什么是序列化

1.定义：将内存中保存的对象变为二进制数据流的形式进行传输，或者是将其保存在文本中。
2.实现：Java中类若要被序列化输出，该类必须实现Serializable接口（该接口是一个标识接口，表示该类具有序列化的功能）。

序列化与反序列化

如果要想实现序列化与反序列化的对象操作，在java.io包中提供有两个处理类:ObjectOutputStream、
ObjectInputStream
继承结构：

public class ObjectOutputStream
    extends OutputStream implements ObjectOutput, ObjectStreamConstants
public class ObjectInputStream
    extends InputStream implements ObjectInput, ObjectStreamConstants

构造方法：

 public ObjectOutputStream(OutputStream out) throws IOException 
 public ObjectInputStream(InputStream in) throws IOException

将对象序列化输出方法：

public final void writeObject(Object obj) throws IOException

将对象序列化输入方法：

 public final Object readObject()
        throws IOException, ClassNotFoundException

范例：对象的序列化输出

import java.io.*;
import java.io.File;
import java.util.Date;
class Person implements Serializable{
    private String name;
    private String genter;
    private int age;

    public Person(String name, String genter, int age) {
        this.name = name;
        this.genter = genter;
        this.age = age;
    }

    @Override
    public String toString() {
        return "姓名："+name+",性别："+genter+",年龄："+age;
    }
}
public class Test {
    public static void main(String[] args)throws IOException {
        File file = new File("C:Users" + File.separator + "Administrator"
                + File.separator + "Desktop" + File.separator + "Test.txt");
        OutputStream out = new FileOutputStream(file);
        ObjectOutputStream oos=new ObjectOutputStream(out);
        Person p=new Person("HL","female",18);
        oos.writeObject(p);
        oos.close();
    }
}

范例：对象的序列化输入（对象反序列化）

import java.io.*;
import java.io.File;
import java.util.Date;
class Person implements Serializable{
    private String name;
    private String genter;
    private int age;

    public Person(String name, String genter, int age) {
        this.name = name;
        this.genter = genter;
        this.age = age;
    }

    @Override
    public String toString() {
        return "姓名："+name+",性别："+genter+",年龄："+age;
    }
}
public class Test {
    public static void main(String[] args)throws Exception {
        File file = new File("C:Users" + File.separator + "Administrator"
                + File.separator + "Desktop" + File.separator + "Test.txt");
        InputStream in=new FileInputStream(file);
       ObjectInputStream ois=new ObjectInputStream(in);
       Object str;
       str=ois.readObject();
        System.out.println(str);//因为覆写了toString()
        ois.close();
    }
}

transient关键字

Serializable默认会将对象中所有属性进行序列化保存，如果现在某些属性不希望被保存了，那么就可以
使用transient关键字。

范例：transient关键字的使用

import java.io.*;
import java.io.File;
import java.util.Date;
class Person implements Serializable{
    private String name;
    private transient String genter;
    private transient int age;

    public Person(String name, String genter, int age) {
        this.name = name;
        this.genter = genter;
        this.age = age;
    }

    @Override
    public String toString() {
        return "姓名："+name+",性别："+genter+",年龄："+age;
    }
}
public class Test {
    public static void main(String[] args)throws Exception {
       File file = new File("C:Users" + File.separator + "Administrator"
                + File.separator + "Desktop" + File.separator + "Test.txt");
        //序列化输出
        ObjectOutputStream oos=new ObjectOutputStream(new FileOutputStream(file));
        Person p=new Person("HL","female",18);
        oos.writeObject(p);
        oos.close();
        //反序列化
        ObjectInputStream ois=new ObjectInputStream(new FileInputStream(file));
        Object str;
        str=ois.readObject();
        System.out.println(str);//因为覆写了toString()
        ois.close();
    }
}