In-depth analysis: the practical application effect of Golang interceptor

Golang interceptor (interceptor) is a powerful design pattern that can realize many functions in practical applications, such as logging, error handling, permission control, etc. This article will deeply analyze the actual application effect of Golang interceptor, and demonstrate its usage and effect through specific code examples.

1. What is Golang interceptor

Golang interceptor is an aspect-oriented programming (AOP) design pattern. By adding a layer of proxies before and after function calls, functions can be controlled. Interception and expansion. Interceptors can intervene in functions before, after, or when an error occurs to achieve more flexible control and operation.

2. Practical application effect

2.1 Logging

Interceptors are often used to record input and output parameters, execution time and other information of functions to facilitate tracking, debugging and performance optimization. Here is an example of a simple logging interceptor:

package interceptor

import (
    "log"
    "time"
)

func Logger(next http.HandlerFunc) http.HandlerFunc {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        start := time.Now()
        log.Printf("Start: %s %s", r.Method, r.URL.Path)

        next(w, r)

        elapsed := time.Since(start)
        log.Printf("End: %s %s took %s", r.Method, r.URL.Path, elapsed)
    })
}

2.2 Error handling

The interceptor can capture errors during function execution, perform unified processing and return, and improve the robustness of the code. Here is an example of a simple error handling interceptor:

package interceptor

import (
    "log"
    "net/http"
)

func ErrorHandler(next http.HandlerFunc) http.HandlerFunc {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        defer func() {
            if err := recover(); err != nil {
                log.Printf("Panic: %v", err)
                http.Error(w, "Internal Server Error", http.StatusInternalServerError)
            }
        }()

        next(w, r)
    })
}

2.3 Permission Control

Interceptors can also be used to implement permission control, determine the user's identity and permissions, and decide whether to allow access to a certain function. The following is an example of a simple permission control interceptor:

package interceptor

import (
    "net/http"
)

func AuthMiddleware(next http.HandlerFunc) http.HandlerFunc {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        if checkPermission(r) {
            next(w, r)
        } else {
            http.Error(w, "Permission Denied", http.StatusForbidden)
        }
    })
}

func checkPermission(r *http.Request) bool {
    // Determine user permissions based on request
    return true
}

3. Code example

The following uses a simple HTTP server example to demonstrate how to use interceptors to implement logging, error handling and permission control:

package main

import (
    "net/http"

    "github.com/gorilla/mux"
    "github.com/yourusername/interceptor" // Import the interceptor package

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

    r.HandleFunc("/hello", interceptor.Logger(interceptor.ErrorHandler(handleHello)))
    r.HandleFunc("/admin", interceptor.Logger(interceptor.ErrorHandler(interceptor.AuthMiddleware(handleAdmin))))

    http.Handle("/", r)
    http.ListenAndServe(":8080", nil)
}

func handleHello(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("Hello, World!"))
}

func handleAdmin(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("Admin Panel"))
}

In the above example, by using three interceptors: interceptor.Logger, interceptor.ErrorHandler and interceptor.AuthMiddleware, the interceptor is implemented Logging, error handling and permission control for the two routes /hello and /admin.

4. Summary

Golang interceptor is a powerful design pattern that can implement logging, error handling, permission control and other functions to improve code reusability and scalability. In actual development, rational use of interceptors can simplify code logic and improve code quality, which is worthy of in-depth study and practice by developers.

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