一個golang http包內建的絕佳樣本

這是一個建立於 的文章，其中的資訊可能已經有所發展或是發生改變。

package mainimport ("bytes""expvar""flag""fmt""io""log""net/http""os""os/exec""strconv""sync")// hello world, the web servervar helloRequests = expvar.NewInt("hello-requests")func HelloServer(w http.ResponseWriter, req *http.Request) {helloRequests.Add(1)io.WriteString(w, "hello, world!\n")}// Simple counter server. POSTing to it will set the value.type Counter struct {mu sync.Mutex // protects nn  int}// This makes Counter satisfy the expvar.Var interface, so we can export// it directly.func (ctr *Counter) String() string {ctr.mu.Lock()defer ctr.mu.Unlock()return fmt.Sprintf("%d", ctr.n)}func (ctr *Counter) ServeHTTP(w http.ResponseWriter, req *http.Request) {ctr.mu.Lock()defer ctr.mu.Unlock()switch req.Method {case "GET":ctr.n++case "POST":buf := new(bytes.Buffer)io.Copy(buf, req.Body)body := buf.String()if n, err := strconv.Atoi(body); err != nil {fmt.Fprintf(w, "bad POST: %v\nbody: [%v]\n", err, body)} else {ctr.n = nfmt.Fprint(w, "counter reset\n")}}fmt.Fprintf(w, "counter = %d\n", ctr.n)}// simple flag servervar booleanflag = flag.Bool("boolean", true, "another flag for testing")func FlagServer(w http.ResponseWriter, req *http.Request) {w.Header().Set("Content-Type", "text/plain; charset=utf-8")fmt.Fprint(w, "Flags:\n")flag.VisitAll(func(f *flag.Flag) {if f.Value.String() != f.DefValue {fmt.Fprintf(w, "%s = %s [default = %s]\n", f.Name, f.Value.String(), f.DefValue)} else {fmt.Fprintf(w, "%s = %s\n", f.Name, f.Value.String())}})}// simple argument serverfunc ArgServer(w http.ResponseWriter, req *http.Request) {for _, s := range os.Args {fmt.Fprint(w, s, " ")}}// a channel (just for the fun of it)type Chan chan intfunc ChanCreate() Chan {c := make(Chan)go func(c Chan) {for x := 0; ; x++ {c <- x}}(c)return c}func (ch Chan) ServeHTTP(w http.ResponseWriter, req *http.Request) {io.WriteString(w, fmt.Sprintf("channel send #%d\n", <-ch))}// exec a program, redirecting outputfunc DateServer(rw http.ResponseWriter, req *http.Request) {rw.Header().Set("Content-Type", "text/plain; charset=utf-8")date, err := exec.Command("/bin/date").Output()if err != nil {http.Error(rw, err.Error(), 500)return}rw.Write(date)}func Logger(w http.ResponseWriter, req *http.Request) {log.Print(req.URL)http.Error(w, "oops", 404)}var webroot = flag.String("root", os.Getenv("HOME"), "web root directory")func main() {flag.Parse()// The counter is published as a variable directly.ctr := new(Counter)expvar.Publish("counter", ctr)http.Handle("/counter", ctr)http.Handle("/", http.HandlerFunc(Logger))http.Handle("/go/", http.StripPrefix("/go/", http.FileServer(http.Dir(*webroot))))http.Handle("/chan", ChanCreate())http.HandleFunc("/flags", FlagServer)http.HandleFunc("/args", ArgServer)http.HandleFunc("/go/hello", HelloServer)http.HandleFunc("/date", DateServer)err := http.ListenAndServe(":12345", nil)if err != nil {log.Panicln("ListenAndServe:", err)}}

curl http://localhost:12345/counter

curl http://localhost:12345/

curl http://localhost:12345/go

curl http://localhost:12345/chan

curl http://localhost:12345/flags

curl http://localhost:12345/args

curl http://localhost:12345/go/hello

curl http://localhost:12345/date

curl http://localhost:12345/xx