关于serialization 机制作用于Serializeble Object ？高手请进！

mimi_eleven 2002-11-16 11:15:05

出自Thinking In Java 书中的一例： p630
//: c11:MyWorld.java
import java.io.*;
import java.util.*;

class House implements Serializable {}

class Animal implements Serializable {
String name;
House preferredHouse;
Animal(String nm, House h) {
name = nm;
preferredHouse = h;
}
public String toString() {
return name + "[" + super.toString() +
"], " + preferredHouse + "\n";
}
}

public class MyWorld {
public static void main(String[] args)
throws IOException, ClassNotFoundException {
House house = new House();
ArrayList animals = new ArrayList();
animals.add(
new Animal("Bosco the dog", house));
animals.add(
new Animal("Ralph the hamster", house));
animals.add(
new Animal("Fronk the cat", house));
System.out.println("animals: " + animals);

ByteArrayOutputStream buf1 =
new ByteArrayOutputStream();
ObjectOutputStream o1 =
new ObjectOutputStream(buf1);
o1.writeObject(animals);
o1.writeObject(animals); // Write a 2nd set
// Write to a different stream:
ByteArrayOutputStream buf2 =
new ByteArrayOutputStream();
ObjectOutputStream o2 =
new ObjectOutputStream(buf2);
o2.writeObject(animals);
// Now get them back:
ObjectInputStream in1 =
new ObjectInputStream(
new ByteArrayInputStream(
buf1.toByteArray()));
ObjectInputStream in2 =
new ObjectInputStream(
new ByteArrayInputStream(
buf2.toByteArray()));
ArrayList animals1 =
(ArrayList)in1.readObject();
ArrayList animals2 =
(ArrayList)in1.readObject();
ArrayList animals3 =
(ArrayList)in2.readObject();
System.out.println("animals1: " + animals1);
System.out.println("animals2: " + animals2);
System.out.println("animals3: " + animals3);
}
} ///:~

某次执行的结果：
animals: [Bosco the dog[Animal@1cc76c], House@1cc769
, Ralph the hamster[Animal@1cc76d], House@1cc769
, Fronk the cat[Animal@1cc76e], House@1cc769
]
animals1: [Bosco the dog[Animal@1cca0c], House@1cca16
, Ralph the hamster[Animal@1cca17], House@1cca16
, Fronk the cat[Animal@1cca1b], House@1cca16
]
animals2: [Bosco the dog[Animal@1cca0c], House@1cca16
, Ralph the hamster[Animal@1cca17], House@1cca16
, Fronk the cat[Animal@1cca1b], House@1cca16
]
animals3: [Bosco the dog[Animal@1cca52], House@1cca5c
, Ralph the hamster[Animal@1cca5d], House@1cca5c
, Fronk the cat[Animal@1cca61], House@1cca5c
]

关于 animals1,animals2 and animals3的回复过程为什么会有差别，请指点！
以及书中的此句： "when animals3 is recovered the system has no way of knowing that the objects in this other stream are aliases of the objects in the first stream, so it makes a completely different web of objects."
说，为什么animals3被回复时，系统会制造出完全不同的对象网络来呢？

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