序列化和反序列化

Posted 2020-09-28 快乐的小银龙

将内存中的数据持久化到硬盘---序列化

将硬盘上的数据持久化到内存---反序列化

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace D_003
{
   [Serializable]//证明这个类是可被序列化的(类)
   public  class Person
    {
        public string Name { get; set; }
        public int Age { get; set; }
    }
}

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.Serialization.Formatters.Binary;
using System.Text;
using System.Threading.Tasks;

namespace D_003
{
    class Program
    {
        static void Main(string[] args)
        {
            #region 序列化
            //List<Person> list = new List<Person>();
            //Person p = new Person();
            //p.Name = "小明";
            //p.Age = 12;
            //list.Add(p);
            ////序列化器  二进制序列化器
            //BinaryFormatter bf = new BinaryFormatter();
            //Stream stream = new FileStream("save.bin", FileMode.Create);
            //bf.Serialize(stream, list);
            //stream.Close();
            //Console.WriteLine("Ok"); 
            #endregion
            #region 反序列化
            Stream fs = new FileStream("save.bin",FileMode.Open);
            BinaryFormatter bf = new BinaryFormatter();
            List<Person> list = (List<Person>)bf.Deserialize(fs);
            foreach (Person item in list)
            {
                Console.WriteLine(item.Name+""+item.Age);
            }
            fs.Close();
            #endregion
            Console.ReadKey();
        }
    }
}

 对象序列化

(1).对象序列化,就是将Object转换成byte序列,反之叫对象的反序列

(2).序列化流(ObjectOutStream),是过滤器----writeObject

     反序列化流(ObjectInPutStream)---readObject

(3).序列化接口(Serializable)

对象必须实现序列化接口,才能进行序列化,否则将会出现异常

这个接口,没有任何方法,只是一个标准

(4).对象序列化就是保存对象

实际作用

序列化相当于加密，反序列化相当于解密，作用是方便储存和传输

序列化 (Serialization)将对象的状态信息转换为可以存储或传输的形式的过程。在序列化期间，对象将其当前状态写入到临时或持久性存储区。以后，可以通过从存储区中读取或反序列化对象的状态，重新创建该对象。

 

目的

1、以某种存储形式使自定义对象持久化；

2、将对象从一个地方传递到另一个地方。

3、使程序更具维护性。

 

案例

对象序列化

package cn.happy.com;

import java.io.Serializable;

/**
 * 对student对象进行序列化
 * @author CY
 *
 */
public class Student implements Serializable{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private String stuno;
    private String stuname;
    private int stuage;
    public Student(String stuno, String stuname, int stuage) {
        super();
        this.stuno = stuno;
        this.stuname = stuname;
        this.stuage = stuage;
    }
    public String getStuno() {
        return stuno;
    }
    @Override
    public String toString() {
        return "Student [stuno=" + stuno + ", stuname=" + stuname + ", stuage=" + stuage + "]";
    }
    public Student() {
        super();
        // TODO Auto-generated constructor stub
    }
    public void setStuno(String stuno) {
        this.stuno = stuno;
    }
    public String getStuname() {
        return stuname;
    }
    public void setStuname(String stuname) {
        this.stuname = stuname;
    }
    public int getStuage() {
        return stuage;
    }
    public void setStuage(int stuage) {
        this.stuage = stuage;
    }
}

package cn.happy.com;

import java.io.*;

public class ObjectSeriaDemo1 {
/**
 * 对象进行保存
 * @param args
 * @throws Exception 
 * @throws FileNotFoundException 
 */
    public static void main(String[] args) throws Exception {
        //路径
        String file="demp/object.dat";
        //1.对象的序列化
        /*ObjectOutputStream oos=new ObjectOutputStream(
                new FileOutputStream(file));
        Student stu=new Student("1001","张三",20);
        oos.writeObject(stu);
        oos.flush();
        oos.close();*/
        ObjectInputStream ois=new ObjectInputStream(
                new FileInputStream(file));
        Student stu=(Student)ois.readObject();
        System.out.println(stu);
        ois.close();
    }
}

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

package cn.happy.com;

import java.io.Serializable;

