javac

<target name="compile-java">
  <javac destdir="${dir.build}" srcdir="${dir.src}">
   <compilerarg line="-encoding UTF-8 "/>   
   <classpath refid="all-libs"/>
  </javac> 
 </target>

Java

<target name="shanhy" depends="compile">  
    <!-- 指明要调用的java类的名称 -->  
    <java classname="Test" fork="true" failonerror="true">  
        <sysproperty key="file.encoding" value="UTF-8" />  
        <!-- 指明要调用的java类的class路径 -->  
        <classpath path="F:\androidWorkspace\apkPacker\bin">  
        </classpath>  
    </java>  
</target>  

Q.E.D.