Go 语言读取文件内容（或逐行读取文件内容）

读取全文（适合小文件内容）

package main

import (
    "fmt"
    "log"
    "os"
)

func main() {
    content, err := os.ReadFile("file.txt")
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(string(content))
}

输出

Hello World!
This is txt file read by Go!

逐行读取文件内容

package main

import (
    "bufio"
    "fmt"
    "log"
    "os"
)

func main() {
    // open file
    f, err := os.Open("file.txt")
    if err != nil {
        log.Fatal(err)
    }
    // remember to close the file at the end of the program
    defer f.Close()

    // read the file line by line using scanner
    scanner := bufio.NewScanner(f)

    for scanner.Scan() {
        // do something with a line
        fmt.Printf("line: %s\n", scanner.Text())
    }

    if err := scanner.Err(); err != nil {
        log.Fatal(err)
    }
}

输出

line: Hello World!
line: This is txt file read by Go!

逐字读取文件内容

package main

import (
    "bufio"
    "fmt"
    "log"
    "os"
)

func main() {
    // open file
    f, err := os.Open("file.txt")
    if err != nil {
        log.Fatal(err)
    }
    // remember to close the file at the end of the program
    defer f.Close()

    // read the file word by word using scanner
    scanner := bufio.NewScanner(f)
    scanner.Split(bufio.ScanWords)

    for scanner.Scan() {
        // do something with a word
        fmt.Println(scanner.Text())
    }

    if err := scanner.Err(); err != nil {
        log.Fatal(err)
    }
}

输出

Hello
World!
This
is
txt
file
read
by
Go!

分块读取文件（适合大文件读取）

package main

import (
    "fmt"
    "io"
    "log"
    "os"
)

const chunkSize = 10

func main() {
    // open file
    f, err := os.Open("file.txt")
    if err != nil {
        log.Fatal(err)
    }
    // remember to close the file at the end of the program
    defer f.Close()

    buf := make([]byte, chunkSize)

    for {
        n, err := f.Read(buf)
        if err != nil && err != io.EOF {
            log.Fatal(err)
        }

        if err == io.EOF {
            break
        }

        fmt.Println(string(buf[:n]))
    }
}

输出

Hello Worl
d!
This is
 txt file 
read by Go
!

转载自：https://gosamples.dev/read-file/#:~:text=The%20simplest%20way%20of%20reading%20a%20text%20or,the%20file%20line%20by%20line%20or%20in%20chunks.