Netty 快速入门系列 - Chapter 5 Netty之序列化【第十二讲】 Java Serializable

Java 版本序列化
Player
package com.john.netty.learn.ch07.java;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Player implements java.io.Serializable {

/**
*
*/
private static final long serialVersionUID = 1L;

private long playerId;

private String name;

private int age;

private List<Integer> skills;

public Player(long playerId, String name, int age) {

this.playerId = playerId;
this.name = name;
this.age = age;

skills = new ArrayList<>();
}

public long getPlayerId() {
return playerId;
}

public String getName() {
return name;
}

public int getAge() {
return age;
}

public List<Integer> getSkills() {
return skills;
}

public void addSkill(int skill) {

skills.add(skill);

}

@Override
public String toString() {

return "playerId:" +playerId +" name:" + name +" age:" + this.age +" skills:" + Arrays.toString(this.skills.toArray(new Integer[this.skills.size()]));
}

}
Java2Bytes： 通过ObjectOutputStream 序列化对象

ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();

ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);


这里再给大家普及一个知识： 
为什么实现Serializable方法，最好提供[b]serialVersionUID 数值呢？[/b]
[b]例如： private static final long serialVersionUID = 1L;  数值不重要[/b]
如果我们不提供[b]serialVersionUID static 变量，那么 一旦对象变更，例如Player 增加 address 字段，[/b]
原来Player将无法支持反序列化这个新的Player对象序列化的值，尽管我们可以将新的address 可以设置为null，当由于Player变更了，[b]serialVersionUID 由JVM 生成，数值变化了，导致反[b]序列化失败，如何避免呢？通过提供[b]serialVersionUID数值即可。 [/b][/b][/b]
Old Player 序列化对象 -网络传输到Server端-》New Player 可以反序列化，由于[b]serialVersionUID数值没有变化， 通过新增的address 字段将会赋值为Null。[/b]package com.john.netty.learn.ch07.java;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Arrays;

public class Java2Bytes {

public Java2Bytes() {

}

public static void main(String[] args) throws Exception {

Player player = new Player(1l, "John Hao", 12);

player.addSkill(1001);
player.addSkill(1002);
player.addSkill(1003);

byte[] bytes = toBytes(player);

System.out.println(Arrays.toString(bytes));

System.out.println(toObject(Player.class, bytes));
}

public static <T> T toObject(Class<T> clz, byte[] bytes) throws Exception {

ByteArrayInputStream is = new ByteArrayInputStream(bytes);

ObjectInputStream objectInputStream = new ObjectInputStream(is);

Object obj = objectInputStream.readObject();

objectInputStream.close();

is.close();

return (T) obj;

}

public static byte[] toBytes(Object bean) throws IOException {

ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();

ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);

objectOutputStream.writeObject(bean);

objectOutputStream.flush();

objectOutputStream.close();

return byteArrayOutputStream.toByteArray();
}

}
Java结果: 与Protobuff 相比， 非常大的字节流，即占用更多的带宽及反序列化也将占用更多的资源



所有源码下载 ：https://download.csdn.net/download/netcobol/10308871