Go语言开发,step by step (Part 1:从hello world到网站开发)

ProgrammingIsStory · · 1531 次点击 · · 开始浏览    
这是一个创建于 的文章,其中的信息可能已经有所发展或是发生改变。

 

通过上一篇转载的文章 "Yesterday Once More ---再次遇到Go语言",可以搭建Go语言开发环境了。

现在开始Go语言(Golang)程序开发, here we Go.

 

Example 1. 最简单的程序Let's Go:

package main // There must be a so-called main package for a Go EXE.

import  "fmt" // fmt is a package including Print

func main(){ //The entry of a Go EXE
 fmt.Print("Hello,Let's Go") //Main program context
}


 

程序代码非常简单,任何有编程功底的人都可以看懂。

在Eclipse中Run即可在Console中看到打印结果:

Hello,Let's Go


 

Example 2. 并行程序(多协程,可以简单地理解成多线程程序)

 (*注1,协程者,轻量级线程也,因其轻量级,系统中的协程可以百万计)。具体实现此处不细表。

*注2,紫色颜色处代码表示本例子是改自上面的例子,同时紫色本身代码表示修改/添加的代码。这样更方便读者阅读。)


 这基本上是一个Go语言中并发程序的雏形;但是大家其实可能已经看出,主进程在创建协程后即退出,因此可能该协程根本没有机会执行。

 

package main // There must be a so-called main package for a Go EXE.

import  "fmt" // fmt is a package including Print

func Coroutine(){ //Coroutine function
	fmt.Println("go")
}

func main(){ //The entry of a Go EXE
	//Main program context
	fmt.Println("Hello,Let's ..."); 
	go Coroutine();
}



 

Example 3. 引入同步机制,实现真正的并行程序

Golang中用channel实现协程间通信, 可以用sync包中的Mutex, RWMutex来实现协程间同步以及资源共享,channel也可以用来协程间同步。

Golang中的channel就类似于linux中的管道,原理一样。

 

 

package main // There must be a so-called main package for a Go EXE.

import  "fmt" // fmt is a package including Print

func Coroutine(ch chan int, i int ){ //Coroutine function
	fmt.Println("go", i);
	ch <- i; //write a int value to chan
}

func main(){ //The entry of a Go EXE
	//Main program context
	fmt.Println("Hello,Let's ..."); 
	chs := make([]chan int, 10); //make an array containning 10 chan
	for i := 0; i < 10; i++{ // 
		chs[i] = make(chan int); //create a chan value
		go Coroutine(chs[i], i); //run a coroutine
	}
	
	//For the main process, read value from the chan array
	for _,ch := range(chs){ //loop the array
		//read value from each chan if there's a value; 
		//otherwise, it is locked.
		c := <- ch; 
					
		fmt.Println("Main Process gets from Coroutine:", c)
	}
}

 



 

(*Go程序每句结束不必用分号;但是我个人习惯还是加了个分号。)
此程序创建了10个协程,主程序与协程之间通信以及同步。

输出:

Hello,Let's ...
go 0
go 1
go 2
go 3
go 4
go 5
go 6
go 7
go 8
go 9
Main Process gets from Coroutine: 0
Main Process gets from Coroutine: 1
Main Process gets from Coroutine: 2
Main Process gets from Coroutine: 3
Main Process gets from Coroutine: 4
Main Process gets from Coroutine: 5
Main Process gets from Coroutine: 6
Main Process gets from Coroutine: 7
Main Process gets from Coroutine: 8
Main Process gets from Coroutine: 9


Example 4. 加点高级技巧:使用匿名函数+多核支持

(*注,匿名函数与是否多核完全没有联系,只是为了在一个例子同时用这个2个技巧)

 

package main // There must be a so-called main package for a Go EXE.

import "fmt" // fmt is a package including Print
import "runtime"

func main(){ //The entry of a Go EXE
	//Main program context
	fmt.Println("Hello,Let's ..."); 
	chs := make([]chan int, 10); //make an array containning 10 chan
	
	runtime.GOMAXPROCS(10);//Make the coroutines running in 10 CPUs
	for i := 0; i < 10; i++{ // 
		chs[i] = make(chan int); //create a chan value
		go func(ch chan int, i int){//Use anonymous function instead
			fmt.Println("go", i);
			ch <- i; //write a int value to chan
		}(chs[i],i); //pass the value into funciton
	}
	
	//For the main process, read value from the chan array
	for _,ch := range(chs){ //loop the array
		//read value from each chan if there's a value; 
		//otherwise, it is locked.
		c := <- ch; 
					
		fmt.Println("Main Process gets from Coroutine:", c)
	}
}
 


 

 

这样,我们就实现了一个完整的在多核系统上运行的并行程序。
此例在我的系统上(Intel Core 2 Duo) 的输出结果是:

Hello,Let's ...
go 0
go 4
go 5
go 6
go 7
Main Process gets from Coroutine: 0
go 2
go 8
go 9
go 1
Main Process gets from Coroutine: 1
Main Process gets from Coroutine: 2
go 3
Main Process gets from Coroutine: 3
Main Process gets from Coroutine: 4
Main Process gets from Coroutine: 5
Main Process gets from Coroutine: 6
Main Process gets from Coroutine: 7
Main Process gets from Coroutine: 8
Main Process gets from Coroutine: 9


Example 5. 做一个最简单的网站, Let's Go!

 Webserver监听8080端口,收到客户端的yes的时候,做出回答。

 

package main // There must be a so-called main package for a Go EXE.

import(	"fmt";"io";"log";"net/http")


func mainHandler(w http.ResponseWriter, r *http.Request){
	io.WriteString(w,"Let's Go");	
}

func main(){
	http.HandleFunc("/yes", mainHandler);
	fmt.Print("Sever is ready, shall we go?");
	err := http.ListenAndServe(":8080",nil);
	if err != nil{
		log.Fatal("ListenAndServe:",err.Error());
	}
}
 


 

程序可以在Eclipse中执行,也可以在命令行中执行,如下图。

客户端是用IE浏览器访问http://localhost:8080,并写消息"yes"到8080端口。

(*注,我遇到问题是我的杀毒软件一直阻挡我的main程序,这种情况下,需要暂时关闭该保护)

 

 

第一部分就到此为止;用意是用鲜明的例子激起大家(包括我自己)对这门语言的好奇或者喜爱。

 

参考文献

1. golang.org

2. 《Go语言编程》徐世伟 吕桂华等编著,人民邮电出版社

本文来自:CSDN博客

感谢作者:ProgrammingIsStory

查看原文:Go语言开发,step by step (Part 1:从hello world到网站开发)

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