• Gin 基础

    官网
    github
    middleware
    Gin是一个用Go (Golang)编写的HTTP web框架。它的特点是一个类似Martini-like API，由于使用了httprouter，它的性能提高了40倍。如果您需要性能和良好的生产力，您将爱上Gin。

    Martini 是 Go 生态中的一个 Web 框架：
    Martini-like API 是指 Gin 框架内部的 API 命名风格、传参形式跟 Martini 类似。比如定义一个路由分组：

    // Martini
m.Group("/users", func(r martini.Router) {
    r.Post("/", CreateUserEndpoint)
    r.Get("/:id", GetUserEndpoint)
    r.Put("/:id", UpdateUserEndpoint)
    r.Delete("/:id", DeleteUserEndpoint)
})

// Gin
r := engine.Group("/users") {
    r.POST("/", CreateUserEndpoint)
    r.GET("/:id", GetUserEndpoint)
    r.PUT("/:id", UpdateUserEndpoint)
    r.DELETE("/:id", DeleteUserEndpoint)
}

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    因为 Martini 诞生的比较早（2013 年），所以作为 2015 年才出现的“后辈” Gin 来说保持一个跟当时比较流行的框架一样的 API，比较容易吸引人们去学习和理解、也降低了开发者们现有项目的迁移成本。

    一、Gin v1. stable

    1.1 特点：

    1、零配置路由器
    2、仍然是最快的http路由器和框架。从路由到写入。
    3、完整的单元测试套件。
    4、Battle tested
    5、API被冻结，新版本不会破坏你的代码。

    1.2 Build with jsoniter

    jsoniter

    一个对“encoding/json” 100%兼容的高性能插拔的替换

    Gin使用 encoding/json 作为默认的json包，但你可以通过从其他标签构建来更改为 jsoniter。

    go build -tags=jsoniter .

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    go-json

    go build -tags=go_json .

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    sonic

    you have to ensure that your cpu support avx instruction

    go build -tags="sonic avx" .

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    构建时不使用MsgPack渲染功能

    Gin默认启用MsgPack渲染功能。但是可以通过指定nomsgpack构建标记禁用此功能。

    go build -tags=nomsgpack .

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    这有助于减少可执行文件的二进制大小

    1.4 部署

    Gin项目可以轻松地部署在任何云提供商上。

    1.5 测试

    如何为Gin写测试用例?
    包net/http/httptest是HTTP测试的首选方法。

    // example.go
package main

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

func setupRouter() *gin.Engine {
	r := gin.Default()
	r.GET("/ping", func(c *gin.Context) {
		c.String(200, "pong")
	})
	return r
}

func main() {
	r := setupRouter()
	r.Run(":8080")
}

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    测试上面的代码示例:

    // example_test.go
package main

import (
	"net/http"
	"net/http/httptest"
	"testing"
	"github.com/stretchr/testify/assert"
)

func TestPingRoute(t *testing.T) {
	router := setupRouter()

	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/ping", nil)
	router.ServeHTTP(w, req)

	assert.Equal(t, 200, w.Code)
	assert.Equal(t, "pong", w.Body.String())
}

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    二、API

    gin 包

    1) SetMode()

    func SetMode(value string)
    SetMode根据输入字符串设置gin模式

    const (
	// DebugMode indicates gin mode is debug.
	DebugMode = "debug"
	// ReleaseMode indicates gin mode is release.
	ReleaseMode = "release"
	// TestMode indicates gin mode is test.
	TestMode = "test"
)

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    gin.SetMode(gin.ReleaseMode)

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    2) Engine

    type Engine struct {
}

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    gin.Default() 返回一个已经附加了 Logger 和 Recovery 中间件的引擎实例(Engine)。

    // ServeHTTP遵循 http.Handler 接口
func (engine *Engine) ServeHTTP(w http.ResponseWriter, req *http.Request)

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    3) Context

    type Context struct {
	writermem responseWriter
	Request   *http.Request
	Writer    ResponseWriter

	Params   Params
	handlers HandlersChain
	index    int8
	fullPath string

	engine       *Engine
	params       *Params
	skippedNodes *[]skippedNode

	// This mutex protects Keys map.
	mu sync.RWMutex

	// Keys is a key/value pair exclusively for the context of each request.
	Keys map[string]any

	// Errors is a list of errors attached to all the handlers/middlewares who used this context.
	Errors errorMsgs

	// Accepted defines a list of manually accepted formats for content negotiation.
	Accepted []string

	// queryCache caches the query result from c.Request.URL.Query().
	queryCache url.Values

	// formCache caches c.Request.PostForm, which contains the parsed form data from POST, PATCH,
	// or PUT body parameters.
	formCache url.Values

	// SameSite allows a server to define a cookie attribute making it impossible for
	// the browser to send this cookie along with cross-site requests.
	sameSite http.SameSite
}

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    1、String()

    String 将给定的字符串写入响应体
    func (c *Context) String(code int, format string, values ...any)

    2、AbortWithStatus()
    func (c *Context) AbortWithStatus(code int)

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    AbortWithStatus调用’ Abort() '并使用指定的状态代码写入 header。
    例如，验证请求的失败尝试可以用:context.AbortWithStatus(401)。

    3、 ShouldBindJSON()
    func (c *Context) ShouldBindJSON(obj any) error

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    ShouldBindJSON is a shortcut for c.ShouldBindWith(obj, binding.JSON).
    ShouldBindQuery 函数只绑定查询参数，而不绑定post数据

    ShouldBind

    func (c *Context) ShouldBind(obj any) error

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    ShouldBind函数即可绑定查询参数，也可绑定post数据

    4、JSON()
    func (c *Context) JSON(code int, obj any)

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    JSON将给定的结构作为JSON序列化到响应体中。它还将Content-Type设置为“application/json”。

