Golang 请求重定向实现

在 Go 语言中，HTTP 请求重定向可以通过多种方式实现。以下是几种常见的重定向方法：

1. 使用标准库 `net/http` 实现重定向

临时重定向 (302)

package main

import (
	"net/http"
)

func redirectHandler(w http.ResponseWriter, r *http.Request) {
	// 临时重定向(302)
	http.Redirect(w, r, "https://www.example.com", http.StatusFound)
}

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

永久重定向 (301)

func permanentRedirectHandler(w http.ResponseWriter, r *http.Request) {
	// 永久重定向(301)
	http.Redirect(w, r, "https://www.example.com", http.StatusMovedPermanently)
}

2. Gin 框架中的重定向

如果你使用 Gin Web 框架：

package main

import (
	"github.com/gin-gonic/gin"
)

func main() {
	r := gin.Default()

	r.GET("/old-path", func(c *gin.Context) {
		// 临时重定向(302)
		c.Redirect(http.StatusFound, "/new-path")
		
		// 或者永久重定向(301)
		// c.Redirect(http.StatusMovedPermanently, "/new-path")
	})

	r.GET("/new-path", func(c *gin.Context) {
		c.String(http.StatusOK, "Welcome to the new path!")
	})

	r.Run(":8080")
}

3. HTTP/HTTPS 强制跳转

func httpsRedirect(w http.ResponseWriter, r *http.Request) {
	target := "https://" + r.Host + r.URL.Path
	if len(r.URL.RawQuery) > 0 {
		target += "?" + r.URL.RawQuery
	}
	
	log.Printf("redirect to: %s", target)
	
    // Permanent Redirect (308 for POST/PUT/DELETE requests to preserve method)
    if r.Method == http.MethodPost || 
       r.Method == http.MethodPut || 
       r.Method == http.MethodDelete {
        w.Header().Set("Connection", "close")
        url := fmt.Sprintf("https://%s%s", r.Host, r.RequestURI)
        http.Redirect(w, r, url, http.StatusPermanentRedirect)
    } else {
        // For GET/HEAD requests use standard redirect (301 or 302)
        http.Redirect(w, r, target, http.StatusMovedPermanently)
    }
}

func main() {
	go func() {
	    // HTTP server that redirects to HTTPS
	    if err := http.ListenAndServe(":80", 
	        http.HandlerFunc(httpsRedirect)); err != nil {
	        log.Fatalf("ListenAndServe error: %v", err)
	    }
    }()
    
    // Your HTTPS server setup here...
}

4. URL路由参数保留的重定向

func redirectWithParams(c *gin.Context) {
	name := c.Param("name")
	id := c.Query("id")
	
	newPath := fmt.Sprintf("/new-location/%s?id=%s&from=redirect", name, id)
	c.Redirect(http.StatusFound, newPath)
}