Golang gRPC 使用

一、概念

1、gRPC默认使用protocol buffers，这是google开源的一套成熟的结构数据序列化机制（当然也可以使用其他数据格式如JSON），可以用proto files创建gRPC服务，用protocol buffers消息类型来定义方法参数和返回类型。

二、安装

1、yum install autoconf automake libtool  （centos 系统）

2、protocal buffer安装

从 https://github.com/google/protobuf/releases下载安装包，解压，然后操作以下命令：

./autogen.sh
./configure
make
make install

最后设置环境变量即可：export LD_LIBRARY_PATH=/usr/local/lib

3、安装 golang protobuf

go get -u github.com/golang/protobuf/proto // golang protobuf 库
go get -u github.com/golang/protobuf/protoc-gen-go //protoc --go_out 工具

4、安装 gRPC-go

go get google.golang.org/grpc

无法下载的话去 https://github.com/grpc/grpc-go 下载

三、使用

1、编写 proto 文件，helloworld.proto

syntax = "proto3";

option objc_class_prefix = "HLW";

package helloworld;

// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}

• syntax="proto3":指定protobuf的版本
• package helloworld:声明一个报名，一般与文件目录名相同
• import "xxx/xx.proto":导入其他的包，这样你就可以使用其他的包的数据结构
• required、optional、repeated:表示该字段是否必须填充；required表示必须指定且只能指定一个；当optional表示可选，可指定也可不指定，但不可超过一个不指定值的时候会采用空值，如string类型的字段会用字符串表示；repeated表示可以重复，类似与编程语言中的list
• message Author：在一个message体内定义一个message结构体
• enum：是枚举类型结构体
• 数字：字段的标识符，不可重复
• 数据类型： int32、int64、uint32、uint64、sint32、sint64、double、float、 string、bool、bytes、enum、message等等

2、使用protoc命令生成相关文件：

protoc --go_out=plugins=grpc:. helloworld.proto
ls
helloworld.pb.go    helloworld.proto

这里用了plugins选项，提供对grpc的支持，否则不会生成Service的接口，方便编写服务器和客户端程序

helloworld.pb.go 文件如下：

 // Code generated by protoc-gen-go. DO NOT EDIT.
 // source: helloworld.proto

 package helloworld

 import (
     context "context"
     fmt "fmt"
     proto "github.com/golang/protobuf/proto"
     grpc "google.golang.org/grpc"
     math "math"
 )

 // Reference imports to suppress errors if they are not otherwise used.
 var _ = proto.Marshal
 var _ = fmt.Errorf
 var _ = math.Inf

 // This is a compile-time assertion to ensure that this generated file
 // is compatible with the proto package it is being compiled against.
 // A compilation error at this line likely means your copy of the
 // proto package needs to be updated.
 const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package

 // The request message containing the user's name.
 type HelloRequest struct {
     Name                 string   `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
     XXX_NoUnkeyedLiteral struct{} `json:"-"`
     XXX_unrecognized     []byte   `json:"-"`
     XXX_sizecache        int32    `json:"-"`
 }

 func (m *HelloRequest) Reset()         { *m = HelloRequest{} }
 func (m *HelloRequest) String() string { return proto.CompactTextString(m) }
 func (*HelloRequest) ProtoMessage()    {}
 func (*HelloRequest) Descriptor() ([]byte, []int) {
     return fileDescriptor_17b8c58d586b62f2, []int{0}
 }

 func (m *HelloRequest) XXX_Unmarshal(b []byte) error {
     return xxx_messageInfo_HelloRequest.Unmarshal(m, b)
 }
 func (m *HelloRequest) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
     return xxx_messageInfo_HelloRequest.Marshal(b, m, deterministic)
 }
 func (m *HelloRequest) XXX_Merge(src proto.Message) {
     xxx_messageInfo_HelloRequest.Merge(m, src)
 }
 func (m *HelloRequest) XXX_Size() int {
     return xxx_messageInfo_HelloRequest.Size(m)
 }
 func (m *HelloRequest) XXX_DiscardUnknown() {
     xxx_messageInfo_HelloRequest.DiscardUnknown(m)
 }

 var xxx_messageInfo_HelloRequest proto.InternalMessageInfo

 func (m *HelloRequest) GetName() string {
     if m != nil {
         return m.Name
     }
     return ""
 }

