序列化协议Protobuf

「爱情、让人受尽委屈。」 2022-03-21 02:27 241阅读 0赞

### 1.序列化和反序列化 ###

**    序列化**: 将对象序列化为二进制数据（字节数组），一般也将序列化称为编码（Enccode），主要用于网络传输，数据持久化。

**   反序列化**:  将从网络上，磁盘等读取的字节数组还原成原始对象，一般也将反序列化称为解码(Decode),主要用于网络传输对象的解码，以便完成远程调用。

### 2.选择序列化协议时，需要考虑什么？ ###

*  序列化之后的码流大小（占用网络带宽）
 *  序列化和反序列化的性能（cpu资源占用）
 *  是否支持跨语言

### 3.测试Java自带的序列化类 ###

objectoutputstream /objectInputstream是Java自带的序列化类，测试它序列化的效率。

Teacher类是待序列化的类，它的定义如下：

import java.io.Serializable;
    public class Teacher implements Serializable{
        private static final long serialVersionnUID = 8619259453444471644L;
        private Long id;
        private int age;
        private String name;
    
        public Teacher(Long id,int age,String name ){
            this.id = id;
            this.age = age;
            this.name = name;
        }
    }

序列化和反序列化的定义如下：

import java.io.ByteArrayOutputStream;
    import java.io.ByteArrayInputStream;
    import java.io.ObjectInputStream;
    import java.io.ObjectOutputStream;
    import java.util.Arrays;
    import java.io.Serializable;
    public class TestJavaSerializer
    {
        //序列化
        private static byte[] serialize(Teacher t) throws Exception{
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(out);
            oos.writeObject(t);
            byte[] array = out.toByteArray();
            return array;
        }
       //反序列化
        private static Teacher deserialize(byte[] byteArray) throws Exception{
            ByteArrayInputStream ins = new ByteArrayInputStream(byteArray);
            ObjectInputStream ois = new  ObjectInputStream(ins);
            Teacher t = (Teacher)ois.readObject();
            return t;
        }
    
        public static void main(String []args) throws Exception{  
            Teacher t = new Teacher(1L, 22, "April");
            byte[] byteArray = serialize(t);
            System.out.println(Arrays.toString(byteArray));  
            System.out.println("Length = " + byteArray.length); 
            Teacher t1 = deserialize(byteArray);
        }
    }

输出结果如下：

[-84, -19, 0, 5, 115, 114, 0, 7, 84, 101, 97, 99, 104, 101, 114, -19, 83, 98, -77, 62, -23, 40, 8, 2, 0, 3, 73, 0, 3, 97, 103, 101, 76, 0, 2, 105, 100, 116, 0, 16, 76, 106, 97, 118, 97, 47, 108, 97, 110, 103, 47, 76, 111, 110, 103, 59, 76, 0, 4, 110, 97, 109, 101, 116, 0, 18, 76, 106, 97, 118, 97, 47, 108, 97, 110, 103, 47, 83, 116, 114, 105, 110, 103, 59, 120, 112, 0, 0, 0, 22, 115, 114, 0, 14, 106, 97, 118, 97, 46, 108, 97, 110, 103, 46, 76, 111, 110, 103, 59, -117, -28, -112, -52, -113, 35, -33, 2, 0, 1, 74, 0, 5, 118, 97, 108, 117, 101, 120, 114, 0, 16, 106, 97, 118, 97, 46, 108, 97, 110, 103, 46, 78, 117, 109, 98, 101, 114, -122, -84, -107, 29, 11, -108, -32, -117, 2, 0, 0, 120, 112, 0, 0, 0, 0, 0, 0, 0, 1, 116, 0, 5, 65, 112, 114, 105, 108]
    Length = 176

使用Java自带的序列化类objectoutputstream /objectInputstream对Teacher对象序列化后的长度为176。

### 4.Protobuf序列化 ###

用proto文件定义Teacher类，文件名为Teacher.proto，使用命令生成TeacherSerializer.java文件。

syntax = "proto2";
    option java_package = "com.netty.protobuf";
    option java_outer_classname = "TeacherSerializer";
    
    
    message Teacher{
        required int64 id = 1;
        required int32 age =2;
        required string name = 3;
    }

序列化和反序列化的定义如下：

package com.netty.protobuf;
    
    import java.util.Arrays;
    import com.netty.protobuf.TeacherSerializer.Teacher;
    import com.netty.protobuf.TeacherSerializer.Teacher.Builder;
    
    public class TestProtobuf {
    	//序列化
    	private static byte[] serialize()
    	{
    		Builder builder = TeacherSerializer.Teacher.newBuilder();
    		builder.setId(1L).setAge(22).setName("April");
    		Teacher t = builder.build();
    		return t.toByteArray();
    	}
    	//反序列化
    	private static Teacher deserialize(byte[] data) throws Exception
    	{
    		Teacher t = TeacherSerializer.Teacher.parseFrom(data);
    		return t;
    	}
    	
    	public static void main(String[] args) throws Exception {
    		byte[] data = serialize();
    		System.out.println(Arrays.toString(data));
    		System.out.println("Length = " + data.length);
    		Teacher t = deserialize(data);
    	}
    }

输出结果如下：

[8, 1, 16, 22, 26, 5, 65, 112, 114, 105, 108]
    Length = 11

使用Protobuf对Teacher对象序列化后的长度为11。序列化后的数据长度比java自带的序列化类短了很多。

### 5.结论 ###

使用Java自带的序列化类objectoutputstream /objectInputstream对Teacher对象序列化后的长度为176。而使用Protobuf序列化后的长度仅为11。占用带宽和消耗CPU都会比较小，所以使用**Protobuf效率更高**。