到目前为止，您的ProtoBuf模式仅包含嵌套消息的定义（电话，地址和大学）；但不是Student消息类型中它们各自的字段。并且，您不需要在代码中具有单独的结构。它们已经在.pb.h生成的.pb.cc和protoc文件中声明和定义。使用那些。否则，除非您有充分的理由这样做，否则在使用已经为您完成的序列化/反序列化库/框架时手动维护代码中的这些类型将是自欺欺人的。

更新后的ProtoBuf模式将是（请观察下面的字段5、6和7）：

studentinfo.proto

syntax = "proto2";

package test;

message Student
{
    required int32 id = 1;
    required string name = 2;
    required double age = 3;
    optional string email = 4;

    enum PhoneType
    {
        DESK = 1;
        MOBILE = 2;
        WIRELESS = 3;
    };

    message Phone
    {
        required PhoneType type = 1;
        required string number = 2;
    }

    message Address {
        required string address1 = 1;
        optional string address2 = 2;
    }

    message College {
        required string name = 1;
        optional string address = 2;
    }

    required Phone phone = 5;
    required Address address = 6;
    optional College college = 7;
}

一旦有了所需的架构和生成的文件，就可以继续创建和填充类型，然后对消息进行序列化以通过网络发送并在另一端反序列化。

这是一个完整的工作示例：

main.cpp

#include <iostream>
#include <string>
#include "studentinfo.pb.h"

int main()
{
    using namespace test;

    // Serialization

    Student s;
    s.set_name("Test");
    s.set_id(123);
    s.set_age(24);

    s.mutable_phone()->set_type(Student_PhoneType_DESK);
    s.mutable_phone()->set_number("+00 123 1234567");

    s.mutable_address()->set_address1("House # 1,Street # 1");
    s.mutable_address()->set_address2("House # 2,Street # 2");

    s.mutable_college()->set_name("XYZ College");
    s.mutable_college()->set_address("College Address Here");

    std::cout << "Serialization:\n\n" << s.DebugString() << "\n\n";
    //s.PrintDebugString();

    std::string serialized;
    if ( !s.SerializeToString( &serialized ) )
    {
        std::cerr << "ERROR: Unable to serialize!\n";
        return -1;
    }

    // Deserialization

    Student deserialized;
    if ( !deserialized.ParseFromString( serialized ) )
    {
        std::cerr << "ERROR: Unable to deserialize!\n";
        return -1;
    }

    std::cout << "Deserialization:\n\n";
    deserialized.PrintDebugString();

    // deserialized.name();
    // deserialized.id();
    // ...
    // deserialized.phone().type();
    // deserialized.phone().number()
    // ...

    return 0;
}

输出：

Serialization:

id: 123
name: "Test"
age: 24
phone {
  type: DESK
  number: "+00 123 1234567"
}
address {
  address1: "House # 1,Street # 1"
  address2: "House # 2,Street # 2"
}
college {
  name: "XYZ College"
  address: "College Address Here"
}


Deserialization:

id: 123
name: "Test"
age: 24
phone {
  type: DESK
  number: "+00 123 1234567"
}
address {
  address1: "House # 1,Street # 2"
}
college {
  name: "XYZ College"
  address: "College Address Here"
}

看看.pb.h文件中可能需要操纵消息的变异器和访问器。