Go HTTP服务器：POST表单数据解析与常见陷阱规避指南

[request setPostValue:@"userid" forKey:@"<a class="__cf_email__" data-cfemail="cbadafadb88ba1a0a1a7ade5a8a6" href="/cdn-cgi/l/email-protection">[email protected]</a>"];
[request setPostValue:@"pwd" forKey:@"fdsfdsfdkskfjhds"];

package main

import (
    "fmt"
    "log"
    "net/http"
    "strings"
)

// loginHandler 处理 /login 路径的请求
func loginHandler(rw http.ResponseWriter, req *http.Request) {
    // 1. 检查请求方法是否为 POST
    if req.Method != http.MethodPost {
        http.Error(rw, "Method Not Allowed", http.StatusMethodNotAllowed)
        return
    }

    // 2. 显式调用 req.ParseForm() 解析请求体
    // 这是获取 POST 表单数据的关键步骤。
    // 对于 application/x-www-form-urlencoded 或 multipart/form-data 类型的请求体，
    // ParseForm 会将其解析并填充到 req.Form 和 req.PostForm 中。
    err := req.ParseForm()
    if err != nil {
        http.Error(rw, fmt.Sprintf("Error parsing form: %v", err), http.StatusBadRequest)
        return
    }

    // 3. 使用 req.Form.Get() 或 req.PostForm.Get() 获取表单值
    // 确保客户端发送的键名与这里获取的键名完全匹配。
    userID := strings.TrimSpace(req.Form.Get("userid")) // 从 req.Form 中获取 userid
    password := req.Form.Get("pwd")                    // 从 req.Form 中获取 pwd

    fmt.Println("Received POST data:")
    fmt.Println("userid:", userID)
    fmt.Println("pwd:", password)

    // 简单的输入验证
    if userID == "" || password == "" {
        http.Error(rw, "User ID and Password cannot be empty", http.StatusBadRequest)
        return
    }

    // 示例：根据获取到的数据进行响应
    fmt.Fprintf(rw, "Welcome back, %s!", userID)
}

func main() {
    // 注册路由处理器
    http.HandleFunc("/login", loginHandler)

    fmt.Println("Server listening on :8080")
    // 启动 HTTP 服务器
    log.Fatal(http.ListenAndServe(":8080", nil))
}

package main

import (
    "fmt"
    "io/ioutil"
    "net/http"
    "net/url"
    "strings"
)

func main() {
    // 构造表单数据，键名必须与服务器端期望的键名一致
    data := url.Values{}
    data.Set("userid", "golanguser") // 键名为 "userid"
    data.Set("pwd", "securepassword") // 键名为 "pwd"

    // 发送 POST 请求，Content-Type 会自动设置为 application/x-www-form-urlencoded
    resp, err := http.PostForm("http://127.0.0.1:8080/login", data)
    if err != nil {
        fmt.Println("Error sending request:", err)
        return
    }
    defer resp.Body.Close()

    // 读取并打印服务器响应
    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        fmt.Println("Error reading response:", err)
        return
    }

    fmt.Println("Response Status:", resp.Status)
    fmt.Println("Response Body:", string(body))
}

curl -X POST -d "userid=testuser&pwd=mypassword" http://127.0.0.1:8080/login