    5、 ShouldBindWith()
    func (c *Context) ShouldBindWith(obj any, b binding.Binding) error

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    ShouldBindWith 使用指定的绑定引擎绑定传递的结构指针

    6、SaveUploadedFile()
    func (c *Context) SaveUploadedFile(file *multipart.FileHeader, dst string) error

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    SaveUploadedFile 将表单文件上传到特定的 dst。

    7、Static()
    func (group *RouterGroup) Static(relativePath, root string) IRoutes

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    Static为来自给定文件系统 root 的文件提供服务。
    内部使用是http.FileServer，因此使用http.NotFound被用来代替Router的NotFound处理程序。

    StaticFS

    func (group *RouterGroup) StaticFS(relativePath string, fs http.FileSystem) IRoutes

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    StaticFile

    func (group *RouterGroup) StaticFile(relativePath, filepath string) IRoutes

func (group *RouterGroup) StaticFileFS(relativePath, filepath string, fs http.FileSystem) IRoutes

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    8、Set()
    func (c *Context) Set(key string, value any)

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    Set用于专门为该上下文中存储一个新的键/值对。如果之前没有使用过 c.Keys，它也会惰性初始化它。

    Get

    func (c *Context) Get(key string) (value any, exists bool) 

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    Get返回给定键的值，即:(value, true)。
    如果值不存在，则返回(nil, false)

    MustGet

    func (c *Context) MustGet(key string) any

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    9、Copy()
    func (c *Context) Copy() *Context

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    Copy返回当前上下文的副本，可以安全地在请求的作用域之外使用。
    当必须将上下文传递给goroutine时，必须使用此方法。

    4) LoggerWithFormatter

    2.1 Using GET, POST, PUT, PATCH, DELETE and OPTIONS

    func main() {
  // Creates a gin router with default middleware:
  // logger and recovery (crash-free) middleware
  router := gin.Default()

  router.GET("/someGet", getting)
  router.POST("/somePost", posting)
  router.PUT("/somePut", putting)
  router.DELETE("/someDelete", deleting)
  router.PATCH("/somePatch", patching)
  router.HEAD("/someHead", head)
  router.OPTIONS("/someOptions", options)

  // By default it serves on :8080 unless a
  // PORT environment variable was defined.
  router.Run()
  // router.Run(":3000") for a hard coded port
}

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    RouterGroup

    func (group *RouterGroup) GET(relativePath string, handlers ...HandlerFunc) IRoutes

// HandlerFunc defines the handler used by gin middleware as return value.
type HandlerFunc func(*Context)

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    2.2 参数

    2.2.1 路径参数

    1、func (c *Context) Param(key string) string
    Param 返回URL参数的值。
    It is a shortcut for c.Params.ByName(key)

    2、func (c *Context) FullPath() string
    FullPath返回匹配的路由全路径。没有找到路由则返回一个空字符串。

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

  // This handler will match /user/john but will not match /user/ or /user
  router.GET("/user/:name", func(c *gin.Context) {
    name := c.Param("name")
    c.String(http.StatusOK, "Hello %s", name)
  })

  // However, this one will match /user/john/ and also /user/john/send
  // If no other routers match /user/john, it will redirect to /user/john/
  router.GET("/user/:name/*action", func(c *gin.Context) {
    name := c.Param("name")
    action := c.Param("action")
    message := name + " is " + action
    c.String(http.StatusOK, message)
  })

  // For each matched request Context will hold the route definition
  router.POST("/user/:name/*action", func(c *gin.Context) {
    b := c.FullPath() == "/user/:name/*action" // true
    c.String(http.StatusOK, "%t", b)
  })

  // This handler will add a new router for /user/groups.
  // Exact routes are resolved before param routes, regardless of the order they were defined.
  // Routes starting with /user/groups are never interpreted as /user/:name/... routes
  router.GET("/user/groups", func(c *gin.Context) {
    c.String(http.StatusOK, "The available groups are [...]")
  })

  router.Run(":8080")
}

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    2.2.2 Querystring parameters

    1、func (c *Context) Query(key string) (value string)
    Query 则返回url查询值，如果不存在返回空字符串("")。
    它是c.Request.URL.Query().Get(key)的快捷方式

    GET /path?id=1234&name=Manu&value=
    c.Query(“id”) == “1234”
    c.Query(“name”) == “Manu”
    c.Query(“value”) == “”
    c.Query(“wtf”) == “”

    2、func (c *Context) DefaultQuery(key, defaultValue string) string
    DefaultQuery将返回 url查询值，如果不存在，将返回指定的字符串

    3、func (c *Context) GetQuery(key string) (string, bool)
    GetQuery类似于Query()，它返回键控的url查询值
    如果它存在 (value, true) (即使值是空字符串)，
    否则返回(""，false) 。

    It is shortcut for `c.Request.URL.Query().Get(key)`
    GET /?name=Manu&lastname=
    ("Manu", true) == c.GetQuery("name")
    ("", false) == c.GetQuery("id")
    ("", true) == c.GetQuery("lastname")

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

  // Query string parameters are parsed using the existing underlying request object.
  // The request responds to a url matching:  /welcome?firstname=Jane&lastname=Doe
  router.GET("/welcome", func(c *gin.Context) {
    firstname := c.DefaultQuery("firstname", "Guest")
    lastname := c.Query("lastname") // shortcut for c.Request.URL.Query().Get("lastname")

    c.String(http.StatusOK, "Hello %s %s", firstname, lastname)
  })
  router.Run(":8080")
}

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    2.2.3 query + post form

    查询参数和POST格式可以同时存在

    POST /post?id=1234&page=1 HTTP/1.1
Content-Type: application/x-www-form-urlencoded

name=manu&message=this_is_great

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    2.2.4 Map为查询字符串或postform参数

