Go bytes包
bytes包基本方法的使用
package main
import (
"bytes"
)
func writeUInt16(buff []byte, data uint16) {
for i := 0; i < 2; i++ {
buff[i] = byte(data >> uint(i*8))
}
}
func spilt(r rune) bool {
if r == 'c' {
return true
}
return false
}
func main() {
println("hello world")
buff1 := make([]byte, 2) // 创建一个切片
writeUInt16(buff1, uint16(12))
buff2 := make([]byte, 2) // 创建一个切片
writeUInt16(buff2, uint16(12))
// 比较两个字节数组切片
res := bytes.Compare(buff1, buff2)
println(res)
// 字符串转换为字节数组
buff3 := []byte("hello world hello world")
seq := []byte("hello")
// Count counts the number of non-overlapping instances of sep in s
res = bytes.Count(buff3, seq)
println(res)
// Contains reports whether subslice is within b
contains := bytes.Contains(buff3, seq) //true
println(contains)
res = bytes.Index(buff3, seq) // 0
println(res)
res = bytes.LastIndex(buff3, seq)
println(res)
/**
Rune literals are just an integer value (as you've written).
They are "mapped" to their unicode codepoint.
*/
a := rune('e')
res = bytes.IndexRune(buff3, a) // -1
println(res)
println("------------")
buff5 := []byte("abcabcabcabc")
// SplitN 以 sep 为分隔符，将 s 切分成多个子串，结果中不包含 sep 本身
// 如果 sep 为空，则将 s 切分成 Unicode 字符列表
// 如果 s 中没有 sep，则将整个 s 作为 [][]byte 的第一个元素返回
// 参数 n 表示最多切分出几个子串，超出的部分将不再切分
// 如果 n 为 0，则返回 nil，如果 n 小于 0，则不限制切分个数，全部切分
arr := bytes.SplitN(buff5, []byte("a"), 3)
for _, v := range arr {
for _, t := range v {
print(t)
print(",")
}
println("|")
}
// Fields 以连续的空白字符为分隔符，将 s 切分成多个子串，结果中不包含空白字符本身
// 空白字符有：\t, \n, \v, \f, \r, ' ', U+0085 (NEL), U+00A0 (NBSP)
// 如果 s 中只包含空白字符，则返回一个空列表
println("------------")
buff6 := []byte("abc abc abc abc")
arr = bytes.Fields(buff6)
for _, v := range arr {
for _, t := range v {
print(t)
print(",")
}
println("|")
}
// FieldsFunc 以一个或多个连续的满足 f(rune) 的字符为分隔符，
// 将 s 切分成多个子串，结果中不包含分隔符本身
// 如果 s 中没有满足 f(rune) 的字符，则返回一个空列表
println("------------")
buff7 := []byte("abcabcabcabc")
arr = bytes.FieldsFunc(buff7, spilt)
for _, v := range arr {
for _, t := range v {
print(t)
print(",")
}
println("|")
}
buff8 := []byte("我是中国人")
// 将 s 切分为 Unicode 码点列表
data := bytes.Runes(buff8)
for _, elem := range data {
println(string(elem))
}
// Title 将 s 中的所有单词的首字母修改为其 Title 格式
buff9 := bytes.Title(buff7)
println(string(buff9))
// Map 将 s 中满足 mapping(rune) 的字符替换为 mapping(rune) 的返回值
// 如果 mapping(rune) 返回负数，则相应的字符将被删除
buff10 := bytes.Map(func(r rune) rune {
if r == 'c' {
return 'a'
}
return r
}, buff7)
println(string(buff10))
}
bytes包结构体-bytes.Reader
reader.go文件
// A Reader implements the io.Reader, io.ReaderAt, io.WriterTo, io.Seeker,
// io.ByteScanner, and io.RuneScanner interfaces by reading from
// a byte slice.
// Unlike a Buffer, a Reader is read-only and supports seeking.
type Reader struct {
s []byte
i int64 // current reading index
prevRune int // index of previous rune; or < 0
}Reader实现了以下接口，
io.Reader
io.ReaderAt
io.WriterTo
io.Seeker
io.ByteScanner
io.RuneScannerUnlike a Buffer, a Reader is read-only and supports seeking.
Reader结构体所属的方法，
func NewReader(b []byte) *Reader
func (r *Reader) Len() int
// Read implements the io.Reader interface
// Read 将 len(b) 个字节读取到 b 中。
func (r *Reader) Read(b []byte) (n int, err error)
// ReadAt implements the io.ReaderAt interface
// 从偏移量off开始读取len(b)个字节到 b 中
func (r *Reader) ReadAt(b []byte, off int64) (n int, err error)
func (r *Reader) ReadByte() (byte, error)
func (r *Reader) ReadRune() (ch rune, size int, err error)
func (r *Reader) Reset(b []byte)
// Seek implements the io.Seeker interface.
