CSVPrinter 僅從 header 中刪除引號

Question

當引用值時，我需要在模式下使用來自 Apache 的 commons 的 CSVPrinter，但 header 不是。 看起來報價模式只有一個選項，影響 header 和值。 這可以獨立完成嗎？

CSVFormat format = CSVFormat.DEFAULT.withHeader(new String(){"a", "b"})
                .withQuoteMode(QuoteMode.ALL);
CSVPrinter printer = new CSVPrinter(new FileWriter(new File("out.csv")), format);
printer.printRecord("a val", "b val");
printer.printRecord("1", "2");
printer.flush();
printer.close();

給出：

"a", "b"
"a val", "b val"
"1", "2"

但要求是：

a,b
"a val", "b val"
"1", "2"

Answer 1

您可以對 header 使用一種格式，對記錄使用另一種格式：

FileWriter writer = new FileWriter(new File("out.csv"));
CSVFormat formatHeader = CSVFormat.DEFAULT
                    .withHeader(new String[]{"a", "b"})
                    .withEscape('"').withQuoteMode(QuoteMode.NONE);
CSVFormat formatRecord = CSVFormat.DEFAULT.withQuoteMode(QuoteMode.ALL);
CSVPrinter headerPrinter = new CSVPrinter(writer, formatHeader);
headerPrinter.flush();
CSVPrinter recordPrinter = new CSVPrinter(writer, formatRecord);
recordPrinter.printRecord("a val", "b val");
recordPrinter.printRecord("1", "2");
recordPrinter.flush();
recordPrinter.close();
headerPrinter.close();

Answer 2

事實上，由於 stream 是使用 FileWriter 截斷的，答案是使用另一種輸出 stream：

Path target = Files.createTempFile(null, ".csv");
BufferedWriter writer = Files.newBufferedWriter(
        target,
        StandardOpenOption.APPEND,
        StandardOpenOption.CREATE);
CSVFormat formatHeader = CSVFormat.DEFAULT.withHeader(new String[]{"a", "b"}).withEscape('"').withQuoteMode(QuoteMode.NONE);
CSVPrinter headerPrinter = new CSVPrinter(writer, formatHeader);
headerPrinter.flush(); 
headerPrinter.close(); 

CSVFormat format = CSVFormat.DEFAULT.withQuoteMode(QuoteMode.ALL);
writer = Files.newBufferedWriter(target, StandardOpenOption.APPEND, StandardOpenOption.CREATE); 
CSVPrinter printer = new CSVPrinter(writer, format)
printer.printRecord("a val", "b val");
printer.printRecord("1", "2");
printer.flush();
printer.close();