    POST /post?ids[a]=1234&ids[b]=hello HTTP/1.1
Content-Type: application/x-www-form-urlencoded

names[first]=thinkerou&names[second]=tianou

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

  router.POST("/post", func(c *gin.Context) {

    ids := c.QueryMap("ids")
    names := c.PostFormMap("names")

    fmt.Printf("ids: %v; names: %v", ids, names)
  })
  router.Run(":8080")
}
// ids: map[b:hello a:1234]; names: map[second:tianou first:thinkerou]

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    2.3 Multipart/Urlencoded Form

    接收post表单提交的数据

    1、func (c *Context) PostForm(key string) (value string)
    PostForm从POST urlenencoded或multipart form 表单返回指定的键，如果它存在，则返回一个空字符串’ (“”)’
    只能获取 TEXT 类型

    2、func (c *Context) DefaultPostForm(key, defaultValue string) string

    3、func (c *Context) GetPostForm(key string) (string, bool)

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

  router.POST("/form_post", func(c *gin.Context) {
    message := c.PostForm("message")
    nick := c.DefaultPostForm("nick", "anonymous")

    c.JSON(http.StatusOK, gin.H{
      "status":  "posted",
      "message": message,
      "nick":    nick,
    })
  })
  router.Run(":8080")
}

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    表单数据处理

    1）（enctype）

    表单的默认编码方式 application/x-www-form-urlencoded

    上传文件的编码方式 multipart/form-data

    互联网应用常用编码 application/json

    传统企业级服务编码 application/xml

    2）urlencoded 格式
    Key1= value1&key2=value2&abc=123…

    只能将字符串发送服务端
    3) 上传文件

    4) JSON

    2.4 上传文件

    2.4.1 Single file

    file.Filename SHOULD NOT be trusted.

    1) FormFile

    func (c *Context) FormFile(name string) (*multipart.FileHeader, error)
    FormFile 返回提供的表单键的第一个文件。

    func main() {
  router := gin.Default()
  // Set a lower memory limit for multipart forms (default is 32 MiB)
  router.MaxMultipartMemory = 8 << 20  // 8 MiB
  router.POST("/upload", func(context *gin.Context) {
		file, _ := context.FormFile("file")
		log.Println(file.Filename)

		fileName := filepath.Base(file.Filename)
		if err := context.SaveUploadedFile(file, fileName); err != nil {
			context.String(http.StatusBadRequest, "upload file err: %s", err.Error())
			return
		}

		context.String(http.StatusOK, "File %s uploaded successfully.", file.Filename)
	})
	
  router.Run(":8080")
}

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    curl -X POST http://localhost:8080/upload \
  -F "file=@/Users/appleboy/test.zip" \
  -H "Content-Type: multipart/form-data"

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    2.4.2 Multiple files

    	r.POST("/multi-upload", func(context *gin.Context) {
		form, _ := context.MultipartForm()
		files := form.File["upload[]"]
		for _, file := range files {

			//file, _ := context.FormFile("file")
			log.Println(file.Filename)

			fileName := filepath.Base(file.Filename)
			if err := context.SaveUploadedFile(file, fileName); err != nil {
				context.String(http.StatusBadRequest, "upload file err: %s", err.Error())
				return
			}

		}

		context.String(http.StatusOK, "%d files uploaded!", len(files))
	})

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    curl -X POST http://localhost:8080/upload \
  -F "upload[]=@/Users/appleboy/test1.zip" \
  -F "upload[]=@/Users/appleboy/test2.zip" \
  -H "Content-Type: multipart/form-data"

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    2.5 分组路由

    2.5.1 Engine.Group()

    func (group *RouterGroup) Group(relativePath string, handlers ...HandlerFunc) *RouterGroup

    Group创建一个新的路由器组。您应该添加所有具有公共中间件或相同路径前缀的路由。
    例如，所有使用公共中间件进行授权的路由都可以分组。

      router := gin.Default()

  // Simple group: v1
  v1 := router.Group("/v1")
  {
    v1.POST("/login", loginEndpoint)
    v1.POST("/submit", submitEndpoint)
    v1.POST("/read", readEndpoint)
  }

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    2.6 默认没有中间件的空白Gin

    2.6.1 func New() *Engine

    New返回一个新的空白引擎实例，不附加任何中间件。

    By default, the configuration is:
 - RedirectTrailingSlash:  true
 - RedirectFixedPath:      false
 - HandleMethodNotAllowed: false
 - ForwardedByClientIP:    true
 - UseRawPath:             false
 - UnescapePathValues:     true

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    Use

    r := gin.New()

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    instead of

    // Default With the Logger and Recovery middleware already attached
r := gin.Default()

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    2.7 使用中间件

    2.7.1 Engine.Use()

    func (engine *Engine) Use(middleware ...HandlerFunc) IRoutes
    Use将全局中间件附加到路由器。例如，通过Use()附加的中间件将包含在每个请求的处理程序链中。甚至是404,405，静态文件…
    例如，这是logger 或 error管理中间件的合适位置。

    func main() {
  // Creates a router without any middleware by default
  r := gin.New()

  // Global middleware
  // Logger middleware will write the logs to gin.DefaultWriter even if you set with GIN_MODE=release.
  // By default gin.DefaultWriter = os.Stdout
  r.Use(gin.Logger())

  // Recovery middleware recovers from any panics and writes a 500 if there was one.
  r.Use(gin.Recovery())

  // Per route middleware, you can add as many as you desire.
  r.GET("/benchmark", MyBenchLogger(), benchEndpoint)

  // Authorization group
  // authorized := r.Group("/", AuthRequired())
  // exactly the same as:
  authorized := r.Group("/")
  // per group middleware! in this case we use the custom created
  // AuthRequired() middleware just in the "authorized" group.
  authorized.Use(AuthRequired())
  {
    authorized.POST("/login", loginEndpoint)
    authorized.POST("/submit", submitEndpoint)
    authorized.POST("/read", readEndpoint)

