面试题

    一些面试题，自己总结的，也是自己觉得应该深入理解的问题。

 

1、单例模式经过序列化和反序列化时产生的对象一致吗？如果不一致的话如何解决？

http://blog.csdn.net/huangbiao86/article/details/6896565

 

/**
 * Singleton pattern with serializable
 * @author Peter Zhang
 * @since 2015-4-28
 * @version
 */
public class SeriaSingleton implements Serializable {
    private static final long serialVersionUID = 1L;
    private final static SeriaSingleton INSTANCE = new SeriaSingleton();

    private SeriaSingleton() {
    }

    public static SeriaSingleton getInstance() {
	return INSTANCE;
    }

    //important
    public Object readResolve() {
	return INSTANCE;
    }
}

 

 

 /**
     * 单例模式序列化和反序列化会产生多个实例对象，如果加上readResolve就会产生同一个对象
     * @throws Exception
     */
    @Test
    public void tSeriaSingleton() throws Exception {
	final String path = "D:/workspace/Practise/src/com/javapattern/singleton/test.txt";
	SeriaSingleton expected = SeriaSingleton.getInstance();

	//serializable and deserializable
	FileOutputStream fos = new FileOutputStream(new File(path));
	ObjectOutputStream oos = new ObjectOutputStream(fos);
	oos.writeObject(expected);

	FileInputStream fis = new FileInputStream(new File(path));
	ObjectInputStream ois = new ObjectInputStream(fis);
	SeriaSingleton actual = (SeriaSingleton) ois.readObject();

	Assert.assertEquals(expected, actual);
	

    }