Java 使用Ant条件标记

我想做这样的事情

<target name="init" description="Create build directories.
    >
    <mkdir dir="bin" />
    <mkdir dir="dist" />
            <!-- Check for the presence of dependent JARs -->
            <condition property="dependent.files.available">
               <and>
                 <available file="../../xx.jar" />
                 <available file="../../yy.jar" />
               </and>
            </condition>
</target>

<!--- Compile -->
<target name="compile" depends="init" description="Compile java sources 
    and create classes">
         <if>
           <isset property="dependent.files.available"/>
             <then>
       <javac srcdir="src" destdir="bin" classpathref="ext_jar_classpath"/>
             </then>
             <else>
                <echo message="Either xx.jar or yy.jar not found"/>
             </else>
         </if>  
</target>

您需要让jar在运行时可见，或者按照链接中的描述正确配置它

事情归结起来就是让Ant加载任务定义，因此如果您将
Ant contrib
放入Ant/lib，您只需要

<taskdef resource="net/sf/antcontrib/antcontrib.properties"/>

只是一个建议。对于ant 1.9.1及以后的版本，您可以在没有ant contrib（）的情况下使用if/除非执行相同的操作

你的目标是

<target name="init" description="Create build directories.
    >
    <mkdir dir="bin" />
    <mkdir dir="dist" />
            <!-- Check for the presence of dependent JARs -->
            <condition property="dependent.files.available">
               <and>
                 <available file="../../xx.jar" />
                 <available file="../../yy.jar" />
               </and>
            </condition>
</target>

<!--- Compile -->
<target name="compile" depends="init" description="Compile java sources 
    and create classes" if="dependent.files.available">

       <javac srcdir="src" destdir="bin" classpathref="ext_jar_classpath"/>

</target>

给出的解决方案肯定会对您有所帮助。
<target name="init" description="Create build directories.
    >
    <mkdir dir="bin" />
    <mkdir dir="dist" />
            <!-- Check for the presence of dependent JARs -->
            <condition property="dependent.files.available">
               <and>
                 <available file="../../xx.jar" />
                 <available file="../../yy.jar" />
               </and>
            </condition>
</target>

<!--- Compile -->
<target name="compile" depends="init" description="Compile java sources 
    and create classes" if="dependent.files.available">

       <javac srcdir="src" destdir="bin" classpathref="ext_jar_classpath"/>

</target>