如何使用 CSVWriter 從逗號分隔鍵寫入 csv：字符串的值列表

Question

我有一個 k:v 格式的字符串列表，如下所示：

List<String> data = new ArrayList();

data[0] = "acctHolderName:null,auctEndDt:2021-04-23,auctTitle:2 X BUCKLE RACING SEAT BELT HARNESS,bankName:null,buyerId:22494074,byrCntryId:1,cardlastFourDigits:1234,checkoutStatus:2,cityShipAddr:null,ckCompleteDate:2021-04-04 08:06:27,cnvstnIdList:null,countryShipAddr:null,createdTime:2021-04-04 08:06:27,firstTrackingDtlId:17824011,gmvBuyerLcAmt:59.990000000,gmvSellerLcAmt:59.9900000000000000,gmvUsdAmt:59.9900000000000000,instrumentType:null,itemId:4966893,itemPrice:59.99,itemSiteId:100,nonPciAccountId:null,omsExternalRfrncId:17-06848-86625,omsOrderId:170000684886625,orderStsId:0,paidDate:2021-04-04 08:06:27,paymentMethod:[34],"


data[1] = "acctHolderName:null,auctEndDt:2021-04-22,auctTitle:2 X BELT,bankName:null,buyerId:22491011,byrCntryId:2,cardlastFourDigits:5678,checkoutStatus:2,cityShipAddr:null,ckCompleteDate:2020-05-04 08:06:26,cnvstnIdList:null,countryShipAddr:null,createdTime:2020-05-04 08:06:27,firstTrackingDtlId:17834022,gmvBuyerLcAmt:59.990000000,gmvSellerLcAmt:59.9900000000000000,gmvUsdAmt:59.9900000000000000,instrumentType:null,itemId:4955893,itemPrice:59.99,itemSiteId:101,nonPciAccountId:null,omsExternalRfrncId:17-06848-86625,omsOrderId:170000684886625,orderStsId:0,paidDate:2021-03-04 08:06:27,paymentMethod:[34],"

如何使用opencsv CSVWriter寫入 csv ，其中冒號之前是列名，之后是值。

因此，例如在上述情況下： acctHolderName:null ， acctHolderName是列名， null 是它的值。

Answer 1

您可以使用方法CSVWriter.writeAll(List<String[]> list)來編寫整個列表。 為了從您的列表中以所需格式List<String[]>獲取適當的數據，您只需要提取標題，例如從列表的第一個元素中提取標題，以及從列表的所有元素中提取所需的所有值。 為此，只需將每個字符串拆分為, , stream 到結果數組上，再次拆分: map 到第一個元素作為列名，到第二個元素作為值。

例如，假設您的數據格式正確並且所有行都有相同數量的“列”，這是第一種沒有異常處理的方法：

public static void writeListToFile(List<String> list, String fileName) throws IOException {
    
    List<String[]> out = new ArrayList<>();
    
    //extract headers
    String[] columns = Arrays.stream(list.get(0).split(","))
                             .map(str -> str.split(":")[0])
                             .toArray(String[]::new);
    
    //extract values
    List<String[]> rows = list.stream()
                              .map(line -> Arrays.stream(line.split(","))
                                                 .map(str -> str.split(":")[1])
                                                 .toArray(String[]::new))
                              .collect(Collectors.toList());
    
    out.add(columns);
    out.addAll(rows);
    
    try (CSVWriter writer = new CSVWriter(new FileWriter(fileName))) {
        writer.writeAll(out);
    }
}

並調用上面的方法

public static void main(String[] args) throws IOException {
    List<String> data = List.of("acctHolderName:null,auctEndDt:2021-04-23,auctTitle:2 X BUCKLE RACING SEAT BELT HARNESS,bankName:null,buyerId:22494074,byrCntryId:1,cardlastFourDigits:1234,checkoutStatus:2,cityShipAddr:null,ckCompleteDate:2021-04-04 08:06:27,cnvstnIdList:null,countryShipAddr:null,createdTime:2021-04-04 08:06:27,firstTrackingDtlId:17824011,gmvBuyerLcAmt:59.990000000,gmvSellerLcAmt:59.9900000000000000,gmvUsdAmt:59.9900000000000000,instrumentType:null,itemId:4966893,itemPrice:59.99,itemSiteId:100,nonPciAccountId:null,omsExternalRfrncId:17-06848-86625,omsOrderId:170000684886625,orderStsId:0,paidDate:2021-04-04 08:06:27,paymentMethod:[34],",
                                "acctHolderName:null,auctEndDt:2021-04-22,auctTitle:2 X BELT,bankName:null,buyerId:22491011,byrCntryId:2,cardlastFourDigits:5678,checkoutStatus:2,cityShipAddr:null,ckCompleteDate:2020-05-04 08:06:26,cnvstnIdList:null,countryShipAddr:null,createdTime:2020-05-04 08:06:27,firstTrackingDtlId:17834022,gmvBuyerLcAmt:59.990000000,gmvSellerLcAmt:59.9900000000000000,gmvUsdAmt:59.9900000000000000,instrumentType:null,itemId:4955893,itemPrice:59.99,itemSiteId:101,nonPciAccountId:null,omsExternalRfrncId:17-06848-86625,omsOrderId:170000684886625,orderStsId:0,paidDate:2021-03-04 08:06:27,paymentMethod:[34],");

    writeListToFile(data, "C:\\Users\\Atihska\\Downloads\\mydata.csv");
}