仍然在终端中输出一些日志消息，并且可以添加一个 BookCreate handler 来创建一个新的 Book。
首先，让我们解决 handlers.go。
package main
import (
"encoding/json"
"fmt"
"io"
"io/ioutil"
"net/http"
"github.com/julienschmidt/httprouter"
)
func Index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
fmt.Fprint(w, "Welcome!\n")
}
// Handler for the books Create action
// POST /books
func BookCreate(w http.ResponseWriter, r *http.Request, params httprouter.Params) {
book := &Book{}
if err := populateModelFromHandler(w, r, params, book); err != nil {
writeErrorResponse(w, http.StatusUnprocessableEntity, "Unprocessible Entity")
return
}
bookstore[book.ISDN] = book
writeOKResponse(w, book)
}
// Handler for the books index action
// GET /books
func BookIndex(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
books := []*Book{}
for _, book := range bookstore {
books = append(books, book)
}
writeOKResponse(w, books)
}
// Handler for the books Show action
// GET /books/:isdn
func BookShow(w http.ResponseWriter, r *http.Request, params httprouter.Params) {
isdn := params.ByName("isdn")
book, ok := bookstore[isdn]
if !ok {
// No book with the isdn in the url has been found
writeErrorResponse(w, http.StatusNotFound, "Record Not Found")
return
}
writeOKResponse(w, book)
}
// Writes the response as a standard JSON response with StatusOK
func writeOKResponse(w http.ResponseWriter, m interface{}) {
w.Header().Set("Content-Type", "application/json; charset=UTF-8")
w.WriteHeader(http.StatusOK)
if err := json.NewEncoder(w).Encode(&JsonResponse{Data: m}); err != nil {
writeErrorResponse(w, http.StatusInternalServerError, "Internal Server Error")
}
}
// Writes the error response as a Standard API JSON response with a response code
func writeErrorResponse(w http.ResponseWriter, errorCode int, errorMsg string) {
w.Header().Set("Content-Type", "application/json; charset=UTF-8")
w.WriteHeader(errorCode)
json.
NewEncoder(w).
Encode(&JsonErrorResponse{Error: &ApiError{Status: errorCode, Title: errorMsg}})
}
//Populates a model from the params in the Handler
func populateModelFromHandler(w http.ResponseWriter, r *http.Request, params httprouter.Params, model interface{}) error {
body, err := ioutil.ReadAll(io.LimitReader(r.Body, 1048576))
if err != nil {
return err
}
if err := r.Body.Close(); err != nil {
return err
}
if err := json.Unmarshal(body, model); err != nil {
return err
}
return nil
}
我创建了两个函数，writeOKResponse 用于将 StatusOK 写入响应，其返回一个 model 或一个 model slice，writeErrorResponse 将在发生预期或意外错误时将 JSON 错误作为响应。像任何一个优秀的 gopher 一样，我们不应该 panic。我还添加了一个名为 populateModelFromHandler 的函数，它将内容从 body 中解析成所需的任何 model（struct）。在这种情况下，我们在 BookCreate handler 中使用它来填充一个 Book。
现在，我们来看看日志。我们简单地创建一个 Logger 函数，它包装了 handler 函数，并在执行 handler 函数之前和之后打印日志消息。
package main
import (
"log"
"net/http"
"time"
"github.com/julienschmidt/httprouter"
)
// A Logger function which simply wraps the handler function around some log messages
func Logger(fn func(w http.ResponseWriter, r *http.Request, param httprouter.Params)) func(w http.ResponseWriter, r *http.Request, param httprouter.Par