IM通讯协议专题学习(二)：快速理解Protobuf的背景、原理、使用、优缺点

本文由vivo技术团队Li Guanyun分享，为了提升阅读体验，进行了较多修订和重新排版。

if(protocolVersion=1) {

doSomething();

} elseif(protocolVersion=2) {

doOtherThing();

} ...

Why the name "Protocol Buffers"?

The name originates from the early days of the format, before we had the protocol buffer compiler to generate classes for us. At the time, there was a class called ProtocolBuffer which actually acted as a buffer for an individual method. Users would add tag/value pairs to this buffer individually by calling methods like AddValue(tag, value). The raw bytes were stored in a buffer which could then be written out once the message had been constructed.

Since that time, the "buffers" part of the name has lost its meaning, but it is still the name we use. Today, people usually use the term "protocol message" to refer to a message in an abstract sense, "protocol buffer" to refer to a serialized copy of a message, and "protocol message object" to refer to an in-memory object representing the parsed message.

syntax = "proto3";

package domain;

option java_package = "com.Protobuf.generated.domain";

option java_outer_classname = "CustomerProtos";

message Customers {

repeated Customer customer = 1;

}

message Customer {

int32 id= 1;

string firstName = 2;

string lastName = 3;

enum EmailType {

PRIVATE = 0;

PROFESSIONAL = 1;

}

message EmailAddress {

string email = 1;

EmailType type= 2;

}

repeated EmailAddress email = 5;

}

1protoc --java_out=./src/main/java./src/main/idl/customer.proto

CustomerProtos.Customer.EmailAddress email = CustomerProtos.Customer.EmailAddress.newBuilder()

.setType(CustomerProtos.Customer.EmailType.PROFESSIONAL)

.setEmail("crichardson@email.com").build();

CustomerProtos.Customer customer = CustomerProtos.Customer.newBuilder()

.setId(1)

.setFirstName("Lee")

.setLastName("Richardson")

.addEmail(email)

.build();

// 序列化

byte[] binaryInfo = customer.toByteArray();

System.out.println(bytes_String16(binaryInfo));

System.out.println(customer.toByteArray().length);

// 反序列化

CustomerProtos.Customer anotherCustomer = CustomerProtos.Customer.parseFrom(binaryInfo);

System.out.println(anotherCustomer.toString());

1{"id":1,"firstName":"Chris","lastName":"Richardson","email":[{"type":"PROFESSIONAL","email":"crichardson@email.com"}]}

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