初探go-golang语言初体验
2017/2/24
一、初体验
1、环境
wget https://storage.googleapis.com/golang/go1.8.linux-amd64.tar.gz
tar -C /usr/local -xzf go1.8.linux-amd64.tar.gz
cat <<‘_EOF‘ >>/etc/profile
#golang
export PATH=$PATH:/usr/local/go/bin
export GOPATH=/opt/go
_EOF
source /etc/profile
2、教程
# go tool tour &
访问：http://127.0.0.1:3999/
3、第一个程序
# cd $GOPATH
# mkdir src/abc.com/demo/hello -p
# vim src/abc.com/demo/hello/hello.go
package main
import "fmt"
func main() {
fmt.Printf("Hello, world.\n")
}
# go install abc.com/demo/hello
# bin/hello
Hello, world.
4、第一个包
# mkdir src/abc.com/demo/stringutil -p
# vim src/abc.com/demo/stringutil/reverse.go
// Package stringutil contains utility functions for working with strings.
package stringutil
// Reverse returns its argument string reversed rune-wise left to right.
func Reverse(s string) string {
r := []rune(s)
for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {
r[i], r[j] = r[j], r[i]
}
return string(r)
}
# go build abc.com/demo/stringutil
# cat src/abc.com/demo/hello/hello.go
package main
import (
"fmt"
"abc.com/demo/stringutil"
)
func main() {
fmt.Printf(stringutil.Reverse("!oG ,olleH"))
}
# go install abc.com/demo/hello
# bin/hello
Hello, Go!
5、目录结构
# tree /opt/go
/opt/go
├── bin # install 后生成的可执行文件目录
│ └── hello
├── pkg # install 后生成的包目录
│ └── linux_amd64
│ └── abc.com
│ └── demo
│ └── stringutil.a
└── src # 源码目录
└── abc.com
└── demo
├── hello
│ └── hello.go
└── stringutil
└── reverse.go
10 directories, 4 files
6、引入测试
# vim src/abc.com/demo/stringutil/reverse_test.go
package stringutil
import "testing"
func TestReverse(t *testing.T) {
cases := []struct {
in, want string
}{
{"Hello, world", "dlrow ,olleH"},
{"Hello, 世界", "界世 ,olleH"},
{"", ""},
}
for _, c := range cases {
got := Reverse(c.in)
if got != c.want {
t.Errorf("Reverse(%q) == %q, want %q", c.in, got, c.want)
}
}
}
# go test abc.com/demo/stringutil
ok abc.com/demo/stringutil 0.007s
7、使用远程的包
示例，从git上指定的url获取包，go get 将完成 fetch, build 和 install的操作：
# go get github.com/golang/example/hello
# bin/hello
Hello, Go examples!
8、查看当前 go 的环境变量
[root@tvm01 go]# go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/opt/go"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build679741147=/tmp/go-build"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
二、试着写一个小的程序
1、设定目标
1）尽量多的用到go语言的语法基础内容：packages, variables ,functions Flow control, method, interface, concurrency
2）请求 url，获取状态等；
2、代码示例
[root@tvm01 go]# cat src/abc.com/demo/website/website.go
/*
# go demo: website
# 2017/2/24
*/
package main
import (
"fmt"
"log"
"time"
"net/http"
"io/ioutil"
"strings"
"strconv"
"os"
)
type taskstat struct {
success int
failure int
}
func checkError(err error, method string) bool {
if err != nil {
log.Printf("[E] %s : %v", method, err)
return true
}
return false
}
func getHosts() ([]string) {
var hosts []string
data, err := ioutil.ReadFile("hosts.txt")
if checkError(err, "outil.ReadFile") {
return hosts
}
for _, h := range strings.Split(string(data), "\n") {
if h == "" {
continue
}
hosts = append(hosts, h)
}
return hosts
}
func request_url(cnt int, url string, ch chan string, stat *taskstat) {
head, err := http.Head(url)
if checkError(err, "http.Head") {
stat.failure += 1
ch <- "[" + strconv.Itoa(cnt) + "]" + url
ch <- "[" + strconv.Itoa(cnt) + "]failed"
return
}
stat.success += 1
status := head.Status
ch <- "[" + strconv.Itoa(cnt) + "]" + url + " : " + status
res, err := http.Get(url)
if checkError(err, "http.Get") {
return
}
data, err := ioutil.ReadAll(res.Body)
if checkError(err, "ioutil.ReadAll") {
return
}
ch <- "[" + strconv.Itoa(cnt) + "]" + "Got size: " + strconv.Itoa(len(data))
}
func main() {
var cnt int = 10
var err error
var hosts []string
var stat = taskstat{0, 0}
dt_start := time.Now()
if len(os.Args) > 2 {
cnt, err = strconv.Atoi(os.Args[1])
if checkError(err, "strconv.Atoi") {
return
}
if len(os.Args) == 3 {
hosts = append(hosts, os.Args[2])
} else {
hosts = getHosts()
}
}
for _, url := range hosts {
ch := make(chan string)
for i := 0; i < cnt; i++ {
go request_url(i, "http://"+url, ch, &stat)
}
for t := 0; t < cnt; t++ {
fmt.Println(<-ch)
fmt.Println(<-ch)
}
}
fmt.Printf("\nsuccess: %d, failure: %d\n", stat.success, stat.failure)
log.Printf("Time Cost: %v", time.Since(dt_start))
}
3、如何运行
1）直接运行
[root@tvm01 go]# go run src/abc.com/demo/website/website.go 3 www.qq.com
[0]http://www.qq.com : 200 OK
[1]http://www.qq.com : 200 OK
[2]http://www.qq.com : 200 OK
[0]Got size: 251425
[1]Got size: 251425
[2]Got size: 251425
success: 3, failure: 0
2017/02/24 16:59:40 Time Cost: 118.27674ms
2）编译
当前为 linux 环境
[root@tvm01 go]# go install abc.com/demo/website
运行
[root@tvm01 go]# bin/website 3 www.qq.com
3）交叉编译
以 windows 平台为例：
[root@tvm01 go]# GOOS="windows" go install abc.com/demo/website
[root@tvm01 go]# sz bin/windows_amd64/website.exe
下载到windows下执行，符合预期
XYXW、参考
1、golang
https://golang.org/doc
https://golang.org/doc/code.html#Workspaces
2、the-way-to-go_ZH_CN
https://github.com/Unknwon/the-way-to-go_ZH_CN/blob/master/eBook/directory.md原文地址：http://nosmoking.blog.51cto.com/3263888/1900991
