直接回答：小文件直接用 os.ReadFile 一把读进来，大文件用 bufio.Scanner 逐行处理，要拷贝文件用 io.Copy，只读一部分就自己开 File 加 Read；取文件名用 filepath.Base，去后缀用 strings.TrimSuffix。
读取文件的四种方法
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| package main
import (
"bufio"
"fmt"
"io"
"io/ioutil"
"os"
"time"
)
func read0(path string) string {
f, err := ioutil.ReadFile(path)
if err != nil {
fmt.Printf("%s\n", err)
panic(err)
}
return string(f)
}
func read1(path string) string {
fi, err := os.Open(path)
if err != nil {
panic(err)
}
defer fi.Close()
chunks := make([]byte, 1024, 1024)
buf := make([]byte, 512)
for {
n, err := fi.Read(buf)
if err != nil && err != io.EOF {
panic(err)
}
if 0 == n {
break
}
chunks = append(chunks, buf[:n]...)
}
return string(chunks)
}
func read2(path string) string {
fi, err := os.Open(path)
if err != nil {
panic(err)
}
defer fi.Close()
r := bufio.NewReader(fi)
chunks := make([]byte, 1024, 1024)
buf := make([]byte, 1024)
for {
n, err := r.Read(buf)
if err != nil && err != io.EOF {
panic(err)
}
if 0 == n {
break
}
chunks = append(chunks, buf[:n]...)
}
return string(chunks)
}
func read3(path string) string {
fi, err := os.Open(path)
if err != nil {
panic(err)
}
defer fi.Close()
fd, err := ioutil.ReadAll(fi)
return string(fd)
}
func main() {
file := "../test.go"
start := time.Now()
read0(file)
t0 := time.Now()
fmt.Printf("Cost time %v\n", t0.Sub(start))
read1(file)
t1 := time.Now()
fmt.Printf("Cost time %v\n", t1.Sub(t0))
read2(file)
t2 := time.Now()
fmt.Printf("Cost time %v\n", t2.Sub(t1))
read3(file)
t3 := time.Now()
fmt.Printf("Cost time %v\n", t3.Sub(t2))
}
|
取文件名与去掉后缀
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| package main
import (
"fmt"
"path"
"strings"
)
func main() {
fullFilename := "test.txt"
var filenameWithSuffix string
filenameWithSuffix = path.Base(fullFilename)
var fileSuffix string
fileSuffix = path.Ext(filenameWithSuffix)
var filenameOnly string
filenameOnly = strings.TrimSuffix(filenameWithSuffix, fileSuffix)
fmt.Println("filenameOnly =", filenameOnly)
}
|
这篇笔记整理自我自己的实践记录，如果做法有出入，或者你踩过别的坑，欢迎到留言板一起聊聊。
