对象序列化

定义：通过使用ObjectInputStream和ObjectOutputStream类保存和对象读取的机制叫做序列化机制

简单说就是变成本地文件，导弹来了都不怕，硬盘不坏 数据不丢

ObjectInputStream：对象输入流
ObjectOutputStream：对象输出流

假如现在有一student信息项目，（代码如下）

student.java类

public class Student {
    /**
     * 
     */
    
    //封装
    private int stu_id;
    private String stu_name;
    private int age;
    private String school;
    //自动生成get和set方法
    public int getStu_id() {
        return stu_id;
    }
    public void setStu_id(int stu_id) {
        this.stu_id = stu_id;
    }
    public String getStu_name() {
        return stu_name;
    }
    public void setStu_name(String stu_name) {
        this.stu_name = stu_name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getSchool() {
        return school;
    }
    public void setSchool(String school) {
        this.school = school;
    }
    //将地址 ----可视化的string
    @Override
    public String toString() {
        return "Student [stu_id=" + stu_id + ", stu_name=" + stu_name + ", age=" + age + ", school=" + school + "]";
    }
}

ObjcetStudy类；

public static void main(String[] args) {
       Student s =new Student();
       s.setStu_id(1000);
       s.setStu_name("张三");
       s.setAge(23);
       s.setSchool("北大");
       

为了防止执行崩溃，丢失数据，现在将它序列化

先将对象实例化，添加文件流、对象流，并将文件放在一指定磁盘中

所以修改ObjcetStudy类中代码

public static void main(String[] args) {
        Student s =new Student();
        s.setStu_id(1000);
        s.setStu_name("张三");
        s.setAge(23);
        s.setSchool("北大");
        
        //对象实例化
        //先文件输出流
        FileOutputStream fos=null;
        //对象输出流
        ObjectOutputStream oos =null;
        
        //实例化低级流的对象
        try {
            fos=new FileOutputStream("E:/zhangsan.bin");//要放在本地磁盘中的路径，自己定义
            oos= new ObjectOutputStream(fos);
            //写出对象
            oos.writeObject(s);
            System.out.println("执行完毕");
            
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            try {
                oos.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

修改完ObjcetStudy类此时 还无法执行 代码，

需要在Student类中 添加Serializable 标识接口

该标识此类对象支持序列化

public class Student implements Serializable{

此时需要自动添加一ID

public class Student implements Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    //封装
    private int stu_id;
    private String stu_name;
    private int age;
    private String school;
    //自动生成get和set方法
    public int getStu_id() {
        return stu_id;
    }
    public void setStu_id(int stu_id) {
        this.stu_id = stu_id;
    }
    public String getStu_name() {
        return stu_name;
    }
    public void setStu_name(String stu_name) {
        this.stu_name = stu_name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getSchool() {
        return school;
    }
    public void setSchool(String school) {
        this.school = school;
    }
    //将地址 ----可视化的string
    @Override
    public String toString() {
        return "Student [stu_id=" + stu_id + ", stu_name=" + stu_name + ", age=" + age + ", school=" + school + "]";
    }
    

ObjcetStudy 类

public class ObjcetStudy {
    public static void main(String[] args) {
        Student s =new Student();
        s.setStu_id(1000);
        s.setStu_name("张三");
        s.setAge(23);
        s.setSchool("北大");
        
        //对象实例化
        //先文件输出流
        FileOutputStream fos=null;
        //对象输出流
        ObjectOutputStream oos =null;
        
        //实例化低级流的对象
        try {
            fos=new FileOutputStream("E:/zhangsan.bin");//要放在本地磁盘中的路径，自己定义
            oos= new ObjectOutputStream(fos);
            //写出对象
            oos.writeObject(s);
            System.out.println("执行完毕");
            
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            try {
                oos.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

执行代码，去fos=new FileOutputStream("E:/zhangsan.bin");中自己定义的文件存放路径中查看自己的文件

反序列化

将文件读取到java程序中

//文件输入流
        FileInputStream fis=null;
        //对象输入流
        ObjectInputStream ois=null;
        try {
            fis=new FileInputStream("E:/zhangsan.bin");
            ois=new ObjectInputStream(fis);
            //输入对象
            Student ss=(Student)ois.readObject();
            System.out.println(ss);
            
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            try {
                ois.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

执行输出：