jsonrpc 服务器接受请求的小写方法名称（用于大写注册服务）

Question

我正在尝试编写一个 jsonrpc 服务器，它将接受请求的小写方法名称，例如 Arith.multiply，并将它们正确地路由到相应的大写方法，例如 Arith.Multiply。这可能吗？PS 它是用于测试的生产服务器的轻量级克隆，API 是固定的，包括小写的方法名称，所以我无法将请求的方法名称更改为大写。package mainimport (    "log"    "net/http"    "github.com/gorilla/mux"    "github.com/gorilla/rpc"    "github.com/gorilla/rpc/json")type Args struct {    A, B int}type Arith inttype Result intfunc (t *Arith) Multiply(r *http.Request, args *Args, result *Result) error {    log.Printf("Multiplying %d with %d\n", args.A, args.B)    *result = Result(args.A * args.B)    return nil}func main() {    s := rpc.NewServer()    s.RegisterCodec(json.NewCodec(), "application/json")    s.RegisterCodec(json.NewCodec(), "application/json;charset=UTF-8")    arith := new(Arith)    s.RegisterService(arith, "")    r := mux.NewRouter()    r.Handle("/rpc", s)    http.ListenAndServe(":1234", r)}

Answer 1

看来您可以将某些东西偷偷放入自定义编解码器中，以将小写方法定向到正确的大写方法。编写 gorilla/rpc/json 实现的 CodecRequest，您可以继续使用所有 gorilla 机器来处理请求。

下面的工作示例。看起来很长，但都是评论。

package main

import (

    "fmt"

    "log"

    "net/http"

    "strings"

    "unicode"

    "unicode/utf8"

    "github.com/gorilla/mux"

    "github.com/gorilla/rpc"

    "github.com/gorilla/rpc/json"

)

type Args struct {

    A, B int

}

type Arith int

type Result int

func (t *Arith) Multiply(r *http.Request, args *Args, result *Result) error {

    log.Printf("Multiplying %d with %d\n", args.A, args.B)

    *result = Result(args.A * args.B)

    return nil

}

// UpCodec creates a CodecRequest to process each request.

type UpCodec struct {

}

// NewUpCodec returns a new UpCodec.

func NewUpCodec() *UpCodec {

    return &UpCodec{}

}

// NewRequest returns a new CodecRequest of type UpCodecRequest.

func (c *UpCodec) NewRequest(r *http.Request) rpc.CodecRequest {

    outerCR := &UpCodecRequest{}   // Our custom CR

    jsonC := json.NewCodec()       // json Codec to create json CR

    innerCR := jsonC.NewRequest(r) // create the json CR, sort of.

    // NOTE - innerCR is of the interface type rpc.CodecRequest.

    // Because innerCR is of the rpc.CR interface type, we need a

    // type assertion in order to assign it to our struct field's type.

    // We defined the source of the interface implementation here, so

    // we can be confident that innerCR will be of the correct underlying type

    outerCR.CodecRequest = innerCR.(*json.CodecRequest)

    return outerCR

}

// UpCodecRequest decodes and encodes a single request. UpCodecRequest

// implements gorilla/rpc.CodecRequest interface primarily by embedding

// the CodecRequest from gorilla/rpc/json. By selectively adding

// CodecRequest methods to UpCodecRequest, we can modify that behaviour

// while maintaining all the other remaining CodecRequest methods from

// gorilla's rpc/json implementation

type UpCodecRequest struct {

    *json.CodecRequest

}

// Method returns the decoded method as a string of the form "Service.Method"

// after checking for, and correcting a lowercase method name

// By being of lower depth in the struct , Method will replace the implementation

// of Method() on the embedded CodecRequest. Because the request data is part

// of the embedded json.CodecRequest, and unexported, we have to get the

// requested method name via the embedded CR's own method Method().

// Essentially, this just intercepts the return value from the embedded

// gorilla/rpc/json.CodecRequest.Method(), checks/modifies it, and passes it

// on to the calling rpc server.

func (c *UpCodecRequest) Method() (string, error) {

    m, err := c.CodecRequest.Method()

    if len(m) > 1 && err == nil {

        parts := strings.Split(m, ".")

        service, method := parts[0], parts[1]

        r, n := utf8.DecodeRuneInString(method) // get the first rune, and it's length

        if unicode.IsLower(r) {

            upMethod := service + "." + string(unicode.ToUpper(r)) + method[n:]

            log.Printf("lowercase method %s requested: treated as %s\n", m, upMethod)

            return upMethod, err

        }

    }

    return m, err

}

func main() {

    s := rpc.NewServer()

    // Register our own Codec

    s.RegisterCodec(NewUpCodec(), "application/json")

    s.RegisterCodec(NewUpCodec(), "application/json;charset=UTF-8")

    arith := new(Arith)

    s.RegisterService(arith, "")

    r := mux.NewRouter()

    r.Handle("/rpc", s)

    fmt.Println(http.ListenAndServe(":1234", r))

}

通过以下方式调用方法：

curl -X POST -H "Content-Type: application/json" -d '{"id": 1, "method": "Arith.multiply", "params": [{"A": 10, "B": 30}]}' 127.0.0.1:1234/rpc