good good study, day day up!

vendor/gopl.io/ch7/http4/main.go

@@ -0,0 +1,47 @@
+// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+
+// See page 195.
+
+// Http4 is an e-commerce server that registers the /list and /price
+// endpoint by calling http.HandleFunc.
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+)
+
+//!+main
+
+func main() {
+	db := database{"shoes": 50, "socks": 5}
+	http.HandleFunc("/list", db.list)
+	http.HandleFunc("/price", db.price)
+	log.Fatal(http.ListenAndServe("localhost:8000", nil))
+}
+
+//!-main
+
+type dollars float32
+
+func (d dollars) String() string { return fmt.Sprintf("$%.2f", d) }
+
+type database map[string]dollars
+
+func (db database) list(w http.ResponseWriter, req *http.Request) {
+	for item, price := range db {
+		fmt.Fprintf(w, "%s: %s\n", item, price)
+	}
+}
+
+func (db database) price(w http.ResponseWriter, req *http.Request) {
+	item := req.URL.Query().Get("item")
+	if price, ok := db[item]; ok {
+		fmt.Fprintf(w, "%s\n", price)
+	} else {
+		w.WriteHeader(http.StatusNotFound) // 404
+		fmt.Fprintf(w, "no such item: %q\n", item)
+	}
+}