protobuf c++ 接口分析

最近学习protobuf, 遇到好多问题, 最主要的就是接口的使用, 现在还没搞明白, 一边总结一边补充吧

首先编写一个 .proto,格式网上都有很多,我用的是 person.proto

message person {  required string name = 1;   //name  optional uint32 age = 2; // age}

然后用protoc  person.proto  --cpp_out=.  编译 将目标文件放到当前目录下面 这时有了

person.pb.h

// Generated by the protocol buffer compiler.  DO NOT EDIT!// source: person.proto#ifndef PROTOBUF_person_2eproto__INCLUDED#define PROTOBUF_person_2eproto__INCLUDED#include <string>#include <google/protobuf/stubs/common.h>#if GOOGLE_PROTOBUF_VERSION < 2005000#error This file was generated by a newer version of protoc which is#error incompatible with your Protocol Buffer headers.  Please update#error your headers.#endif#if 2005000 < GOOGLE_PROTOBUF_MIN_PROTOC_VERSION#error This file was generated by an older version of protoc which is#error incompatible with your Protocol Buffer headers.  Please#error regenerate this file with a newer version of protoc.#endif#include <google/protobuf/generated_message_util.h>#include <google/protobuf/message.h>#include <google/protobuf/repeated_field.h>#include <google/protobuf/extension_set.h>#include <google/protobuf/unknown_field_set.h>// @@protoc_insertion_point(includes)// Internal implementation detail -- do not call these.void  protobuf_AddDesc_person_2eproto();void protobuf_AssignDesc_person_2eproto();void protobuf_ShutdownFile_person_2eproto();class person;// ===================================================================class person : public ::google::protobuf::Message { public:  person();  virtual ~person();  person(const person& from);  inline person& operator=(const person& from) {    CopyFrom(from);    return *this;  }  inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {    return _unknown_fields_;  }  inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {    return &_unknown_fields_;  }  static const ::google::protobuf::Descriptor* descriptor();  static const person& default_instance();  void Swap(person* other);  // implements Message ----------------------------------------------  person* New() const;  void CopyFrom(const ::google::protobuf::Message& from);  void MergeFrom(const ::google::protobuf::Message& from);  void CopyFrom(const person& from);  void MergeFrom(const person& from);  void Clear();  bool IsInitialized() const;  int ByteSize() const;  bool MergePartialFromCodedStream(      ::google::protobuf::io::CodedInputStream* input);  void SerializeWithCachedSizes(      ::google::protobuf::io::CodedOutputStream* output) const;  ::google::protobuf::uint8* SerializeWithCachedSizesToArray(::google::protobuf::uint8* output) const;  int GetCachedSize() const { return _cached_size_; }  private:  void SharedCtor();  void SharedDtor();  void SetCachedSize(int size) const;  public:  ::google::protobuf::Metadata GetMetadata() const;  // nested types ----------------------------------------------------  // accessors -------------------------------------------------------  // required string name = 1;  inline bool has_name() const;  inline void clear_name();  static const int kNameFieldNumber = 1;  inline const ::std::string& name() const;  inline void set_name(const ::std::string& value);  inline void set_name(const char* value);  inline void set_name(const char* value, size_t size);  inline ::std::string* mutable_name();  inline ::std::string* release_name();  inline void set_allocated_name(::std::string* name);  // optional uint32 age = 2;  inline bool has_age() const;  inline void clear_age();  static const int kAgeFieldNumber = 2;  inline ::google::protobuf::uint32 age() const;  inline void set_age(::google::protobuf::uint32 value);  // @@protoc_insertion_point(class_scope:person) private:  inline void set_has_name();  inline void clear_has_name();  inline void set_has_age();  inline void clear_has_age();  ::google::protobuf::UnknownFieldSet _unknown_fields_;  ::std::string* name_;  ::google::protobuf::uint32 age_;  mutable int _cached_size_;  ::google::protobuf::uint32 _has_bits_[(2 + 31) / 32];  friend void  protobuf_AddDesc_person_2eproto();  friend void protobuf_AssignDesc_person_2eproto();  friend void protobuf_ShutdownFile_person_2eproto();  void InitAsDefaultInstance();  static person* default_instance_;};// ===================================================================// ===================================================================// person// required string name = 1;inline bool person::has_name() const {  return (_has_bits_[0] & 0x00000001u) != 0;}inline void person::set_has_name() {  _has_bits_[0] |= 0x00000001u;}inline void person::clear_has_name() {  _has_bits_[0] &= ~0x00000001u;}inline void person::clear_name() {  if (name_ != &::google::protobuf::internal::kEmptyString) {    name_->clear();  }  clear_has_name();}inline const ::std::string& person::name() const {  return *name_;}inline void person::set_name(const ::std::string& value) {  set_has_name();  if (name_ == &::google::protobuf::internal::kEmptyString) {    name_ = new ::std::string;  }  name_->assign(value);}inline void person::set_name(const char* value) {  set_has_name();  if (name_ == &::google::protobuf::internal::kEmptyString) {    name_ = new ::std::string;  }  name_->assign(value);}inline void person::set_name(const char* value, size_t size) {  set_has_name();  if (name_ == &::google::protobuf::internal::kEmptyString) {    name_ = new ::std::string;  }  name_->assign(reinterpret_cast<const char*>(value), size);}inline ::std::string* person::mutable_name() {  set_has_name();  if (name_ == &::google::protobuf::internal::kEmptyString) {    name_ = new ::std::string;  }  return name_;}inline ::std::string* person::release_name() {  clear_has_name();  if (name_ == &::google::protobuf::internal::kEmptyString) {    return NULL;  } else {    ::std::string* temp = name_;    name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);    return temp;  }}inline void person::set_allocated_name(::std::string* name) {  if (name_ != &::google::protobuf::internal::kEmptyString) {    delete name_;  }  if (name) {    set_has_name();    name_ = name;  } else {    clear_has_name();    name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);  }}// optional uint32 age = 2;inline bool person::has_age() const {  return (_has_bits_[0] & 0x00000002u) != 0;}inline void person::set_has_age() {  _has_bits_[0] |= 0x00000002u;}inline void person::clear_has_age() {  _has_bits_[0] &= ~0x00000002u;}inline void person::clear_age() {  age_ = 0u;  clear_has_age();}inline ::google::protobuf::uint32 person::age() const {  return age_;}inline void person::set_age(::google::protobuf::uint32 value) {  set_has_age();  age_ = value;}// @@protoc_insertion_point(namespace_scope)#ifndef SWIGnamespace google {namespace protobuf {}  // namespace google}  // namespace protobuf#endif  // SWIG// @@protoc_insertion_point(global_scope)#endif  // PROTOBUF_person_2eproto__INCLUDED

