netty04-序列化反序列化

╰+哭是因爲堅強的太久メ 2022-05-31 04:50 302阅读 0赞

# 序列化协议基础 #

*  基础类型int在内存中的原始序列化

*  基于nio的序列化

*  基于netty的序列化

## int类型序列化 ##

int类型序列化方式有两种

大端序列：先写高位，在写低位

小端序列：先写低位，在写高位

左边是高位 右边是低位

00000000 00000000 00000000 00001011 = 11

/**
     * 将int数值转换为占四个字节的byte数组， 低位在前，高位在后 
     */    
    public static byte[] intToBytes(int value)   
    {
        byte[] byteArray = new byte[4];  
        // 最高位放在最后一个字节 ，也就是向右移动3个字节 = 24位
        byteArray[3] = (byte) ((value & 0xFF000000)>>3*8);// 最高位，放在字节数组最后
        byteArray[2] = (byte) ((value & 0x00FF0000)>>2*8);// 左边第二个字节
        byteArray[1] = (byte) ((value & 0x0000FF00)>>1*8);    
        byteArray[0] = (byte) ((value & 0x000000FF));     // 最低位     
        //[11,0,0,0]
        return byteArray;  
    }

value & 0xFF000000解释：

00000000 00000000 00000000 00001011

& 11111111 00000000 00000000 00000000

=  00000000 00000000 00000000 00000000 = 0

## int类型反序列化 ##

/**
     * byte数组转int; 低位在前，高位在后
     */    
    public static int bytesToInt(byte[] byteArray) {  
        return (byteArray[0]&0xFF)|
              ((byteArray[1]<<1*8) & 0xFF00)|
              ((byteArray[2]<<2*8) & 0xFF0000)|
              ((byteArray[3]<<3*8) & 0xFF000000);  
    }

写个测试方法，代码如下：

public static void main(String[] args) throws Exception {
       int a = 11;
       int b = 22;
       int c = 88;
       ByteArrayOutputStream os = new ByteArrayOutputStream();
       //os.write(a);// 为什么不用这个？
       os.write(intToBytes(a));
       os.write(intToBytes(b));
       os.write(intToBytes(c));
       byte[] byteArray = os.toByteArray();
       System.out.println(Arrays.toString(byteArray));
       
       ByteArrayInputStream is = new ByteArrayInputStream(byteArray);
       byte[] aBytes = new byte[4];
       byte[] bBytes = new byte[4];
       byte[] cBytes = new byte[4];
       is.read(aBytes);
       is.read(bBytes);
       is.read(cBytes);
       System.out.println("a: " + bytesToInt(aBytes));
       System.out.println("b: " + bytesToInt(bBytes));
       System.out.println("c: " + bytesToInt(cBytes));
    }

运行结果：

![SouthEast][]

## nio序列化反序列化 ##

public static void main(String[] args) {
          int a = 11;
          int b = 22;
          // 序列化
          ByteBuffer buffer = ByteBuffer.allocate(8);
          buffer.putInt(a);
          buffer.putInt(b);
    //    buffer.putInt(2);
          byte[] array = buffer.array();
          System.out.println(Arrays.toString(buffer.array()));
          // 反序列化
          ByteBuffer bb = ByteBuffer.wrap(array);
          System.out.println("a: " + bb.getInt());
          System.out.println("b: " + bb.getInt());
       }

对比传统序列化可以看出简便很多，但是也有缺点就是ByteBuffer不是动态扩容的，默认是多少是不能增加的。即解决复杂的运算但是不支持扩容。有没有两者兼得的呢？netty。。。

## netty序列化反序列化 ##

public static void main(String[] args) {
       ChannelBuffer buffer = ChannelBuffers.dynamicBuffer();
       buffer.writeInt(11);
       buffer.writeInt(22);
       buffer.writeLong(23);
       buffer.writeLong(23);
       // byte数组的大小由buffer中写指针的位置决定
       // 往ChannelBuffer中写数据的时候，这个写指针就会移动写的数据的长度
       byte[] bytes = new byte[buffer.writerIndex()];
       buffer.readBytes(bytes); // 序列化
       System.out.println(Arrays.toString(bytes));
       // 反序列化
       ChannelBuffer wrappedBuffer = ChannelBuffers.wrappedBuffer(bytes);
       System.out.println(wrappedBuffer.readInt());
       System.out.println(wrappedBuffer.readInt());
    }

# 对象序列化 #

## Java原始对象序列化 ##

ObjectInputStream,ObjectOutStream

package com.hotpot.netty04.java;
    
    import java.io.ByteArrayInputStream;
    import java.io.ByteArrayOutputStream;
    import java.io.ObjectInputStream;
    import java.io.ObjectOutputStream;
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.List;
    
    /**
     * 描述:java原始序列化
     * ObjectOutputStream  序列化
     * ObjectInputStream  反序列化
     * @author: myx
     * @date: 2018/2/7 0007
     * Copyright © 2018-ganinfo. All rights reserved.
     */
    public class JavaSeri {
       public static void main(String[] args) throws Exception{
          // 序列化
          byte[] result = serialize();
          System.out.println(Arrays.toString(result));
          // 反序列化
          SubscribeReq req = deserialize(result);
          System.out.println(req.getSubReqID());
          System.out.println(req.getUserName());
          System.out.println(req.getProductName());
          System.out.println(req.getAddressList().get(0));
          System.out.println(req.getAddressList().get(1));
       }
       
