Golang (1) | from environmental preparation to quick start

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Preface

This column Will teach you how to achieve zero foundation One adoption REST style +JSON Built API The server , This is a Go API A combination commonly used in development , This mode can meet most demand scenarios . It shows through actual combat API Each process in the construction process （ Get ready -> Design -> Development -> test
[ Optional ] -> Deploy ） Implementation method .

Outline presentation

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GO A basic introduction to language

Go Characteristics of language

Go Language ensures the security and performance of statically compiled languages , It also achieves the speed and maintainability of dynamic language development , It's been described Go Language ： Go = C + Python , explain Go Language both Yes C The speed of static language programs , It can reach Python The rapid development of dynamic language .Go The languages are as follows
characteristic ：

• Automatic garbage collection : C/C++ The biggest headache is the pointer problem , If you are not careful, the pointer will go wild or cross the boundary again . stay Go Don't worry about language anymore , Don't worry delete or person free, The system will automatically recycle .
• Function can return multiple values : This is amazing , Most languages can only return one value ,Go Languages can return multiple values . This function makes developers no longer have to think hard about how to return value design , There is no need to define a structure for value transfer .
• Concurrent programming : Go Language is naturally concurrent , Just the keywords “go” Can Let the function execute concurrently , Make concurrent programming easier , This is also Go The greatest advantage of language .
• No dependence on hell , Even glibc
• Compile once , Copy anywhere , Deployment is extremely convenient : Don't look like python The project also needs to install the required dependencies ,GO The deployment of the project is simple 、 quick ！

GO Language development environment configuration

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Go Installation

Go There are many ways to install , Such as :Go Source code installation 、Go Standard package installation 、 Third party tools （yum、apt-get etc. ） install

Introduction of two environment variables ：
GOROOT：GOROOT Namely Go Installation path for
GOPATH：GOPATH It is the storage destination of compiled binary and import The search path of the package （ In fact, it's yours working directory , Deposit GO Path to file ）

GOPATH Detailed explanation

go_code // ( example go_code by GOPATH Catalog ) 
-- bin // golang Compile executable file storage path , Can automatically generate . 
-- pkg // golang Compilation of *.a Intermediate file storage path , Can automatically generate . 
-- src // go Source path . according to golang Default Convention ,go run,go install The current working path of the command （ That is, on this road   Execute the above command directly ）

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Linux Lower installation GO

1. Get the installation package

$ yum install wget -y
$ wget https://golang.google.cn/dl/go1.18.3.linux-amd64.tar.gz 
$ tar -xzvf go1.18.3.linux-amd64.tar.gz 
$ mv go /usr/local/

2. Set the environment variable

stay ~/.bashrc Add GOPATH Variable

#  The installation directory  
export GOROOT=/usr/local/go 
#  Code directory  
export GOPATH=~/code 
export PATH=$PATH:$GOPATH:$GOROOT/bin

#  Be careful ： If you have installed it before, you want to choose the latest version 
export PATH=$PATH:$GOROOT/bin:$GOPATH

When I'm done , Save the file , And implement source ~/.bashrc

3. Test for successful installation

$ go version 
go version go1.18.3 linux/amd64

notice go version Command output go Version number go1.10.2 linux/amd64 , explain go Command installed successfully .

Mac Platform installation GO

$ brew install go 
$ go version 
go version go1.18.3 darwin/amd64

Windows Platform installation GO

• download
  Download path ：https://golang.google.cn/dl/go1.18.3.windows-amd64.msi

• install msi file

• Add the installation path to the environment variable

Such as ：go The installation to D:\GO_APP
Add environment variables GOPATH ( Code storage directory ）==》D:\GO_code
Add environment variables GOROOT( Software installation directory ） ==》 D:\GO_APP
And add %GOPATH%\bin To PATH
And add %GOROOT%\bin To PATH

• Check whether the installation is successful
  open cmd Command line , Input go version

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IDE Installation

Linux platform Vim To configure ： Vim yes Linux The most basic tool developed under , You can configure a Vim IDE. We can use open source installation tools , Here, you can directly use this tool to realize one click configuration , The specific configuration steps are as follows ：

