1.返回值使用通道
func main() { // 生成随机数作为一个服务 randService := randGenerator() // 从服务中读取随机数并打印 fmt.Printf("%d\n",<-randService) } func randGenerator() chan int { // 创建通道 out := make(chan int) // 创建协程 go func() { for { //向通道内写入数据,如果无人读取会等待 out <- rand.Int() } }() return out }
2.参数使用通道
//一个查询结构体 type query struct { //参数Channel sql chan string //结果Channel result chan string } //执行Query func execQuery(q query) { //启动协程 go func() { //获取输入 sql := <-q.sql //访问数据库,输出结果通道 q.result <- "get" + sql }() } func main() { //初始化Query q := query{make(chan string, 1),make(chan string, 1)} //执行Query,注意执行的时候无需准备参数 execQuery(q) //准备参数 q.sql <- "select * from table" //获取结果 fmt.Println(<-q.result) }
3.并发循环
func doSomething(num int) (sum int) { for i := 1; i <= 10; i++ { fmt.Printf("%d + %d = %d\n", num, num + i, num + num + i) sum = sum + num + i } return sum } func testLoop() { // 建立计数器,通道大小为cpu核数 var NumCPU = runtime.NumCPU() fmt.Printf("NumCPU = %d\n", NumCPU) sem :=make(chan int, NumCPU); //FOR循环体 data := []int{1, 11, 21, 31, 41, 51, 61, 71, 81, 91} for _,v:= range data { //建立协程 go func (v int) { fmt.Printf("doSomething(%d)...\n", v) sum := doSomething(v); //计数 sem <- sum; } (v); } // 等待循环结束 var total int = 0 for i := 0; i < len(data); i++ { temp := <- sem fmt.Printf("%d <- sem\n", temp) total = total + temp } fmt.Printf("total = %d\n", total) } func main() { testLoop() }
4.利用channel计算素数
// Send the sequence 2, 3, 4, ... to channel 'in'. func Generate(ch chan int) { for i := 2; ; i++ { ch<- i // Send 'i' to channel 'in'. } } // Copy the values from channel 'in' to channel 'out', // removing those divisible by 'prime'. func Filter(in chan int, out chan int, prime int) { for { i := <-in // Receive valuefrom 'in'. if i%prime != 0 { out <- i // Send'i' to 'out'. } } } func main() { in := make(chan int) go Generate(in) // Launch Generate goroutine. for i := 0; i < 100; i++ { prime := <-in print(prime, "\n") out := make(chan int) go Filter(in, out, prime) in = out } }
5.共享变量的读写
//共享变量有一个读通道和一个写通道组成 type shardedVar struct { reader chan int writer chan int } //共享变量维护协程 func whachdog(v shardedVar) { go func() { //初始值 var value int = 0 for { //监听读写通道,完成服务 select { case value = <-v.writer: case v.reader <-value: } } }() } func main() { //初始化,并开始维护协程 v := shardedVar{make(chan int), make(chan int)} whachdog(v) //读取初始值 fmt.Println(<-v.reader) //写入一个值 v.writer <- 1 //读取新写入的值 fmt.Println(<-v.reader) }
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