JarArchiver jar = new JarArchiver();
jar.setDestFile(file.getAbsoluteFile());
Manifest manifest = new Manifest();
Attribute attr = new Attribute();
attr.setName("Class-Path");
StringBuilder b = new StringBuilder(8000);
for (URI cp : classPath) {
b.append(cp.toURL().toExternalForm()).append(' ');
}
attr.setValue(b.toString());
manifest.getMainSection().addConfiguredAttribute(attr);
attr = new Attribute();
attr.setName("Main-Class");
attr.setValue(cls.getName());
manifest.getMainSection().addConfiguredAttribute(attr);
jar.addConfiguredManifest(manifest);
jar.createArchive();