build.xml

<?xml version="1.0"?>
<project name="websocket" default="build" basedir=".">

    <fileset id="all-jars" dir="lib">
        <include name="**/*.jar" />
    </fileset>

    <path id="classpath-jars">
		<fileset refid="all-jars" />
    </path>

	<pathconvert property="manifest.classpath" refid="classpath-jars" pathsep=" " dirsep="/">
		<map from="${basedir}" to="." />
	</pathconvert>

	<target name="build">
		<antcall target="package"/>
	</target>

	<target name="package" depends="compile">
		<jar destfile="websocket.jar">
			<fileset dir="./build/classes" />
			<manifest>
				<attribute name="Main-Class" value="jp.paulownia.sample.websocket.Main"/>
				<attribute name="Class-Path" value="${manifest.classpath}"/>
			</manifest>
		</jar>
	</target>

	<target name="compile">
		<mkdir dir="./build/classes" />
		<javac srcdir="./src" destdir="./build/classes" classpathref="classpath-jars" />
	</target>
</project>