Demystifying the interceptor mechanism in Golang

Interceptor is a design pattern that allows custom behavior to be inserted before and after method execution. In Go, it can be implemented through net/http middleware. It has the advantages of scalability, reusability, testability, etc., and can be used in scenarios such as authentication, authorization, caching, logging, and custom error handling.

Demystifying the interceptor mechanism in Golang

Introduction

Interceptor is a design pattern. Allows custom behavior to be inserted before or after method execution. In Go, interceptors can be implemented by writing net/http middleware.

Specific implementation

The following is an example of writing an interceptor using net/http:

package main

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

func main() {
    // 创建一个新的中间件函数
    logMiddleware := func(next http.Handler) http.Handler {
        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
            log.Println("Request received:", r.URL.Path)
            // 调用下一个处理程序
            next.ServeHTTP(w, r)
        })
    }

    // 创建一个新的 HTTP 处理程序
    mux := http.NewServeMux()
    mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        fmt.Fprint(w, "Hello, World!")
    })

    // 将中间件应用到处理程序
    http.Handle("/", logMiddleware(mux))

    // 启动 HTTP 服务器
    log.Println("Listening on port 8080")
    http.ListenAndServe(":8080", nil)
}

Principle

This interceptor uses net/http.HandlerFunc to create a new HTTP handler. This handler is executed before and after the request reaches the original handler. In our example, logMiddleware logs the received request before the handler receives the request and calls the next handler.

Practical cases

Interceptors can be used in various scenarios, including:

• Authentication and authorization
• Cache
• Logging and Monitoring
• Custom Error Handling

Advantages

• Scalability: Interception The tool allows you to easily add new functionality to your application without modifying existing code.
• Reusability: Interceptors can be reused across multiple endpoints or handlers.
• Testability: Interceptors are modular components that are easy to test and maintain.

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