让我们开始吧。首先创建一个基本端点：
package main
import (
"fmt"
"log"
"net/http"
)
func Index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
fmt.Fprint(w, "Welcome!\n")
}
func main() {
router := httprouter.New()
router.GET("/", Index)
log.Fatal(http.ListenAndServe(":8080", router))
}
现在我们可以让 API 变得复杂一点。我们现在有一个名为 Book 的实体，可以把 ISDN 字段作为唯一标识。让我们创建更多的动作，即分表代表着 Index 和 Show 动作的 GET /books 和 GET /books/:isdn。 我们的 main.go 文件此时如下：
package main
import (
"encoding/json"
"fmt"
"log"
"net/http"
)
func Index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
fmt.Fprint(w, "Welcome!\n")
}
type Book struct {
// The main identifier for the Book. This will be unique.
ISDN string `json:"isdn"`
Title string `json:"title"`
Author string `json:"author"`
Pages int `json:"pages"`
}
type JsonResponse struct {
// Reserved field to add some meta information to the API response
Meta interface{} `json:"meta"`
Data interface{} `json:"data"`
}
type JsonErrorResponse struct {
Error *ApiError `json:"error"`
}
type ApiError struct {
Status int16 `json:"status"`
Title string `json:"title"`
}
// A map to store the books with the ISDN as the key
// This acts as the storage in lieu of an actual database
var bookstore = make(map[string]*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)
}
response := &JsonResponse{Data: &books}
w.Header().Set("Content-Type", "application/json; charset=UTF-8")
w.WriteHeader(http.StatusOK)
if err := json.NewEncoder(w).Encode(response); err != nil {
panic(err)
}
}
// 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]
w.Header().Set("Content-Type", "application/json; charset=UTF-8")
if !ok {
// No book with the isdn in the url has been found
w.WriteHeader(http.StatusNotFound)
response := JsonErrorResponse{Error: &ApiError{Status: 404, Title: "Record Not Found"}}
if err := json.NewEncoder(w).Encode(response); err != nil {
panic(err)
}
}
response := JsonResponse{Data: book}
if err := json.NewEncoder(w).Encode(response); err != nil {
panic(err)
}
}
func main() {
router := httprouter.New()
router.GET("/", Index)
router.GET("/books", BookIndex)
router.GET("/books/:isdn", BookShow)
// Create a couple of sample Book entries
bookstore["123"] = &Book{
ISDN: "123",
Title: "Silence of the Lambs",
Author: "Thomas Harris",
Pages: 367,
}
bookstore["124"] = &Book{
ISDN: "124",
Title: "To Kill a Mocking Bird",
Author: "Harper Lee",
Pages: 320,
}
log.Fatal(http.ListenAndServe(":8080", router))
}
{
"meta": null,
"data": [
{
"isdn": "123",
"title": "Silence of the Lambs",
"author": "Thomas Harris",
"pages": 367
},
{
"isdn": "124",
"title": "To Kill a Mocking Bird",
"author": "Harper Lee",
"pages": 320
}
]
}
让我们来重构一下代码。 到目前为止，我们所有的代码都放置在同一个文件中：main.go。我们可以把它们移到各个单独的文件中。此时我们有一个目录：
.
├── handlers.go
├── main.go
├── models.go
└── responses.go
package main
import (
"net/http"
"net/http/httptest"
"testing"
)
func TestBookIndex(t *testing.T) {
// Create an entry of the book to the bookstore map
testBook := &Book{
ISDN: "111",
Title: "test title",
Author: "test author",
Pages: 42,
}
bookstore["111"] = testBook
// A request with an existing isdn
req1, err := http.NewRequest("GET", "/books", nil)
if err != nil {
t.Fatal(err)
}
rr1 := newRequestRecorder(req1, "GET", "/books", BookIndex)
if rr1.Code != 200 {
t.Error("Expected response code to be 200")
}
// expected response
er1 := "{\"meta\":null,\"data\":[{\"isdn\":\"111\",\"title\":\"test title\",\"author\":\"test author\",\"pages\":42}]}\n"
if rr1.Body.String() != er1 {
t.Error("Response body does not match")
}
}
// Mocks a handler and returns a httptest.ResponseRecorder
func newRequestRecorder(req *http.Request, method string, strPath string, fnHandler func(w http.ResponseWriter, r *http.Request, param httprouter.Params)) *httptest.ResponseRecorder {
router := httprouter.New()
router.Handle(method, strPath, fnHandler)
// We create a ResponseRecorder (which satisfies http.ResponseWriter) to record the response.
rr := httptest.NewRecorder()
// Our handlers satisfy http.Handler, so we can call their ServeHTTP method
// directly and pass in our Request and ResponseRecorder.
router.ServeHTTP(rr, req)
return rr
}
package main
import (
"encoding/json"
"fmt"
"io"
"io/ioutil"
"net/http"
)
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"
)
// 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.Params) {
return func(w http.ResponseWriter, r *http.Request, param httprouter.Params) {
start := time.Now()
log.Printf("%s %s", r.Method, r.URL.Path)
fn(w, r, param)
log.Printf("Done in %v (%s %s)", time.Since(start), r.Method, r.URL.Path)
}
}
我们来看看路由。首先，在一个地方集中定义所有路由，比如 routes.go。
package main
import
/*
Define all the routes here.
A new Route entry passed to the routes slice will be automatically
translated to a handler with the NewRouter() function
*/
type Route struct {
Name string
Method string
Path string
HandlerFunc httprouter.Handle
}
type Routes []Route
func AllRoutes() Routes {
routes := Routes{
Route{"Index", "GET", "/", Index},
Route{"BookIndex", "GET", "/books", BookIndex},
Route{"Bookshow", "GET", "/books/:isdn", BookShow},
Route{"Bookshow", "POST", "/books", BookCreate},
}
return routes
}
package main
import
//Reads from the routes slice to translate the values to httprouter.Handle
func NewRouter(routes Routes) *httprouter.Router {
router := httprouter.New()
for _, route := range routes {
var handle httprouter.Handle
handle = route.HandlerFunc
handle = Logger(handle)
router.Handle(route.Method, route.Path, handle)
}
return router
}
您的目录此时应该像这样：
.
├── handlers.go
├── handlers_test.go
├── logger.go
├── main.go
├── models.go
├── responses.go
├── router.go
└── routes.go
这应该可以让你开始编写你自己的 API 服务器了。 你当然需要把你的功能放在不同的包中，所以一个好办法就是：
.
├── LICENSE
├── README.md
├── handlers
│ ├── books_test.go
│ └── books.go
├── models
│ ├── book.go
│ └── *
├── store
│ ├── *
└── lib
| ├── *
├── main.go
├── router.go
├── rotes.go
如果您有一个大的单体服务器，您还可以将 handlers、models 和所有路由功能都放在另一个名为 app 的包中。只要记住，go 不像 Java 或 Scala 那样可以有循环的包调用。因此你必须格外小心您的包结构。
这就是全部内容，希望本教程能对您有用。干杯！
注
- [1]
- [2]
- [3]
- [4]
- [Gorilla mux]
- [httprouter]
- [bone]