golang-101-hacks(5)——go get

羊羽shine

发布于 2019-05-29 16:33:56

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发布于 2019-05-29 16:33:56

文章被收录于专栏：Golang开发

“go get”命令是下载和安装包以及相关依赖项的标准方法，让我们通过一个示例来说明go get使用细节：（1）在GitHub创建项目playstack （2）项目的包含playstack文件夹下包含一个LICENSE文件和play目录（3）play文件夹包含一个main.go文件

package main

import (
    "fmt"
    "github.com/NanXiao/stack"
)

func main() {
    s := stack.New()
    s.Push(0)
    s.Push(1)
    s.Pop()
    fmt.Println(s)
}

main包需要依赖:[stack]包(https://github.com/NanXiao/stack)。实际上，为了达到简单的演示目的，当前main() 函数的功能很简单，当前“playstack”的目录结构如下所示:

.
├── LICENSE
└── play
    └── main.go

1 directory, 2 files

清理$GOPATH目录，使用go get下载依赖包playstack

# tree
.

0 directories, 0 files
# go get github.com/NanXiao/playstack
package github.com/NanXiao/playstack: no buildable Go source files in /root/gocode/src/github.com/NanXiao/playstack

go get 会提示错误：没有可执行的go源文件因为go get “去获取”“命令抱怨”“没有可构建的去源文件…”，这是因为go get需要依赖包文件而不是工程仓库目录，在playstack目录下是没有go源文件的，不是一个有效的包结构。清空$GOPATH目录，然后执行go get github.com/NanXiao/playstack/play

# tree
.

0 directories, 0 files
# go get github.com/NanXiao/playstack/play
# tree
.
├── bin
│   └── play
├── pkg
│   └── linux_amd64
│       └── github.com
│           └── NanXiao
│               └── stack.a
└── src
    └── github.com
        └── NanXiao
            ├── playstack
            │   ├── LICENSE
            │   └── play
            │       └── main.go
            └── stack
                ├── LICENSE
                ├── README.md
                ├── stack.go
                └── stack_test.go

11 directories, 8 files

我们不仅可以看到“playstack”及其依赖项(“stack”)都已下载，而且可执行文件命令play和依赖库stack也会在存放到相对应的目录下。

“go get”命令背后的原理是获取包和依赖项的源码库(例如，使用“git clone”)，可以通过“go get -x”查看go get详细的执行流程:

# tree
.

0 directories, 0 files
# go get -x github.com/NanXiao/playstack/play
cd .
git clone https://github.com/NanXiao/playstack /root/gocode/src/github.com/NanXiao/playstack
cd /root/gocode/src/github.com/NanXiao/playstack
git submodule update --init --recursive
cd /root/gocode/src/github.com/NanXiao/playstack
git show-ref
cd /root/gocode/src/github.com/NanXiao/playstack
git submodule update --init --recursive
cd .
git clone https://github.com/NanXiao/stack /root/gocode/src/github.com/NanXiao/stack
cd /root/gocode/src/github.com/NanXiao/stack
git submodule update --init --recursive
cd /root/gocode/src/github.com/NanXiao/stack
git show-ref
cd /root/gocode/src/github.com/NanXiao/stack
git submodule update --init --recursive
WORK=/tmp/go-build054180753
mkdir -p $WORK/github.com/NanXiao/stack/_obj/
mkdir -p $WORK/github.com/NanXiao/
cd /root/gocode/src/github.com/NanXiao/stack
/usr/local/go/pkg/tool/linux_amd64/compile -o $WORK/github.com/NanXiao/stack.a -trimpath $WORK -p github.com/NanXiao/stack -complete -buildid de4d90fa03d8091e075c1be9952d691376f8f044 -D _/root/gocode/src/github.com/NanXiao/stack -I $WORK -pack ./stack.go
mkdir -p /root/gocode/pkg/linux_amd64/github.com/NanXiao/
mv $WORK/github.com/NanXiao/stack.a /root/gocode/pkg/linux_amd64/github.com/NanXiao/stack.a
mkdir -p $WORK/github.com/NanXiao/playstack/play/_obj/
mkdir -p $WORK/github.com/NanXiao/playstack/play/_obj/exe/
cd /root/gocode/src/github.com/NanXiao/playstack/play
/usr/local/go/pkg/tool/linux_amd64/compile -o $WORK/github.com/NanXiao/playstack/play.a -trimpath $WORK -p main -complete -buildid e9a3c02979f7c6e57ce4452278c52e3e0e6a48e8 -D _/root/gocode/src/github.com/NanXiao/playstack/play -I $WORK -I /root/gocode/pkg/linux_amd64 -pack ./main.go
cd .
/usr/local/go/pkg/tool/linux_amd64/link -o $WORK/github.com/NanXiao/playstack/play/_obj/exe/a.out -L $WORK -L /root/gocode/pkg/linux_amd64 -extld=gcc -buildmode=exe -buildid=e9a3c02979f7c6e57ce4452278c52e3e0e6a48e8 $WORK/github.com/NanXiao/playstack/play.a
mkdir -p /root/gocode/bin/
mv $WORK/github.com/NanXiao/playstack/play/_obj/exe/a.out /root/gocode/bin/play

从上面的输出中，我们可以看到首先git clone了“playstack”源码项仓库，然后是下载依赖项“stack”，最后执行编译和安装。如果只是下载源文件，而不需要编译和安装，使用“' go get -d '”命令即可:

# tree
.

0 directories, 0 files
# go get -d github.com/NanXiao/playstack/play
# tree
.
└── src
    └── github.com
        └── NanXiao
            ├── playstack
            │   ├── LICENSE
            │   └── play
            │       └── main.go
            └── stack
                ├── LICENSE
                ├── README.md
                ├── stack.go
                └── stack_test.go

6 directories, 6 files

使用go get -u更新包文件和包之间的依赖

参考与引用: Command go; How does "go get" command know which files should be downloaded?.

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原始发表：2019.05.25 ，如有侵权请联系 cloudcommunity@tencent.com 删除