    // nested group
    testing := authorized.Group("testing")
    // visit 0.0.0.0:8080/testing/analytics
    testing.GET("/analytics", analyticsEndpoint)
  }

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

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    2.8 自定义恢复行为

      // Recovery middleware recovers from any panics and writes a 500 if there was one.
  r.Use(gin.CustomRecovery(func(c *gin.Context, recovered interface{}) {
    if err, ok := recovered.(string); ok {
      c.String(http.StatusInternalServerError, fmt.Sprintf("error: %s", err))
    }
    c.AbortWithStatus(http.StatusInternalServerError)
  }))

	engine.GET("/panic", func(c *gin.Context) {
		// panic with a string -- the custom middleware could save this to a database or report it to the user
		panic("foo")
	})

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    Gin源码分析 - 中间件（5）- Recovery
    Recovery中间件，能够捕获HTTP请求处理过程中产生的所有panic，并返回500错误。

    没有使用recovery中间件，没有返回任何数据，浏览器展示如下：
    在这里插入图片描述

    2.9 日志

    2.9.1 如何写日志文件

     To support coloring in Windows use:
 		import "github.com/mattn/go-colorable"
 		gin.DefaultWriter = colorable.NewColorableStdout()

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    func main() {
    // Disable Console Color, you don't need console color when writing the logs to file.
    gin.DisableConsoleColor()

    // Logging to a file.
    f, _ := os.Create("gin.log")
    gin.DefaultWriter = io.MultiWriter(f)

    // Use the following code if you need to write the logs to file and console at the same time.
    // gin.DefaultWriter = io.MultiWriter(f, os.Stdout)

    router := gin.Default()
    router.GET("/ping", func(c *gin.Context) {
        c.String(http.StatusOK, "pong")
    })

    router.Run(":8080")
}

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    2.9.2 自定义日志格式

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

  // LoggerWithFormatter middleware will write the logs to gin.DefaultWriter
  // By default gin.DefaultWriter = os.Stdout
  router.Use(gin.LoggerWithFormatter(func(param gin.LogFormatterParams) string {

    // your custom format
    return fmt.Sprintf("%s - [%s] \"%s %s %s %d %s \"%s\" %s\"\n",
        param.ClientIP,
        param.TimeStamp.Format(time.RFC1123),
        param.Method,
        param.Path,
        param.Request.Proto,
        param.StatusCode,
        param.Latency,
        param.Request.UserAgent(),
        param.ErrorMessage,
    )
  }))
  router.Use(gin.Recovery())

  router.GET("/ping", func(c *gin.Context) {
    c.String(http.StatusOK, "pong")
  })

  router.Run(":8080")
}

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    ::1 - [Fri, 07 Dec 2018 17:04:38 JST] "GET /ping HTTP/1.1 200 122.767µs "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.80 Safari/537.36" "

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    2.10 模型绑定和验证

    要将请求主体绑定到类型（type）中，请使用模型绑定。目前支持JSON、XML、YAML、TOML和标准表单值的绑定(foo=bar&boo=baz)。

    Gin使用go-playground/validator/v10进行验证。查看tag使用

    注意，需要在想要绑定的所有字段上设置相应的绑定标记。例如，当从JSON绑定时，设置JSON:"fieldname"。

    此外，Gin还提供了两组绑定方法:

    • Type - Must bind
      Methods - Bind, BindJSON, BindXML, BindQuery, BindYAML, BindHeader, BindTOML
      Behavior 这些方法在底层使用MustBindWith。如果存在绑定错误，则使用c.AbortWithError(400, err).SetType(ErrorTypeBind)终止请求。这将把响应状态码设置为400，并将Content-Type报头设置为text/plain; charset=utf-8。注意，如果您尝试在此之后设置响应代码，它将导致一个警告[GIN-debug] [WARNING] Headers were already written. Wanted to override status code 400 with 422。如果希望对行为有更大的控制，可以考虑使用ShouldBind等效方法。
    • Type - Should bind
      Methods ShouldBind, ShouldBindJSON, ShouldBindXML, ShouldBindQuery, ShouldBindYAML, ShouldBindHeader, ShouldBindTOML,
      Behavior 这些方法在底层使用ShouldBindWith。如果存在绑定错误，则返回错误，开发人员有责任适当地处理请求和错误。
    // Binding from JSON
type Login struct {
  User     string `form:"user" json:"user" xml:"user"  binding:"required"`
  Password string `form:"password" json:"password" xml:"password" binding:"required"`
}

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

  // Example for binding JSON ({"user": "manu", "password": "123"})
  router.POST("/loginJSON", func(c *gin.Context) {
    var json Login
    if err := c.ShouldBindJSON(&json); err != nil {
      c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
      return
    }

    if json.User != "manu" || json.Password != "123" {
      c.JSON(http.StatusUnauthorized, gin.H{"status": "unauthorized"})
      return
    }

    c.JSON(http.StatusOK, gin.H{"status": "you are logged in"})
  })

  // Example for binding XML (
  //  
  //  
  //    manu
  //    123
  //  )
  router.POST("/loginXML", func(c *gin.Context) {
    var xml Login
    if err := c.ShouldBindXML(&xml); err != nil {
      c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
      return
    }

    if xml.User != "manu" || xml.Password != "123" {
      c.JSON(http.StatusUnauthorized, gin.H{"status": "unauthorized"})
      return
    }

    c.JSON(http.StatusOK, gin.H{"status": "you are logged in"})
  })

  // Example for binding a HTML form (user=manu&password=123)
  router.POST("/loginForm", func(c *gin.Context) {
    var form Login
    // This will infer what binder to use depending on the content-type header.
    if err := c.ShouldBind(&form); err != nil {
      c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
      return
    }

    if form.User != "manu" || form.Password != "123" {
      c.JSON(http.StatusUnauthorized, gin.H{"status": "unauthorized"})
      return
    }

    c.JSON(http.StatusOK, gin.H{"status": "you are logged in"})
  })

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

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    $ curl -v -X POST \
  http://localhost:8080/loginJSON \
  -H 'content-type: application/json' \
  -d '{ "user": "manu" }
//返回
{"error":"Key: 'Login.Password' Error:Field validation for 'Password' failed on the 'required' tag"}

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    If use binding:"-" for Password, then it will not return error when running the above example again.

