Golang项目实践：简单API服务器实现

net/http

User

package main

import (
    "encoding/json"
    "fmt"
    "log"
    "net/http"
    "strconv" // 引入strconv用于字符串转整数
    "strings" // 引入strings用于路径处理
    "sync"    // 引入sync用于并发安全
)

// User 结构体定义了用户的基本信息
type User struct {
    ID    int    `json:"id"`
    Name  string `json:"name"`
    Email string `json:"email"`
}

// 模拟一个简单的内存数据库
var (
    users      = make(map[int]User)
    nextUserID = 1
    mu         sync.Mutex // 保护共享资源，确保并发安全
)

func init() {
    // 初始化一些示例数据
    mu.Lock()
    defer mu.Unlock()
    users[nextUserID] = User{ID: nextUserID, Name: "Alice", Email: "alice@example.com"}
    nextUserID++
    users[nextUserID] = User{ID: nextUserID, Name: "Bob", Email: "bob@example.com"}
    nextUserID++
}

// getUsersHandler 处理获取所有用户的请求
func getUsersHandler(w http.ResponseWriter, r *http.Request) {
    if r.Method != http.MethodGet {
        http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
        return
    }

    mu.Lock()
    defer mu.Unlock()

    // 将map转换为切片以便JSON编码
    userList := make([]User, 0, len(users))
    for _, user := range users {
        userList = append(userList, user)
    }

    w.Header().Set("Content-Type", "application/json")
    if err := json.NewEncoder(w).Encode(userList); err != nil {
        log.Printf("Error encoding users: %v", err)
        http.Error(w, "Internal server error", http.StatusInternalServerError)
    }
}

// createUserHandler 处理创建新用户的请求
func createUserHandler(w http.ResponseWriter, r *http.Request) {
    if r.Method != http.MethodPost {
        http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
        return
    }

    var newUser User
    if err := json.NewDecoder(r.Body).Decode(&newUser); err != nil {
        http.Error(w, "Invalid request body", http.StatusBadRequest)
        return
    }

    mu.Lock()
    defer mu.Unlock()

    newUser.ID = nextUserID
    users[newUser.ID] = newUser
    nextUserID++

    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(http.StatusCreated) // 返回201 Created
    if err := json.NewEncoder(w).Encode(newUser); err != nil {
        log.Printf("Error encoding new user: %v", err)
        http.Error(w, "Internal server error", http.StatusInternalServerError)
    }
}

// getUserByIDHandler 处理获取单个用户的请求
func getUserByIDHandler(w http.ResponseWriter, r *http.Request) {
    if r.Method != http.MethodGet {
        http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
        return
    }

    // 从URL路径中解析ID，例如 /users/1
    pathParts := strings.Split(r.URL.Path, "/")
    if len(pathParts) < 3 || pathParts[2] == "" { // 期望 /users/{id}
        http.Error(w, "Invalid user ID format", http.StatusBadRequest)
        return
    }
    idStr := pathParts[2]
    id, err := strconv.Atoi(idStr)
    if err != nil {
        http.Error(w, "Invalid user ID", http.StatusBadRequest)
        return
    }

    mu.Lock()
    defer mu.Unlock()

    user, ok := users[id]
    if !ok {
        http.Error(w, "User not found", http.StatusNotFound)
        return
    }

    w.Header().Set("Content-Type", "application/json")
    if err := json.NewEncoder(w).Encode(user); err != nil {
        log.Printf("Error encoding user: %v", err)
        http.Error(w, "Internal server error", http.StatusInternalServerError)
    }
}

func main() {
    // 注册处理 /users 路径的处理器
    http.HandleFunc("/users", func(w http.ResponseWriter, r *http.Request) {
        switch r.Method {
        case http.MethodGet:
            getUsersHandler(w, r)
        case http.MethodPost:
            createUserHandler(w, r)
        default:
            http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
        }
    })

    // 注册处理 /users/{id} 路径的处理器
    // 注意：http.HandleFunc 对带路径参数的路由支持有限，
    // 它会匹配所有以 "/users/" 开头的路径。在处理器内部需要手动解析ID。
    // 实际项目中，通常会使用如 Gorilla Mux 这样的第三方路由库来简化路径参数的提取。
    http.HandleFunc("/users/", getUserByIDHandler)

    fmt.Println("Server starting on port 8080...")
    log.Fatal(http.ListenAndServe(":8080", nil))
}

http.HandleFunc

getUsersHandler

http.ResponseWriter

*http.Request

json.NewEncoder

json.NewDecoder

sync.Mutex

users

gorilla/mux

GORM

try-catch

error

if err != nil { return err }

http.Error