1. download Vim Configuration tool

$ yum install git -y  # It is best to enter /tmp Install under 
$ git clone https://github.com/lexkong/lexVim

2. Get into lexVim Catalog , download go ide The required binaries

$ cd lexVim 
$ git clone https://github.com/lexkong/vim-go-ide-bin

It's all binary files , File size , Please be patient ！

3. Start the installation script

$ ./start_vim.sh

After starting , Will enter an interactive environment , Input in sequence ： 1 ==> user name ==》 mailbox （ You can input any ）. The script finally outputs this vim config is success ! Description installation successful . It's simple , just 3 You can choose to install successfully , To configure IDE so easy.

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If the installation package is downloaded too slowly , But a private letter asks me for a compressed package

##  decompression zip Compressed package 

#  install zip
yum install unzip -y

#  decompression zip file 
unzip start_vim.sh

##  encounter Windows Files on Linux There is a format error when running on 
[[email protected] lexVim]# sh start_vim.sh
start_vim.sh: That's ok 9: $'\r':  Command not found 
start_vim.sh: That's ok 11: $'\r':  Command not found 
start_vim.sh: That's ok 12:  Unexpected symbols  `$'\r''  There are grammar errors nearby  'tart_vim.sh: That's ok 12: `function prompt() 

# terms of settlement 
yum install dos2unix

# transformation 
dos2unix start_vim.sh

Vim IDE Common functions

• Jump to the source code ：ctrl+] or gd
• Jump out of the source code ：ctrl+o
• Jump to the end ：shift+G
• Delete all ：d+gg
• Delete a line ：d
• < F1> Open help , :q sign out
• < F2> Open the directory window , Press again to close the directory window
• < F4> List of recent documents , :q sign out
• < F6> Add function comments
• stay vim Paste text in , need :set paste It can be pasted normally

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Test tool installation

Linux platform Curl Tools

$ yum install curl

Usage method ：
https://www.ruanyifeng.com/blog/2011/09/curl.html
https://www.ruanyifeng.com/blog/2019/09/curl-reference.html

Windows platform APIPOST install

Download address ：https://www.apipost.cn/?utm_source=10039&bd_vid=10756414022759907776

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GO Get started quickly

1. Create a .go The file of

//  Declare the package where the file is located , If it is the main program, it is main 
package main 
//  Import library ,fmt Used to process standard input and output  
import "fmt" 
// main  Function is the entry to the whole program ,main  The package name of the function must also be `main` 
func main() {
     
//  call fmt Bag Println Method , Output information on the screen 
fmt.Println("Hello World!") 
}

Be careful ：
Single-line comments ： //
Multiline comment ：/* sth */

2. Run code
   Direct operation

$ go run first.go
Hello World!

Compile first and execute

$ go build first.go
$ ./first   

3. GO Language configuration

Go It's a compiled language ,Go The tool chain of language converts the source code and its dependencies into the machine instructions of the computer （ Translation notes ： Static compilation ）

#  Set up module management model  
$ go env -w GO111MODULE=on
#  Set download source  
$ go env -w GOPROXY=https://goproxy.cn  

##  China's most reliable  Go  Module agent :https://goproxy.cn

# modify env
## echo "export GOPROXY=https://goproxy.cn" >> ~/.profile && source ~/.profile

Try to deploy GO project

1. Write code

package main

import (
	"fmt"
	"github.com/jinzhu/configor"
)

func main() {
    
	fmt.Println("vim-go",configor.Config{
    })
}

2. Initialize project ： It mainly solves the problem of package management dependency

#  initialization  
go mod init account 
#  Solve the problem of dependence （ Check , Delete the wrong or unused modules, Did you download it download Of package） 
go mod tidy

3. function

# go run proj.go 
vim-go {
     false false false false 0s <nil> false}

GO Language multi version and package management

go module

GOMODULE In mode ：

• All dependent packages are stored in GOPATH/pkg/mod Under the table of contents
• All third-party binary executables are placed in GOPATH/bin Under the table of contents
• The project can be placed in GOPATH Out of the path
• It is required that go.mod file （ The document passed go mod init Command initialization can generate ）

