安装Goland2022.2.5 版本

1.官网下载goland-2022.2.5.dmg版本（Mac)版本。如果是windows版本也可以直接下载）

2.配置gopath，基本都是配置.我这里配置为/usr/local/go 作为全目录，如果是windows，直接在环境中配置path路径就好。

3.查看版本 go version 

go version
go version go1.19.3 darwin/amd64

建立工作目录gowork

基本目录结构为gowork/hello

                         gowork/greetings 2个目录文件

目录结构为：

 

建立hello.go文件

package main

import (
	"fmt"

	"example.com/greetings"
)

func main() {
	// Get a greeting message and print it.
	message := greetings.Hello("XiaMenKeny")
	fmt.Println(message)
}

保存的时候，会提示错误。因为里面有调用example.com/greetings的引用包

建立greetings.go文件，在greetings目录下

package main

import (
	"fmt"

	"example.com/greetings"
)

func main() {
	// Get a greeting message and print it.
	message := greetings.Hello("XiaMenKeny")
	fmt.Println(message)
}

分别建立2个文件。这个时候再进行会提示找不到 

example.com/hello module to use your local example.com/greetings

需要在原先环境下编辑一下mod，用命令，实际是修改到本地的目录文件上

go mod edit -replace example.com/greetings=../greetings

打开看go.mod 就可以看到已经变为，说明已经修改到本地目录上的

module example.com/hello

go 1.19

require (
	example.com/greetings v0.0.0-00010101000000-000000000000
	github.com/isdamir/gotype v0.0.0-20200101084212-6aa1591106b2
	rsc.io/quote v1.5.2
)

require (
	golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c // indirect
	rsc.io/sampler v1.3.0 // indirect
)

replace example.com/greetings => ../greetings

运行Hello 调用greetings里面的函数方法

 go run hello.go
Hi, XiaMenKeny. Welcome by keny16999 from Beijing !

说明hello.go 已经调用了greetings.go里面的Hello方法。传输的参数是字符串

代码需要完善如果不知道谁调动的，需要返回一个错误

hello.go 修改带2参数的判断error

package main

import (
	"fmt"
	"log"

	"example.com/greetings"
)

func main() {
	// Get a greeting message and print it.

	log.SetPrefix("greetings: ")
	log.SetFlags(0)

	// Request a greeting message.
	message, err := greetings.Hello("")
	// If an error was returned, print it to the console and
	// exit the program.
	if err != nil {
		log.Fatal(err)
	}

	//greetings.Hello("XiaMenKeny")
	fmt.Println(message)
}
G

我们可以直接运行这里直接传入一个空串，查看是否有错误出现,正确返回错误信息，

 go run hello.go
greetings: empty name
exit status 1

空的名称确实不好，这样修改为随机返回一个字符串

package greetings

import (
	"errors"
	"fmt"
	"math/rand"
	"time"
)

// Hello returns a greeting for the named person.
func Hello(name string) (string, error) {
	// If no name was given, return an error with a message.
	if name == "" {
		return name, errors.New("empty name")
	}
	// Create a message using a random format.
	message := fmt.Sprintf(randomFormat(), name)
	return message, nil
}

// init sets initial values for variables used in the function.
func init() {
	rand.Seed(time.Now().UnixNano())
}

// randomFormat returns one of a set of greeting messages. The returned
// message is selected at random.
func randomFormat() string {
	// A slice of message formats.
	formats := []string{
		"Hi, %v. Welcome by keny16999 from Beijing !",
		"Great to see you, %v!",
		"Hail, %v! Well met!",
	}

	// Return a randomly selected message format by specifying
	// a random index for the slice of formats.
	return formats[rand.Intn(len(formats))]
}

修改hello.go

实践上代码是随机抽取字符串的3个字符串，代码比较简单，直接过就好。

#go run hello.go
Great to see you, Gladys!
#go run hello.go
Hi, kenyabc. Welcome by keny16999 from Beijing !
#go run hello.go
Hail, kenyabc! Well met!

