GolangでシンプルなWebサーバーをどのように構築しますか？

是的，使用Go的net/http包可以轻松构建一个简单的Web服务器，只需几行代码即可实现路由处理、静态文件服务和结构化处理器，通过http.ListenAndServe启动服务器并监听指定端口，最终运行go run main.go并在浏览器访问http://localhost:8080即可看到效果，整个过程无需外部依赖且适合学习和小型工具开发。

Building a simple web server in Go is straightforward thanks to the built-in net/http package. You don’t need external dependencies for basic functionality. Here’s how to create a minimal but functional web server.

Set up a basic HTTP server

The core of a Go web server is the http.ListenAndServe function, which starts a server on a specified port and listens for incoming requests.

package main

import (
    "fmt"
    "net/http"
)

func main() {
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        fmt.Fprintf(w, "Hello, World! This is a simple Go web server.")
    })

    fmt.Println("Server is running on http://localhost:8080")
    http.ListenAndServe(":8080", nil)
}

This code:

• Registers a handler for the root path (/) using http.HandleFunc.
• Uses an anonymous function to write a response.
• Starts the server on port 8080.

Run it with go run main.go, then visit http://localhost:8080 in your browser.

Handle different routes

You can register multiple routes easily:

http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Welcome to the home page!")
})

http.HandleFunc("/about", func(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "This is the about page.")
})

http.HandleFunc("/user/", func(w http.ResponseWriter, r *http.Request) {
    path := r.URL.Path
    username := path[len("/user/"):] // Extract username from path
    fmt.Fprintf(w, "User profile: %s", username)
})

Note that Go’s default multiplexer matches prefixes for routes ending in /, so /user/alex will trigger the third handler.

Serve static files

To serve static assets like CSS, JavaScript, or images, use http.FileServer:

fs := http.FileServer(http.Dir("static/"))
http.Handle("/static/", http.StripPrefix("/static/", fs))

Place your files in a folder named static, and they’ll be accessible at /static/filename.ext.

Improve structure with a custom handler

Instead of defining everything in main, you can define named handler functions:

func homeHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Home page")
}

func jsonHandler(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    fmt.Fprintf(w, `{"message": "Hello from JSON"}`)
}

func main() {
    http.HandleFunc("/", homeHandler)
    http.HandleFunc("/json", jsonHandler)

    fmt.Println("Server starting on :8080")
    if err := http.ListenAndServe(":8080", nil); err != nil {
        fmt.Printf("Server failed: %v\n", err)
    }
}

This makes your code more modular and testable.

A few practical notes:

• Always handle errors from ListenAndServe—it won’t return unless there’s an error.
• The second argument in ListenAndServe is for a custom router. Passing nil uses the default http.DefaultServeMux.
• For production use, consider timeouts, graceful shutdowns, and middleware, but this basic version is perfect for learning or small tools.

Basically, that’s all it takes to get a working web server in Go. It’s simple, fast, and requires no extra tools.

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