GOMODULE Patterns and GOPATH The same pattern specifies the location of the dependent package , The difference lies in GOMODULE Of go.mod The specific version of the dependent package is recorded in the file , It realizes the reuse of dependent packages between projects , And solved GOPATH In this mode, different projects cannot rely on different versions of the same package
problem

1. Use GO MODULE Pattern , You need to start the configuration first

$ export GO111MODULE=on 
 or 
$ go env -w GO111MODULE=on

Be careful ： After the module support is turned on , Not with GOPATH coexistence , Therefore, the project cannot be placed in GOPATH Under the table of contents ！！

About GO111MODULE If you are interested, please refer to this article ： The article links

go mod Use of commands

#  Initialize working directory  ->  Generate go.mod file  
$ go mod init code 
$ go mod tidy 
#  download gin, Download to pkg Catalog  
$ go get github.com/gin-gonic/gin

Common commands

$ go get   golang.org/x/tools/cmd/guru
$ go build golang.org/x/tools/cmd/guru
$ mv guru $(go env GOROOT)/bin

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Standard library -fmt library

fmt Is a common library for input and output , You can refer to the official website ：GO Chinese official website

stay fmt package , There are two kinds of methods for formatting input and output ： Scan （ Input function ） and Print （ Output function ）, Respectively in scan.go and print.go In file

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GO Language commonly used management commands

• go version： obtain Go edition
• go env: see Go environment variable
• go help： see Go Help order
• go get： Get remote package （ It needs to be installed in advance git or hg）
• go build： Compile and generate executable programs
• go run： Run the program directly
• go fmt： Format source code
• go install： Compile the package file and the whole program
• go test： go Unit test commands provided by native
• go clean： Remove the files compiled and generated in the current source package and the associated source package
• go tool： upgrade Go version , Fix old code
• godoc -http:80： Open a local 80 Port of web file
• gdb Executable name ： debugging Go Compiled file

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GO Summary of common language errors

encounter Windows Files on Linux There is a format error when running on

[[email protected] lexVim]# sh start_vim.sh
start_vim.sh: That's ok 9: $'\r':  Command not found 
start_vim.sh: That's ok 11: $'\r':  Command not found 
start_vim.sh: That's ok 12:  Unexpected symbols  `$'\r''  There are grammar errors nearby  'tart_vim.sh: That's ok 12: `function prompt() 

# Download tool 
yum install dos2unix

# transformation 
dos2unix zjh.sh


# Add executable rights 
chmod -x  file name 
./ file name   # It can be carried out （ No suffix ）

obtain GO Wrong time

[[email protected] code]# go get golang.org/x/tools/cmd/guru
go: go.mod file not found in current directory or any parent directory.
	'go get' is no longer supported outside a module.
	To build and install a command, use 'go install' with a version,
	like 'go install example.com/[email protected]'
	For more information, see https://golang.org/doc/go-get-install-deprecation
	or run 'go help get' or 'go help install'.


##  resolvent 
go mod init mycode  # Initialize the directory mod Directory of patterns 

environment variable GOPROXY Modification of （ It mainly solves the problem of slow download ）

echo "export GOPROXY=https://goproxy.cn" >> ~/.profile && source ~/.profile

# https://goproxy.cn  It is the most reliable in China  Go  Module agent 

perform go mod tidy Times wrong

 appear go mod tidy newspaper "all" matched no packages The reason is go.mod And execution go mod tidy The directory is not in a directory 

[[email protected] proj01]# go mod tidy # Help me install the dependent packages used 
go: warning: "all" matched no packages

After importing the package, you need to use , If it is not used, an error will be reported ！！

[[email protected] proj01]# go run proj.go
# command-line-arguments
./proj.go:6:2: imported and not used: "github.com/gin-gonic/gin"

Input ctrl+] Cannot jump to source

$ go get   golang.org/x/tools/cmd/guru
$ go build golang.org/x/tools/cmd/guru
$ mv guru $(go env GOROOT)/bin