单例模式（序列化）

public class SerialibleSingleton implements Serializable {
	
	private static final long serialVersionUID = -7760114349097906512L;
	
	private static SerialibleSingleton instance = new SerialibleSingleton(); 
	private SerialibleSingleton() {}
	
	public static SerialibleSingleton getInstance() {
		return instance;
	}
	
	/**
	 * 该方法在对象反序列化之前调用
	 * 在此返回instance
	 * 为了在内存中始终保存一个单例对象
	 * @return
	 */
	private Object readResolve() {
		return instance;
	}
	
}