go-文件操作

删除文件

import (
    "log"
    "os"
)
func main() {
    err := os.Remove("test.txt")
    if err != nil {
        log.Fatal(err)
    }
}

文件是否存在

import (
    "log"
    "os"
)
var (
    fileInfo *os.FileInfo
    err      error
)
func main() {
    // 文件不存在则返回error
    fileInfo, err := os.Stat("test.txt")
    if err != nil {
        if os.IsNotExist(err) {
            log.Fatal("File does not exist.")
        }
    }
    log.Println("File does exist. File information:")
    log.Println(fileInfo)
}

读取文件

import(  
    "fmt"  
    "os"  
    "flag"  
    "io"  
    "io/ioutil"  
    "bufio"  
    "time"  
)  

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,1024)  
    for{  
        n,err := fi.Read(buf)  
        if err != nil && err != io.EOF{panic(err)}  
        if 0 ==n {break}  
        chunks=append(chunks,buf[:n]...)  
        // fmt.Println(string(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]...)  
        // fmt.Println(string(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)  
    // fmt.Println(string(fd))  
    return string(fd)  
}  

func main(){  

    flag.Parse()  
    file := flag.Arg(0)  
    f,err := ioutil.ReadFile(file)  
    if err != nil{  
        fmt.Printf("%s\n",err)  
        panic(err)  
    }  
    fmt.Println(string(f))  
    start := time.Now()  
    read1(file)  
    t1 := time.Now()  
    fmt.Printf("Cost time %v\n",t1.Sub(start))  
    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))  

}  

ioutil提供的方法效率最高

改变权限、拥有者、时间戳

import (
    "log"
    "os"
    "time"
)
func main() {
    // 使用Linux风格改变文件权限
    err := os.Chmod("test.txt", 0777)
    if err != nil {
        log.Println(err)
    }
    // 改变文件所有者
    err = os.Chown("test.txt", os.Getuid(), os.Getgid())
    if err != nil {
        log.Println(err)
    }
    // 改变时间戳
    twoDaysFromNow := time.Now().Add(48 * time.Hour)
    lastAccessTime := twoDaysFromNow
    lastModifyTime := twoDaysFromNow
    err = os.Chtimes("test.txt", lastAccessTime, lastModifyTime)
    if err != nil {
        log.Println(err)
    }
}