用 JarURLConnection ，给你写了一段，已测试

public static void main(String[] args) throws Exception {
try {
String baseFile = "D:/admin.war";
JarFile jarFile = new JarFile(baseFile);
Enumeration<JarEntry> entries = jarFile.entries();
while (entries.hasMoreElements()) {
JarEntry jarEntry = entries.nextElement();
if(jarEntry.getName().endsWith(".jar")){
System.out.println("list jar file of " + jarEntry.getName());
URL url = new URL("jar:file:" + baseFile + "!/" + jarEntry.getName());
JarURLConnection urlConnection = (JarURLConnection) url.openConnection();
JarInputStream jarInputStream = new JarInputStream(urlConnection.getInputStream());
JarEntry entry;
int i = 0;
while((entry = jarInputStream.getNextJarEntry()) != null) {
if(entry.isDirectory()){
continue;
}
if(i++ >= 5){
System.out.println();
break;
}
System.out.println(entry.getName());
}
}
}
}catch (Exception e){
e.printStackTrace();
}
}