和person.pb.cc

// Generated by the protocol buffer compiler.  DO NOT EDIT!// source: person.proto#define INTERNAL_SUPPRESS_PROTOBUF_FIELD_DEPRECATION#include "person.pb.h"#include <algorithm>#include <google/protobuf/stubs/common.h>#include <google/protobuf/stubs/once.h>#include <google/protobuf/io/coded_stream.h>#include <google/protobuf/wire_format_lite_inl.h>#include <google/protobuf/descriptor.h>#include <google/protobuf/generated_message_reflection.h>#include <google/protobuf/reflection_ops.h>#include <google/protobuf/wire_format.h>// @@protoc_insertion_point(includes)namespace {const ::google::protobuf::Descriptor* person_descriptor_ = NULL;const ::google::protobuf::internal::GeneratedMessageReflection*  person_reflection_ = NULL;}  // namespacevoid protobuf_AssignDesc_person_2eproto() {  protobuf_AddDesc_person_2eproto();  const ::google::protobuf::FileDescriptor* file =    ::google::protobuf::DescriptorPool::generated_pool()->FindFileByName(      "person.proto");  GOOGLE_CHECK(file != NULL);  person_descriptor_ = file->message_type(0);  static const int person_offsets_[2] = {    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(person, name_),    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(person, age_),  };  person_reflection_ =    new ::google::protobuf::internal::GeneratedMessageReflection(      person_descriptor_,      person::default_instance_,      person_offsets_,      GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(person, _has_bits_[0]),      GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(person, _unknown_fields_),      -1,      ::google::protobuf::DescriptorPool::generated_pool(),      ::google::protobuf::MessageFactory::generated_factory(),      sizeof(person));}namespace {GOOGLE_PROTOBUF_DECLARE_ONCE(protobuf_AssignDescriptors_once_);inline void protobuf_AssignDescriptorsOnce() {  ::google::protobuf::GoogleOnceInit(&protobuf_AssignDescriptors_once_,                 &protobuf_AssignDesc_person_2eproto);}void protobuf_RegisterTypes(const ::std::string&) {  protobuf_AssignDescriptorsOnce();  ::google::protobuf::MessageFactory::InternalRegisterGeneratedMessage(    person_descriptor_, &person::default_instance());}}  // namespacevoid protobuf_ShutdownFile_person_2eproto() {  delete person::default_instance_;  delete person_reflection_;}void protobuf_AddDesc_person_2eproto() {  static bool already_here = false;  if (already_here) return;  already_here = true;  GOOGLE_PROTOBUF_VERIFY_VERSION;  ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(    "\n\014person.proto\"#\n\006person\022\014\n\004name\030\001 \002(\t\022\013"    "\n\003age\030\002 \001(\r", 51);  ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(    "person.proto", &protobuf_RegisterTypes);  person::default_instance_ = new person();  person::default_instance_->InitAsDefaultInstance();  ::google::protobuf::internal::OnShutdown(&protobuf_ShutdownFile_person_2eproto);}// Force AddDescriptors() to be called at static initialization time.struct StaticDescriptorInitializer_person_2eproto {  StaticDescriptorInitializer_person_2eproto() {    protobuf_AddDesc_person_2eproto();  }} static_descriptor_initializer_person_2eproto_;// ===================================================================#ifndef _MSC_VERconst int person::kNameFieldNumber;const int person::kAgeFieldNumber;#endif  // !