go : gin 自定义中间件

背景：
本文实验gin框架下自定义中间件 以日志为例
代码：

 package main

import (
	"log"
	"time"

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

func Logger() gin.HandlerFunc {
	return func(c *gin.Context) {
		t := time.Now()

		// Set example variable
		c.Set("example", "12345")

		// before request

		c.Next()

		// after request
		latency := time.Since(t)
		log.Print(latency)

		// access the status we are sending
		status := c.Writer.Status()
		log.Println(status)
	}
}

func main() {
	r := gin.New()
	r.Use(Logger())

	r.GET("/test", func(c *gin.Context) {
		example := c.MustGet("example").(string)

		// it would print: "12345"
		log.Println(example)
	})

	// Listen and serve on 0.0.0.0:8080
	r.Run(":8080")
}

运行效果

2019/12/05 19:35:13 12345
2019/12/05 19:35:13 214.392µs
2019/12/05 19:35:13 200
2019/12/05 19:35:15 12345
2019/12/05 19:35:15 32.252µs
2019/12/05 19:35:15 200