name}.jar" alias="jason" 
            storepass="rbjhja" keypass="rbjhja" keystore="C:\Users\Emre\Desktop\MasterThesis-BDI\Jason-1.3.9\Jason-1.3.9/src/jasonKeystore" />
        <echo message="**" />
        <echo message="** Java Web Start application created in directory ${ant.project.name}-jws" />
        <echo message="** Update the codebase (in the second line of the .jnlp file)" />
        <echo message="** with the URL where you will upload the application." />
        <echo message="**" />
    </target>   


    <target name="run" depends="compile" >
        <echo message="Running project ${ant.project.name}" />
        <java classname="jason.infra.centralised.RunCentralisedMAS"
              failonerror="true" fork="yes" dir="${basedir}" >
            <classpath refid="project.classpath"/>
            <arg line="${mas2j.project.file} ${debug} "/>
            <!-- jvmarg line="-Xmx500M -Xss8M"/ -->    
        </java>
        <antcall target="user-end" />
    </target>

    <target name="clean" >
        <delete failonerror="no" includeEmptyDirs="true" verbose="true">
            <fileset dir="${basedir}" includes="**/*.class"/>
        </delete>
    </target>



</project>

有人知道該怎么辦嗎？

謝謝

Answer 1

首先，您需要准確地告訴我們哪個類給出了NoClassDefFoundError作為通用答案，原因是該特定類在編譯時可用，但在運行時丟失。 這是jar可執行文件的常見問題。

解決方案：要么在jar本身中包含缺少的類，要么將它們添加到系統類路徑中。