_MSC_VERperson::person()  : ::google::protobuf::Message() {  SharedCtor();}void person::InitAsDefaultInstance() {}person::person(const person& from)  : ::google::protobuf::Message() {  SharedCtor();  MergeFrom(from);}void person::SharedCtor() {  _cached_size_ = 0;  name_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);  age_ = 0u;  ::memset(_has_bits_, 0, sizeof(_has_bits_));}person::~person() {  SharedDtor();}void person::SharedDtor() {  if (name_ != &::google::protobuf::internal::kEmptyString) {    delete name_;  }  if (this != default_instance_) {  }}void person::SetCachedSize(int size) const {  GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();  _cached_size_ = size;  GOOGLE_SAFE_CONCURRENT_WRITES_END();}const ::google::protobuf::Descriptor* person::descriptor() {  protobuf_AssignDescriptorsOnce();  return person_descriptor_;}const person& person::default_instance() {  if (default_instance_ == NULL) protobuf_AddDesc_person_2eproto();  return *default_instance_;}person* person::default_instance_ = NULL;person* person::New() const {  return new person;}void person::Clear() {  if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {    if (has_name()) {      if (name_ != &::google::protobuf::internal::kEmptyString) {        name_->clear();      }    }    age_ = 0u;  }  ::memset(_has_bits_, 0, sizeof(_has_bits_));  mutable_unknown_fields()->Clear();}bool person::MergePartialFromCodedStream(    ::google::protobuf::io::CodedInputStream* input) {#define DO_(EXPRESSION) if (!(EXPRESSION)) return false  ::google::protobuf::uint32 tag;  while ((tag = input->ReadTag()) != 0) {    switch (::google::protobuf::internal::WireFormatLite::GetTagFieldNumber(tag)) {      // required string name = 1;      case 1: {        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==            ::google::protobuf::internal::WireFormatLite::WIRETYPE_LENGTH_DELIMITED) {          DO_(::google::protobuf::internal::WireFormatLite::ReadString(                input, this->mutable_name()));          ::google::protobuf::internal::WireFormat::VerifyUTF8String(            this->name().data(), this->name().length(),            ::google::protobuf::internal::WireFormat::PARSE);        } else {          goto handle_uninterpreted;        }        if (input->ExpectTag(16)) goto parse_age;        break;      }      // optional uint32 age = 2;      case 2: {        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==            ::google::protobuf::internal::WireFormatLite::WIRETYPE_VARINT) {         parse_age:          DO_((::google::protobuf::internal::WireFormatLite::ReadPrimitive<                   ::google::protobuf::uint32, ::google::protobuf::internal::WireFormatLite::TYPE_UINT32>(                 input, &age_)));          set_has_age();        } else {          goto handle_uninterpreted;        }        if (input->ExpectAtEnd()) return true;        break;      }      default: {      handle_uninterpreted:        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==            ::google::protobuf::internal::WireFormatLite::WIRETYPE_END_GROUP) {          return true;        }        DO_(::google::protobuf::internal::WireFormat::SkipField(              input, tag, mutable_unknown_fields()));        break;      }    }  }  return true;#undef DO_}void person::SerializeWithCachedSizes(    ::google::protobuf::io::CodedOutputStream* output) const {  // required string name = 1;  if (has_name()) {    ::google::protobuf::internal::WireFormat::VerifyUTF8String(      this->name().data(), this->name().length(),      ::google::protobuf::internal::WireFormat::SERIALIZE);    ::google::protobuf::internal::WireFormatLite::WriteString(      1, this->name(), output);  }  // optional uint32 age = 2;  if (has_age()) {    ::google::protobuf::internal::WireFormatLite::WriteUInt32(2, this->age(), output);  }  if (!unknown_fields().empty()) {    ::google::protobuf::internal::WireFormat::SerializeUnknownFields(        unknown_fields(), output);  }}::google::protobuf::uint8* person::SerializeWithCachedSizesToArray(    ::google::protobuf::uint8* target) const {  // required string name = 1;  if (has_name()) {    ::google::protobuf::internal::WireFormat::VerifyUTF8String(      this->name().data(), this->name().length(),      ::google::protobuf::internal::WireFormat::SERIALIZE);    target =      ::google::protobuf::internal::WireFormatLite::WriteStringToArray(        1, this->name(), target);  }  // optional uint32 age = 2;  if (has_age()) {    target = ::google::protobuf::internal::WireFormatLite::WriteUInt32ToArray(2, this->age(), target);  }  if (!unknown_fields().empty()) {    target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(        unknown_fields(), target);  }  return target;}int person::ByteSize() const {  int total_size = 0;  if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {    // required string name = 1;    if (has_name()) {      total_size += 1 +        ::google::protobuf::internal::WireFormatLite::StringSize(          this->name());    }    // optional uint32 age = 2;    if (has_age()) {      total_size += 1 +        ::google::protobuf::internal::WireFormatLite::UInt32Size(          this->age());    }  }  if (!unknown_fields().empty()) {    total_size +=      ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(        unknown_fields());  }  GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();  _cached_size_ = total_size;  GOOGLE_SAFE_CONCURRENT_WRITES_END();  return total_size;}void person::MergeFrom(const ::google::protobuf::Message& from) {  GOOGLE_CHECK_NE(&from, this);  const person* source =    ::google::protobuf::internal::dynamic_cast_if_available<const person*>(      &from);  if (source == NULL) {    ::google::protobuf::internal::ReflectionOps::Merge(from, this);  } else {    MergeFrom(*source);  }}void person::MergeFrom(const person& from) {  GOOGLE_CHECK_NE(&from, this);  if (from._has_bits_[0 / 32] & (0xffu << (0 % 32))) {    if (from.has_name()) {      set_name(from.name());    }    if (from.has_age()) {      set_age(from.age());    }  }  mutable_unknown_fields()->MergeFrom(from.unknown_fields());}void person::CopyFrom(const ::google::protobuf::Message& from) {  if (&from == this) return;  Clear();  MergeFrom(from);}void person::CopyFrom(const person& from) {  if (&from == this) return;  Clear();  MergeFrom(from);}bool person::IsInitialized() const {  if ((_has_bits_[0] & 0x00000001) != 0x00000001) return false;  return true;}void person::Swap(person* other) {  if (other != this) {    std::swap(name_, other->name_);    std::swap(age_, other->age_);    std::swap(_has_bits_[0], other->_has_bits_[0]);    _unknown_fields_.Swap(&other->_unknown_fields_);    std::swap(_cached_size_, other->_cached_size_);  }}::google::protobuf::Metadata person::GetMetadata() const {  protobuf_AssignDescriptorsOnce();  ::google::protobuf::Metadata metadata;  metadata.descriptor = person_descriptor_;  metadata.reflection = person_reflection_;  return metadata;}// @@protoc_insertion_point(namespace_scope)// @@protoc_insertion_point(global_scope)

然后编写调用接口的c++文件,这里是1.cpp

#include "person.pb.h"#include <iostream>#include <ios>using namespace std;void InfoStudents(const person& sxy){    cout<< "sxy info:"<<endl;    cout<<"name: "<<sxy.name()<<endl;    cout<<"age: "<<sxy.age()<<endl;}int main(){    person sxy;    sxy.set_name("shixiaoyu");    sxy.set_age(25);    int size = sxy.ByteSize();    cout<<"size: "<<size<<endl;    cout<<"name1: "<<sxy.has_age()<<endl;  //字段是否存在 设置?    unsigned char btc[size];    sxy.SerializeWithCachedSizesToArray(btc);   InfoStudents(sxy);        return 0;    }

编译: g++ 1.cpp -o aa person.pb.cc  -I /usr/local/protobuf/include -L /usr/local/protobuf/lib  -lprotobuf -pthread

运行结果:

size: 13name1: 1sxy info:name: shixiaoyuage: 25