如何使用 CSVWriter 从逗号分隔的键写入 csv：字符串的值列表

Question

我有一个 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 写入 csv，其中冒号之前是列名，之后是值。

例如在上面的例子中：acctHolderName:null,acctHolderName 是一个列名，null 是它的值。

Answer 1

您可以使用CSVWriter.writeAll(List<String[]> list) 方法来编写您的整个列表。为了从您的列表中以所需格式List<String[]> 获取适当的数据，您只需提取标题，例如从列表的第一个元素中提取标题，以及从列表的所有元素中提取所需的所有值。为此，只需在 , 处拆分每个字符串，流过生成的数组，在 : 处再次拆分，映射到第一个元素作为列名，到第二个元素作为值。

例如，假设您的数据格式正确并且所有行都有相同数量的“列”，这是第一种没有异常处理的方法：

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);
    }
}

然后调用上面的方法

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");
}