Oneof 如果您有许多字段的消息，并且最多可以同时设置一个字段，则可以使用Oneof功能来执行此行为并保存内存。一个字段就像常规字段一样，除了单一共享内存中的所有字段，最多可以同时设置一个字段。设置Oneof的任何成员都会自动清除所有其他成员。
Google protobuf 文档#Oneof 示例proto 创建protoOneof.proto 的proto文件
syntax = "proto3"; package oneof_test; option go_package ='.;oneof'; message WeiboUser{ string user_id = 1; string user_nick = 2; } message DouyinUser{ string auth_token = 1; string nick_name = 2; } message User{ oneof user_source{ string weibo_url = 1; string douyin_url = 2; } oneof user_info{ WeiboUser weibo_user_info = 3; DouyinUser douyin_user_info = 4; } } 使用命令生成go代码
protoc --proto_path=. --go_out=paths=source_relative:./oneof ./protoOneof.proto 生成的protoOneof.pb.go代码如下：
// Code generated by protoc-gen-go. DO NOT EDIT. // versions: // protoc-gen-go v1.28.0 // protoc v3.21.3 // source: protoOneof.proto package oneof import ( protoreflect "google.golang.org/protobuf/reflect/protoreflect" protoimpl "google.golang.org/protobuf/runtime/protoimpl" reflect "reflect" sync "sync" ) const ( // Verify that this generated code is sufficiently up-to-date. _ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion) // Verify that runtime/protoimpl is sufficiently up-to-date. _ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20) ) type WeiboUser struct { state protoimpl.MessageState sizeCache protoimpl.SizeCache unknownFields protoimpl.UnknownFields UserId string `protobuf:"bytes,1,opt,name=user_id,json=userId,proto3" json:"user_id,omitempty"` UserNick string `protobuf:"bytes,2,opt,name=user_nick,json=userNick,proto3" json:"user_nick,omitempty"` } func (x *WeiboUser) Reset() { *x = WeiboUser{} if protoimpl.UnsafeEnabled { mi := &file_protoOneof_proto_msgTypes[0] ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x)) ms.StoreMessageInfo(mi) } } func (x *WeiboUser) String() string { return protoimpl.X.MessageStringOf(x) } func (*WeiboUser) ProtoMessage() {} func (x *WeiboUser) ProtoReflect() protoreflect.Message { mi := &file_protoOneof_proto_msgTypes[0] if protoimpl.UnsafeEnabled && x != nil { ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x)) if ms.LoadMessageInfo() == nil { ms.StoreMessageInfo(mi) } return ms } return mi.MessageOf(x) } // Deprecated: Use WeiboUser.ProtoReflect.Descriptor instead. func (*WeiboUser) Descriptor() ([]byte, []int) { return file_protoOneof_proto_rawDescGZIP(), []int{0} } func (x *WeiboUser) GetUserId() string { if x != nil { return x.UserId } return "" } func (x *WeiboUser) GetUserNick() string { if x != nil { return x.UserNick } return "" } type DouyinUser struct { state protoimpl.MessageState sizeCache protoimpl.SizeCache unknownFields protoimpl.UnknownFields AuthToken string `protobuf:"bytes,1,opt,name=auth_token,json=authToken,proto3" json:"auth_token,omitempty"` NickName string `protobuf:"bytes,2,opt,name=nick_name,json=nickName,proto3" json:"nick_name,omitempty"` } func (x *DouyinUser) Reset() { *x = DouyinUser{} if protoimpl.UnsafeEnabled { mi := &file_protoOneof_proto_msgTypes[1] ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x)) ms.StoreMessageInfo(mi) } } func (x *DouyinUser) String() string { return protoimpl.X.MessageStringOf(x) } func (*DouyinUser) ProtoMessage() {} func (x *DouyinUser) ProtoReflect() protoreflect.Message { mi := &file_protoOneof_proto_msgTypes[1] if protoimpl.UnsafeEnabled && x != nil { ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x)) if ms.LoadMessageInfo() == nil { ms.StoreMessageInfo(mi) } return ms } return mi.MessageOf(x) } // Deprecated: Use DouyinUser.ProtoReflect.Descriptor instead. func (*DouyinUser) Descriptor() ([]byte, []int) { return file_protoOneof_proto_rawDescGZIP(), []int{1} } func (x *DouyinUser) GetAuthToken() string { if x != nil { return x.AuthToken } return "" } func (x *DouyinUser) GetNickName() string { if x != nil { return x.NickName } return "" } type User struct { state protoimpl.MessageState sizeCache protoimpl.SizeCache unknownFields protoimpl.UnknownFields // Types that are assignable to UserSource: // *User_WeiboUrl // *User_DouyinUrl UserSource isUser_UserSource `protobuf_oneof:"user_source"` // Types that are assignable to UserInfo: // *User_WeiboUserInfo // *User_DouyinUserInfo UserInfo isUser_UserInfo `protobuf_oneof:"user_info"` } func (x *User) Reset() { *x = User{} if protoimpl.UnsafeEnabled { mi := &file_protoOneof_proto_msgTypes[2] ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x)) ms.StoreMessageInfo(mi) } } func (x *User) String() string { return protoimpl.X.MessageStringOf(x) } func (*User) ProtoMessage() {} func (x *User) ProtoReflect() protoreflect.Message { mi := &file_protoOneof_proto_msgTypes[2] if protoimpl.UnsafeEnabled && x != nil { ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x)) if ms.LoadMessageInfo() == nil { ms.StoreMessageInfo(mi) } return ms } return mi.MessageOf(x) } // Deprecated: Use User.ProtoReflect.Descriptor instead. func (*User) Descriptor() ([]byte, []int) { return file_protoOneof_proto_rawDescGZIP(), []int{2} } func (m *User) GetUserSource() isUser_UserSource { if m != nil { return m.UserSource } return nil } func (x *User) GetWeiboUrl() string { if x, ok := x.GetUserSource().(*User_WeiboUrl); ok { return x.WeiboUrl } return "" } func (x *User) GetDouyinUrl() string { if x, ok := x.GetUserSource().(*User_DouyinUrl); ok { return x.DouyinUrl } return "" } func (m *User) GetUserInfo() isUser_UserInfo { if m != nil { return m.UserInfo } return nil } func (x *User) GetWeiboUserInfo() *WeiboUser { if x, ok := x.GetUserInfo().(*User_WeiboUserInfo); ok { return x.WeiboUserInfo } return nil } func (x *User) GetDouyinUserInfo() *DouyinUser { if x, ok := x.GetUserInfo().(*User_DouyinUserInfo); ok { return x.DouyinUserInfo } return nil } type isUser_UserSource interface { isUser_UserSource() } type User_WeiboUrl struct { WeiboUrl string `protobuf:"bytes,1,opt,name=weibo_url,json=weiboUrl,proto3,oneof"` } type User_DouyinUrl struct { DouyinUrl string `protobuf:"bytes,2,opt,name=douyin_url,json=douyinUrl,proto3,oneof"` } func (*User_WeiboUrl) isUser_UserSource() {} func (*User_DouyinUrl) isUser_UserSource() {} type isUser_UserInfo interface { isUser_UserInfo() } type User_WeiboUserInfo struct { WeiboUserInfo *WeiboUser `protobuf:"bytes,3,opt,name=weibo_user_info,json=weiboUserInfo,proto3,oneof"` } type User_DouyinUserInfo struct { DouyinUserInfo *DouyinUser `protobuf:"bytes,4,opt,name=douyin_user_info,json=douyinUserInfo,proto3,oneof"` } func (*User_WeiboUserInfo) isUser_UserInfo() {} func (*User_DouyinUserInfo) isUser_UserInfo() {} var File_protoOneof_proto protoreflect.FileDescriptor var file_protoOneof_proto_rawDesc = []byte{ 0x0a, 0x10, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x4f, 0x6e, 0x65, 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oneof_test.WeiboUser (*DouyinUser)(nil), // 1: oneof_test.DouyinUser (*User)(nil), // 2: oneof_test.User } var file_protoOneof_proto_depIdxs = []int32{ 0, // 0: oneof_test.User.weibo_user_info:type_name -> oneof_test.WeiboUser 1, // 1: oneof_test.User.douyin_user_info:type_name -> oneof_test.DouyinUser 2, // [2:2] is the sub-list for method output_type 2, // [2:2] is the sub-list for method input_type 2, // [2:2] is the sub-list for extension type_name 2, // [2:2] is the sub-list for extension extendee 0, // [0:2] is the sub-list for field type_name } func init() { file_protoOneof_proto_init() } func file_protoOneof_proto_init() { if File_protoOneof_proto != nil { return } if !protoimpl.UnsafeEnabled { file_protoOneof_proto_msgTypes[0].Exporter = func(v interface{}, i int) interface{} { switch v := v.(*WeiboUser); i { case 0: return &v.state case 1: return &v.sizeCache case 2: return &v.unknownFields default: return nil } } file_protoOneof_proto_msgTypes[1].Exporter = func(v interface{}, i int) interface{} { switch v := v.(*DouyinUser); i { case 0: return &v.state case 1: return &v.sizeCache case 2: return &v.unknownFields default: return nil } } file_protoOneof_proto_msgTypes[2].Exporter = func(v interface{}, i int) interface{} { switch v := v.(*User); i { case 0: return &v.state case 1: return &v.sizeCache case 2: return &v.unknownFields default: return nil } } } file_protoOneof_proto_msgTypes[2].OneofWrappers = []interface{}{ (*User_WeiboUrl)(nil), (*User_DouyinUrl)(nil), (*User_WeiboUserInfo)(nil), (*User_DouyinUserInfo)(nil), } type x struct{} out := protoimpl.TypeBuilder{ File: protoimpl.DescBuilder{ GoPackagePath: reflect.TypeOf(x{}).PkgPath(), RawDescriptor: file_protoOneof_proto_rawDesc, NumEnums: 0, NumMessages: 3, NumExtensions: 0, NumServices: 0, }, GoTypes: file_protoOneof_proto_goTypes, DependencyIndexes: file_protoOneof_proto_depIdxs, MessageInfos: file_protoOneof_proto_msgTypes, }.Build() File_protoOneof_proto = out.File file_protoOneof_proto_rawDesc = nil file_protoOneof_proto_goTypes = nil file_protoOneof_proto_depIdxs = nil } 测试代码：
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