 // The response message containing the greetings
 type HelloReply struct {
     Message              string   `protobuf:"bytes,1,opt,name=message,proto3" json:"message,omitempty"`
     XXX_NoUnkeyedLiteral struct{} `json:"-"`
     XXX_unrecognized     []byte   `json:"-"`
     XXX_sizecache        int32    `json:"-"`
 }

 func (m *HelloReply) Reset()         { *m = HelloReply{} }
 func (m *HelloReply) String() string { return proto.CompactTextString(m) }
 func (*HelloReply) ProtoMessage()    {}
 func (*HelloReply) Descriptor() ([]byte, []int) {
     return fileDescriptor_17b8c58d586b62f2, []int{1}
 }

 func (m *HelloReply) XXX_Unmarshal(b []byte) error {
     return xxx_messageInfo_HelloReply.Unmarshal(m, b)
 }
 func (m *HelloReply) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
     return xxx_messageInfo_HelloReply.Marshal(b, m, deterministic)
 }
 func (m *HelloReply) XXX_Merge(src proto.Message) {
     xxx_messageInfo_HelloReply.Merge(m, src)
 }
 func (m *HelloReply) XXX_Size() int {
     return xxx_messageInfo_HelloReply.Size(m)
 }
 func (m *HelloReply) XXX_DiscardUnknown() {
     xxx_messageInfo_HelloReply.DiscardUnknown(m)
 }

 var xxx_messageInfo_HelloReply proto.InternalMessageInfo

 func (m *HelloReply) GetMessage() string {
     if m != nil {
         return m.Message
     }
     return ""
 }

 func init() {
     proto.RegisterType((*HelloRequest)(nil), "helloworld.HelloRequest")
     proto.RegisterType((*HelloReply)(nil), "helloworld.HelloReply")
 }

 func init() { proto.RegisterFile("helloworld.proto", fileDescriptor_17b8c58d586b62f2) }

 var fileDescriptor_17b8c58d586b62f2 = []byte{
     // 149 bytes of a gzipped FileDescriptorProto
     0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0x12, 0xc8, 0x48, 0xcd, 0xc9,
     0xc9, 0x2f, 0xcf, 0x2f, 0xca, 0x49, 0xd1, 0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x17, 0xe2, 0x42, 0x88,
     0x28, 0x29, 0x71, 0xf1, 0x78, 0x80, 0x78, 0x41, 0xa9, 0x85, 0xa5, 0xa9, 0xc5, 0x25, 0x42, 0x42,
     0x5c, 0x2c, 0x79, 0x89, 0xb9, 0xa9, 0x12, 0x8c, 0x0a, 0x8c, 0x1a, 0x9c, 0x41, 0x60, 0xb6, 0x92,
     0x1a, 0x17, 0x17, 0x54, 0x4d, 0x41, 0x4e, 0xa5, 0x90, 0x04, 0x17, 0x7b, 0x6e, 0x6a, 0x71, 0x71,
     0x62, 0x3a, 0x4c, 0x11, 0x8c, 0x6b, 0xe4, 0xc9, 0xc5, 0xee, 0x5e, 0x94, 0x9a, 0x5a, 0x92, 0x5a,
     0x24, 0x64, 0xc7, 0xc5, 0x11, 0x9c, 0x58, 0x09, 0xd6, 0x25, 0x24, 0xa1, 0x87, 0xe4, 0x02, 0x64,
     0xcb, 0xa4, 0xc4, 0xb0, 0xc8, 0x14, 0xe4, 0x54, 0x2a, 0x31, 0x38, 0xb1, 0x2d, 0x62, 0x62, 0xf6,
     0xf0, 0x09, 0x4f, 0x62, 0x03, 0xbb, 0xd8, 0x18, 0x10, 0x00, 0x00, 0xff, 0xff, 0xbe, 0xde, 0x1d,
     0x2e, 0xc5, 0x00, 0x00, 0x00,
 }

