二 golang包管理工具go module

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一 golang包

1.1 包的引出

main.goutils.go

1.2 包的原理图

包的本质实际上就是创建不同的文件夹，来存放程序文件。

1.3 包的基本概念

go 的每一个文件都是属于一个包的，也就是说 go 是以包的形式来管理文件和项目目录结构的

包的三大作用：

1. 区分相同名字的函数、变量等标识符
2. 当程序文件很多时,可以很好的管理项目
3. 控制函数、变量等访问范围，即作用域

语法：

package 包名

import "包的路径"

1.4 实例演示

func Calutils.goutils.goutils.goimport 该包

目录结构：

utils.go 文件：

package utils

import "fmt"

func Cal(n1 float64, n2 float64, operator byte) float64 {
	var res float64
	switch operator {
	case '+':
		res = n1 + n2
	case '-':
		res = n1 - n2
	case '*':
		res = n1 * n2
	case '/':
		res = n1 / n2
	default:
		fmt.Println("符号错误")
	}
	return res
}

main.go 文件：

package main

import (
	"fmt"
	"go_pro/utils"
)

func main() {
	var n1 float64 = 1.2
	var n2 float64 = 2.3
	var operator byte = '+'
	result := utils.Cal(n1, n2, operator)
	fmt.Println("result = ", result)
}

运行结果：

[Running] go run "c:\Users\Mechrevo\Desktop\go_pro\main\main.go"
result =  3.5

1.5 注意事项

包名.函数名

二 golang包管理工具go module

Go modules是golang 1.11新加的特性，用来管理模块中包的依赖关系。

2.1 Go mod使用方法

Go mod init <项目模块名称>

Go mod tidy

Go mod vendor

Go list -m all

Go list -m -json all

Go mod download [path@version]

2.2 自定义包实例演示

目录结构：

go mode init go_pro

PS C:\Users\Mechrevo\Desktop\go_pro> go mod init go_pro
go: creating new go.mod: module go_pro
go: to add module requirements and sums:
        go mod tidy

自动生成了一个go.mod文件，内容如下：

Run go mod tidy
module go_pro

go 1.18

编辑utils目录下utils.go文件:

package utils

import "fmt"

func Cal(n1 float64, n2 float64, operator byte) float64 {
	var res float64
	switch operator {
	case '+':
		res = n1 + n2
	case '-':
		res = n1 - n2
	case '*':
		res = n1 * n2
	case '/':
		res = n1 / n2
	default:
		fmt.Println("符号错误")
	}
	return res
}

go build

PS C:\Users\Mechrevo\Desktop\go_pro> cd .\utils\
PS C:\Users\Mechrevo\Desktop\go_pro\utils> go build

在main.go中导入utils包：

package main

import (
	"fmt"
	"go_pro/utils"	// 引入包
)

func main() {
	var n1 float64 = 1.2
	var n2 float64 = 2.3
	var operator byte = '+'
	result := utils.Cal(n1, n2, operator) // 使用导入的包内函数
	fmt.Println("result = ", result)
}