    2.10.1 自定义的校验器

    // Booking contains binded and validated data.
type Booking struct {
	CheckIn  time.Time `form:"check_in" binding:"required,bookabledate" time_format:"2006-01-02"`
	CheckOut time.Time `form:"check_out" binding:"required,gtfield=CheckIn" time_format:"2006-01-02"`
}

var bookableDate validator.Func = func(fl validator.FieldLevel) bool {
	date, ok := fl.Field().Interface().(time.Time)
	if ok {
		today := time.Now()
		if today.After(date) {
			return false
		}
	}
	return true
}

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

	if v, ok := binding.Validator.Engine().(*validator.Validate); ok {
		v.RegisterValidation("bookabledate", bookableDate)
	}

	route.GET("/bookable", getBookable)
	route.Run(":8085")
}

func getBookable(c *gin.Context) {
	var b Booking
	if err := c.ShouldBindWith(&b, binding.Query); err == nil {
		c.JSON(http.StatusOK, gin.H{"message": "Booking dates are valid!"})
	} else {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
	}
}

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    2.10.2 只绑定查询字符串

    ShouldBindQuery 函数只绑定查询参数，而不绑定post数据

    type Person struct {
  Name    string `form:"name"`
  Address string `form:"address"`
}

func main() {
  route := gin.Default()
  route.Any("/testing", startPage)
  route.Run(":8080")
}

func startPage(c *gin.Context) {
  var person Person
  if c.ShouldBindQuery(&person) == nil {
    log.Println("====== Only Bind By Query String ======")
    log.Println(person.Name)
    log.Println(person.Address)
  }
  c.String(http.StatusOK, "Success")
}

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    2.10.3 Bind Query String or Post Data

    ShouldBind函数即可绑定查询参数，也可绑定post数据

    type Person struct {
        Name       string    `form:"name"`
        Address    string    `form:"address"`
        Birthday   time.Time `form:"birthday" time_format:"2006-01-02" time_utc:"1"`
        CreateTime time.Time `form:"createTime" time_format:"unixNano"`
        UnixTime   time.Time `form:"unixTime" time_format:"unix"`
}

func main() {
  route := gin.Default()
  route.GET("/testing", startPage)
  route.Run(":8085")
}

func startPage(c *gin.Context) {
  var person Person
  // If `GET`, only `Form` binding engine (`query`) used.
  // If `POST`, first checks the `content-type` for `JSON` or `XML`, then uses `Form` (`form-data`).
  // See more at https://github.com/gin-gonic/gin/blob/master/binding/binding.go#L88
        if c.ShouldBind(&person) == nil {
                log.Println(person.Name)
                log.Println(person.Address)
                log.Println(person.Birthday)
                log.Println(person.CreateTime)
                log.Println(person.UnixTime)
        }

  c.String(http.StatusOK, "Success")
}

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    2.10.4 Bind Uri(绑定路径参数)

    type Person struct {
  ID string `uri:"id" binding:"required,uuid"`
  Name string `uri:"name" binding:"required"`
}

func main() {
  route := gin.Default()
  route.GET("/:name/:id", func(c *gin.Context) {
    var person Person
    if err := c.ShouldBindUri(&person); err != nil {
      c.JSON(http.StatusBadRequest, gin.H{"msg": err.Error()})
      return
    }
    c.JSON(http.StatusOK, gin.H{"name": person.Name, "uuid": person.ID})
  })
  route.Run(":8088")
}

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    2.10.5 Bind Header

    ShouldBindHeader

    type testHeader struct {
  Rate   int    `header:"Rate"`
  Domain string `header:"Domain"`
}

func main() {
  r := gin.Default()
  r.GET("/", func(c *gin.Context) {
    h := testHeader{}

    if err := c.ShouldBindHeader(&h); err != nil {
      c.JSON(http.StatusOK, err)
    }

    fmt.Printf("%#v\n", h)
    c.JSON(http.StatusOK, gin.H{"Rate": h.Rate, "Domain": h.Domain})
  })

  r.Run()

// client
// curl -H "rate:300" -H "domain:music" 127.0.0.1:8080/
// output
// {"Domain":"music","Rate":300}
}

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    2.10.6 Bind HTML checkboxes

    type myForm struct {
    Colors []string `form:"colors[]"`
}

...

func formHandler(c *gin.Context) {
    var fakeForm myForm
    c.ShouldBind(&fakeForm)
    c.JSON(http.StatusOK, gin.H{"color": fakeForm.Colors})
}

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    form.html

    <form action="/" method="POST">
    <p>Check some colorsp>
    <label for="red">Redlabel>
    <input type="checkbox" name="colors[]" value="red" id="red">
    <label for="green">Greenlabel>
    <input type="checkbox" name="colors[]" value="green" id="green">
    <label for="blue">Bluelabel>
    <input type="checkbox" name="colors[]" value="blue" id="blue">
    <input type="submit">
form>

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    2.10.7 Multipart/Urlencoded binding

    type ProfileForm struct {
  Name   string                `form:"name" binding:"required"`
  Avatar *multipart.FileHeader `form:"avatar" binding:"required"`

