JAVA序列化与反序列化三种格式存取（默认格式、XML格式、JSON格式）

什么是序列化  
java中的序列化(serialization)机制能够将一个实例对象的状态信息写入到一个字节流中，使其可以通过socket进行传输、或者持久化存储到数据库或文件系统中；然后在需要的时候，可以根据字节流中的信息来重构一个相同的对象。序列化机制在java中有着广泛的应用，EJB、RMI等技术都是以此为基础的。 

正确使用序列化机制  
一般而言，要使得一个类可以序列化，只需简单实现 java.io.Serializable 接口即可（ 还要实现无参数的构造方法 ）。该接口是一个标记式接口，它本身不包含任何内容，实现了该接口则表示这个类准备支持序列化的功能。如下例定义了类Person，并声明其可以序列化。

上面两段来源： http://lionheart.iteye.com/blog/139540

public class Person implements Serializable {

	private static final long serialVersionUID = 1L;
	
	private String name;;
	private int age;
	public Person(){
		
	}
	public Person(String str,int n){
		System.out.println("Inside Person's Constructor");
		name = str;
		age = n;
	}
	public String getName() {
		return name;
	}
	public int getAge() {
		return age;
	}
}

下面为三种格式转换的代码:

1.默认格式.

public class SerializeToFlatFile {
	public static void main(String[] args) {
		SerializeToFlatFile ser = new SerializeToFlatFile();
		ser.savePerson();
		ser.restorePerson();
	}
	
	public void savePerson(){
		Person myPerson = new Person("Jay", 24);
		try{
			FileOutputStream fos = new FileOutputStream("E:\\person.txt");
			ObjectOutputStream oos = new ObjectOutputStream(fos);
			System.out.println("Person--Jay,24---Written");
			
			oos.writeObject(myPerson);
			oos.flush();
			oos.close();
		}catch(Exception e){
			e.printStackTrace();
		}
	}
	
	@SuppressWarnings("resource")
	public void restorePerson(){
		try{
			FileInputStream fls = new FileInputStream("E:\\person.txt");
			ObjectInputStream ois = new ObjectInputStream(fls);
			
			Person myPerson = (Person)ois.readObject();
			System.out.println("\n---------------------\n");
			System.out.println("Person --read:");
			System.out.println("Name is:"+myPerson.getName());
			System.out.println("Age is :"+myPerson.getAge());
			
		}catch(Exception e){
			e.printStackTrace();
		}
	}
}

输出结果： sr test.serializable.Person      
 I ageL namet Ljava/lang/String;xp   t Jay

2.XML格式

//参考:http://www.cnblogs.com/bluesky5304/archive/2010/04/07/1706061.html
public class SerializeXML {

	public static void main(String[] args) {
		SerializeXML ser = new SerializeXML();
		ser.serializeToXml();
		ser.deSerializeFromXml();
	}
	public void serializeToXml(){
		Person[] myPersons = new Person[2];
		myPersons[0] = new Person("Jay", 24);
		myPersons[1] = new Person("Tom", 23);
		
		XStream xStream = new XStream();
		xStream.alias("Person", Person.class);
		try{
			FileOutputStream foStream = new FileOutputStream("E:\\persons.xml");
			xStream.toXML(myPersons,foStream);
		}catch(Exception e){
			e.printStackTrace();
		}
	}
	public void deSerializeFromXml(){
		XStream xStream = new XStream();
		xStream.alias("Person", Person.class);
		Person[] myPersons = null;
		try{
			FileInputStream flStream = new FileInputStream("E:\\persons.xml");
			myPersons = (Person[])xStream.fromXML(flStream);
			if(myPersons!=null){
				for(Person person:myPersons){
					System.out.println(person.getName());
					System.out.println(person.getAge());
				}
			}
		}catch(Exception e){
			e.printStackTrace();
		}
	}
}

输出结果：

<Person-array>
  <Person>
    <name>Jay</name>
    <age>24</age>
  </Person>
  <Person>
    <name>Tom</name>
    <age>23</age>
  </Person>
</Person-array>

3.JSON格式

//参考:http://www.cnblogs.com/hoojo/archive/2011/04/22/2025197.html
public class SerializeJSON {

	public static void main(String[] args) {
		SerializeJSON serializeJSON = new SerializeJSON();
		serializeJSON.writeJSON();
		serializeJSON.readJSON();
	}

	public void writeJSON(){
		XStream xStream = new XStream(new JettisonMappedXmlDriver());
		Person person = new Person("geniushehe", 16);
		try {
			FileOutputStream fos = new FileOutputStream("E:\\json.js");
			xStream.setMode(XStream.NO_REFERENCES);
			xStream.alias("Person", Person.class);
			xStream.toXML(person, fos);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
	}
	public void readJSON(){
		XStream xStream = new XStream(new JettisonMappedXmlDriver());
		Person person = null;
		try {
			FileInputStream fis = new FileInputStream("E:\\json.js");
			xStream.setMode(XStream.NO_REFERENCES);
			xStream.alias("Person", Person.class);
			person = (Person)xStream.fromXML(fis);
			System.out.println(person.getName());
			System.out.println(person.getAge());
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
	}
}

输出结果：

{"Person":{"name":"geniushehe","age":16}}