golang源码分析：connectrpc/connect-go

mkdir connect-go-example
cd connect-go-example
go mod init example

go install github.com/bufbuild/buf/cmd/buf@latest
go install github.com/fullstorydev/grpcurl/cmd/grpcurl@latest
go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
go install connectrpc.com/connect/cmd/protoc-gen-connect-go@latest

mkdir -p greet/v1
touch greet/v1/greet.proto

syntax = "proto3";

package greet.v1;

option go_package = "example/gen/greet/v1;greetv1";

message GreetRequest {
  string name = 1;
}

message GreetResponse {
  string greeting = 1;
}

service GreetService {
  rpc Greet(GreetRequest) returns (GreetResponse) {}
}

% buf config init

version: v2
plugins:
  - local: protoc-gen-go
    out: gen
    opt: paths=source_relative
  - local: protoc-gen-connect-go
    out: gen
    opt: paths=source_relative

buf lint
buf generate

|____greet
| |____v1
| | |____greet.proto
|____go.mod
|____buf.yaml
|____go.sum
|____gen
| |____greet
| | |____v1
| | | |____greetv1connect
| | | | |____greet.connect.go
| | | |____greet.pb.go
|____buf.gen.yaml

// Code generated by protoc-gen-connect-go. DO NOT EDIT.
//
// Source: greet/v1/greet.proto
package greetv1connect
import (
    context "context"
    errors "errors"
    v1 "example/gen/greet/v1"
    "fmt"
    http "net/http"
    strings "strings"
    connect "connectrpc.com/connect"
)
// This is a compile-time assertion to ensure that this generated file and the connect package are
// compatible. If you get a compiler error that this constant is not defined, this code was
// generated with a version of connect newer than the one compiled into your binary. You can fix the
// problem by either regenerating this code with an older version of connect or updating the connect
// version compiled into your binary.
const _ = connect.IsAtLeastVersion1_13_0
const (
    // GreetServiceName is the fully-qualified name of the GreetService service.
    GreetServiceName = "greet.v1.GreetService"
)
// These constants are the fully-qualified names of the RPCs defined in this package. They're
// exposed at runtime as Spec.Procedure and as the final two segments of the HTTP route.
//
// Note that these are different from the fully-qualified method names used by
// google.golang.org/protobuf/reflect/protoreflect. To convert from these constants to
// reflection-formatted method names, remove the leading slash and convert the remaining slash to a
// period.
const (
    // GreetServiceGreetProcedure is the fully-qualified name of the GreetService's Greet RPC.
    GreetServiceGreetProcedure = "/greet.v1.GreetService/Greet"
)
// GreetServiceClient is a client for the greet.v1.GreetService service.
type GreetServiceClient interface {
    Greet(context.Context, *connect.Request[v1.GreetRequest]) (*connect.Response[v1.GreetResponse], error)
}
// NewGreetServiceClient constructs a client for the greet.v1.GreetService service. By default, it
// uses the Connect protocol with the binary Protobuf Codec, asks for gzipped responses, and sends
// uncompressed requests. To use the gRPC or gRPC-Web protocols, supply the connect.WithGRPC() or
// connect.WithGRPCWeb() options.
//
// The URL supplied here should be the base URL for the Connect or gRPC server (for example,
// http://api.acme.com or https://acme.com/grpc).
func NewGreetServiceClient(httpClient connect.HTTPClient, baseURL string, opts ...connect.ClientOption) GreetServiceClient {
    baseURL = strings.TrimRight(baseURL, "/")
    greetServiceMethods := v1.File_greet_v1_greet_proto.Services().ByName("GreetService").Methods()
    return &greetServiceClient{
        greet: connect.NewClient[v1.GreetRequest, v1.GreetResponse](
            httpClient,
            baseURL+GreetServiceGreetProcedure,
            connect.WithSchema(greetServiceMethods.ByName("Greet")),
            connect.WithClientOptions(opts...),
        ),
    }
}
// greetServiceClient implements GreetServiceClient.
type greetServiceClient struct {
    greet *connect.Client[v1.GreetRequest, v1.GreetResponse]
}
// Greet calls greet.v1.GreetService.Greet.
func (c *greetServiceClient) Greet(ctx context.Context, req *connect.Request[v1.GreetRequest]) (*connect.Response[v1.GreetResponse], error) {
    return c.greet.CallUnary(ctx, req)
}
// GreetServiceHandler is an implementation of the greet.v1.GreetService service.
type GreetServiceHandler interface {
    Greet(context.Context, *connect.Request[v1.GreetRequest]) (*connect.Response[v1.GreetResponse], error)
}
// NewGreetServiceHandler builds an HTTP handler from the service implementation. It returns the
// path on which to mount the handler and the handler itself.
//
// By default, handlers support the Connect, gRPC, and gRPC-Web protocols with the binary Protobuf
// and JSON codecs. They also support gzip compression.
func NewGreetServiceHandler(svc GreetServiceHandler, opts ...connect.HandlerOption) (string, http.Handler) {
    greetServiceMethods := v1.File_greet_v1_greet_proto.Services().ByName("GreetService").Methods()
    greetServiceGreetHandler := connect.NewUnaryHandler(
        GreetServiceGreetProcedure,
        svc.Greet,
        connect.WithSchema(greetServiceMethods.ByName("Greet")),
        connect.WithHandlerOptions(opts...),
    )
    return "/greet.v1.GreetService/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        fmt.Println(r.URL.Path)
        switch r.URL.Path {
        case GreetServiceGreetProcedure:
            greetServiceGreetHandler.ServeHTTP(w, r)
        default:
            http.NotFound(w, r)
        }
    })
}
// UnimplementedGreetServiceHandler returns CodeUnimplemented from all methods.
type UnimplementedGreetServiceHandler struct{}
func (UnimplementedGreetServiceHandler) Greet(context.Context, *connect.Request[v1.GreetRequest]) (*connect.Response[v1.GreetResponse], error) {
    return nil, connect.NewError(connect.CodeUnimplemented, errors.New("greet.v1.GreetService.Greet is not implemented"))
}