  // or for multiple files
  // Avatars []*multipart.FileHeader `form:"avatar" binding:"required"`
}

func main() {
  router := gin.Default()
  router.POST("/profile", func(c *gin.Context) {
    // you can bind multipart form with explicit binding declaration:
    // c.ShouldBindWith(&form, binding.Form)
    // or you can simply use autobinding with ShouldBind method:
    var form ProfileForm
    // in this case proper binding will be automatically selected
    if err := c.ShouldBind(&form); err != nil {
      c.String(http.StatusBadRequest, "bad request")
      return
    }

    err := c.SaveUploadedFile(form.Avatar, form.Avatar.Filename)
    if err != nil {
      c.String(http.StatusInternalServerError, "unknown error")
      return
    }

    // db.Save(&form)

    c.String(http.StatusOK, "ok")
  })
  router.Run(":8080")
}

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    test:

    curl -X POST -v --form name=user --form "avatar=@./avatar.png" http://localhost:8080/profile

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    2.10.8 XML, JSON, YAML和ProtoBuf渲染

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

  // gin.H is a shortcut for map[string]interface{}
  r.GET("/someJSON", func(c *gin.Context) {
    c.JSON(http.StatusOK, gin.H{"message": "hey", "status": http.StatusOK})
  })

  r.GET("/moreJSON", func(c *gin.Context) {
    // You also can use a struct
    var msg struct {
      Name    string `json:"user"`
      Message string
      Number  int
    }
    msg.Name = "Lena"
    msg.Message = "hey"
    msg.Number = 123
    // Note that msg.Name becomes "user" in the JSON
    // Will output  :   {"user": "Lena", "Message": "hey", "Number": 123}
    c.JSON(http.StatusOK, msg)
  })

  r.GET("/someXML", func(c *gin.Context) {
    c.XML(http.StatusOK, gin.H{"message": "hey", "status": http.StatusOK})
  })

  r.GET("/someYAML", func(c *gin.Context) {
    c.YAML(http.StatusOK, gin.H{"message": "hey", "status": http.StatusOK})
  })

  r.GET("/someProtoBuf", func(c *gin.Context) {
    reps := []int64{int64(1), int64(2)}
    label := "test"
    // The specific definition of protobuf is written in the testdata/protoexample file.
    data := &protoexample.Test{
      Label: &label,
      Reps:  reps,
    }
    // Note that data becomes binary data in the response
    // Will output protoexample.Test protobuf serialized data
    c.ProtoBuf(http.StatusOK, data)
  })

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

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    SecureJSON

    使用SecureJSON防止json被劫持。如果给定的结构是数组值，Default会在响应体前加上"while(1) "。

    JSONP

    使用 JSONP 从不同域中的服务器请求数据。如果查询参数callback存在，则将callback添加到响应体中。

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

  r.GET("/JSONP", func(c *gin.Context) {
    data := gin.H{
      "foo": "bar",
    }

    //callback is x
    // Will output  :   x({\"foo\":\"bar\"})
    c.JSONP(http.StatusOK, data)
  })

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

        // client
        // curl http://127.0.0.1:8080/JSONP?callback=x
}

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    JSONP 说明
    JSONP(JSON with Padding)是JSON的一种“使用模式”，可用于解决主流浏览器的跨域数据访问的问题。

    AsciiJSON

    使用AsciiJSON生成仅有Ascii JSON，并且转义非ascii字符的。

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

  r.GET("/someJSON", func(c *gin.Context) {
    data := gin.H{
      "lang": "GO语言",
      "tag":  "
    "    ,
    }

    // will output : {"lang":"GO\u8bed\u8a00","tag":"\u003cbr\u003e"}
    c.AsciiJSON(http.StatusOK, data)
  })

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

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    PureJSON

    通常，JSON用它们的unicode实体替换特殊的HTML字符，例如<变成\u003c。如果您想按字面意思编码这样的字符，您可以使用PureJSON代替。该特性在Go 1.6及以下版本中不可用。

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

  // Serves unicode entities
  r.GET("/json", func(c *gin.Context) {
    c.JSON(http.StatusOK, gin.H{
      "html": "Hello, world!",
    })
  })

  // Serves literal characters
  r.GET("/purejson", func(c *gin.Context) {
    c.PureJSON(http.StatusOK, gin.H{
      "html": "Hello, world!",
    })
  })

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

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    2.11 提供静态文件

    func main() {
  router := gin.Default()
  router.Static("/assets", "./assets")
  router.StaticFS("/more_static", http.Dir("my_file_system"))
  router.StaticFile("/favicon.ico", "./resources/favicon.ico")
  router.StaticFileFS("/more_favicon.ico", "more_favicon.ico", http.Dir("my_file_system"))
  
  // Listen and serve on 0.0.0.0:8080
  router.Run(":8080")
}

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    2.12 从文件中提供数据

    func (c *Context) File(filepath string)

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    File以高效的方式将指定的文件写入正文流。

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

  router.GET("/local/file", func(c *gin.Context) {
    c.File("local/file.go")
  })

  var fs http.FileSystem = // ...
  router.GET("/fs/file", func(c *gin.Context) {
    c.FileFromFS("fs/file.go", fs)
  })
}

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    2.13 从 reader 中提供数据

    func main() {
  router := gin.Default()
  router.GET("/someDataFromReader", func(c *gin.Context) {
    response, err := http.Get("https://raw.githubusercontent.com/gin-gonic/logo/master/color.png")
    if err != nil || response.StatusCode != http.StatusOK {
      c.Status(http.StatusServiceUnavailable)
      return
    }

    reader := response.Body
     defer reader.Close()
    contentLength := response.ContentLength
    contentType := response.Header.Get("Content-Type")

    extraHeaders := map[string]string{
      "Content-Disposition": `attachment; filename="gopher.png"`,
    }

    c.DataFromReader(http.StatusOK, contentLength, contentType, reader, extraHeaders)
  })
  router.Run(":8080")
}

