golang读取文件操作
import (
"bytes"
"io"
"io/ioutil"
"log"
"os"
)
// ReadFile
// ioutil.ReadFile(filename string) 调用了ioutil.readAll()
// ioutil.readAll()对os.Open os.Close 封装实现
func ReadFile(filename string) (s string, err error) {
f, err := ioutil.ReadFile(filename)
if err != nil {
log.Println(err.Error())
}
s = string(f)
return
}
// ReadAll
// 和ReadFile一样，同样是调用了ioutil.readAll()
func ReadAll(filename string) (s string, err error) {
f, err := os.Open(filename)
if err != nil {
log.Println(err.Error())
}
b, err := ioutil.ReadAll(f)
if err != nil {
log.Println(err.Error())
}
s = string(b)
return
}
// Read
func Read(filename string) (s string, err error) {
f, err := os.Open(filename)
if err != nil {
log.Println(err.Error())
}
defer f.Close()
var n int64 = bytes.MinRead
if fi, err := f.Stat(); err == nil {
if size := fi.Size() + bytes.MinRead; size > n {
n = size
}
}
var buf bytes.Buffer
defer func() {
e := recover()
if e == nil {
return
}
if panicErr, ok := e.(error); ok && panicErr == bytes.ErrTooLarge {
err = panicErr
} else {
panic(e)
}
}()
if int64(int(n)) == n {
buf.Grow(int(n))
}
_, err = buf.ReadFrom(f)
s = string(buf.Bytes())
return
}
// OpenRead
func OpenRead(filename string) (s string, err error) {
f, err := os.Open(filename)
if err != nil {
log.Println(err.Error())
}
defer f.Close()
buf := make([]byte, 1024)
_, err = f.Read(buf)
if err != nil && err != io.EOF {
panic(err)
}
s = string(buf)
return
}