go語言csv文件的讀取與寫入

go語言csv文件的讀取

暫時未整理

package main

import (
    "encoding/csv"
    "fmt"
    "io"
    "log"
    "os"
)

func main() {
    //準備讀取文件
    fileName := "D:\\gotest\\src\\source\\test.csv"
    fs, err := os.Open(fileName)
    if err != nil {
        log.Fatalf("can not open the file, err is %+v", err)
    }
    defer fs.Close()

    r := csv.NewReader(fs)
    //針對大文件，一行一行的讀取文件
    for {
        row, err := r.Read()
        if err != nil && err != io.EOF {
            log.Fatalf("can not read, err is %+v", err)
        }
        if err == io.EOF {
            break
        }
        fmt.Println(row)
    }

    //針對小文件，也可以一次性讀取所有的文件
    //注意，r要重新賦值，因為readall是讀取剩下的
    fs1, _ := os.Open(fileName)
    r1 := csv.NewReader(fs1)
    content, err := r1.ReadAll()
    if err != nil {
        log.Fatalf("can not readall, err is %+v", err)
    }
    for _, row := range content {
        fmt.Println(row)
    }

    //創建一個新文件
    newFileName := "D:\\gotest\\src\\source\\newfile.csv"
    //這樣打開，每次都會清空文件內容
    //nfs, err := os.Create(newFileName)

    //這樣可以追加寫
    nfs, err := os.OpenFile(newFileName, os.O_RDWR|os.O_CREATE, 0666)
    if err != nil {
        log.Fatalf("can not create file, err is %+v", err)
    }
    defer nfs.Close()
    nfs.Seek(0, io.SeekEnd)

    w := csv.NewWriter(nfs)
    //設置屬性
    w.Comma = ','
    w.UseCRLF = true
    row := []string{"1", "2", "3", "4", "5,6"}
    err = w.Write(row)
    if err != nil {
        log.Fatalf("can not write, err is %+v", err)
    }
    //這里必須刷新，才能將數據寫入文件。
    w.Flush()

    //一次寫入多行
    var newContent [][]string
    newContent = append(newContent, []string{"1", "2", "3", "4", "5", "6"})
    newContent = append(newContent, []string{"11", "12", "13", "14", "15", "16"})
    newContent = append(newContent, []string{"21", "22", "23", "24", "25", "26"})
    w.WriteAll(newContent)

}