Gin 框架中，解决 JSON 格局的参数绑定时，默认采纳的规范包 encoding/json，然而规范包不能满足咱们的一些要求，比方兼容字符串整型、PHP空数组、工夫格局等。

最简略的形式

开发 API 时，须要用到 ShouldBindJSON 绑定传入的参数到构造体：

// github.com/gin-gonic/gin@v1.6.3/context.go:643// ShouldBindJSON is a shortcut for c.ShouldBindWith(obj, binding.JSON).func (c *Context) ShouldBindJSON(obj interface{}) error {    return c.ShouldBindWith(obj, binding.JSON)}

Gin 默认采纳 encoding/json 包：

// github.com/gin-gonic/gin@v1.6.3/internal/json/json.go// +build !jsoniterpackage jsonimport "encoding/json"var (    // Marshal is exported by gin/json package.    Marshal = json.Marshal    // Unmarshal is exported by gin/json package.    Unmarshal = json.Unmarshal    // MarshalIndent is exported by gin/json package.    MarshalIndent = json.MarshalIndent    // NewDecoder is exported by gin/json package.    NewDecoder = json.NewDecoder    // NewEncoder is exported by gin/json package.    NewEncoder = json.NewEncoder)

同时咱们看到还反对了 jsoniter

// github.com/gin-gonic/gin@v1.6.3/internal/json/jsoniter.go// +build jsoniterpackage jsonimport "github.com/json-iterator/go"var (    json = jsoniter.ConfigCompatibleWithStandardLibrary    // Marshal is exported by gin/json package.    Marshal = json.Marshal    // Unmarshal is exported by gin/json package.    Unmarshal = json.Unmarshal    // MarshalIndent is exported by gin/json package.    MarshalIndent = json.MarshalIndent    // NewDecoder is exported by gin/json package.    NewDecoder = json.NewDecoder    // NewEncoder is exported by gin/json package.    NewEncoder = json.NewEncoder)

那咱们怎么能力应用到 jsoniter 呢？源码中曾经明确了编译tag：

// +build jsoniter

所以，咱们只需在编译时带上这个 tag 就能够了，例如：

go build -tags=jsoniter main.go// 或者go run -tags=jsoniter main.go

自定义的形式

Gin 框架反对的 jsoniter 是默认配置 jsoniter.ConfigCompatibleWithStandardLibrary。当咱们须要其余配置或增加一些自定义扩大（比方工夫解决）时，就好受了。于是咱们就要本人入手了~

打开源码，咱们能看到 binding.JSON 其实应用的是 jsonBinding{} 这个构造体：

// github.com/gin-gonic/gin@v1.6.3/binding/binding.go:73// These implement the Binding interface and can be used to bind the data// present in the request to struct instances.var (    JSON          = jsonBinding{}    // 其余省略了...)

打开 jsonBinding 源码看看：

// github.com/gin-gonic/gin@v1.6.3/binding/json.gotype jsonBinding struct{}func (jsonBinding) Name() string {    return "json"}func (jsonBinding) Bind(req *http.Request, obj interface{}) error {    if req == nil || req.Body == nil {        return fmt.Errorf("invalid request")    }    return decodeJSON(req.Body, obj)}func (jsonBinding) BindBody(body []byte, obj interface{}) error {    return decodeJSON(bytes.NewReader(body), obj)}

发现实现了 BindingBody 这个接口：

// github.com/gin-gonic/gin@v1.6.3/binding/binding.go:36// Binding describes the interface which needs to be implemented for binding the// data present in the request such as JSON request body, query parameters or// the form POST.type Binding interface {    Name() string    Bind(*http.Request, interface{}) error}// BindingBody adds BindBody method to Binding. BindBody is similar with Bind,// but it reads the body from supplied bytes instead of req.Body.type BindingBody interface {    Binding    BindBody([]byte, interface{}) error}

那接下来就简略了，咱们只有实现了这个接口即可，例如：

package customimport (    "bytes"    "fmt"    "io"    "net/http"    jsoniter "github.com/json-iterator/go"    "github.com/gin-gonic/gin/binding")// BindingJSON 替换Gin默认的binding，反对更丰盛JSON性能var BindingJSON = jsonBinding{}// 能够自定义jsoniter配置或者增加插件var json = jsoniter.ConfigCompatibleWithStandardLibrarytype jsonBinding struct{}func (jsonBinding) Name() string {    return "json"}func (jsonBinding) Bind(req *http.Request, obj interface{}) error {    if req == nil || req.Body == nil {        return fmt.Errorf("invalid request")    }    return decodeJSON(req.Body, obj)}func (jsonBinding) BindBody(body []byte, obj interface{}) error {    return decodeJSON(bytes.NewReader(body), obj)}func decodeJSON(r io.Reader, obj interface{}) error {    decoder := json.NewDecoder(r)    if binding.EnableDecoderUseNumber {        decoder.UseNumber()    }    if binding.EnableDecoderDisallowUnknownFields {        decoder.DisallowUnknownFields()    }    if err := decoder.Decode(obj); err != nil {        return err    }    return validate(obj)}func validate(obj interface{}) error {    if binding.Validator == nil {        return nil    }    return binding.Validator.ValidateStruct(obj)}

自定义 jsonBinding 曾经写好了，可应用有2种形式：

// binding.JSON 替换成自定义的ctx.ShouldBindWith(&params, binding.JSON)ctx.ShouldBindBodyWith(&params, binding.JSON)

上述自定义的形式，还能够用于其余包，不仅限于 iterator。从这个方面体现出了 Gin 框架良好的接口设计????

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原文地址: https://shockerli.net/post/gin-binding-jsoniter/