Java オブジェクトのシリアル化 NIO NIO2 の詳細な紹介と分析

// 创建个ObjectOutputStream输出流
ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("object.txt"));

// 将一个Person对象输出到输出流中
oos.writeObject(per);

public class NbaPlayer implements java.io.Serializable
{
  private String name;
  private int number;
  // 注意此处没有提供无参数的构造器!
  public NbaPlayer(String name, int number)
  {
    System.out.println("有参数的构造器");
    this.name = name;
    this.number = number;
  }

  // name的setter和getter方法
  public void setName(String name)
  {
    this.name = name;
  }
  public String getName()
  {
    return this.name;
  }

  // number的setter和getter方法
  public void setNumber(int number)
  {
    this.number = number;
  }
  public int getNumber()
  {
    return this.number;
  }
}

import java.io.*;

public class WriteObject
{
  public static void main(String[] args)
  {
    try(
      // 创建一个ObjectOutputStream输出流
      ObjectOutputStream oos = new ObjectOutputStream(
        new FileOutputStream("object.txt")))
    {
      NbaPlayer player = new NbaPlayer("维斯布鲁克", 0);
      // 将player对象写入输出流
      oos.writeObject(player);
    }
    catch (IOException ex)
    {
      ex.printStackTrace();
    }
  }
}

// 创建个ObjectInputStream输出流
ObjectInputStream ois = new ObjectInputStream(new FileInputStream("object.txt"));

// 从输入流中读取一个Java对象，并将其强制类型转换为Person类
Person p = (Person)ois.readObject();

import java.io.*;
public class ReadObject
{
  public static void main(String[] args)
  {
    try(
      // 创建一个ObjectInputStream输入流
      ObjectInputStream ois = new ObjectInputStream(
        new FileInputStream("object.txt")))
    {
      // 从输入流中读取一个Java对象，并将其强制类型转换为NbaPlayer类
      NbaPlayer player = (NbaPlayer)ois.readObject();
      System.out.println("名字为：" + player.getName()
        + "\n号码为：" + player.getNumber());
    }
    catch (Exception ex)
    {
      ex.printStackTrace();
    }
  }
}

public class AllStar implements java.io.Serializable
{
  private String name;
  private NbaPlayer player;
  public AllStar(String name, NbaPlayer player)
  {
    this.name = name;
    this.player = player;
  }
  // 此处省略了name和player的setter和getter方法

  // name的setter和getter方法
  public String getName()
  {
    return this.name;
  }

  public void setName(String name)
  {
    this.name = name;
  }

  // player的setter和getter方法
  public NbaPlayer getPlayer() 
  {
    return player;
  }

  public void setPlayer(NbaPlayer player) 
  {
    this.player = player;
  }
}

import java.io.*;
public class WriteAllStar
{
  public static void main(String[] args)
  {
    try(
      // 创建一个ObjectOutputStream输出流
      ObjectOutputStream oos = new ObjectOutputStream(
        new FileOutputStream("allStar.txt")))
    {
      NbaPlayer player = new NbaPlayer("詹姆斯哈登", 13);
      AllStar allStar1 = new AllStar("西部全明星", player);
      AllStar allStar2 = new AllStar("首发后卫", player);
      // 依次将四个对象写入输出流
      oos.writeObject(allStar1);
      oos.writeObject(allStar2);
      oos.writeObject(player);
      oos.writeObject(allStar2);
    }
    catch (IOException ex)
    {
      ex.printStackTrace();
    }
  }
}

import java.io.*;

public class SerializeMutable
{
  public static void main(String[] args)
  {

    try(
      // 创建一个ObjectOutputStream输入流
      ObjectOutputStream oos = new ObjectOutputStream(
        new FileOutputStream("mutable.txt"));
      // 创建一个ObjectInputStream输入流
      ObjectInputStream ois = new ObjectInputStream(
        new FileInputStream("mutable.txt")))
    {
      NbaPlayer player = new NbaPlayer("斯蒂芬库里", 30);
      // 系统会player对象转换字节序列并输出
      oos.writeObject(player);
      // 改变per对象的name实例变量
      player.setName("塞斯库里");
      // 系统只是输出序列化编号，所以改变后的name不会被序列化
      oos.writeObject(player);
      NbaPlayer player1 = (NbaPlayer)ois.readObject();  //①
      NbaPlayer player2 = (NbaPlayer)ois.readObject();  //②
      // 下面输出true，即反序列化后player1等于player2
      System.out.println(player1 == player2);
      // 下面依然看到输出"斯蒂芬库里"，即改变后的实例变量没有被序列化
      System.out.println(player2.getName());
    }
    catch (Exception ex)
    {
      ex.printStackTrace();
    }
  }
}