如何将字符串时间戳转换为具有特定时区的时间戳

Question

我正在尝试将其中包含时区的字符串时间戳转换为具有相同时区的时间戳。 但是，在执行以下代码时，我得到了默认的系统时间戳。 有人可以帮我解决这个问题。 下面是我正在尝试的代码。

try {
    Date dt = new Date();
    SimpleDateFormat f = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ");
    f.setTimeZone(TimeZone.getTimeZone("GMT"));
    String dateString = f.format(dt);
    System.out.println("DateString: "+dateString);
    Date parsedDate = f.parse(dateString);
    System.out.println("ParsedDate: "+parsedDate);
    Timestamp timestamp = new Timestamp(parsedDate.getTime());
    System.out.println("Timestamp: "+timestamp);
    
}catch (Exception e) {
    // TODO: handle exception
}

执行上述代码时，我得到以下结果：

DateString: 2021-03-26T06:57:05.982+0000
ParsedDate: Fri Mar 26 12:27:05 IST 2021
Timestamp: 2021-03-26 12:27:05.982

但我必须在时间戳中获得 output 为 2021-03-26T06:57:05.982+0000

Answer 1

您的代码使用 java.time 类：

        ZonedDateTime zdt = ZonedDateTime.now();
        DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ");
        DateTimeFormatter dfGMT = df.withZone(ZoneId.of("GMT"));
        
        String dateString = dfGMT.format(zdt);
        System.out.println("DateString: "+dateString);
        
        ZonedDateTime parsedDate = ZonedDateTime.parse(dateString,dfGMT);
        System.out.println("ParsedDate: "+ parsedDate);
        Timestamp timestamp = Timestamp.from(parsedDate.toInstant());
        System.out.println("Zoned Timestamp: "+timestamp);
        
        //ignoring zone info from date string
        LocalDateTime ldt = LocalDateTime.from(dfGMT.parse(dateString));
        timestamp = Timestamp.valueOf(ldt);
        System.out.println("Zone stripped GMT timestamp: "+timestamp);
        
        
        ZonedDateTime zdt1 = ldt.atZone(ZoneId.of("GMT"));
        zdt1 = zdt1.withZoneSameInstant(ZoneId.of("America/Chicago"));
        timestamp = Timestamp.valueOf(zdt1.toLocalDateTime());
        System.out.println("Zone stripped CST timestamp: "+timestamp);

Output：

DateString: 2021-03-26T09:10:37.537+0000
ParsedDate: 2021-03-26T09:10:37.537Z[GMT]
Zoned Timestamp: 2021-03-26 14:40:37.537
Zone stripped GMT timestamp: 2021-03-26 09:10:37.537
Zone stripped CST timestamp: 2021-03-26 04:10:37.537

Answer 2

java.time 和 JDBC 4.2

您不需要任何格式化、解析或转换。 要将当前时间戳插入 SQL 数据库：

    OffsetDateTime currentTimestamp = OffsetDateTime.now(ZoneOffset.UTC);
    String sql = "insert into your_table(your_timestamp_with_time_zone_column) values (?);";
    try (PreparedStatement prepStmt = yourDatabaseConnection.prepareStatement(sql)) {
        prepStmt.setObject(1, currentTimestamp);
        prepStmt.executeUpdate();
    }