对象工厂 - 黑马程序员技术交流社区

/**
* 简单的对象创建工厂
*
* @author lazyp
* @since 1.0
*/
public final class SimpleObjectFactory {
private static final Logger logger = Logger.getLogger(SimpleObjectFactory.class);
private static final Lock LOCK = new ReentrantLock();
private static final ConcurrentHashMap<String, Object> OBJ_CACHE = new ConcurrentHashMap<String, Object>(16);
/**
* 需要一个无参构造函数
*
* @param cls
* @return
*/
public static <T> T createInstance(Class<T> cls) {
String classStr = cls.getCanonicalName();
return createInstance(classStr);
}
@SuppressWarnings("unchecked")
public static <T> T createInstance(String classStr) {
if (StringUtils.isBlank(classStr)) {
return null;
}
logger.debug(classStr);
if (OBJ_CACHE.get(classStr) != null) {
return (T) OBJ_CACHE.get(classStr);
}
try {
LOCK.lock();
if (OBJ_CACHE.get(classStr) != null) {
return (T) OBJ_CACHE.get(classStr);
}
logger.info("Create The " + classStr + " instance.");
T instance = (T) Class.forName(classStr).newInstance();
OBJ_CACHE.putIfAbsent(classStr, instance);
return instance;
} catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
logger.error(e.getMessage());
return null;
} finally {
LOCK.unlock();
}
}
public static void main(String[] args) {
}
}

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