方法1：
message person
{
required int32 age = 1;
required int32 userid = 2;
optional string name = 3;
}
message test
{
required int32 time = 1;
required int32 userid = 2;
required float price = 3;
optional string desc = 4;
}
#include <string>
#include <iostream>
#include <assert.h>
#include <stdint.h> #include "person.pb.h"
#include "test.pb.h" using namespace std; class ProtoMsgHandle
{
public:
/* 注册消息处理函数 */
void initHandles()
{
registerHandle(&ProtoMsgHandle::handleProtoPerson);
registerHandle(&ProtoMsgHandle::handleProtoTest);
} /* 处理网络消息
* data 为一个完整的数据包
*/
void handle(const char* data)
{
bool ret = false; const char * current=data; //在网络上传输的一个数据包总长度
int packetLength=; //从第一个位置上获取到数据包总长度
memcpy(&packetLength, data, sizeof(int32_t)); //指针后移
current+=sizeof(int32_t); //Message名字的长度
int protoNameLength=; //从第二个位置上获取Message的名字的长度
memcpy(&protoNameLength, current, sizeof(int32_t)); //指针后移
current+=sizeof(int32_t); //从第三个位置上获取Message的名字
string name(current,protoNameLength); //指针后移
current+=protoNameLength; //取得Message的字节数
int messageSize=packetLength-(sizeof(int32_t)+sizeof(int32_t)+protoNameLength); do{ msg_handle callback = m_callbacks[name]; assert(callback != NULL); if(callback == NULL)
{
std::cout<<"proto "<<name<<" had not register handler"<<std::endl;
break;
}
const ::google::protobuf::Descriptor* descriptor = m_descriptors[name];
assert(descriptor != NULL);
if(descriptor == NULL)
{
std::cout<<"proto "<<name<<" had no descriptor"<<std::endl;
break;
}
const google::protobuf::Message* prototype = google::protobuf::MessageFactory::generated_factory()->GetPrototype(descriptor);
assert(prototype != NULL);
if(prototype == NULL)
{
std::cout<<"proto "<<name<<" had no prototype"<<std::endl;
break;
}
google::protobuf::Message* msg = prototype->New();
ret = msg->ParseFromArray(current,messageSize);
if(ret)
{
(this->*callback)(msg);
}
else
{
std::cout<<"proto "<<name<<" parse fail"<<std::endl;
} }while();
}
private:
void handleProtoTest(test* test)
{
cout <<"test->price()="<< test->price() << endl;
cout << "test->userid()="<<test->userid() << endl;
cout << "test->time()="<<test->time() << endl;
}
void handleProtoPerson(person* person)
{
cout << "person->age()="<<person->age() << endl;
cout << "person->userid()="<<person->userid() << endl;
cout << "person->name()="<<person->name() << endl;
} private: typedef void (ProtoMsgHandle::*msg_handle)(::google::protobuf::Message*); map<string, msg_handle> m_callbacks; map<string, const ::google::protobuf::Descriptor*> m_descriptors; template<typename MSGTYPE> void registerHandle(void (ProtoMsgHandle::*callback)(MSGTYPE*))
{
const ::google::protobuf::Descriptor*des =MSGTYPE::descriptor();
assert(des != NULL);
if(des != NULL)
{
m_callbacks[des->full_name()] = (msg_handle)callback;
m_descriptors[des->full_name()] = des;
}
} }; class ProtoMessageSender
{
public:
/* 发送proto msg到指定缓冲区
* int32_t packetLength 数据包总长度
* int32_t messageNameLength 消息名长度
* char[] messageName 消息名
* char[] Message 消息
* char* buffer 缓冲区
* int maxLength 消息的最大长度
*/
template<typename MSGTYPE> static int sendMessageToBuffer(MSGTYPE& msg, char* buffer, int maxLength){ char * current=buffer; //Message的字节数
int messageSize=msg.ByteSize(); //Message的名字
string messageName=MSGTYPE::descriptor()->full_name(); //Message名字的长度
size_t messageNameLength=messageName.size(); //消息组成 messageSize+messageNameLength+messageName+Message
size_t packetLength=sizeof(int32_t)+sizeof(int32_t)+messageNameLength+messageSize; if (packetLength>maxLength) {
return -;
} //将数据包总长度放在第一个位置
memcpy(current, &packetLength, sizeof(int32_t)); //指针后移
current+=sizeof(int32_t); //将Message名称长度放在第二个位置
memcpy(current, &messageNameLength, sizeof(int32_t)); //指针后移
current+=sizeof(int32_t); //将协议名称放在第三个位置上
strcpy(current,messageName.c_str()); //指针后移
current+=messageNameLength; //将Message放在第四个位置上
msg.SerializeToArray(current,messageSize); return (int)packetLength; }
}; int main()
{ ProtoMsgHandle msghandle;
msghandle.initHandles(); test t;
t.set_price(100.0);
t.set_userid();
t.set_time(); person person;
person.set_age();
person.set_userid();
person.set_name("irons"); char tmp[*];
ProtoMessageSender::sendMessageToBuffer(t, tmp, sizeof(tmp));
msghandle.handle(tmp); ProtoMessageSender::sendMessageToBuffer(person, tmp, sizeof(tmp));
msghandle.handle(tmp); cin.get();
return ;
}
方法2：
http://my.oschina.net/cxh3905/blog/159122
比较：
方法1把每种消息注册到链表中，当有消息来时，迭代处理，每个消息对应一个回调函数。
方法2只有1种消息，里面有个成员msg type，根据这个type做相应的处理。
前者更直观，结构清晰，每个消息占用空间合理，但效率地下。
后者效率更高，但所有数据混杂在一起，代码阅读性差。