Go语言学习（十）| module 使用

requirement

go module 是在go 1.11版本才开始有的，需要将环境变量 GO111MODULE 设置为 on 才能正常使用文章源自编程技术分享-https://mervyn.life/1eefbb84.html

例：文章源自编程技术分享-https://mervyn.life/1eefbb84.html

export GO111MODULE=on

初次使用

Go1.11新增了命令 go mod 用于支持 module。文章源自编程技术分享-https://mervyn.life/1eefbb84.html

➜  demo go help mod
Go mod provides access to operations on modules.

Note that support for modules is built into all the go commands,
not just 'go mod'. For example, day-to-day adding, removing, upgrading,
and downgrading of dependencies should be done using 'go get'.
See 'go help modules' for an overview of module functionality.

Usage:

    go mod <command> [arguments]

The commands are:

    download    download modules to local cache
    edit        edit go.mod from tools or scripts
    graph       print module requirement graph
    init        initialize new module in current directory
    tidy        add missing and remove unused modules
    vendor      make vendored copy of dependencies
    verify      verify dependencies have expected content
    why         explain why packages or modules are needed

Use "go help mod <command>" for more information about a command.

1. 创建项目 demo

cd ~/go && mkdir demo && cd demo

2. 初始化 mod

go mod init

注意： 如果创建的项目 demo 所属目录不再 GOPATH 内， 则 init 时需要制定名字文章源自编程技术分享-https://mervyn.life/1eefbb84.html

go mod init demo

这时目录中会出现一个 go.mod 的文件文章源自编程技术分享-https://mervyn.life/1eefbb84.html

module demo

go 1.12

require (
    github.com/gin-contrib/sse v0.0.0-20190301062529-5545eab6dad3 // indirect
    github.com/gin-gonic/gin v1.3.0
    github.com/golang/protobuf v1.3.0 // indirect
    github.com/mattn/go-isatty v0.0.6 // indirect
    github.com/ugorji/go/codec v0.0.0-20190309163734-c4a1c341dc93 // indirect
    gopkg.in/go-playground/validator.v8 v8.18.2 // indirect
    gopkg.in/yaml.v2 v2.2.2 // indirect
)

3. 新建入口文件 main.go

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()
}

4. 执行 go build

执行完目录中会出现一个名为 go.sum 的文件,内容如下：文章源自编程技术分享-https://mervyn.life/1eefbb84.html

github.com/gin-contrib/sse v0.0.0-20190301062529-5545eab6dad3 h1:t8FVkw33L+wilf2QiWkw0UV77qRpcH/JHPKGpKa2E8g=
github.com/gin-contrib/sse v0.0.0-20190301062529-5545eab6dad3/go.mod h1:VJ0WA2NBN22VlZ2dKZQPAPnyWw5XTlK1KymzLKsr59s=
github.com/gin-gonic/gin v1.3.0 h1:kCmZyPklC0gVdL728E6Aj20uYBJV93nj/TkwBTKhFbs=
github.com/gin-gonic/gin v1.3.0/go.mod h1:7cKuhb5qV2ggCFctp2fJQ+ErvciLZrIeoOSOm6mUr7Y=
github.com/golang/protobuf v1.3.0 h1:kbxbvI4Un1LUWKxufD+BiE6AEExYYgkQLQmLFqA1LFk=
github.com/golang/protobuf v1.3.0/go.mod h1:Qd/q+1AKNOZr9uGQzbzCmRO6sUih6GTPZv6a1/R87v0=
github.com/mattn/go-isatty v0.0.6 h1:SrwhHcpV4nWrMGdNcC2kXpMfcBVYGDuTArqyhocJgvA=
github.com/mattn/go-isatty v0.0.6/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
github.com/ugorji/go v1.1.2 h1:JON3E2/GPW2iDNGoSAusl1KDf5TRQ8k8q7Tp097pZGs=
github.com/ugorji/go v1.1.2/go.mod h1:hnLbHMwcvSihnDhEfx2/BzKp2xb0Y+ErdfYcrs9tkJQ=
github.com/ugorji/go/codec v0.0.0-20190309163734-c4a1c341dc93 h1:JnDJ9gMf6CfErtoOXnghtY5hhMuDtW4tUBaWSBrqvKs=
github.com/ugorji/go/codec v0.0.0-20190309163734-c4a1c341dc93/go.mod h1:iT03XoTwV7xq/+UGwKO3UbC1nNNlopQiY61beSdrtOA=
golang.org/x/net v0.0.0-20180906233101-161cd47e91fd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
google.golang.org/genproto v0.0.0-20180831171423-11092d34479b/go.mod h1:JiN7NxoALGmiZfu7CAH4rXhgtRTLTxftemlI0sWmxmc=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/go-playground/validator.v8 v8.18.2 h1:lFB4DoMU6B626w8ny76MV7VX6W2VHct2GVOI3xgiMrQ=
gopkg.in/go-playground/validator.v8 v8.18.2/go.mod h1:RX2a/7Ha8BgOhfk7j780h4/u/RRjR0eouCJSH80/M2Y=
gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

go.sum 是一个模块版本内容的校验值，用来验证当前缓存的模块。go.sum 包含了直接依赖和间接依赖的包的信息，比 go.mod 要多一些。文章源自编程技术分享-https://mervyn.life/1eefbb84.html

此时的代码存放在 $GOPATH/pkg/mod 目录下文章源自编程技术分享-https://mervyn.life/1eefbb84.html

go.mod 指令

go.mod 文件有四种指令：module，require，exclude，replace。文章源自编程技术分享-https://mervyn.life/1eefbb84.html

• module：模块名称
• require：依赖包列表以及版本
• exclude：禁止依赖包列表（仅在当前模块为主模块时生效）
• replace：替换依赖包列表 （仅在当前模块为主模块时生效）

其他命令

go mod tidy //拉取缺少的模块，移除不用的模块。
go mod download //下载依赖包
go mod graph //打印模块依赖图
go mod vendor //将依赖复制到vendor下
go mod verify //校验依赖
go mod why //解释为什么需要依赖
go list -m -json all //依赖详情