func handleGet(w http.ResponseWriter, r *http.Request) {
    // 确保是GET请求
    if r.Method != "GET" {
        http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
        return
    }

    // 获取查询参数
    name := r.URL.Query().Get("name")
    age := r.URL.Query().Get("age")

    if name == "" {
        name = "Guest"
    }

    fmt.Fprintf(w, "Hello %s, you are %s years old", name, age)
}

// 注册路由
http.HandleFunc("/get", handleGet)

func handlePostForm(w http.ResponseWriter, r *http.Request) {
    if r.Method != "POST" {
        http.Error(w, "Invalid method", http.StatusMethodNotAllowed)
        return
    }

    // 解析表单（支持application/x-www-form-urlencoded）
    err := r.ParseForm()
    if err != nil {
        http.Error(w, "Bad request", http.StatusBadRequest)
        return
    }

    username := r.FormValue("username")
    email := r.FormValue("email")

    fmt.Fprintf(w, "Received: %s (%s)", username, email)
}

type User struct {
    Name  string `json:"name"`
    Email string `json:"email"`
}

func handlePostJSON(w http.ResponseWriter, r *http.Request) {
    if r.Method != "POST" {
        http.Error(w, "Invalid method", http.StatusMethodNotAllowed)
        return
    }

    // 判断Content-Type是否为application/json
    if r.Header.Get("Content-Type") != "application/json" {
        http.Error(w, "Content-Type must be application/json", http.StatusUnsupportedMediaType)
        return
    }

    var user User
    decoder := json.NewDecoder(r.Body)
    if err := decoder.Decode(&user); err != nil {
        http.Error(w, "Invalid JSON", http.StatusBadRequest)
        return
    }
    defer r.Body.Close()

    fmt.Fprintf(w, "User: %+v", user)
}

func handler(w http.ResponseWriter, r *http.Request) {
    switch r.Method {
    case "GET":
        handleGet(w, r)
    case "POST":
        handlePostForm(w, r)
    default:
        http.Error(w, "Unsupported method", http.StatusMethodNotAllowed)
    }
}