ObjectInputStream.java 文件源码

/**
    * Verifies that this (possibly subclass) instance can be constructed
    * without violating security constraints: the subclass must not override
    * security-sensitive non-final methods, or else the
    * "enableSubclassImplementation" SerializablePermission is checked.
    */
   private void verifySubclass() {
Class cl = getClass();
if (cl == ObjectInputStream.class) {
    return; 
}
SecurityManager sm = System.getSecurityManager();
if (sm == null) {
    return;
}
processQueue(Caches.subclassAuditsQueue, Caches.subclassAudits);
WeakClassKey key = new WeakClassKey(cl, Caches.subclassAuditsQueue);
Boolean result = Caches.subclassAudits.get(key);
if (result == null) {
    result = Boolean.valueOf(auditSubclass(cl));
    Caches.subclassAudits.putIfAbsent(key, result);
}
if (result.booleanValue()) {
    return;
}
sm.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
   }