通常一个简单http服务框架，就是注册一堆路由，然后根据路由调用不同的逻辑去处理。
但实际上可能有一些统一的处理对几乎所有的路由都涉及到，比如日志，比如权限等等。
那么这个时候搞一个中间做预处理，是一个不错的想法。
定义一个中间件单元：
我要评论 1 package main
2
3 import (
4 "net/http"
5 )
6
7 // adaptorhandle middleware func type
8 type adaptorhandle func(w http.responsewriter, r *http.request) (next bool, err error)
9
10 // middlewareadaptor router middlewares mapped by url
11 type middlewareadaptor struct {
12 urls map[string][]adaptorhandle
13 }
14
15 // makemiddlewareadaptor make a middleware adaptor
16 func makemiddlewareadaptor() *middlewareadaptor {
17 mwa := &middlewareadaptor{
18 urls: make(map[string][]adaptorhandle),
19 }
20
21 return mwa
22 }
23
24 // regist regist a adaptor
25 func (mw *middlewareadaptor) regist(url string, adaptor ...adaptorhandle) {
26 for _, adp := range adaptor {
27 mw.urls[url] = append(mw.urls[url], adp)
28 // mw.urls[url] = adp
29 }
30 }
31
32 // exec exec middleware adaptor funcs...
33 func (mw *middlewareadaptor) exec(url string, w http.responsewriter, r *http.request) (bool, error) {
34 if adps, ok := mw.urls[url]; ok {
35 for _, adp := range adps {
36 if next, err := adp(w, r); !next || (err != nil) {
37 return next, err
38 }
39 }
40 }
41 return true, nil
42 }
然后将路由处理函数用中间件入口包裹起来：
1 func middlewarehandler(next http.handler) http.handler {
2 return http.handlerfunc(func(w http.responsewriter, r *http.request) {
3 // before call handler
4 start := time.now()
5 do, _ := mwa.exec(r.url.path, w, r) // exec middleware
6 // call next handler
7 if do {
8 log.println("middleware done. next...")
9 next.servehttp(w, r)
10 } else {
11 log.println("middleware done.break...")
12 }
13 // after call handle
14 log.printf("comleted %s in %v", r.url.path, time.since(start))
15 })
16 }
17
18 mux.handle("/", middlewarehandler(&uplusrouterhandler{}))
19
20 type uplusrouterhandler struct {
21 }
22
23 func (rh *uplusrouterhandler) servehttp(w http.responsewriter, r *http.request) {
24 ...
25 }
最后注册你需要的中间件即可：
mwa = makemiddlewareadaptor() // init middleware
mwa.regist("/", testmwafunc, testmwafunc2) // regist middleware
...
func testmwafunc(w http.responsewriter, r *http.request) (bool, error) {
log.println("我是第一个中间件...")
log.printf("started %s %s", r.method, r.url.path)
return true, nil
}
func testmwafunc2(w http.responsewriter, r *http.request) (bool, error) {
log.println("我是第二个中间件...")
return false, nil // return false,break follow-up actions.
}
代码虽然简单，记录一个思路。
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