chapter 6 之序列化

package chapter6;
import java.io.*;

public class SerializableClass {
	//1.简单序列化(ObjectOutputStream和ObjectInputStream用于序列化)
	public void simpleSerializable(){
		Cat c =new Cat();
		try {
			FileOutputStream fs =new FileOutputStream("testSer.ser");//注意：由于要用ObjectOutputStream包装，所以要用字节形式打开文件
			ObjectOutputStream os =new ObjectOutputStream(fs);
			os.writeObject(c);//工作：1.序列化对象；2.将序列化的对象写入文件
			os.close();
		} catch (FileNotFoundException e) {//在打开文件时，会抛出的异常
			e.printStackTrace();
		} catch (IOException e) {			
			e.printStackTrace();
		}
		try {
			FileInputStream fis =new FileInputStream("testSer.ser");
			ObjectInputStream ois =new ObjectInputStream(fis);
			c =(Cat)ois.readObject();//抛出异常ClassNotFundException，返回的是Object
			ois.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}
	
	//2.对象图，Java序列化机制会负责保存对象的整个对象图，将所需的一些内容进行深复制.
	public void ObjectGramm(){
		Collar col =new Collar(3);
		Cat c =new Cat(col,5);
		System.out.println("before:collar size is "+c.getCollar().getCollarSize());
		try {
			FileOutputStream fs =new FileOutputStream("testSer.ser");//换成.txt文件结果是一样的，但是打开txt后，内容基本都是乱码
			ObjectOutputStream os= new ObjectOutputStream(fs);
			os.writeObject(c);
			os.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		try {
			FileInputStream fis =new FileInputStream("testSer.ser");
			ObjectInputStream ois =new ObjectInputStream(fis);
			c =(Cat)ois.readObject();
			ois.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		System.out.println("after: collar size is " +c.getCollar().getCollarSize());
		//outPut is :
		//before:collar size is 3
		//after: collar size is 3
	}
	
	//3.若不能访问Collar的代码，即无法通过修改的方式实现Serializable接口，可用transient修饰符跳过Collar,然后通过两个私有方法，writeObject()和readObject()，来实现序列化
	public void transientUse(){
		Collar col =new Collar(3);
		Dog d =new Dog(col,5);
		System.out.println("before:collar size is "+d.getCollar().getCollarSize());
		try {
			FileOutputStream fs =new FileOutputStream("testSer.ser");
			ObjectOutputStream os= new ObjectOutputStream(fs);
			os.writeObject(d);
			os.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		try {
			FileInputStream fis =new FileInputStream("testSer.ser");
			ObjectInputStream ois =new ObjectInputStream(fis);
			d =(Dog)ois.readObject();
			ois.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		System.out.println("after: collar size is " +d.getCollar().getCollarSize());
		//outPut is :
		//before:collar size is 3
		//after: collar size is 3
	}
	
	//继承关系对序列化的影响,即：子类可以序列化而父类不可以序列化的情况
	//反序列化时，实现Serializable的类，不会调用构造函数，不会初始化；为实现Serializable的类，将初始化。用transient修饰的，若没有上面的那一组方法，则变量为0，对象为null
	public void superNotSerial(){
		Human h =new Human(35, "HaHa");
		System.out.println("before: "+h.name+" "+h.weight);
		try {
			FileOutputStream fs =new FileOutputStream("testSer.ser");
			ObjectOutputStream os= new ObjectOutputStream(fs);
			os.writeObject(h);
			os.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		try {
			FileInputStream fis =new FileInputStream("testSer.ser");
			ObjectInputStream ois =new ObjectInputStream(fis);
			h =(Human)ois.readObject();
			ois.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		System.out.println("after:  "+h.name+" "+h.weight);
		//outPut is:
		//before: HaHa 35
		//after:  HaHa 42
	}
	
	
	public static void main(String[] args){
		SerializableClass sc =new SerializableClass();
		//sc.simpleSerializable();
		//sc.ObjectGramm();
		//sc.transientUse();
		//sc.superNotSerial();
	}
	/**
	 * 
	 *  .ser文件是Java程序源代码中的一种文件。
	 *	Java 程序包括源代码（.java文件）、由编译器生成的类（.class文件）、
	 *	由归档工具jar生成的.jar文件、对象状态序列化.ser文件。
	 *  .jar文件是安装的数据文件，.jad文件是安装的信息文件
	 * */
}

Cat类：
package chapter6;

import java.io.*;

class Cat implements Serializable{
	private Collar theCollar;
	private int catSize;
	public Cat(Collar collar,int size){
		theCollar =collar;
		catSize =size;
	}
	public Cat() {
	}
	public Collar getCollar(){
		return theCollar;
	}
	
}

Collar类
package chapter6;

import java.io.Serializable;

public class Collar implements Serializable{//所有进行深复制的对象，都必须实现Serializable接口
	private int collarSize;
	public Collar(int size) {
		collarSize =size;
	}
	public int getCollarSize(){
		return collarSize;
	}
}

Dog类：
package chapter6;

import java.io.*;

public class Dog implements Serializable {
	transient private Collar theCollar;//transient关键字，表明不用再序列化Collar类了
	private int dogSize;
	public Dog(Collar collar,int size){
		theCollar =collar;
		dogSize =size;
	}
	public Collar getCollar(){
		return theCollar;
	}
	
	private void writeObject(ObjectOutputStream os){
		try {
			os.defaultWriteObject();//告诉JVM对该对象执行常规的序列化过程
			os.writeInt(theCollar.getCollarSize());//将一个额外的Int写入到序列化Dog的流中
		} catch (IOException e) {
			e.printStackTrace();
		}	
	}
	private void readObject(ObjectInputStream is){
		try {
			is.defaultReadObject();//注意读出的时候，要和写入时候的顺序相同。
			theCollar =new Collar(is.readInt());
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
}

Human类：
package chapter6;

import java.io.Serializable;

public class Human extends Animal implements Serializable {
	String name;
	public Human(int w,String n) {
		weight =w;
		name =n;
	}
}

Animal类：
package chapter6;

public class Animal {
	int weight =42;//初始化为42
}