序列化

序列化的作用

1.数据的持久化。存在磁盘上，以磁信息存储，01-高低电平-电流-电磁转换-磁

2.网络数据传输。

Java原生序列化的局限性

1.只能针对java语言

2.序列化的性能不是很好。

3.没有对序列化后的数据的压缩处理机制。

package com.liming.serializable;

import java.io.Serializable;

public class Student implements Serializable{
	String name;
	String gender;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}
	@Override
	public String toString() {
		return "Student [name=" + name + ", gender=" + gender + "]";
	}
}

package com.liming.serializable;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

import org.junit.Test;

public class TestDemo {
	@Test
	public void test01() throws Exception{
		ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(new File("1.txt")));
		Student student = new Student();
		student.setName("zuo");
		student.setGender("woman");
		out.writeObject(student);
		out.close();
	}
	@Test
	public void test02() throws Exception{
		ObjectInputStream in = new ObjectInputStream(new FileInputStream(new File("1.txt")));
		Student s = (Student) in.readObject();
		System.out.println(s.toString());
	}
}

当该变对象结构（此处为给student加一个字段），那么会报错，反序列化不成功。

serialVersionUID，如果序列化和反序列化时id不一致那么会报错。

解决方法自己定义一个serialVersionUID；

package com.liming.serializable;

import java.io.Serializable;

public class Student implements Serializable{
	/**
	 * 
	 */
	private static final long serialVersionUID = -285105176413201102L;
	String name;
	String gender;
	String likes;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}
	@Override
	public String toString() {
		return "Student [name=" + name + ", gender=" + gender + "]";
	}
}