如何在Java中将日期转换为字符串从2018年12月17日到2018-12-17.我想将其存储到MYSQL数据库 [英] How to convert date as string from 17-Dec-2018 to 2018-12-17 in java. I want to store it to MYSQL database

问题描述

我已成功将日期列从excel导入到Java代码中.但是，我无法将日期格式从2018年12月17日更改为2018-12-17.请帮助.

I have successfully imported date column from excel to the java code. However, I am unable to change the date format from 17-Dec-2018 to 2018-12-17. Kindly help.

public  void saveToDatabase(Vector dataHolder) throws ParseException {
          System.out.println(dataHolder);
          for(Iterator iterator = dataHolder.iterator();iterator.hasNext();) {
              List list = (List) iterator.next();
                fullName = list.get(0).toString();
                idNumberString = list.get(1).toString();
                                //idNumber = Integer.parseInt ( idNumberString );
                committee = list.get(2).toString();
                amountString = list.get(3).toString();
                                //amount = Integer.parseInt ( amountString );
                bosaFosa = list.get(4).toString();
                purpose = list.get(5).toString();
                paymentsType = list.get(6).toString();
                supportingDocuments = list.get(7).toString();
                entryDate = list.get(8).toString();
                }

当月从excel列中获取数据后，代码现在以文本形式显示为"Dec"，即"2018年12月17日" 我希望最终的字符串输出为"2018-12-17"，以便我可以将DATE Type存储在MYSQL数据库中.

The code now after fetching data from excel column the month is in text as "Dec" that is "17-Dec-2018" I expect the final output in string as "2018-12-17" so that I can store in MYSQL database as DATE Type.

推荐答案

java.time

    DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("d-MMM-uuuu", Locale.ENGLISH);

    String fullName = "Emmanuel Macron";
    int idNumber = 42;
    String entryDateString = "17-Dec-2018";

    LocalDate entryDate = LocalDate.parse(entryDateString, dateFormatter);

    PreparedStatement insertStatement = yourDbConnection.prepareStatement(
            "insert into your_table (name, id, entry) values (?, ?, ?);");
    insertStatement.setString(1, fullName);
    insertStatement.setInt(2, idNumber);
    insertStatement.setObject(3, entryDate);
    int rowsInserted = insertStatement.executeUpdate();

该示例比您的示例简单一些，但是应该可以回答您的要求，因此我相信其余的内容.我正在使用(并强烈推荐)现代Java日期和时间API java.time，用于Java中的所有日期工作.

The example is a bit simpler than yours, but should answer what you are asking about, so I trust the rest to you. I am using (and warmly recommending) java.time, the modern Java date and time API, for all date work in Java.

该日期涉及的步骤是:

1. 将日期字符串解析为LocalDate. LocalDate.parse(entryDateString, dateFormatter)执行此操作.在格式模式字符串中，d-MMM-uuuu d表示月份中的1或2位数字，MMM表示月份的缩写，uuuu表示4位数字的年份.月的缩写是特定于区域设置的.由于我将Dec设为英语，因此我为格式化程序指定了英语语言环境.如果您的日期字符串使用其他语言，请更正.
2. 将LocalDate传递到您的PreparedStatement. insertStatement.setObject(3, entryDate);这样做.

1. Parse the date string into a LocalDate. LocalDate.parse(entryDateString, dateFormatter) does this. In the format pattern string, d-MMM-uuuu d means day of month in 1 or 2 digits, MMM means month abbreviation, and uuuu means 4 digit year. The month abbreviation is locale specific. Since I took Dec to be English, I have specified English locale for the formatter; please correct if your date strings are in some other language.
2. Pass the LocalDate to your PreparedStatement. insertStatement.setObject(3, entryDate); does this.

如果您要检查第一点是否按预期工作:

If you want to check that the first point worked as expected:

    System.out.println("Entry date was parsed into " + entryDate);

输出:

输入日期被解析为2018-12-17

Entry date was parsed into 2018-12-17

PS您可能还想检查是否可以通过其他方式从Excel获取日期.如果您使用的是Apache POI之类的较旧的库，恐怕另一个选择是老式的Date对象，然后需要转换该对象，因此是否值得这样做是一个问题.

PS You may also want to check whether you can get the date from Excel in a different way. If you are using an older library such as Apache POI, I am afraid that the other option is an old-fashioned Date object, which you would then need to convert, so it’s a question whether it’s worth it.

链接: Oracle教程:日期时间解释如何使用java.time.

Link: Oracle tutorial: Date Time explaining how to use java.time.

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