在golang中通过多个HTTP处理程序包含上下文对象

传递上下文

首先,您可以更改签名以接受上下文

type appHandler func(http.ResponseWriter,*http.Request,context.Context) *appError

func (fn appHandler) ServeHTTP(w http.ResponseWriter,r *http.Request) {
        if e := fn(w,r,nil); e != nil { // e is *appError,not os.Error.
                http.Error(w,e.Code)
        }
}

现在我假设AuthHandler与身份验证有关,并在上下文对象中设置用户.

你可以做的是创建另一个设置上下文的类型处理程序.像这样

type authHandler func(http.ResponseWriter,context.Context) *appError

func (fn authHandler) ServeHTTP(w http.ResponseWriter,r *http.Request) {           
    // setup authentication here                                                    
    uid := 1                                                                        

    // setup the context the way you want                                           
    parent := context.TODO()                                                        
    ctx := context.WithValue(parent,userIdKey,uid)                                
    if e := fn(w,ctx); e != nil { // e is *appError,not os.Error.              
        http.Error(w,e.Code)                                            
    }                                                                               
}

这样您就可以通过以下方式使用它

func init() {                                                                         
    http.Handle("/view",appHandler(viewRecord))      // don't require authentication 
    http.Handle("/viewAuth",authHandler(viewRecord)) // require authentication       
}

这是完整的代码

package main

import (
        "fmt"
        "net/http"

        "code.google.com/p/go.net/context"
)

type appError struct {
        Error   error
        Message string
        Code    int
}

type key int

const userIdKey key = 0

type appHandler func(http.ResponseWriter,e.Code)
        }
}

type authHandler func(http.ResponseWriter,r *http.Request) {
        // setup authentication here
        uid := 1

        // setup the context the way you want
        parent := context.TODO()
        ctx := context.WithValue(parent,uid)
        if e := fn(w,e.Code)
        }
}

func viewRecord(w http.ResponseWriter,r *http.Request,c context.Context) *appError {

        if c == nil {
                fmt.Fprintf(w,"User are not logged in")
        } else {
                uid := c.Value(userIdKey)
                fmt.Fprintf(w,"User logged in with uid: %d",uid)
        }

        return nil
}

func init() {
        http.Handle("/view",appHandler(viewRecord))      // viewRecord is an appHandler function
        http.Handle("/viewAuth",authHandler(viewRecord)) // viewRecord is an authHandler function
}

func main() {
        http.ListenAndServe(":8080",nil)
}

创建地图上下文

您可以创建,而不是传递上下文

var contexts map[*http.Request]context.Context

并使用上下文[r]获取上下文.

但由于map不是线程安全的,因此必须使用互斥锁保护对映射的访问.

猜猜看,这是大猩猩的背景为你做的,我认为这是更好的方法

https://github.com/gorilla/context/blob/master/context.go#l20-28

这是完整的代码

package main

import (
        "fmt"
        "net/http"

        "github.com/gorilla/context"
)

type appError struct {
        Error   error
        Message string
        Code    int
}

type key int

const userIdKey key = 0

type appHandler func(http.ResponseWriter,*http.Request) *appError

func (fn authHandler) ServeHTTP(w http.ResponseWriter,r *http.Request) {
        // setup authentication here
        uid := 1

        context.Set(r,r *http.Request) *appError {

        if uid,ok := context.GetOk(r,userIdKey); !ok {
                fmt.Fprintf(w,"User are not logged in")
        } else {
                fmt.Fprintf(w,appHandler(viewRecord))      // don't require authentication
        http.Handle("/viewAuth",authHandler(viewRecord)) // require authentication
}

func main() {
        http.ListenAndServe(":8080",nil)
}

您也可以选择包装函数而不是auth的类型函数

func AuthHandler(h appHandler) appHandler {                                   
    return func(w http.ResponseWriter,r *http.Request) *appError {
        // setup authentication here                                          
        uid := 1                                                              

        context.Set(r,uid)                                        
        return h(w,r)                                                        
    }                                                                        
}  

func init() {                                                                                    
    http.Handle("/view",appHandler(viewRecord))                  // don't require authentication
    http.Handle("/viewAuth",appHandler(AuthHandler(viewRecord))) // require authentication      
}