Golang从stdin行读取多个字段

$ echo "A 1 2 3 4" | go run test.go 
entire:  A
next field:  A

I need to read several lines from standard input that are like "A 1 2 3 4" (code does one line for now) and something goes wrong. Scanln should read the entire line and Fields should split it by newlines? Why does Scanln read only one word?

package main

import (
    "fmt"
    "strings"
)

func main() {
    var line string
    fmt.Scanln(&line)
    fmt.Println("entire: ",line)
    for _,x := range strings.Fields(line) {
        fmt.Println("next field: ",x)
    }
}

$ echo "A 1 2 3 4" | go run test.go 
entire:  A
next field:  A

Have you tried:

package main

import (
    "fmt"
    "os"
    "bufio"
    "strings"
)

func main() {
    var line string
    scanner := bufio.NewScanner(os.Stdin)
    for scanner.Scan() {
        line = scanner.Text()
        fmt.Println("Got line:", line)
        for _, x := range strings.Fields(line) {
            fmt.Println("next field: ",x)
        }
    }
}

Then:

$ printf "aa bb 
 cc dd " | go run 1.go  
Got line: aa bb
next field:  aa
next field:  bb
Got line:  cc dd
next field:  cc
next field:  dd

I got mislead by another question's answer that said Scanln reads an entire line. No, Scanln is only a Scan that reads words (space separated strings) and as many as actual variables specified, but quits parsing on a newline. Its totally confusing what the readline equivalent would be in Go.