Golang Gin框架 涉及到的context和middleware的使用示例

用到的库:
go get -u go.uber.org/zap
go get -u github.com/gin-gonic/gin

地址：
https://pkg.go.dev/go.uber.org/zap （zap：Package zap provides fast, structured, leveled logging.）
https://github.com/gin-gonic/gin

package main

import (
	"github.com/gin-gonic/gin"
	"go.uber.org/zap"
	"math/rand"
	"time"
)

const keyReqId = "requestId"

func main() {
	r := gin.Default()
	// _ 暂不处理err
	logger, _ := zap.NewProduction()
	// func (engine *Engine) Use(middleware ...HandlerFunc) IRoutes 
	// middleware的使用
	r.Use(func(c *gin.Context){
		s := time.Now()
		// 利用r.Use 写日志内容 包括: log latency, response code, path
		c.Next()
		logger.Info("incoming status", zap.String("path", c.Request.URL.Path),
			zap.Int("path", c.Writer.Status()),
			zap.Duration("elapsed:", time.Now().Sub(s)))
	},func(c *gin.Context){
		// context的使用：set一个reqId
		c.Set(keyReqId, rand.Int())
		c.Next()
	})
	// 插入一个requestId
	r.GET("/ping", func(c *gin.Context) {
		hs := gin.H{
			"message": "pong",
		}
		if rid, exist := c.Get(keyReqId); exist {
			hs[keyReqId] = rid
		}
		c.JSON(200, hs)
	})
	r.GET("/hello", func(c *gin.Context) {
		c.String(200, "hello")
	})
	r.Run() // listen and serve on 0.0.0.0:8080 (for windows "localhost:8080")
}