对象的序列化和反序列化

对象的序列化：是指把对象写到一个输出流中

对象的反序列：是指从一个从一个输入流中读取一个对象。

java语言要求只有实现了java.io.serialable接口的类才能序列化和反序列化

对象的序列化包括一下步骤：

（1）创建一个对象输出流

ObjectOutputStream out = new ObjectOutputStream();

new File OutputStream("D:\\objectFile.obj");

(2)通过对象输出流writeObject()方法写对象

out.writeObject("helllo");

out.writeObject(new Date());

对象的反序列化包括一下步骤

（1）创建一个对象输入流

ObjectInputStream input = new ObjectInputStream(new FileInputStream("D:\\obectFile.obj"));

(2)通过对象输入流readObject()方法读取对象

String obj1 = inputStream .readObject();

Date obj2 = out.readObject();

为了能够读出正确的数据，必须保证输出流写入对象和输入流读取对象的顺序一致。

=====================================================================

public class ObjectSaver {

/**
* @param args
* @throws IOException
* @throws FileNotFoundException
* @throws ClassNotFoundException
*/
public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {


ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("F:\\objectFile.obj"));
String obj1 = "hello";
Date obj2 = new Date();
Customer obj3 = new Customer("姚一平", 25);


//序列化对象
out.writeObject(obj1);
out.writeObject(obj2);
out.writeObject(obj3);
out.close();

//反序列对象
ObjectInputStream in = new ObjectInputStream(new FileInputStream("F:\\objectFile.obj"));

String obj11 = (String) in.readObject();
System.out.println("obj11:"+obj11);
System.out.println("obj11 == obj1 "+(obj1==obj11));
System.out.println("obj1.equal(obj1)"+obj1.equals(obj1));

Date obj22 = (Date) in.readObject();
System.out.println("obj22:"+obj22);
System.out.println("obj22 == obj2 "+(obj22==obj2));
System.out.println("obj22.equal(obj2)"+obj22.equals(obj2));

Customer obj33 = (Customer) in.readObject();
System.out.println("obj33:"+obj33);
System.out.println("obj33 == obj3 "+(obj33==obj3));
System.out.println("obj33.equal(obj3)"+obj33.equals(obj3));

}

}

public class Customer { //implements某个东东

private String name ;
private int age;

public Customer(String name,int age) {

this.name = name;
this.age = age;
System.out.println("call second constructor");
}

public boolean equals(Object o){

if(this == o) return true;
if(!(o instanceof Customer)) return false;

final Customer other = (Customer) o;
if(this.name.equals(other.name)&&this.age==other.age)
return true;
else
return false;


}

public String toString(){return "name="+name+",age="+age;};

}

==================================================================================================================================

public class User {//implements这里要实现某个东东

private String name;
private transient String password;//transient
public User(String name, String password) {
super();
this.name = name;
this.password = password;
}

public String toString(){

return name +" "+password;
}

public static void main(String[] args) throws IOException, ClassNotFoundException {
User user = new User("邓宏伟","5188");

System.out.println("Before Serialization:"+user);

ByteArrayOutputStream buf = new ByteArrayOutputStream();

//把user对象序列化到一个字节缓冲容器当中去
ObjectOutputStream o = new ObjectOutputStream(buf);
o.writeObject(user);

//从字节缓存中反序列化User对象
ObjectInputStream in =
new ObjectInputStream(new ByteArrayInputStream(buf.toByteArray()));
user = (User) in.readObject();
System.out.println("After Serialization: "+user);



}

}