protobuf demo
这篇文章记录一下测试protobuf examples踩的坑。
Prerequisite
安装protoc
- 访问release page下载
protoc-$tag-$distro-$arch.tar.gz - 解压tar.gz
- 将
protoc二进制放到PATH下 - 将
include目录放到/usr/local/
安装Go protoc plugin
$ go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
设置PATH
$ export PATH=$PATH:$(go env GOPATH)/bin
"google.protobuf.Timestamp" is not defined
google/protobuf/timestamp.proto: File not found.
addressbook.proto:13:1: Import "google/protobuf/timestamp.proto" was not found or had errors.
addressbook.proto:49:3: "google.protobuf.Timestamp" is not defined.
- 确定/usr/local/include
[root@localhost examples]# tree /usr/local/include/
/usr/local/include/
└── google
└── protobuf
├── any.proto
├── api.proto
├── compiler
│ └── plugin.proto
├── descriptor.proto
├── duration.proto
├── empty.proto
├── field_mask.proto
├── source_context.proto
├── struct.proto
├── timestamp.proto # the timestamp type
├── type.proto
└── wrappers.proto
3 directories, 12 files
- protoc的参数中通过
-I指定
修改Makefile中的-I参数
go/tutorialpb/addressbook.pb.go: addressbook.proto
mkdir -p go/tutorialpb # make directory for go package
protoc -I /usr/local/include -I . --go_opt=paths=source_relative --go_out=go/tutorialpb addressbook.proto
运行目标:
make go/tutorialpb/addressbook.pb.go
查看输出:
[root@localhost examples]# tree go
go
├── cmd
│ ├── add_person
│ │ ├── add_person.go
│ │ └── add_person_test.go
│ └── list_people
│ ├── list_people.go
│ └── list_people_test.go
├── go.mod
├── go.sum
└── tutorialpb
└── addressbook.pb.go # protoc的输出
Getter
自动生成的代码里有一堆Getter
测试protobuf
- 编译go源码
make go
这会将go/cmd/add_person等编译为二进制，放到examples目录下
- 测试序列化和反序列化
- 序列化
[root@localhost examples]# ./add_person_go addressbook.data
Enter person ID number: 23
Enter name: fada
Enter email address (blank for none): cssacd
- 反序列化
[root@localhost examples]# ./list_people_go addressbook.data
Person ID: 2
Name: cicac
E-mail address: oneslide
Home phone #: 183234
Person ID: 23
Name: fada
E-mail address: cssacd
Home phone #: 113241
Home phone #: 23141234
Advanced API usage
- example 1
看看addressbook.pb.go生成的这个函数:
func (x *Person_PhoneNumber) ProtoReflect() protoreflect.Message {
mi := &file_addressbook_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)
}
这个提供类似golang reflect包的功能，能够实现set字段的功能。
不知道为什么没有提供set
修改如下文件：
- list_people.go
func listPeople(w io.Writer, book *pb.AddressBook) {
book.ProtoReflect().Range(func(descriptor protoreflect.FieldDescriptor, value protoreflect.Value) bool {
fmt.Println(descriptor.Name()) // => people
fmt.Println(descriptor.Kind()) // => message
value.List().Get(0).Message().Range(func(d protoreflect.FieldDescriptor, v protoreflect.Value) bool {
fmt.Println(d.Name()) // => name
fmt.Println(d.Kind()) // => string
fmt.Println(v.String()) // => cicac
value.List().Get(0).Message().Set(d,protoreflect.ValueOfString("hello world!!")) // => change "cicac" to "hello world"
return false
})
return false
})
for _, p := range book.People {
writePerson(w, p)
}
}
重新运行一波：
[root@localhost examples]# make go
cd go && go build -o ../list_people_go ./cmd/list_people
[root@localhost examples]# ./list_people_go addressbook.data
people
message
name
string
cicac
Person ID: 2
Name: hello world!! # 这里修改为"hello world!!"了
E-mail address: oneslide
Home phone #: 183234
