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; //id
string 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;
}测试程序
void set_addressbook()
{
AddressBook obj;
Person *p1 = obj.add_people(); //新增加一个Person
p1->set_name("mike");
p1->set_id(1);
p1->set_email("[email protected]");
Person::PhoneNumber *phone1 = p1->add_phones(); //增加一个phone
phone1->set_number("110");
phone1->set_type(Person::MOBILE);
Person::PhoneNumber *phone2 = p1->add_phones(); //增加一个phone
phone2->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people
cout << "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;
}
}
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; //id
string 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;
}测试程序
void set_addressbook()
{
tutorial::AddressBook obj;
tutorial::Person *p1 = obj.add_people(); //新增加一个Person
p1->set_name("mike");
p1->set_id(1);
p1->set_email("[email protected]");
tutorial::Person::PhoneNumber *phone1 = p1->add_phones(); //增加一个phone
phone1->set_number("110");
phone1->set_type(tutorial::Person::MOBILE);
tutorial::Person::PhoneNumber *phone2 = p1->add_phones(); //增加一个phone
phone2->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people
cout << "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;
}
}本教程源代码下载地址：http://download.csdn.net/detail/tennysonsky/9884335（在下载包中，有在文件夹下有addressbook.pb.h和addressbook.pb.cc文件由protoc编译器依据addressbook.proto文件生成）
转自：https://blog.csdn.net/tennysonsky/article/details/73921295