 // Reference imports to suppress errors if they are not otherwise used.
 var _ context.Context
 var _ grpc.ClientConn

 // This is a compile-time assertion to ensure that this generated file
 // is compatible with the grpc package it is being compiled against.
 const _ = grpc.SupportPackageIsVersion4

 // GreeterClient is the client API for Greeter service.
 //
 // For semantics around ctx use and closing/ending streaming RPCs, please refer to https://godoc.org/google.golang.org/grpc#ClientConn.NewStream.
 type GreeterClient interface {
     // Sends a greeting
     SayHello(ctx context.Context, in *HelloRequest, opts ...grpc.CallOption) (*HelloReply, error)
 }

 type greeterClient struct {
     cc *grpc.ClientConn
 }

 func NewGreeterClient(cc *grpc.ClientConn) GreeterClient {
     return &greeterClient{cc}
 }

 func (c *greeterClient) SayHello(ctx context.Context, in *HelloRequest, opts ...grpc.CallOption) (*HelloReply, error) {
     out := new(HelloReply)
     err := c.cc.Invoke(ctx, "/helloworld.Greeter/SayHello", in, out, opts...)
     if err != nil {
         return nil, err
     }
     return out, nil
 }

 // GreeterServer is the server API for Greeter service.
 type GreeterServer interface {
     // Sends a greeting
     SayHello(context.Context, *HelloRequest) (*HelloReply, error)
 }

 func RegisterGreeterServer(s *grpc.Server, srv GreeterServer) {
     s.RegisterService(&_Greeter_serviceDesc, srv)
 }

 func _Greeter_SayHello_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
     in := new(HelloRequest)
     if err := dec(in); err != nil {
         return nil, err
     }
     if interceptor == nil {
         return srv.(GreeterServer).SayHello(ctx, in)
     }
     info := &grpc.UnaryServerInfo{
         Server:     srv,
         FullMethod: "/helloworld.Greeter/SayHello",
     }
     handler := func(ctx context.Context, req interface{}) (interface{}, error) {
         return srv.(GreeterServer).SayHello(ctx, req.(*HelloRequest))
     }
     return interceptor(ctx, in, info, handler)
 }

 var _Greeter_serviceDesc = grpc.ServiceDesc{
     ServiceName: "helloworld.Greeter",
     HandlerType: (*GreeterServer)(nil),
     Methods: []grpc.MethodDesc{
         {
             MethodName: "SayHello",
             Handler:    _Greeter_SayHello_Handler,
         },
     },
     Streams:  []grpc.StreamDesc{},
     Metadata: "helloworld.proto",
 }

3、服务器程序

package main

import (
    "log"
    "net"

    pb "test_grpc/helloworld"
    "google.golang.org/grpc"
    "golang.org/x/net/context"
)

const (
    PORT = ":50001"
)

type server struct {}

func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
    log.Println("request: ", in.Name)
    return &pb.HelloReply{Message: "Hello " + in.Name}, nil
}

func main() {
    lis, err := net.Listen("tcp", PORT)

    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }

    s := grpc.NewServer()
    pb.RegisterGreeterServer(s, &server{})
    log.Println("rpc服务已经开启")
    s.Serve(lis)
}

4、客户端程序

package main

import (
    "log"
    "os"

    pb "test_grpc/helloworld"
    "golang.org/x/net/context"
    "google.golang.org/grpc"
)

const (
    address = "localhost:50001"
)

func main() {
    conn, err := grpc.Dial(address, grpc.WithInsecure())

    if err != nil {
        log.Fatalf("did not connect: %v", err)
    }

    defer conn.Close()

    c := pb.NewGreeterClient(conn)

    name := "lin"
    if len(os.Args) > 1 {
        name = os.Args[1]
    }

    r, err := c.SayHello(context.Background(), &pb.HelloRequest{Name: name})

    if err != nil {
        log.Fatalf("could not greet: %v", err)
    }

    log.Println(r.Message)
}