go 生成器读取csv文件 写csv文件 指定或不指定headers写入

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package main   import (     "encoding/csv"     "encoding/json"     "fmt"     "io"     "os"     "strconv"     "strings"     "time" )   func readCsvYield(fPath string, seq rune, printNum int) chan map[string]interface{} {     /*         fPath: 输入文件         seq: 分隔符         printNum: 打印的行数     */     // var yield chan map[string]interface{}     yield := make(chan map[string]interface{})     var resDict map[string]interface{}     resDict = make(map[string]interface{})     go func() {         file, err := os.Open(fPath)         if err != nil {             fmt.Println(err)             close(yield)         }         defer file.Close()         reader := csv.NewReader(file)         // 设置分隔符seq         reader.Comma = seq         //reader.Comment = '\xEF\xBB\xBF'         totalRows := -1         var keys []string         for {             row, err := reader.Read()             if err != nil && err != io.EOF {                 fmt.Printf("can not read , err is %s", err)                 close(yield)             }             if err == io.EOF {                 fmt.Println("total:", totalRows)                 close(yield)                 break             }             // 获取key             if totalRows == -1 {                 for _, r := range row {                     // utf-8 bom去掉                     r = strings.Replace(r, "\uFEFF", "", -1)                     keys = append(keys, r)                 }                   totalRows += 1                 continue             }             // 组合成字典             for idx, item := range row {                 resDict[keys[idx]] = item             }             totalRows += 1             yield <- resDict             resDict = make(map[string]interface{})             if totalRows%printNum == 0 {                 fmt.Println(totalRows)             }         }     }()     return yield }   func writeCsv(outFile string, data []map[string]interface{}) {     file, err := os.OpenFile(outFile, os.O_CREATE|os.O_RDWR, 0644)     if err != nil {         fmt.Println(err)     }     defer file.Close()     // 写入UTF-8 BOM 防止中文乱码     file.WriteString("\xEF\xBB\xBF")     w := csv.NewWriter(file)       var key []string     for idx, item := range data {         var values []string         // 第一行写入 获取key 写入第一行         if idx == 0 {             var tmpV []string             for k, v := range item {                 key = append(key, k)                 v := Strval(v)                 tmpV = append(tmpV, v)             }             w.Write(key)             w.Write(tmpV)             continue         }         for _, k := range key {             v := Strval(item[k])             values = append(values, v)         }         w.Write(values)         w.Flush()     }   }   func writeCsvWithHeader(outFile string, data []map[string]interface{}, headers []string) {     file, err := os.OpenFile(outFile, os.O_CREATE|os.O_RDWR, 0644)     if err != nil {         fmt.Println(err)     }     defer file.Close()     var key []string     // 写入UTF-8 BOM 防止中文乱码     file.WriteString("\xEF\xBB\xBF")     w := csv.NewWriter(file)     key = append(key, headers...)     w.Write(key)       for _, item := range data {         var values []string         for _, k := range key {             v := Strval(item[k])             values = append(values, v)         }         w.Write(values)         w.Flush()     }   }   func getHeader(inFile string, seq rune) []string{     var headers []string     file, err := os.Open(inFile)     if err != nil {         fmt.Println("读取文件出错", err)         return headers     }     reader := csv.NewReader(file)     reader.Comma = seq           recon, _ := reader.Read()       headers = append(headers, recon...)       defer file.Close()     return headers }     func Strval(value interface{}) string {     var key string     if value == nil {         return key     }       switch value.(type) {     case float64:         ft := value.(float64)         key = strconv.FormatFloat(ft, 'f', -1, 64)     case float32:         ft := value.(float32)         key = strconv.FormatFloat(float64(ft), 'f', -1, 64)     case int:         it := value.(int)         key = strconv.Itoa(it)     case uint:         it := value.(uint)         key = strconv.Itoa(int(it))     case int8:         it := value.(int8)         key = strconv.Itoa(int(it))     case uint8:         it := value.(uint8)         key = strconv.Itoa(int(it))     case int16:         it := value.(int16)         key = strconv.Itoa(int(it))     case uint16:         it := value.(uint16)         key = strconv.Itoa(int(it))     case int32:         it := value.(int32)         key = strconv.Itoa(int(it))     case uint32:         it := value.(uint32)         key = strconv.Itoa(int(it))     case int64:         it := value.(int64)         key = strconv.FormatInt(it, 10)     case uint64:         it := value.(uint64)         key = strconv.FormatUint(it, 10)     case string:         key = value.(string)     case []byte:         key = string(value.([]byte))     default:         newValue, _ := json.Marshal(value)         key = string(newValue)     }       return key }   func main() {           fileName := "D:\\tmp\\20220228\\9982.csv"     startTime := time.Now()     var res []map[string]interface{}     for line := range readCsvYield(fileName, ',', 100000) {         //fmt.Println(line["credit_code"])         //fmt.Println(line["name"])         res = append(res, line)     }     fmt.Println(res)     fmt.Println(len(res))           endTime := time.Now()     fmt.Println(endTime.Sub(startTime))             }