type PipeWriter
type PipeWriter struct {
// contains filtered or unexported fields
}
</div>
(1)func (w *PipeWriter) Close() error关闭管道，关闭时正在进行的Read操作将返回EOF，若管道内仍有未读取的数据，后续仍可正常读取
import (
"fmt"
"io"
)
func main() {
r, w := io.Pipe()
go w.Write([]byte("hello word"))
data := make([]byte, 10)
n, err := r.Read(data)
w.Close()
if err == io.EOF {
fmt.Println("executing read return EOF")
fmt.Println("executing read reads number", n)
}
n, _ = r.Read(data)
fmt.Println(string(data)) //hello word
fmt.Println("next read number", n) //next read number 0
}
</div>
(2)func (w *PipeWriter) CloseWithError(err error) error这个函数和read里边的CloseWithError是大同小异的，关闭管道，关闭时正在进行的Read操作将返回参数传入的异常，若管道内仍有未读取的数据，后续仍可正常读取
import (
"errors"
"fmt"
"io"
)
func main() {
r, w := io.Pipe()
go w.Write([]byte("hello widuu"))
newerr := errors.New("your daye 突然关闭了")
w.CloseWithError(newerr)
data := make([]byte, 10)
_, err := r.Read(data)
if err != nil {
fmt.Println(err) //your daye 突然关闭了
}
}
</div>
(3)func (w *PipeWriter) Write(data []byte) (n int, err error)终于来打write了，这个是把字节切片写入管道，返回的是写入字节数和error,前边用到的太多了，随便哪一个吧
import (
"fmt"
"io"
)
func main() {
r, w := io.Pipe()
go w.Write([]byte("hello widuu")) //写入的是[]byte,注意官方文档写的是，写入管道阻塞，一直到所有数据的读取结束
data := make([]byte, 11)
n, _ := r.Read(data)
fmt.Println(string(data)) //hello widuu
fmt.Println("read number", n) //read number 10
}
</div>
type Reader
type Reader interface {
Read(p []byte) (n int, err error)
}
</div>
(1)func LimitReader(r Reader, n int64) Reader，我们之前就说了Reader这个结构，其实这就是对Reader的一次封装，限定了它读取字节数，其实他实现的就是io.LimitedReader{}这个结构
import (
"fmt"
"io"
"os"
"reflect"
)
func main() {
f, _ := os.Open("test.txt")
defer f.Close()
reader := io.LimitReader(f, 5)
p := make([]byte, 5)
fmt.Println(reflect.TypeOf(reader)) //*io.LimitedReader
var total int
for {
n, err := reader.Read(p)
if err == io.EOF {
fmt.Println("read value", string(p[:total])) //read value hello
fmt.Println(total) //5
break
}
total = total + n
}
}
</div>
(2)func MultiReader(readers ...Reader) Reader这个函数一看就知道是封装了多个readers,跟上边的方法差不多，只是封装了多个而已，当然还去除了读取的限制，我们代码给大家测试一下
import (
"fmt"
"io"
"os"
"reflect"
)
func main() {
f1, _ := os.Open("test1.txt")
f2, _ := os.Open("test.txt")
defer f1.Close()
defer f2.Close()
reader := io.MultiReader(f1, f2) //*io.multiReader
fmt.Println(reflect.TypeOf(reader))
p := make([]byte, 10)
var total int
var data string
for {
n, err := reader.Read(p)
if err == io.EOF {
fmt.Println("read end", total) //read end 17
break
}
total = total + n
data = data + string(p[:n])
}
fmt.Println("read value", data) //read value widuu2hello widuu
fmt.Println("read count", total) // read count 17
}
</div>
(3)既然上边介绍读了，我这介绍个写吧type Write`func MultiWriter(writers ...Writer) Writer一样的作用只不过是这次换成写了
import (
"fmt"
"io"
"io/ioutil"
"os"
)
func main() {
f1, _ := os.Create("1.txt")
f2, _ := os.Create("2.txt")
writer := io.MultiWriter(f1, f2)
writer.Write([]byte("widuu"))
//千万别这么逻辑来 ，我这是测试用的哈
r1, _ := ioutil.ReadFile("1.txt")
r2, _ := ioutil.ReadFile("2.txt")
fmt.Println(string(r1)) //widuu
fmt.Println(string(r2)) //widuu
}
</div>
(4)func TeeReader(r Reader, w Writer) Reader这个方法有意思是从r中读取数据然后写入到w中，这个没有内部缓冲区，看下代码
import (
"fmt"
"io"
"os"
"reflect"
)
func main() {
r, _ := os.Open("test.txt")
w, _ := os.Create("test2.txt")
reader := io.TeeReader(r, w)
fmt.Println(reflect.TypeOf(reader)) //*io.teeReader
p := make([]byte, 10)
n, _ := reader.Read(p)
fmt.Println(string(p[:n])) //hello widu
}
</d