package com.hwlcn.security.util;
public abstract class AbstractFactory<T> implements Factory<T> {
private boolean singleton;
private T singletonInstance;
public AbstractFactory() {
this.singleton = true;
}
public boolean isSingleton() {
return singleton;
}
public void setSingleton(boolean singleton) {
this.singleton = singleton;
}
public T getInstance() {
T instance;
if (isSingleton()) {
if (this.singletonInstance == null) {
this.singletonInstance = createInstance();
}
instance = this.singletonInstance;
} else {
instance = createInstance();
}
if (instance == null) {
String msg = "Factory 'createInstance' implementation returned a null object.";
throw new IllegalStateException(msg);
}
return instance;
}
protected abstract T createInstance();
}