Java中的序列化问题

       Java序列化是指将Java中的类对象状态以字节的形式保存，需要的时候可以解码获取，通常用于共享数据交互、网络通信等。在Java中，属于对象的状态才应该保存，因此，静态数据成员不能保存；如果不愿意保存某个变量，可以将此变量声明为transient；另外，并不是所有的对象都可以序列化，系统级的类对象如Thread、OutputStream、Socket等类及其子类对象是不可以序列化的。

       要序列化某个对象，只需要类实现java.io.Serializable接口。如下例子：

package de.vogella.java.serilization;

import java.io.Serializable;

public class Person implements Serializable {
  private String firstName;
  private String lastName;
  // stupid example for transient
  transient private Thread myThread;

  public Person(String firstName, String lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.myThread = new Thread();
  }

  public String getFirstName() {
    return firstName;
  }

  public void setFirstName(String firstName) {
    this.firstName = firstName;
  }

  public String getLastName() {
    return lastName;
  }

  public void setLastName(String lastName) {
    this.lastName = lastName;
  }

  @Override
  public String toString() {
    return "Person [firstName=" + firstName + ", lastName=" + lastName
        + "]";
  }

} 

package de.vogella.java.serilization;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

public class Main {
  public static void main(String[] args) {
    String filename = "time.ser";
    Person p = new Person("Lars", "Vogel");

    // Save the object to file
    FileOutputStream fos = null;
    ObjectOutputStream out = null;
    try {                                                     // 编码（序列化）的一般形式 
17       fos = new FileOutputStream(filename); //定义保存的文件对象
18       out = new ObjectOutputStream(fos);   //定义对象输出流对象
19       out.writeObject(p);

      out.close();
    } catch (Exception ex) {
      ex.printStackTrace();
    }
    // Read the object from file
    // Save the object to file
    FileInputStream fis = null;
    ObjectInputStream in = null;
    try {
30       fis = new FileInputStream(filename);  // 解码（反序列化）的一般形式
31       in = new ObjectInputStream(fis);
32       p = (Person) in.readObject();
      out.close();
    } catch (Exception ex) {
      ex.printStackTrace();
    }
    System.out.println(p);
  }
}