golang implements http routing

In web development, routing is a very important concept. Routing determines how requests are processed and is an important part of the web framework. This article will introduce how to use Golang to implement HTTP routing.

Golang is a new programming language launched by Google. It is characterized by simplicity, efficiency, security, and support for concurrent programming. It is a programming language very suitable for Web development. Therefore, Golang is used as the programming language to implement HTTP routing in this article.

1. Introduction

HTTP routing is the process by which an application maps user requests to handlers. When a request arrives at the web server, it looks for a handler based on the request's URL and HTTP method (GET, POST, PUT, etc.) and passes the request to that handler. HTTP routing is at the heart of web applications and determines how users interact with the application.

In Golang, HTTP routing can be implemented in various ways. Among them, the more commonly used ones are the http package in the standard library and the third-party package mux.

2. http package in the standard library

In the Golang standard library, there is a package called http, which provides the implementation of HTTP client and HTTP server. In this package, a function http.HandleFunc is provided. By calling this function, a function can be registered in the routing table.

This function requires two parameters. The first is a string type routing address, and the second is a function. This function must comply with the http.HandlerFunc protocol.

The following is an example:

package main

import (
    "fmt"
    "net/http"
)

func main() {
    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)
}

func handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hello, Golang HTTP server!")
}

In the above code, a handler function is defined, which accepts an HTTP request and sends "Hello, Golang HTTP server!" back to the client. Then, use the http.HandleFunc() function to register the handler function on the URL "/" and use the http.ListenAndServe() function to start the HTTP server.

This line of code causes the server to listen locally on port 8080, and all requests entering this port will be handed over to the http package for processing.

If you run this program in the command line and open the web page http://localhost:8080/, you will see the message "Hello, Golang HTTP server!"

3. Third-party package mux

Although the http package implements basic routing functions, it is still not flexible enough to support multiple HTTP methods, multiple parameters and other advanced Routing function. Therefore, in actual development, third-party routing packages are usually used, of which mux is the more popular one.

mux is a powerful HTTP request router and scheduler, which can be used to handle Golang's HTTP requests. mux provides many advanced routing features, including regular expression matching, middleware, and more.

Here is an example:

package main

import (
    "fmt"
    "net/http"

    "github.com/gorilla/mux"
)

func main() {
    r := mux.NewRouter()

    r.HandleFunc("/", homeHandler).Methods(http.MethodGet)

    r.HandleFunc("/products", productsHandler).Methods(http.MethodGet)
    r.HandleFunc("/products/{key}", productHandler).Methods(http.MethodGet)

    http.ListenAndServe(":8080", r)
}

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

func productsHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Product Page")
}

func productHandler(w http.ResponseWriter, r *http.Request) {
    vars := mux.Vars(r)
    key := vars["key"]
    fmt.Fprintf(w, "Product ID: %s", key)
}

In the above example, we use the mux.NewRouter() function to create a new router.

Use the r.HandleFunc() function to add routing rules to the router.

Corresponds exactly to the GET request that the browser enters http://localhost:8080/ after the container is started, then the router will match the route "/" and call the homeHandler() function.

Exactly corresponds to the GET request that the browser enters http://localhost:8080/products after the container is started, then the router will match the route "/products" and call the productsHandler() function.

Correctly corresponds to the GET request of http://localhost:8080/products/123 entered by the browser after the container is started, then the router will match the route "/products/{key}" and call the productHandler() function , where "123" is the value of the variable "key".

4. Summary

This article introduces two ways to use Golang to implement HTTP routing: the standard library http package and the third-party routing package mux. Although the http package in the standard library is simple and easy to use, it is not flexible enough to support advanced routing functions. Therefore, in actual development, it is recommended to use the third-party routing package mux, which provides rich routing rules and advanced functions to meet the needs of various web applications.

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