ant调试的一个小问题，希望高手能帮忙解决下！

<?xml version="1.0" encoding="UTF-8"?>
<project default="dist" name="project argon">
<description>A simple java project</description>
<property name="srcDir" location="src" />
<property name="buildDir" location="build" />
<property name="distDir" location="dist" />

<target name="init">
<tstamp>
</tstamp>
<mkdir dir="${buildDir}" />
<mkdir dir="${distDir}" />
</target>

<target name="complie" depends="init">
<javac srcdir="${srcDir}" destdir="${buildDir}" />
</target>

<target name="dist" depends="complie">
<jar destfile="${distDir}/package-${DSTAMP}.jar" basedir="${buildDir}">
<manifest>
<attribute name="Built-By" value="${user.name}" />
<attribute name="Main-Class" value="package.Main" />
</manifest>
</jar>
<jar destfile="${distDir}/package-src-${DSTAMP}.jar" basedir="${srcDir}"></jar>
</target>

<target name="clean">
<delete dir="${buildDir}">
</delete>
<delete dir="${distDir}" />
</target>

</project>

调试后出现：
Buildfile: D:\workspace\hello\build.xml
init:
complie:
[javac] Compiling 2 source files to D:\workspace\hello\build

BUILD FAILED
D:\workspace\hello\build.xml:16: 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

Total time: 750 milliseconds


我估计要添加一个classpath程序，但不知道怎么添加，希望高手能指导的详细点！谢谢！