       // 序列化
       public static byte[] serialize() throws Exception{
          SubscribeReq req = new SubscribeReq();
          
          req.setSubReqID(1);
          req.setUserName("abc");
          req.setProductName("netty");
          
          List<String> addressList = new ArrayList<String>();
          addressList.add("北京");
          addressList.add("沧州");
          req.setAddressList(addressList);
          
          ByteArrayOutputStream baos = new ByteArrayOutputStream();
          ObjectOutputStream objectOutputStream = new ObjectOutputStream(baos);
          // 把SubscribeReq对象写入ByteArrayOutputStream中
          objectOutputStream.writeObject(req);
          // 从ByteArrayOutputStream 获取序列化好的字节数组
          byte[] byteArray = baos.toByteArray();
          return byteArray ;
       }
       
       // 反序列化
       public static SubscribeReq deserialize(byte[] byteArray) throws Exception{
          ObjectInputStream objectOutputStream = new ObjectInputStream(
                new ByteArrayInputStream(byteArray));
          SubscribeReq req = (SubscribeReq)objectOutputStream.readObject();
          return req;
       }
    }

运行结果：

[-84, -19, 0, 5, 115, 114, 0, 36, 99, 111, 109, 46, 104, 111, 116, 112, 111, 116, 46, 110, 101, 116, 116, 121, 48, 52, 46, 106, 97, 118, 97, 46, 83, 117, 98, 115, 99, 114, 105, 98, 101, 82, 101, 113, 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 4, 73, 0, 8, 115, 117, 98, 82, 101, 113, 73, 68, 76, 0, 11, 97, 100, 100, 114, 101, 115, 115, 76, 105, 115, 116, 116, 0, 16, 76, 106, 97, 118, 97, 47, 117, 116, 105, 108, 47, 76, 105, 115, 116, 59, 76, 0, 11, 112, 114, 111, 100, 117, 99, 116, 78, 97, 109, 101, 116, 0, 18, 76, 106, 97, 118, 97, 47, 108, 97, 110, 103, 47, 83, 116, 114, 105, 110, 103, 59, 76, 0, 8, 117, 115, 101, 114, 78, 97, 109, 101, 113, 0, 126, 0, 2, 120, 112, 0, 0, 0, 1, 115, 114, 0, 19, 106, 97, 118, 97, 46, 117, 116, 105, 108, 46, 65, 114, 114, 97, 121, 76, 105, 115, 116, 120, -127, -46, 29, -103, -57, 97, -99, 3, 0, 1, 73, 0, 4, 115, 105, 122, 101, 120, 112, 0, 0, 0, 2, 119, 4, 0, 0, 0, 2, 116, 0, 6, -27, -116, -105, -28, -70, -84, 116, 0, 6, -26, -78, -89, -27, -73, -98, 120, 116, 0, 5, 110, 101, 116, 116, 121, 116, 0, 3, 97, 98, 99]

缺点：性能低下。

## protobuf序列化 ##

序列化出来的数据很小。实现方式自行百度。

对比一下：

java

[-84, -19, 0, 5, 115, 114, 0, 46, 99, 111, 109, 46, 116, 117, 108, 105, 110, 103, 46, 110, 101, 116, 116, 121, 46, 100, 97, 121, 51,
     46, 106, 97, 118, 97, 46, 115, 101, 114, 105, 97, 108, 46, 83, 117, 98, 115, 99, 114, 105, 98, 101, 82, 101, 113, 0, 0, 0, 0, 0, 0,
     0, 1, 2, 0, 4, 73, 0, 8, 115, 117, 98, 82, 101, 113, 73, 68, 76, 0, 11, 97, 100, 100, 114, 101, 115, 115, 76, 105, 115, 116, 116, 0,
     16, 76, 106, 97, 118, 97, 47, 117, 116, 105, 108, 47, 76, 105, 115, 116, 59, 76, 0, 11, 112, 114, 111, 100, 117, 99, 116, 78, 97, 
     109, 101, 116, 0, 18, 76, 106, 97, 118, 97, 47, 108, 97, 110, 103, 47, 83, 116, 114, 105, 110, 103, 59, 76, 0, 8, 117, 115, 101, 114,
     78, 97, 109, 101, 113, 0, 126, 0, 2, 120, 112, 0, 0, 0, 1, 115, 114, 0, 19, 106, 97, 118, 97, 46, 117, 116, 105, 108, 46, 65, 114, 
     114, 97, 121, 76, 105, 115, 116, 120, -127, -46, 29, -103, -57, 97, -99, 3, 0, 1, 73, 0, 4, 115, 105, 122, 101, 120, 112, 0, 0, 0,
     2, 119, 4, 0, 0, 0, 2, 116, 0, 6, -23, -107, -65, -26, -78, -103, 116, 0, 6, -26, -73, -79, -27, -100, -77, 120, 116, 0, 5, 110, 
     101, 116, 116, 121, 116, 0, 3, 97, 98, 99]

Protobuf

[8, 1, 18, 3, 97, 98, 99, 26, 5, 110, 101, 116, 116, 121, 34, 6, -23, -107, -65, -26, -78, -103, 34, 6, -26, -73, -79, -27, -100, -77]

int 内存中： 4个字节 32位

protobuf :  1~5个字节

[SouthEast]: /images/20220531/8dc2479f8b364e5ea119fc888eaea7ed.png