对golang goroutine、channel、select、reflect 温习一下，写了几个小例子
* 利用非 buff channel 和 goroutine 实现双goroutine 交易执行例子
```
type Ball struct { hits int }
func player(name string, table chan *Ball) {
for {
ball := <-table
ball.hits++
fmt.Println(name, ball.hits)
time.Sleep(1 * time.Nanosecond)
table <- ball
}
}
func TestChannel(t *testing.T) {
table := make(chan *Ball)
go player("ping", table)
go player("pong", table)
table <- new(Ball) // game on; toss the ball
time.Sleep(10 * time.Nanosecond)
<-table // game over; grab the ball
}
```
* 利用非buff channel单端读写阻塞特性灵活控制代码执行流程
```
func TestGoroutine(t *testing.T) {
var ch = make(chan int)
go func() {
counter := <-ch
for {
counter++
fmt.Println("counter", counter)
time.Sleep(1 * time.Nanosecond)
}
}()
ch <- 0
start := time.Now().Nanosecond()
time.Sleep(10 * time.Nanosecond)
end := time.Now().Nanosecond()
fmt.Println("cost-time", end - start)
}
```
* 下面是一个select检测多个channel的实例
```
func TestSelect(t *testing.T) {
a, b := make(chan string), make(chan string)
go func() { a <- "a" }()
go func() { b <- "b" }()
b = nil
for i := 2; i > 0; i-- {
select {
case s := <-b:
fmt.Println("got", s)
case s := <-a:
fmt.Println("got", s)
}
}
fmt.Println("finished")
}
```
* 下面是一个通过反射构建struct，并通过json.Unmarshal 初始化struct的例子
```
type data struct {
Title string
Firstname, Lastname string
Rank int
}
func TestAnonymousStruct(t *testing.T) {
dValue := reflect.ValueOf(new(data))
dKind := dValue.Kind()
if dKind == reflect.Ptr || dKind == reflect.Ptr {
dValue = dValue.Elem()
}
fmt.Println("dValue", dValue)
d1 := dValue.Interface()
byteArray := bytes.NewBufferString(`{"Title":"title","Firstname":"firstName","Lastname":"lastname","Rank":1}`).Bytes()
err := json.Unmarshal(byteArray, &d1)
if nil != err {
fmt.Println("d1 fill fail ")
}
fmt.Println(d1)
}
```