运行结果：

[Running] go run "c:\Users\Mechrevo\Desktop\go_pro\main\main.go"
result =  3.5

2.3 导入远程包

终端执行 go get -u github.com/gin-gonic/gin 下载

PS C:\Users\Mechrevo\Desktop\go_pro\utils> go get -u github.com/gin-gonic/gin       
go: downloading github.com/gin-gonic/gin v1.8.1
go: downloading github.com/gin-contrib/sse v0.1.0
go: downloading github.com/mattn/go-isatty v0.0.14
go: downloading golang.org/x/net v0.0.0-20210226172049-e18ecbb05110
go: downloading github.com/goccy/go-json v0.9.7
go: downloading github.com/json-iterator/go v1.1.12
go: downloading github.com/pelletier/go-toml/v2 v2.0.1
go: downloading github.com/ugorji/go/codec v1.2.7
go: downloading google.golang.org/protobuf v1.28.0
go: downloading github.com/go-playground/validator/v10 v10.10.0
go: downloading golang.org/x/sys v0.0.0-20210806184541-e5e7981a1069
go: downloading github.com/ugorji/go v1.2.7
go: downloading github.com/go-playground/validator v9.31.0+incompatible
go: downloading github.com/go-playground/validator/v10 v10.11.0
go: downloading github.com/pelletier/go-toml v1.9.5
go: downloading github.com/pelletier/go-toml/v2 v2.0.2
go: downloading github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421
go: downloading github.com/modern-go/reflect2 v1.0.2
go: downloading github.com/go-playground/universal-translator v0.18.0
go: downloading github.com/leodido/go-urn v1.2.1
go: downloading golang.org/x/crypto v0.0.0-20210711020723-a769d52b0f97
go: downloading golang.org/x/text v0.3.6
go: downloading github.com/go-playground/locales v0.14.0
go: downloading github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd
go: downloading golang.org/x/net v0.0.0-20220624214902-1bab6f366d9e
go: downloading golang.org/x/sys v0.0.0-20220624220833-87e55d714810
go: downloading golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d
go: added github.com/gin-contrib/sse v0.1.0
go: added github.com/gin-gonic/gin v1.8.1
go: added github.com/go-playground/locales v0.14.0
go: added github.com/go-playground/universal-translator v0.18.0
go: added github.com/go-playground/validator/v10 v10.11.0
go: added github.com/goccy/go-json v0.9.7
go: added github.com/json-iterator/go v1.1.12
go: added github.com/leodido/go-urn v1.2.1
go: added github.com/mattn/go-isatty v0.0.14
go: added github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd
go: added github.com/modern-go/reflect2 v1.0.2
go: added github.com/pelletier/go-toml/v2 v2.0.2
go: added github.com/ugorji/go/codec v1.2.7
go: added golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d
go: added golang.org/x/net v0.0.0-20220624214902-1bab6f366d9e
go: added golang.org/x/sys v0.0.0-20220624220833-87e55d714810
go: added golang.org/x/text v0.3.7
go: added google.golang.org/protobuf v1.28.0
go: added gopkg.in/yaml.v2 v2.4.0

会看到go.mod文件内添加了很多内容：

module go_pro

go 1.18

require (
	github.com/gin-contrib/sse v0.1.0 // indirect
	github.com/gin-gonic/gin v1.8.1 // indirect
	github.com/go-playground/locales v0.14.0 // indirect
	github.com/go-playground/universal-translator v0.18.0 // indirect
	github.com/go-playground/validator/v10 v10.11.0 // indirect
	github.com/goccy/go-json v0.9.7 // indirect
	github.com/json-iterator/go v1.1.12 // indirect
	github.com/leodido/go-urn v1.2.1 // indirect
	github.com/mattn/go-isatty v0.0.14 // indirect
	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
	github.com/modern-go/reflect2 v1.0.2 // indirect
	github.com/pelletier/go-toml/v2 v2.0.2 // indirect
	github.com/ugorji/go/codec v1.2.7 // indirect
	golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d // indirect
	golang.org/x/net v0.0.0-20220624214902-1bab6f366d9e // indirect
	golang.org/x/sys v0.0.0-20220624220833-87e55d714810 // indirect
	golang.org/x/text v0.3.7 // indirect
	google.golang.org/protobuf v1.28.0 // indirect
	gopkg.in/yaml.v2 v2.4.0 // indirect
)

导入远程包并编辑main.go文件：

package main

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

func main() {
	r := gin.Default()
	r.GET("/ping", func(c *gin.Context) {
		c.JSON(200, gin.H{
			"message": "pong",
		})
	})
	r.Run() // listen and serve on 0.0.0.0:8080 (for windows "localhost:8080")

}

go mod tidy

PS C:\Users\Mechrevo\Desktop\go_pro\utils> cd ..
PS C:\Users\Mechrevo\Desktop\go_pro> go mod tidy
go: downloading github.com/stretchr/testify v1.7.2
go: downloading github.com/google/go-cmp v0.5.5
go: downloading gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c
go: downloading github.com/go-playground/assert/v2 v2.0.1
go: downloading github.com/kr/pretty v0.3.0
go: downloading github.com/kr/text v0.2.0
go: downloading github.com/rogpeppe/go-internal v1.8.0
go: downloading github.com/davecgh/go-spew v1.1.1
go: downloading github.com/pmezard/go-difflib v1.0.0
go: downloading gopkg.in/yaml.v3 v3.0.1

执行main.go文件后访问localhost:8080/ping：

[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    /ping                     --> main.main.func1 (3 handlers)
[GIN-debug] [WARNING] You trusted all proxies, this is NOT safe. We recommend you to set a value.
Please check https://pkg.go.dev/github.com/gin-gonic/gin#readme-don-t-trust-all-proxies for details.
[GIN-debug] Environment variable PORT is undefined. Using port :8080 by default
[GIN-debug] Listening and serving HTTP on :8080
[GIN] 2022/06/27 - 12:22:25 | 200 |            0s |       127.0.0.1 | GET      "/ping"