通道的基本發(fā)送和接收都阻塞。但是，可以使用select和default子句來實現(xiàn)非阻塞發(fā)送，接收，甚至非阻塞多路選擇(select)。
這里是一個非阻塞接收。如果消息上有可用的值，則選擇將使用該值的<-message大小寫。如果不是，它會立即采用默認情況。
非阻塞發(fā)送工作類似。
可以使用多個上面的默認子句來實現(xiàn)多路非阻塞選擇(select)。這里嘗試對消息(message)和信號(signals)的非阻塞接收。
所有的示例代碼，都放在
F:\worksp\golang目錄下。安裝Go編程環(huán)境請參考：http://www.yiibai.com/go/go_environment.html
non-blocking-channel-operations.go的完整代碼如下所示 -
package main
import "fmt"
func main() {
messages := make(chan string)
signals := make(chan bool)
// Here's a non-blocking receive. If a value is
// available on `messages` then `select` will take
// the `<-messages` `case` with that value. If not
// it will immediately take the `default` case.
select {
case msg := <-messages:
fmt.Println("received message", msg)
default:
fmt.Println("no message received")
}
// A non-blocking send works similarly.
msg := "hi"
select {
case messages <- msg:
fmt.Println("sent message", msg)
default:
fmt.Println("no message sent")
}
// We can use multiple `case`s above the `default`
// clause to implement a multi-way non-blocking
// select. Here we attempt non-blocking receives
// on both `messages` and `signals`.
select {
case msg := <-messages:
fmt.Println("received message", msg)
case sig := <-signals:
fmt.Println("received signal", sig)
default:
fmt.Println("no activity")
}
}
執(zhí)行上面代碼，將得到以下輸出結(jié)果 -
F:\worksp\golang>go run non-blocking-channel-operations.go
no message received
no message sent
no activity
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