Web 开发

使用 Go 构建高性能 Web 服务

3 课时

HTTP 基础

Go 标准库 net/http 提供了强大的 HTTP 服务能力，无需第三方框架即可构建生产级别的 Web 服务。

简单 HTTP 服务器

1package main
2 
3import (
4    "fmt"
5    "net/http"
6)
7 
8func helloHandler(w http.ResponseWriter, r *http.Request) {
9    fmt.Fprintf(w, "Hello, %s!", r.URL.Path[1:])
10}
11 
12func main() {
13    http.HandleFunc("/", helloHandler)
14    
15    fmt.Println("Server starting on :8080")
16    http.ListenAndServe(":8080", nil)
17}

路由设计

Go 1.22+ 增强了标准库路由功能，支持路径参数和 HTTP 方法匹配。

RESTful 路由

1package main
2 
3import (
4    "encoding/json"
5    "net/http"
6)
7 
8type User struct {
9    ID   string `json:"id"`
10    Name string `json:"name"`
11}
12 
13func main() {
14    mux := http.NewServeMux()
15    
16    // GET /users/{id}
17    mux.HandleFunc("GET /users/{id}", func(w http.ResponseWriter, r *http.Request) {
18        id := r.PathValue("id")
19        user := User{ID: id, Name: "Alice"}
20        
21        w.Header().Set("Content-Type", "application/json")
22        json.NewEncoder(w).Encode(user)
23    })
24    
25    // POST /users
26    mux.HandleFunc("POST /users", func(w http.ResponseWriter, r *http.Request) {
27        var user User
28        json.NewDecoder(r.Body).Decode(&user)
29        
30        w.WriteHeader(http.StatusCreated)
31        json.NewEncoder(w).Encode(user)
32    })
33    
34    http.ListenAndServe(":8080", mux)
35}

中间件

中间件是处理 HTTP 请求的函数，可以在请求到达处理器之前或之后执行逻辑。

自定义中间件

1package main
2 
3import (
4    "log"
5    "net/http"
6    "time"
7)
8 
9// 日志中间件
10func loggingMiddleware(next http.Handler) http.Handler {
11    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
12        start := time.Now()
13        
14        next.ServeHTTP(w, r)
15        
16        log.Printf("%s %s %v", r.Method, r.URL.Path, time.Since(start))
17    })
18}
19 
20// 认证中间件
21func authMiddleware(next http.Handler) http.Handler {
22    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
23        token := r.Header.Get("Authorization")
24        if token == "" {
25            http.Error(w, "Unauthorized", http.StatusUnauthorized)
26            return
27        }
28        next.ServeHTTP(w, r)
29    })
30}
31 
32func main() {
33    mux := http.NewServeMux()
34    mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
35        w.Write([]byte("Hello"))
36    })
37    
38    // 链式中间件
39    handler := loggingMiddleware(authMiddleware(mux))
40    http.ListenAndServe(":8080", handler)
41}

1package main 2 3import ( 4 "fmt" 5 "net/http" 6) 7 8func helloHandler(w http.ResponseWriter, r *http.Request) { 9 fmt.Fprintf(w, "Hello, %s!", r.URL.Path[1:]) 10} 11 12func main() { 13 http.HandleFunc("/", helloHandler) 14 15 fmt.Println("Server starting on :8080") 16 http.ListenAndServe(":8080", nil) 17}

1package main 2 3import ( 4 "encoding/json" 5 "net/http" 6) 7 8type User struct { 9 ID string `json:"id"` 10 Name string `json:"name"` 11} 12 13func main() { 14 mux := http.NewServeMux() 15 16 // GET /users/{id} 17 mux.HandleFunc("GET /users/{id}", func(w http.ResponseWriter, r *http.Request) { 18 id := r.PathValue("id") 19 user := User{ID: id, Name: "Alice"} 20 21 w.Header().Set("Content-Type", "application/json") 22 json.NewEncoder(w).Encode(user) 23 }) 24 25 // POST /users 26 mux.HandleFunc("POST /users", func(w http.ResponseWriter, r *http.Request) { 27 var user User 28 json.NewDecoder(r.Body).Decode(&user) 29 30 w.WriteHeader(http.StatusCreated) 31 json.NewEncoder(w).Encode(user) 32 }) 33 34 http.ListenAndServe(":8080", mux) 35}

1package main 2 3import ( 4 "log" 5 "net/http" 6 "time" 7) 8 9// 日志中间件 10func loggingMiddleware(next http.Handler) http.Handler { 11 return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { 12 start := time.Now() 13 14 next.ServeHTTP(w, r) 15 16 log.Printf("%s %s %v", r.Method, r.URL.Path, time.Since(start)) 17 }) 18} 19 20// 认证中间件 21func authMiddleware(next http.Handler) http.Handler { 22 return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { 23 token := r.Header.Get("Authorization") 24 if token == "" { 25 http.Error(w, "Unauthorized", http.StatusUnauthorized) 26 return 27 } 28 next.ServeHTTP(w, r) 29 }) 30} 31 32func main() { 33 mux := http.NewServeMux() 34 mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) { 35 w.Write([]byte("Hello")) 36 }) 37 38 // 链式中间件 39 handler := loggingMiddleware(authMiddleware(mux)) 40 http.ListenAndServe(":8080", handler) 41}