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11. Gin Middleware

2022-07-21 00:29:00 【Endless character】

Catalog

Preface
One 、 Use of middleware
Two 、 Custom middleware
3、 ... and 、 Terminate the subsequent logic execution of the middleware
Four 、gin return html
5、 ... and 、 Exit gracefully gin

Preface

Suppose a scenario , We need to count the call duration of each function ; If we record the time at the beginning of each function , Calculate the elapsed time at the end , This is very unusual , And the code is very intrusive
At this time, the middleware solution can be used to solve the above problems

One 、 Use of middleware

router := gin.Default()： By default gin Of Logger and Recovery Middleware

package main

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

func main() {
    
	router := gin.New()
	//  Use logger、recovery middleware , Global all 
	router.Use(gin.Logger(), gin.Recovery())

	//  middleware AuthRequired Only a call "/goods" At the beginning URL It works 
	authrized := router.Group("/goods")
	authrized.Use(AuthRequired)

	router.Run(":8088")
}

func AuthRequired(context *gin.Context) {
    

}

Two 、 Custom middleware

Demand fulfillment ： Use custom middleware , Count the time consumption of each request

package main

import (
	"fmt"
	"net/http"
	"time"

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

func MyLogger() gin.HandlerFunc {
    
	return func(c *gin.Context) {
    
		t := time.Now()
		c.Set("example", "123456")
		// Let the original logic continue 
		c.Next()

		end := time.Since(t)
		fmt.Printf(" Time consuming :%v\n", end)
		status := c.Writer.Status()
		fmt.Println(" state ", status)
	}
}

func main() {
    
	router := gin.Default()
	router.Use(MyLogger())
	router.GET("/ping", func(ctx *gin.Context) {
    
		ctx.JSON(http.StatusOK, gin.H{
    
			"message": "pong",
		})
	})

	router.Run(":8088")
}

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3、 ... and 、 Terminate the subsequent logic execution of the middleware

Use in middleware Abort To prevent the execution of subsequent logic ： Out of commission return To execute

package main

import (
	"fmt"
	"net/http"

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

func TokenRequired() gin.HandlerFunc {
    
	return func(c *gin.Context) {
    
		var token string
		for k, v := range c.Request.Header {
    
			if k == "x-Token" {
     //  Be sure to use capitalization here 
				token = v[0]
			}
			fmt.Println(k, v)
		}
		if token != "test" {
    
			c.JSON(http.StatusUnauthorized, gin.H{
    
				"msg": " Not logged in ",
			})
			// return
			c.Abort() //  If you want to skip the original execution logic , Out of commission return
		}
		c.Next()
	}
}

func main() {
    
	router := gin.Default()
	router.Use(TokenRequired())
	router.GET("/ping", func(ctx *gin.Context) {
    
		ctx.JSON(http.StatusOK, gin.H{
    
			"message": "pong",
		})
	})

	router.Run(":8088")
}

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Four 、gin return html

1 - Use gin return html

Official address ：https://golang.org/pkg/html/template

package main

import (
	"fmt"
	"net/http"
	"os"
	"path/filepath"

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

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

	dir, _ := filepath.Abs(filepath.Dir(os.Args[0]))
	fmt.Println("path -> ", dir)

	// LoadHTMLFiles The files in the specified directory will be loaded ,  Relative catalog 
	router.LoadHTMLFiles("templates/index.tmpl")

	router.GET("/index", func(ctx *gin.Context) {
    
		ctx.HTML(http.StatusOK, "index.tmpl", gin.H{
    
			"title": " Study ",
		})
	})

	router.Run(":8088")
}

index.tmpl

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <h1>
        {
   { .title }}
    </h1>
</body>
</html>

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2 - Load multiple html file

package main

import (
	"fmt"
	"net/http"
	"os"
	"path/filepath"

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

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

	dir, _ := filepath.Abs(filepath.Dir(os.Args[0]))
	fmt.Println("path -> ", dir)

	// LoadHTMLFiles The files in the specified directory will be loaded ,  Relative catalog 
	//router.LoadHTMLFiles("templates/index.tmpl", "templates/goods.html")
	//  If there are too many files , It also needs to be 1 Writing is too complicated , This directly loads all the files in the corresponding directory 
	router.LoadHTMLGlob("templates/*")
	router.GET("/index", func(ctx *gin.Context) {
    
		ctx.HTML(http.StatusOK, "index.tmpl", gin.H{
    
			"title": " Study ",
		})
	})

	router.GET("/goods", func(c *gin.Context) {
    
		c.HTML(http.StatusOK, "goods.html", gin.H{
    
			"name": " Microservice development ",
		})
	})

	router.Run(":8088")
}

goods.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>
    {
   { .name }}
</h1>
</body>
</html>

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3 - File conflict with the same name

Problem introduction ： If there are files with the same name under different folders , How to resolve conflicts
- stay html Join at the beginning ：{ {define “users/list.html”}}
- stay html Add... At the end ：{ {end}}

If not used in the template define Definition Then we can use the default file name to find

main.go

package main

import (
	"fmt"
	"net/http"
	"os"
	"path/filepath"

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

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

	dir, _ := filepath.Abs(filepath.Dir(os.Args[0]))
	fmt.Println("path -> ", dir)

	// LoadHTMLFiles The files in the specified directory will be loaded ,  Relative catalog 
	router.LoadHTMLGlob("templates/**/*")

	router.GET("/goods/list", func(c *gin.Context) {
    
		c.HTML(http.StatusOK, "goods/list.html", gin.H{
    
			"title": " goods ",
		})
	})

	router.GET("/users/list", func(c *gin.Context) {
    
		c.HTML(http.StatusOK, "users/list.html", gin.H{
    
			"title": " user ",
		})
	})

	router.Run(":8088")
}

template/goods/list.html

{
   {define "goods/list.html"}}
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>
     Product list page 
</h1>
</body>
</html>
{
   {end}}

template/users/list.html

{
   {define  "users/list.html"}}
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>
     User list page 
</h1>
</body>
</html>
{
   {end}}

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4 - static Static file processing

static Static file loading ：router.Static("/static", "./static")

5、 ... and 、 Exit gracefully gin

What is graceful exit ： What we should do when we close the program
analysis ： Microservices -> Do one thing before or after startup , Change the current service ip Register the address and port number in the registry -> After the current service is stopped , Did not inform the registry
gin Official documents exit gracefully ：https://gin-gonic.com/docs/examples/graceful-restart-or-stop/

package main

import (
	"fmt"
	"net/http"
	"os"
	"os/signal"
	"syscall"

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

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

	router.GET("/", func(ctx *gin.Context) {
    
		ctx.JSON(http.StatusOK, gin.H{
    
			"msg": "pong",
		})
	})

	go func() {
    
		router.Run(":8088")
	}()

	//  Do not use kill -9  command , The program cannot capture the signal 
	quit := make(chan os.Signal)
	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
	<-quit

	//  Processing subsequent logic 
	fmt.Println(" close server in ...")
	fmt.Println(" Log out of service ...")
}