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    2.14 HTML渲染

    Using LoadHTMLGlob() or LoadHTMLFiles()

    func main() {
  router := gin.Default()
  router.LoadHTMLGlob("templates/*")
  //router.LoadHTMLFiles("templates/template1.html", "templates/template2.html")
  router.GET("/index", func(c *gin.Context) {
    c.HTML(http.StatusOK, "index.tmpl", gin.H{
      "title": "Main website",
    })
  })
  router.Run(":8080")
}

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    templates/index.tmpl

    <html>
  <h1>
    {{ .title }}
  h1>
html>

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    在不同目录中使用相同名称的模板:

    func main() {
  router := gin.Default()
  router.LoadHTMLGlob("templates/**/*")
  router.GET("/posts/index", func(c *gin.Context) {
    c.HTML(http.StatusOK, "posts/index.tmpl", gin.H{
      "title": "Posts",
    })
  })
  router.GET("/users/index", func(c *gin.Context) {
    c.HTML(http.StatusOK, "users/index.tmpl", gin.H{
      "title": "Users",
    })
  })
  router.Run(":8080")
}

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    templates/posts/index.tmpl

    {{ define "posts/index.tmpl" }}
<html><h1>
  {{ .title }}
h1>
<p>Using posts/index.tmplp>
html>
{{ end }}

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    templates/users/index.tmpl

    {{ define "users/index.tmpl" }}
<html><h1>
  {{ .title }}
h1>
<p>Using users/index.tmplp>
html>
{{ end }}

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    2.14.1 自定义模板渲染器

    你也可以使用你自己的html模板渲染

    import "html/template"

func main() {
  router := gin.Default()
  html := template.Must(template.ParseFiles("file1", "file2"))
  router.SetHTMLTemplate(html)
  router.Run(":8080")
}

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    2.14.1 自定义分隔符

      r := gin.Default()
  r.Delims("{[{", "}]}")
  r.LoadHTMLGlob("/path/to/templates")

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    2.14.2 自定义模板函数

    func formatAsDate(t time.Time) string {
    year, month, day := t.Date()
    return fmt.Sprintf("%d/%02d/%02d", year, month, day)
}

func main() {
    router := gin.Default()
    router.Delims("{[{", "}]}")
    router.SetFuncMap(template.FuncMap{
        "formatAsDate": formatAsDate,
    })
    router.LoadHTMLFiles("./testdata/template/raw.tmpl")

    router.GET("/raw", func(c *gin.Context) {
        c.HTML(http.StatusOK, "raw.tmpl", gin.H{
            "now": time.Date(2017, 07, 01, 0, 0, 0, 0, time.UTC),
        })
    })

    router.Run(":8080")
}

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    raw.tmpl

    Date: {[{.now | formatAsDate}]}

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    Multitemplate

    Gin默认允许只使用一个html.Template。 a multitemplate render

    2.15 重定向

    发出HTTP重定向很容易。支持内部和外部位置。

    r.GET("/test", func(c *gin.Context) {
  c.Redirect(http.StatusMovedPermanently, "http://www.google.com/")
})

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    从POST发出HTTP重定向

    r.POST("/test", func(c *gin.Context) {
  c.Redirect(http.StatusFound, "/foo")
})

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    发出一个路由器重定向，使用HandleContext如下所示：

    r.GET("/test", func(c *gin.Context) {
    c.Request.URL.Path = "/test2"
    r.HandleContext(c)
})
r.GET("/test2", func(c *gin.Context) {
    c.JSON(http.StatusOK, gin.H{"hello": "world"})
})

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    2.16 定制中间件

    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")
}

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    2.17 使用BasicAuth()中间件

    // simulate some private data
var secrets = gin.H{
  "foo":    gin.H{"email": "foo@bar.com", "phone": "123433"},
  "austin": gin.H{"email": "austin@example.com", "phone": "666"},
  "lena":   gin.H{"email": "lena@guapa.com", "phone": "523443"},
}

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

  // Group using gin.BasicAuth() middleware
  // gin.Accounts is a shortcut for map[string]string
  authorized := r.Group("/admin", gin.BasicAuth(gin.Accounts{
    "foo":    "bar",
    "austin": "1234",
    "lena":   "hello2",
    "manu":   "4321",
  }))

  // /admin/secrets endpoint
  // hit "localhost:8080/admin/secrets
  authorized.GET("/secrets", func(c *gin.Context) {
    // get user, it was set by the BasicAuth middleware
    user := c.MustGet(gin.AuthUserKey).(string)
    if secret, ok := secrets[user]; ok {
      c.JSON(http.StatusOK, gin.H{"user": user, "secret": secret})
    } else {
      c.JSON(http.StatusOK, gin.H{"user": user, "secret": "NO SECRET :("})
    }
  })

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

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    2.18 中间件中的goroutine

    当在中间件或处理程序（ middleware or handler）中启动新的 Goroutine 时，不应该使用其中的原始上下文（context ），必须使用只读副本

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

  r.GET("/long_async", func(c *gin.Context) {
    // create copy to be used inside the goroutine
    cCp := c.Copy()
    go func() {
      // simulate a long task with time.Sleep(). 5 seconds
      time.Sleep(5 * time.Second)

      // note that you are using the copied context "cCp", IMPORTANT
      log.Println("Done! in path " + cCp.Request.URL.Path)
    }()
  })

  r.GET("/long_sync", func(c *gin.Context) {
    // simulate a long task with time.Sleep(). 5 seconds
    time.Sleep(5 * time.Second)

    // since we are NOT using a goroutine, we do not have to copy the context
    log.Println("Done! in path " + c.Request.URL.Path)
  })

