用ant的javac编译java报错:Perhaps JAVA_HOME does not point to the JDK

<target name="compile" depends="init">

    <echo>JAVA_HOME: ${JAVA_HOME}</echo>

    <javac srcdir="${app.src}" destdir="${app.build}" deprecation="on" encoding="UTF-8">

        <classpath>

            <path refid="classpath.path" />

        </classpath>

    </javac>

    <copy todir="${app.build}" encoding="UTF-8">

        <fileset dir="${app.src}" excludes="**/.java,**/.svn" />

    </copy>

</target>

BUILD FAILED

/home/xxx/linux.xml:64: Unable to find a javac compiler;

com.sun.tools.javac.Main is not on the classpath.

Perhaps JAVA_HOME does not point to the JDK.

It is currently set to "/usr/lib/jvm/java-8-openjdk-amd64/jre"

If you want to run thejavaccompiler of a different JDK, you should tell Ant, where to find the compiler and which version of JDK you will be using so it can choose the correct command line switches. The following example executes a JDK 1.1javacin a new process and uses the correct command line switches even when Ant is running in a JVM of a different version:

<javac srcdir=”${src}”

       destdir=”${build}”

       fork=”yes”

       executable=”/opt/java/jdk1.1/bin/javac”

       compiler=”javac1.1″/>