Golang Web开发之Gin Middleware

func main() {
  // 创建一个r，这一行相当于下面几行
  // 默认使用了Logger(), Recovery()
  r := gin.Default() 


  // 相当于上面的作用
  r := gin.New()
  r.Use(gin.Logger())
  r.Use(gin.Recovery())
}

package main
import (
    "fmt"
    "time"
    
    "github.com/gin-gonic/gin"
)


// 定义中间件
func SelfDefinedMiddleWare() gin.HandlerFunc {
    return func(c *gin.Context) {
        t1 := time.Now()
        fmt.Println("开始执行中间件")
        // 设置您的变量到Context的key中，后续可在控制器逻辑中通过Get()拿到
        c.Set("key1", "value1")
        status := c.Writer.Status()
        fmt.Println("结束执行中间件", status)
        t2 := time.Since(t1)
        fmt.Println("time:", t2)
    }
}


func main() {
    // 默认使用了2个中间件Logger(), Recovery()
    r := gin.Default()
    // 注册中间件
    r.Use(SelfDefinedMiddleWare())
    {
        r.GET("/test_global_middleWare", func(c *gin.Context) {
            value1, _ := c.Get("key1")
            fmt.Println("value1:", value1)
            c.JSON(200, gin.H{"value1": value1})
        })
    }
    r.Run()
}

很显然，一个自定义的全局 Middleware 就已经起作用了：

[GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.


[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
 - using env:   export GIN_MODE=release
 - using code:  gin.SetMode(gin.ReleaseMode)


[GIN-debug] GET    /test_global_middleWare   --> main.main.func1 (4 handlers)
[GIN-debug] Environment variable PORT is undefined. Using port :8080 by default
[GIN-debug] Listening and serving HTTP on :8080
开始执行中间件
结束执行中间件 200
time: 295µs
value1: value1
[GIN] 2021/10/14 - 10:28:50 | 200 |      1.3293ms |       127.0.0.1 | GET      "/test_global_middleWare"