PrepareStatement插入时间

最新推荐文章于 2021-06-27 04:17:47 发布

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最新推荐文章于 2021-06-27 04:17:47 发布

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文章标签： Java SQL JDK

本文详细解释了Java中java.sql.Date和java.sql.Timestamp的区别及使用方法。提醒开发者在处理包含时间的数据时，避免使用java.sql.Date，因为它仅存储日期部分，而时间部分会被设置为午夜。同时介绍了如何正确地从数据库读取包含毫秒的时间戳。

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java.sql.Date stores only date information, not times. Simply converting a java.util.Date into a java.sql.Date will silently set the time to midnight. So, to store date/times to be manipulated as java.util.Date objects, don’t do this:

// BUG: loses time of day
preparedStatement.setDate(1, new java.sql.Date(date.getTime()));

do this instead:

preparedStatement.setTimestamp(1, new java.sql.Timestamp(date.getTime()));
java.sql.Timestamp is not a date

java.sql.Timestamp extends java.util.Date, but it should not be used as a Date. In JDK 1.3.1, Timestamp.getTime() (inherited from Date) returns the time to the nearest second only, but JDK 1.4.2 and JDK 1.5 it returns the time to the nearest millisecond as expected. So in JDK 1.3, when reading a timestamp from a ResultSet, don’t do this:

// Java 1.3
java.util.Date d = resultSet.getTimestamp(1);
long millis = d.getTime(); // BUG: loses fractional seconds in JDK 1.3

To get the full date including milliseconds, you have to do this:

java.sql.Timestamp timestamp = resultSet.getTimestamp(1);
java.util.Date d = new java.util.Date(timestamp.getTime() +
timestamp.getNanos() / 1000000);

In JDK 1.4.2 and JDK 1.5, you can just do this, depending on what you’re going to do with the Date:

// Java 1.4+
java.util.Date d = resultSet.getTimestamp(1);

But this might be safer since it avoids any other potential Timestamp problems:

// Java 1.4+
java.util.Date d = new java.util.Date(resultSet.getTimestamp(1).getTime());

If your code needs to run on JDK 1.3 and later, you’ll have to do this:

java.sql.Timestamp timestamp = resultSet.getTimestamp(1);
long millis = (timestamp.getTime() / 1000) * 1000 + timestamp.getNanos() / 1000000;
java.util.Date d = new java.util.Date(millis);

http://www.thunderguy.com/semicolon/2003/08/14/java-sql-date-is-not-a-real-date/