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

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    2.19 自定义HTTP配置

    直接使用http.ListenAndServe()，像这样:

    func main() {
  router := gin.Default()
  http.ListenAndServe(":8080", router)
}

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    或

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

  s := &http.Server{
    Addr:           ":8080",
    Handler:        router,
    ReadTimeout:    10 * time.Second,
    WriteTimeout:   10 * time.Second,
    MaxHeaderBytes: 1 << 20,
  }
  s.ListenAndServe()
}

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    2.20 支持加密

    支持 HTTPS服务器 , 使用let’s encrypt。

    package main

import (
  "log"
  "net/http"

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

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

  // Ping handler
  r.GET("/ping", func(c *gin.Context) {
    c.String(http.StatusOK, "pong")
  })

  log.Fatal(autotls.Run(r, "example1.com", "example2.com"))
}

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    自定义自动证书管理器示例：

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

  // Ping handler
  r.GET("/ping", func(c *gin.Context) {
    c.String(http.StatusOK, "pong")
  })

  m := autocert.Manager{
    Prompt:     autocert.AcceptTOS,
    HostPolicy: autocert.HostWhitelist("example1.com", "example2.com"),
    Cache:      autocert.DirCache("/var/www/.cache"),
  }

  log.Fatal(autotls.RunWithManager(r, &m))
}

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    2.21 使用Gin运行多个服务

    var (
  g errgroup.Group
)

func router01() http.Handler {
  e := gin.New()
  e.Use(gin.Recovery())
  e.GET("/", func(c *gin.Context) {
    c.JSON(
      http.StatusOK,
      gin.H{
        "code":  http.StatusOK,
        "error": "Welcome server 01",
      },
    )
  })

  return e
}

func router02() http.Handler {
  e := gin.New()
  e.Use(gin.Recovery())
  e.GET("/", func(c *gin.Context) {
    c.JSON(
      http.StatusOK,
      gin.H{
        "code":  http.StatusOK,
        "error": "Welcome server 02",
      },
    )
  })

  return e
}

func main() {
  server01 := &http.Server{
    Addr:         ":8080",
    Handler:      router01(),
    ReadTimeout:  5 * time.Second,
    WriteTimeout: 10 * time.Second,
  }

  server02 := &http.Server{
    Addr:         ":8081",
    Handler:      router02(),
    ReadTimeout:  5 * time.Second,
    WriteTimeout: 10 * time.Second,
  }

  g.Go(func() error {
    err := server01.ListenAndServe()
    if err != nil && err != http.ErrServerClosed {
      log.Fatal(err)
    }
    return err
  })

  g.Go(func() error {
    err := server02.ListenAndServe()
    if err != nil && err != http.ErrServerClosed {
      log.Fatal(err)
    }
    return err
  })

  if err := g.Wait(); err != nil {
    log.Fatal(err)
  }
}

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    2.22 优雅关机或重新启动

    有几种方法可以用于执行优雅的关闭或重新启动。您可以使用专门为此而构建的第三方包，也可以使用内置包中的函数和方法手动执行相同的操作。

    第三方包

    我们可以使用fvbock/endless来替换默认的ListenAndServe。

    router := gin.Default()
router.GET("/", handler)
// [...]
endless.ListenAndServe(":4242", router)

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    Alternatives:
    grace: Graceful restart & zero downtime deploy for Go servers.
    graceful: Graceful is a Go package enabling graceful shutdown of an http.Handler server.
    manners: A polite Go HTTP server that shuts down gracefully.

    手动

    如果您使用的是Go 1.8或更高版本，您可能不需要使用这些库。考虑使用http.Server内置的Shutdown()方法用于正常关机。下面的例子描述了它的用法，我们在这里有更多使用gin的例子。

    func main() {
  router := gin.Default()
  router.GET("/", func(c *gin.Context) {
    time.Sleep(5 * time.Second)
    c.String(http.StatusOK, "Welcome Gin Server")
  })

  srv := &http.Server{
    Addr:    ":8080",
    Handler: router,
  }

  // Initializing the server in a goroutine so that
  // it won't block the graceful shutdown handling below
  go func() {
    if err := srv.ListenAndServe(); err != nil && errors.Is(err, http.ErrServerClosed) {
      log.Printf("listen: %s\n", err)
    }
  }()

  // Wait for interrupt signal to gracefully shutdown the server with
  // a timeout of 5 seconds.
  quit := make(chan os.Signal)
  // kill (no param) default send syscall.SIGTERM
  // kill -2 is syscall.SIGINT
  // kill -9 is syscall.SIGKILL but can't be caught, so don't need to add it
  signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
  <-quit
  log.Println("Shutting down server...")

  // The context is used to inform the server it has 5 seconds to finish
  // the request it is currently handling
  ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
  defer cancel()

  if err := srv.Shutdown(ctx); err != nil {
    log.Fatal("Server forced to shutdown:", err)
  }

  log.Println("Server exiting")
}

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    2.23 用模板构建一个二进制文件

    可以使用embed 包将服务器构建到包含模板的单个二进制文件中。

    //go:embed assets/* templates/*
var f embed.FS

func main() {
  router := gin.Default()
  templ := template.Must(template.New("").ParseFS(f, "templates/*.tmpl", "templates/foo/*.tmpl"))
  router.SetHTMLTemplate(templ)

  // example: /public/assets/images/example.png
  router.StaticFS("/public", http.FS(f))

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

  router.GET("/foo", func(c *gin.Context) {
    c.HTML(http.StatusOK, "bar.tmpl", gin.H{
      "title": "Foo website",
    })
  })

  router.GET("favicon.ico", func(c *gin.Context) {
    file, _ := f.ReadFile("assets/favicon.ico")
    c.Data(
      http.StatusOK,
      "image/x-icon",
      file,
    )
  })

  router.Run(":8080")
}

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  • 原文地址：https://blog.csdn.net/chinusyan/article/details/127615529