package main
import (
    "context"
    "fmt"
    "log"
    "net/http"
    "connectrpc.com/connect"
    "golang.org/x/net/http2"
    "golang.org/x/net/http2/h2c"
    greetv1 "example/gen/greet/v1"        // generated by protoc-gen-go
    "example/gen/greet/v1/greetv1connect" // generated by protoc-gen-connect-go
)
type GreetServer struct{}
func (s *GreetServer) Greet(
    ctx context.Context,
    req *connect.Request[greetv1.GreetRequest],
) (*connect.Response[greetv1.GreetResponse], error) {
    log.Println("Request headers: ", req.Header())
    res := connect.NewResponse(&greetv1.GreetResponse{
        Greeting: fmt.Sprintf("Hello, %s!", req.Msg.Name),
    })
    res.Header().Set("Greet-Version", "v1")
    return res, nil
}
func main() {
    greeter := &GreetServer{}
    mux := http.NewServeMux()
    path, handler := greetv1connect.NewGreetServiceHandler(greeter)
    mux.Handle(path, handler)
    if err := http.ListenAndServe(
        "localhost:8083",
        // Use h2c so we can serve HTTP/2 without TLS.
        h2c.NewHandler(mux, &http2.Server{}),
    ); err != nil {
        fmt.Println(err)
    }
}

curl \
    --header "Content-Type: application/json" \
    -H "Accept: application/json" \
    --data '{"name": "Jane"}' \
    http://localhost:8083/greet.v1.GreetService/Greet
{"greeting":"Hello, Jane!"}

grpcurl \
    -protoset <(buf build -o -) -plaintext \
    -d '{"name": "Jane"}' \
    localhost:8083 greet.v1.GreetService/Greet
{
  "greeting": "Hello, Jane!"
}

package main
import (
    "context"
    "log"
    "net/http"
    greetv1 "example/gen/greet/v1"
    "example/gen/greet/v1/greetv1connect"
    "connectrpc.com/connect"
)
func main() {
    client := greetv1connect.NewGreetServiceClient(
        http.DefaultClient,
        "http://localhost:8083",
    )
    res, err := client.Greet(
        context.Background(),
        connect.NewRequest(&greetv1.GreetRequest{Name: "Jane"}),
    )
    if err != nil {
        log.Println(err)
        return
    }
    log.Println(res.Msg.Greeting)
}

go run ./cmd/client/main.go
2025/05/29 14:47:18 Hello, Jane!

package main
import (
    "context"
    "log"
    "net/http"
    greetv1 "example/gen/greet/v1"
    "example/gen/greet/v1/greetv1connect"
    "connectrpc.com/connect"
)
func main() {
    client := greetv1connect.NewGreetServiceClient(
        http.DefaultClient,
        "http://localhost:8083",
        connect.WithGRPC(),
    )
    res, err := client.Greet(
        context.Background(),
        connect.NewRequest(&greetv1.GreetRequest{Name: "Jane"}),
    )
    if err != nil {
        log.Println(err)
        return
    }
    log.Println(res.Msg.Greeting)
}

% go run ./cmd/client/grpc/main.go
2025/05/29 14:47:29 Hello, Jane!