java.io.Serializable序列化

java.io.Serializable的本质就是将内存的对象，以文本的形式保存到磁盘上，使用的时候再读出来，以减少应用程序的压力.有点类似与虚拟内存.在openJPA里,entity的时候,一般需要使用.
    序列化的时候有以下几点需要注意.
1)先序列化，先读取(FIFO);
2)反序列化的时候，返回的都是Object,要自动转换类型;
3)用关键字transient标记的属性，将不被序列化;
4)对象要继承类java.io.Serializable;
5)序列化用ObjectOutputStream,反序列化用ObjectInputStream;
    下面是2个示例代码，一看就能明白，本人不做过多的解释^_^

package test;

import java.io.Serializable;

public class User implements Serializable {
    private String name;
    private transient int age;

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

    public String toString() {
        return "name=" + name + "\n" + "age=" + age;
    }
}

package test;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Date;

public class TestSerializable {

    public static void main(String[] args) {
        String path = "c:\\myfile";
        serialize(path);
        System.out.println("Object is serializing!");
        deSerialize(path);
    }

    public static void serialize(String fileName) {
        try {
            ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(fileName));
            out.writeObject("phl");// 序列化字符串对象
            out.writeObject(new Date());// 序列化日期对象
            User user = new User("phl", 26);
            out.writeObject(user);// 序列化自定义对象
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void deSerialize(String fileName) {
        try {
            ObjectInputStream in = new ObjectInputStream(new FileInputStream(fileName));
            String name = (String) in.readObject();
            Date date = (Date) in.readObject();
            User user = (User) in.readObject();
            System.out.println(name);
            System.out.println(date);
            System.out.println(user.toString());
            in.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

}

运行结果:
Object is serializing!
phl
Fri Sep 03 19:44:47 CST 2010
name=phl
age=0