io

基础

flowchart TB
subgraph 单接口
    direction LR
    r1(Reader)---w1(Writer)---c1(Closer)---s1(Seeker)
end
subgraph 双接口
    direction LR
    rw(ReadWriter)---rc(ReadCloser)---rs(ReadSeeker)---wc(WriteCloser)---ws(WriteSeeker)
end
subgraph 三接口
    direction LR
    rwc(ReadWriteCloser)---rsc(ReadSeekCloser)---rws(ReadWriteSeeker)
end

单接口 --组合--> 双接口 --组合--> 三接口

• Reader

type Reader interface {
    // 读取len(p)字节到p里面
    // 返回读取成功字节数
    // eof表示正常结束
    Read(p []byte) (n int, err error)
}

• Writer

type Writer interface {
    // 写入p里面内容,len(p)字节
    // 返回写入成功字节数
    Write(p []byte) (n int, err error)
}

类型

flowchart TB
subgraph Byte
    direction LR
    br(ByteReader)---bw(ByteWriter)---bc(ByteScanner)
end
subgraph Rune
    direction LR
    rr(RuneReader)---rw(ByteWriter)---rc(ByteScanner)
end
subgraph String
    direction LR
    sw(StringWriter)
end

扩展

flowchart TB
subgraph 附加
    direction LR
    rf(ReaderFrom)---wt(WriterTo)---ra(ReaderAt)---wa(WriterAt)
end
subgraph 限制
    direction LR
    lr(LimitedReader)---sr(SectionReader)
end
subgraph 内部
    direction LR
    d(discard)---nc(nopCloser)---tr(teeReader镜像)
    mr(multiReader串联)---mw(multiWriter广播)
    pr(PipeReader就地读)--同个pipe,chan实现---pw(PipeWriter就地写)
end

便利函数

WriteString(w Writer, s string) (n int, err error)
ReadAll(r Reader) ([]byte, error)
ReadFull(r Reader, buf []byte) (n int, err error)
ReadAtLeast(r Reader, buf []byte, min int) (n int, err error)
CopyN(dst Writer, src Reader, n int64) (written int64, err error)
Copy(dst Writer, src Reader) (written int64, err error)
CopyBuffer(dst Writer, src Reader, buf []byte) (written int64, err error)

//扩展close接口
NopCloser(r Reader)ReadCloser
//把r读出来内容写一份到w,镜像r到w
TeeReader(r Reader, w Writer) Reader
//最多读n个字节,达到就返回eof
LimitReader(r Reader, n int64) Reader
//串联起多个源头,按顺序依次读完
MultiReader(readers ...Reader) Reader
//把w写入内容广播多个writers中
MultiWriter(writers ...Writer) Writer
//就地成双读写,通过chan []byte实现
Pipe() (*PipeReader, *PipeWriter)

// 切片扩容
if len(b) == cap(b) {
    // Add more capacity (let append pick how much).
    b = append(b, 0)[:len(b)]
}