枚举(enum)

消息格式

当需要定义一个消息类型的时候，可能想为一个字段指定某“预定义值序列”中的一个值，这时候可以通过枚举实现。

syntax = "proto3";//指定版本信息，不指定会报错message Person //message为关键字，作用为定义一种消息类型
{string name = 1;    //姓名int32 id = 2;       //idstring email = 3; //邮件enum PhoneType //枚举消息类型{ MOBILE = 0; //proto3版本中，首成员必须为0，成员不应有相同的值 HOME = 1; WORK = 2;}message PhoneNumber{string number = 1;PhoneType type = 2;}repeated PhoneNumber phones = 4; //phones为数组
}message AddressBook
{repeated Person people = 1;
}
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测试程序

void set_addressbook()
{AddressBook obj;Person *p1 = obj.add_people(); //新增加一个Personp1->set_name("mike");p1->set_id(1);p1->set_email("mike@qq.com");Person::PhoneNumber *phone1 = p1->add_phones(); //增加一个phonephone1->set_number("110");phone1->set_type(Person::MOBILE);Person::PhoneNumber *phone2 = p1->add_phones(); //增加一个phonephone2->set_number("120");phone2->set_type(Person::HOME);fstream output("pb.xxx", ios::out | ios::trunc | ios::binary);bool flag = obj.SerializeToOstream(&output);//序列化if (!flag){cerr << "Failed to write file." << endl;return;}output.close();//关闭文件
}void get_addressbook()
{AddressBook obj;fstream input("./pb.xxx", ios::in | ios::binary);obj.ParseFromIstream(&input);  //反序列化input.close(); //关闭文件for (int i = 0; i < obj.people_size(); i++){const Person& person = obj.people(i);//取第i个peoplecout << "第" << i + 1 << "个信息\n";cout << "name = " << person.name() << endl;cout << "id = " << person.id() << endl;cout << "email = " << person.email() << endl;for (int j = 0; j < person.phones_size(); j++){const Person::PhoneNumber& phone_number = person.phones(j);switch (phone_number.type()){case Person::MOBILE:cout << "  Mobile phone #: ";break;case Person::HOME:cout << "  Home phone #: ";break;case Person::WORK:cout << "  Work phone #: ";break;}cout << phone_number.number() << endl;}cout << endl;}
}
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包（package）

消息格式

.proto文件新增一个可选的package声明符，用来防止不同的消息类型有命名冲突。包的声明符会根据使用语言的不同影响生成的代码。对于C++，产生的类会被包装在C++的命名空间中。

syntax = "proto3";//指定版本信息，不指定会报错package tutorial; //package声明符message Person //message为关键字，作用为定义一种消息类型
{string name = 1;    //姓名int32 id = 2;       //idstring email = 3; //邮件enum PhoneType //枚举消息类型{MOBILE = 0; //proto3版本中，首成员必须为0，成员不应有相同的值HOME = 1;WORK = 2;}message PhoneNumber{string number = 1;PhoneType type = 2;}repeated PhoneNumber phones = 4; //phones为数组
}message AddressBook
{repeated Person people = 1;
}
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测试程序

void set_addressbook()
{tutorial::AddressBook obj;tutorial::Person *p1 = obj.add_people(); //新增加一个Personp1->set_name("mike");p1->set_id(1);p1->set_email("mike@qq.com");tutorial::Person::PhoneNumber *phone1 = p1->add_phones(); //增加一个phonephone1->set_number("110");phone1->set_type(tutorial::Person::MOBILE);tutorial::Person::PhoneNumber *phone2 = p1->add_phones(); //增加一个phonephone2->set_number("120");phone2->set_type(tutorial::Person::HOME);fstream output("pb.xxx", ios::out | ios::trunc | ios::binary);bool flag = obj.SerializeToOstream(&output);//序列化if (!flag){cerr << "Failed to write file." << endl;return;}output.close();//关闭文件
}void get_addressbook()
{tutorial::AddressBook obj;fstream input("./pb.xxx", ios::in | ios::binary);obj.ParseFromIstream(&input);  //反序列化input.close(); //关闭文件for (int i = 0; i < obj.people_size(); i++){const tutorial::Person& person = obj.people(i);//取第i个peoplecout << "第" << i + 1 << "个信息\n";cout << "name = " << person.name() << endl;cout << "id = " << person.id() << endl;cout << "email = " << person.email() << endl;for (int j = 0; j < person.phones_size(); j++){const tutorial::Person::PhoneNumber& phone_number = person.phones(j);switch (phone_number.type()){case tutorial::Person::MOBILE:cout << "  Mobile phone #: ";break;case tutorial::Person::HOME:cout << "  Home phone #: ";break;case tutorial::Person::WORK:cout << "  Work phone #: ";break;}cout << phone_number.number() << endl;}cout << endl;}
}
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本教程源代码下载地址：http://download.csdn.net/detail/tennysonsky/9884335

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