继续修改，返回Map(key,value）值

继续修改greetings.go代码

package greetings

import (
	"errors"
	"fmt"
	"math/rand"
	"time"
)

// Hello returns a greeting for the named person.
func Hello(name string) (string, error) {
	// If no name was given, return an error with a message.
	if name == "" {
		return name, errors.New("empty name")
	}
	// Create a message using a random format.
	message := fmt.Sprintf(randomFormat(), name)
	return message, nil
}

// Hellos returns a map that associates each of the named people
// with a greeting message.
func Hellos(names []string) (map[string]string, error) {
	// A map to associate names with messages.
	messages := make(map[string]string)
	// Loop through the received slice of names, calling
	// the Hello function to get a message for each name.
	for _, name := range names {
		message, err := Hello(name)
		if err != nil {
			return nil, err
		}
		// In the map, associate the retrieved message with
		// the name.
		messages[name] = message
	}
	return messages, nil
}

// Init sets initial values for variables used in the function.
func init() {
	rand.Seed(time.Now().UnixNano())
}

// randomFormat returns one of a set of greeting messages. The returned
// message is selected at random.
func randomFormat() string {
	// A slice of message formats.
	formats := []string{
		"Hi, %v. Welcome!",
		"Great to see you, %v!",
		"Hail, %v! Well met!",
	}

	// Return one of the message formats selected at random.
	return formats[rand.Intn(len(formats))]
}

修改hello.go代码

package main

import (
	"fmt"
	"log"

	"example.com/greetings"
)

func main() {
	// Set properties of the predefined Logger, including
	// the log entry prefix and a flag to disable printing
	// the time, source file, and line number.
	log.SetPrefix("greetings: ")
	log.SetFlags(0)

	// A slice of names.
	names := []string{"机器猫", "多爱猫", "天猫"}

	// Request greeting messages for the names.
	messages, err := greetings.Hellos(names)
	if err != nil {
		log.Fatal(err)
	}
	// If no error was returned, print the returned map of
	// messages to the console.
	fmt.Println(messages)
}

运行结果

go run hello.go
map[多爱猫:Hail, 多爱猫! Well met! 天猫:Hail, 天猫! Well met! 机器猫:Hi, 机器猫. Welcome!]
返回name多个参数，里面有3个全部返回

建立一个测试代码greetings_test.go.

package greetings

import (
    "testing"
    "regexp"
)

// TestHelloName calls greetings.Hello with a name, checking
// for a valid return value.
func TestHelloName(t *testing.T) {
    name := "Gladys"
    want := regexp.MustCompile(`\b`+name+`\b`)
    msg, err := Hello("Gladys")
    if !want.MatchString(msg) || err != nil {
        t.Fatalf(`Hello("Gladys") = %q, %v, want match for %#q, nil`, msg, err, want)
    }
}

// TestHelloEmpty calls greetings.Hello with an empty string,
// checking for an error.
func TestHelloEmpty(t *testing.T) {
    msg, err := Hello("")
    if msg != "" || err == nil {
        t.Fatalf(`Hello("") = %q, %v, want "", error`, msg, err)
    }
}

测试直接用go test运行

下面说明没有发现测试文件。需要查看一下目录

go test
?       example.com/hello       [no test files]

测试文件建立在greetings目录下，要在greetings目录下运行

 go test -v
=== RUN   TestHelloName
--- PASS: TestHelloName (0.00s)
=== RUN   TestHelloEmpty
--- PASS: TestHelloEmpty (0.00s)
PASS
ok      example.com/greetings   0.016s

说明空的参数也通过。

时间上要修改一下greetings.go代码，区别就是参数传递的时候，有个是空的，目的是测试一个空的函数是否提示正确

	// message := fmt.Sprintf(randomFormat(), name)
	
	message := fmt.Sprint(randomFormat())

 TestHelloName
    greetings_test.go:15: Hello("Gladys") = "Hi, %v. Welcome!", <nil>, want match for `\bGladys\b`, nil
--- FAIL: TestHelloName (0.00s)

明显是说明需要参数传递的。

编译和安装代码

$ go build

Mac和linux编译为hello执行文件，如果不可以执行，手工修改一下属性，变成可以执行的

$ go build
 ./hello
map[Gladys:Hail, Gladys! Well met! 多爱猫:Hail, 多爱猫! Well met! 天猫:Hail, 天猫! Well met!]

把代码添加到你的gopath里面去，相当于部署到bin目录中 hello目录下输入go install 将hello新编译的文件已经注册到新的目录去。