文件读写io/bufio/os/ioutil

os

package main

import (
    "log"
    "os"
)

func main() {
    // 1.文件的基础操作，create/open/close/chmod -> go/io库
    f, err := os.Create("create.txt")
    if err != nil {
        log.Fatalf("get file info error: %s\n", err.Error())
    }
    // 文件状态信息 file stats
    fileInfo, err := f.Stat()
    if err != nil {
        log.Fatalf("create file error: %s\n", err.Error())
    }
    log.Printf("File Name is %s\n", fileInfo.Name())
    log.Printf("File Permissions is %s\n", fileInfo.Mode())
    log.Printf("File ModTime is %s\n", fileInfo.ModTime())

    // 关闭文件 close
    err = f.Close()
    if err != nil {
        log.Fatalf("close file failed err=%s\n", err)
    }
    // 删除文件 delete
    err = os.Remove("create.txt")
    if err != nil {
        log.Fatalf("remove file failed err=%s\n", err)
    }
}

ioutil

func ReadAll(r io.Reader) ([]byte, error)

func ReadFile(filename string) ([]byte, error)

func WriteFile(filename string, data []byte, perm os.FileMode) error

func ReadDir(dirname string) ([]os.FileInfo, error)

func TempFile(dir, pattern string) (f *os.File, err error)

func TempDir(dir, pattern string) (name string, err error)

bufio

f, err := os.Open("connect.go")
defer f.Close()
if err != nil {
  panic(err)
}
//func NewReader(rd io.Reader) *Reader
reader := bufio.NewReader(f)
totLine := 0
for {
  //func (b *Reader) ReadLine() (line []byte, isPrefix bool, err error)
  content, isPrefix, err := reader.ReadLine()
  fmt.Println(string(content), isPrefix, err)
  //当单行的内容超过缓冲区时，isPrefix会被置为true；否则为false；
  if !isPrefix {
    totLine++
  }
  if err == io.EOF {
    fmt.Println("一共有", totLine, "行内容")
    break
  }
}

path := "test.txt"
f, err := os.Create(path)
defer f.Close()
if err != nil {
  panic(err)
}
//func NewWriter(w io.Writer) *Writer
bufferWrite := bufio.NewWriter(f)
if err != nil {
  panic(err)
}
demo := "1234567890"
for _, v := range demo {
  // 将数据写入缓冲区
  // func (b *Writer) WriteString(s string) (int, error)
  bufferWrite.WriteString(string(v))
}
data, _ := ioutil.ReadFile(path)
fmt.Println(string(data))   // 输出空的内容
// 将缓冲区的数据写入文件
// func (b *Writer) Flush() error
bufferWrite.Flush()
data, _ = ioutil.ReadFile(path)
fmt.Println(string(data))   // 输出：1234567890