作用
goroutine之间互相通信
无缓冲channel
- make(chan xxx)
- 无缓冲的channel会阻塞，必须等待从channel取出才结束
package main
import "fmt"
func main() {
// 无缓冲channel
c:=make(chan int)
go func() {
defer fmt.Println("goroutine exit")
fmt.Println("goroutine running ...")
// 发送给channel
c<-0
}()
// 读取channel数据
res:= <-c
fmt.Println(res)
defer fmt.Println("main goroutine exit")
}
goroutine running ...
goroutine exit
0
main goroutine exit
有缓冲channel
- make(chan xxx,size)
- channel满了再次添加会阻塞
- channel空了再次取出会阻塞
package main
import (
"fmt"
"time"
)
func main() {
c := make(chan int,3)
fmt.Println("init len:",len(c),"cap:",cap(c))
go func() {
defer fmt.Println("child goroutine exit")
for i:=0;i<5;i++ {
c<-i
fmt.Println("send:",i,"len:",len(c),"cap:",cap(c))
}
}()
time.Sleep(3*time.Second)
for i:=0;i<5;i++{
fmt.Println(<-c)
}
defer fmt.Println("main goroutine exit")
}
init len: 0 cap: 3
send: 0 len: 1 cap: 3
send: 1 len: 2 cap: 3
send: 2 len: 3 cap: 3
0
1
2
3
send: 3 len: 3 cap: 3
send: 4 len: 0 cap: 3
child goroutine exit
4
main goroutine exit
关闭channel
- close(xxx)
- 只有不需要发送数据时才需要关闭channel
- 关闭channel后无法再次发送数据
- 关闭channel后可以继续接受数据
- nil channel不可收发
package main
import "fmt"
func main() {
c:= make(chan int)
go func() {
for i:=0;i<3;i++{
c<-i
}
// 当不需要再次发送数据后需要关闭channel,如果被关闭可能会引发死锁
close(c)
}()
for{
// 如果 channel 没有关闭则 ok 为ture 当channel内没有数据后为false
if res,ok:= <-c;ok{
fmt.Println(res)
}else {
break
}
}
}
0
1
2