/**
 * 对student对象进行序列化
 * @author CY
 *
 */
//序列化中子类和父类构造函数的调用问题
public class Student implements Serializable{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private String stuno;
    private String stuname;
    private transient int stuage;
    //该元素不会进行jvm默认的序列化  也可以自己完成这个元素的序列化
    public Student(String stuno, String stuname, int stuage) {
        super();
        this.stuno = stuno;
        this.stuname = stuname;
        this.stuage = stuage;
    }
    public String getStuno() {
        return stuno;
    }
    @Override
    public String toString() {
        return "Student [stuno=" + stuno + ", stuname=" + stuname + ", stuage=" + stuage + "]";
    }
    public Student() {
        super();
        // TODO Auto-generated constructor stub
    }
    public void setStuno(String stuno) {
        this.stuno = stuno;
    }
    public String getStuname() {
        return stuname;
    }
    public void setStuname(String stuname) {
        this.stuname = stuname;
    }
    public int getStuage() {
        return stuage;
    }
    public void setStuage(int stuage) {
        this.stuage = stuage;
    }
    private void writeObject(java.io.ObjectOutputStream s)
               throws java.io.IOException{
        s.defaultWriteObject();//把jvm能默认序列化的元素进行序列化的操纵
        s.writeInt(stuage);//自己完成stuage的序列化
    }
    private void readObject(java.io.ObjectInputStream s)
               throws java.io.IOException,ClassNotFoundException{
        s.defaultReadObject();//把jvm能默认序列化的元素进行反序列化的操纵
        this.stuage=s.readInt();//自己完成stuage的反序列化
    }
}

package cn.happy.com;

import java.io.*;

public class ObjectSeriaDemo1 {
/**
 * 对象进行保存
 * @param args
 * @throws Exception 
 * @throws FileNotFoundException 
 */
    public static void main(String[] args) throws Exception {
        //路径
        String file="demp/object.dat";
        //1.对象的序列化
        /*ObjectOutputStream oos=new ObjectOutputStream(
                new FileOutputStream(file));
        Student stu=new Student("1001","张三",20);
        oos.writeObject(stu);
        oos.flush();
        oos.close();*/
        ObjectInputStream ois=new ObjectInputStream(
                new FileInputStream(file));
        Student stu=(Student)ois.readObject();
        System.out.println(stu);
        ois.close();
        //并不是所有的对象都被期望序列化
    }
}

package cn.happy.com;

import java.io.*;

public class ObjectSeriaDem02 {
    /**
     * 创建对象的时候递归调用了父类的构造函数
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception{
        /*ObjectOutputStream oos=new ObjectOutputStream(
                new FileOutputStream("demp/object.dat"));
        Foo2 foo2=new Foo2();
        oos.writeObject(foo2);
        oos.flush();
        oos.close();*/
        //反序列化是否递归调用了父类的构造函数
        /*ObjectInputStream ois=new ObjectInputStream(
                new FileInputStream("demp/object.dat"));
        Foo2 foo2=(Foo2)ois.readObject();
        System.out.println(foo2);
        ois.close();*/
        
        
        /*ObjectOutputStream oos=new ObjectOutputStream(
                new FileOutputStream("demp/object.dat"));
        Bar2 bar2=new Bar2();
        oos.writeObject(bar2);
        oos.flush();
        oos.close();*/
        
        ObjectInputStream ois=new ObjectInputStream(
                new FileInputStream("demp/object.dat"));
        Bar2 bar2=(Bar2)ois.readObject();
        System.out.println(bar2);
        ois.close();
        /**
         * 对子类对象进行反序列化操作时
         * 如果其父类没有实现序列化接口
         * 那么其父类的构造函数会被显示调用
         * 
         */
    }

}
//一个类实现了序列化接口他的子类都能实现序列化接口
class Foo implements Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    public Foo(){
        System.out.println("foo...");
    }
}
class Foo1 extends  Foo{
    public Foo1(){
    System.out.println("foo1...");
    }
}
class Foo2 extends Foo1{
    public Foo2(){
        System.out.println("foo2...\'");
    }
}
class Bar{
    public Bar(){
        System.out.println("bar\'");
    }
}
class Bar1 extends Bar implements Serializable{
    public Bar1(){
        System.out.println("bar1...");
    }
}
class Bar2 extends Bar1{
    public Bar2(){
        System.out.println("bar2...");
    }
}