golang-101-hacks(24)——Decorate types to implement io.Reader interface
golang-101-hacks(24)——Decorate types to implement io.Reader interface
羊羽shine
发布于 2019-07-01 11:27:41
发布于 2019-07-01 11:27:41
注：本文是对golang-101-hacks中文翻译
io包提供了一组便捷的读取函数和方法，但同时都需要参数满足io.Reader接口。请看下面的例子:
package main
import (
"fmt"
"io"
)
func main() {
s := "Hello, world!"
p := make([]byte, len(s))
if _, err := io.ReadFull(s, p); err != nil {
fmt.Println(err)
} else {
fmt.Printf("%s\n", p)
}
} 编译程序，会发生如下错误: Compile above program and an error is generated:
read.go:11: cannot use s (type string) as type io.Reader in argument to io.ReadFull:
string does not implement io.Reader (missing Read method)io.ReadFull函数要求参数应该实现了' io.Reader '，但' string '类型没有Read()方法，所以需要对' s '变量做转换。将io.ReadFull(s, p)转换为io.ReadFull(strings.NewReader(s), p)：
package main
import (
"fmt"
"io"
"strings"
)
func main() {
s := "Hello, world!"
p := make([]byte, len(s))
if _, err := io.ReadFull(strings.NewReader(s), p); err != nil {
fmt.Println(err)
} else {
fmt.Printf("%s\n", p)
}
}这次编译成功 运行结果如下
Hello, world!strings.NewReader函数可以将字符串转换成strings.Reader
func (r *Reader) Read(b []byte) (n int, err error) Besides string, another common operation is to use bytes.NewReader to convert a byte slice into a bytes.Reader struct which satisfies io.Reader interface. Do some modifications on the above example:
package main
import (
"bytes"
"fmt"
"io"
"strings"
)
func main() {
s := "Hello, world!"
p := make([]byte, len(s))
if _, err := io.ReadFull(strings.NewReader(s), p); err != nil {
fmt.Println(err)
}
r := bytes.NewReader(p)
if b, err := r.ReadByte(); err != nil {
fmt.Println(err)
} else {
fmt.Printf("%c\n", b)
}
}bytes.NewReader 将p切片转换为bytes.Reader结构。输出结果如下:
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原始发表：2019.06.28 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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