func (r *Reader) Seek(offset int64, whence int) (int64, error)
func (r *Reader) Size() int64
// UnreadByte implements the io.ByteScanner interface
func (r *Reader) UnreadByte() error
// UnreadRune implements the io.RuneScanner interface
func (r *Reader) UnreadRune() error
// WriteTo implements the io.WriteTo interface
// WriteTo writes data to w until there's no more data to write or
// when an error occurs.
func (r *Reader) WriteTo(w io.Writer) (n int64, err error)方法的使用示例，
package main
import (
"bytes"
"fmt"
"io"
)
func main() {
b1 := []byte("Hello World!")
reader := bytes.NewReader(b1)
// Read 方法
buff := make([]byte, 5)
count, err := reader.Read(buff)
if err != nil {
return
}
fmt.Printf("read count = %d,read data = %s\n", count, string(buff))
// ReadAt 方法
buff2 := make([]byte, 5)
count, err = reader.ReadAt(buff2, 6)
if err != nil {
return
}
fmt.Printf("read count = %d,read data = %s\n", count, string(buff2))
for {
// 依次返回未被读取的字节
b, err := reader.ReadByte()
if err == io.EOF {
break
}
println(string(b))
}
println("--------")
b2 := []byte("hello 世界！")
reader2 := bytes.NewReader(b2)
for {
// 依次返回未被读取的rune
r, _, err := reader2.ReadRune()
if err == io.EOF {
break
}
println(string(r))
}
b3 := []byte("string builder")
// Reset resets the Reader to be reading from b.
reader2.Reset(b3)
println(reader2.Len())
println("--------")
reader3 := bytes.NewReader(b1)
// Seek 设置下一次 Read 或 Write 的偏移量为 offset，它的解释取决于 whence：
// 0 表示相对于文件的起始处，1 表示相对于当前的偏移，而 2 表示相对于其结尾处。
// Seek 返回新的偏移量和一个错误，如果有的话。
abs, err := reader3.Seek(-2, 2)
println(abs)
b, _ := reader3.ReadByte()
println(string(b))
}
bytes包结构体-bytes.Buffer
buffer.go文件，
// A Buffer is a variable-sized buffer of bytes with Read and Write methods.
// The zero value for Buffer is an empty buffer ready to use.
type Buffer struct {
buf []byte // contents are the bytes buf[off : len(buf)]
off int // read at &buf[off], write at &buf[len(buf)]
runeBytes [utf8.UTFMax]byte // avoid allocation of slice on each call to WriteRune
bootstrap [64]byte // memory to hold first slice; helps small buffers avoid allocation.
lastRead readOp // last read operation, so that Unread* can work correctly.
}Buffer结构体所属的方法，
func NewBuffer(buf []byte) *Buffer
func NewBufferString(s string) *Buffer
func (b *Buffer) Bytes() []byte
func (b *Buffer) Cap() int
func (b *Buffer) Grow(n int)
func (b *Buffer) Len() int
func (b *Buffer) Next(n int) []byte
func (b *Buffer) Read(p []byte) (n int, err error)
func (b *Buffer) ReadByte() (byte, error)
func (b *Buffer) ReadBytes(delim byte) (line []byte, err error)
func (b *Buffer) ReadFrom(r io.Reader) (n int64, err error)
func (b *Buffer) ReadRune() (r rune, size int, err error)
func (b *Buffer) ReadString(delim byte) (line string, err error)
func (b *Buffer) Reset()
func (b *Buffer) String() string
func (b *Buffer) Truncate(n int)
func (b *Buffer) UnreadByte() error
func (b *Buffer) UnreadRune() error
func (b *Buffer) Write(p []byte) (n int, err error)
func (b *Buffer) WriteByte(c byte) error
func (b *Buffer) WriteRune(r rune) (n int, err error)
func (b *Buffer) WriteString(s string) (n int, err error)
func (b *Buffer) WriteTo(w io.Writer) (n int64, err error)方法的使用示例，
package main
import (
"bytes"
"fmt"
)
func main() {
b1 := []byte("hello world!")
buf := bytes.NewBuffer(b1)
fmt.Printf("buff len=%d\n", buf.Len())
fmt.Printf("buff cap=%d\n", buf.Cap())
buf.Grow(100)
fmt.Printf("buff len=%d\n", buf.Len())
fmt.Printf("buff cap=%d\n", buf.Cap())
b2 := make([]byte, 6)
// Read reads the next len(p) bytes from the buffer or until the buffer is drained. The return value n is the number of bytes read.
// If the buffer has no data to return, err is io.EOF (unless len(p) is zero); otherwise it is nil.
buf.Read(b2)
println(string(b2)) //hello
b3 := buf.Next(5)
println(string(b3)) //world
b4 := buf.Next(3)
println(string(b4))
buf2 := bytes.NewBuffer(b1)
// ReadBytes reads until the first occurrence of delim in the input,
// returning a slice containing the data up to and including the delimiter.
b5, _ := buf2.ReadBytes(byte(' '))
println(len(b5))
println(string(b5))
b6 := []byte("go programming")
buf3 := bytes.NewBuffer(b1)
// Write appends the contents of p to the buffer, growing the buffer as
// needed.
buf3.Write(b6)
println(string(buf3.Bytes()))
}
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