Java代码，用于将东部日期和时间作为日期格式插入数据库

Question

I am using the java code like below to get the current eastern date and time and it should be inserted to database in date format. Using the below code I am able to get the eastern date and time in string format as expected, but I can't insert this string format in SQL database because the column being used in database to store is of type datetime. I also tried changing the formatted Eastern time zone date and time to date type but it returns the date and time in GMT format again.

java.util.Date date = new java.util.Date();
java.util.Date time = new Timestamp(date.getTime());
SimpleDateFormat formatter = new SimpleDateFormat ("yyyy-MM-dd hh:mm:ss.ms");
TimeZone timeZone = TimeZone.getTimeZone("America/New_York"); 
formatter.setTimeZone(timeZone);

System.out.println("EST: " + formatter.format(time)); // Prints date as 2016-03-18 03:12:16.1216 which is string format

java.util.Date time1 = formatter.parse(formatter.format(time));

System.out.println("EST Time Zone: " + time1); // Prints date as Fri Mar 18 07:04:36 GMT 2016 which is date format

//Code to insert into database
dataSource = DataSourceFactoryUtil.initDataSource("net.sourceforge.jtds.jdbc.Driver",
PortletProps.get("exampledatabase.db.url"), PortletProps.get("exampledatabase.db.user"),
PortletProps.get("exampledatabase.db.password"), StringPool.BLANK);

connection = dataSource.getConnection();
stmt = connection.createStatement();
String insertQuery = "INSERT INTO [exampletable] ([Firstname], [Lastname], [address], [Time]) VALUES ('"
                        + firstname + "', '" + lastname + "', '" + address + "', '" + time1 + "')";
stmt.executeUpdate(insertQuery);

In above code, the first System.out.println is printing the date in EST which is as expected to be inserted in database, but I can't insert it as it is in string type, and I get the error as:

Conversion failed when converting date and/or time from character string.

Another System.out.println gives the output in date format but it is not in EST.

How is it possible to get the output as format 2016-03-18 03:12:16.1216, and in date type instead of string so that I can insert into the database which has datetime type as a column.

Answer 1

The Answer by Alisson Vieira is correct but uses outmoded classes.

Do not use strings for date-time values, use date-time types.

Do not use the old date-time classes bundled with the earliest versions of Java, such as java.util.Date/.Calendar. They have proven to be poorly designed, confusing, and troublesome. Those classes have been supplanted by the java.time framework built into Java 8 and later.

A java.time.Instant is a moment on the timeline in UTC. You should do most of your work, your business logic, your database storage, in UTC. Use a time zone only when required by the user or data sink.

Instant instant = Instant.now();

Eventually the JDBC drivers will be updated to deal directly with the java.time types. Until then we must continue to depend on the java.sql types for transferring data in/out of the database. But minimize your use of these classes; convert to java.time as soon as possible in your work flow.

In your database use the standard TIMESTAMP WITH TIME ZONE type to define the date-time column, or the equivalent if your database is not compliant. You should almost never use the without time zone type.

The java.sql.Timestamp class maps to the java.time.Instant type. To this old class a few new methods have been added for conversion to/from java.time such as toInstant and from( Instant ) .

java.sql.Timestamp ts = java.sql.Timestamp.from( instant );

You should always use PreparedStatement to interact with your database for multiple reasons. One very important reason is to eliminate the risk of SQL Injection attacks.

myPreparedStatement.setTimestamp( 4 , ts );

To retrieve use a java.sql.Timestamp to get the data, then convert to java.time.

java.sql.Timestamp ts = myResultSet.getTimestamp( 4 );
Instant instant = ts.toInstant();

Notice that nowhere in the code above did we deal with any particular timezone. We use UTC all the way through, Java ↔ JDBC ↔ SQL ↔ Database. And nowhere did we use Strings for our date-time values.

To see the wall-clock time for a particular time zone, apply a time zone ( ZoneId ) to get a ZonedDateTime . Use proper time zone names, never the 3-4 letter codes such as EST as these are neither standardized nor unique.

ZoneId zoneId = ZoneId.of( "America/New_York" );
ZonedDateTime zdt = ZonedDateTime.ofInstant( instant , zoneId );

To see a textual representation of that date-time value in standard ISO 8601 format, merely call toString . Example output: 2016-03-17T05:19:24.679Z .

String output = zdt.toString();

To generate strings in other formats, search Stack Overflow for many examples on using DateTimeFormatter .

Answer 2

java.sql.Date sqlDate = new java.sql.Date(time1.getTime());

Try to use the java.sql.Date type into your insert SQL.

How you're attempting to insert the record? Are you using some library?

@Edit

The System.out.print() doesn't handles the date as the JDBC does. The first calls the toString() method of Date instance, and the JDBC uses the getTime() , aka the milliseconds representation of the Date.

@Edit2

Change stmt = connection.createStatement();

to

PreparedStatement stmt=connection.prepareStatement("INSERT INTO exampleTable (Firstname, Lastname, address, Time) VALUES (?, ?, ?, ?)");
stmt.setString(1, firstname);
stmt.setString(2, lastname);
stmt.setString(3, address);
stmt.setTimestamp(4, new java.sql.Date(time1.getTime()));
stmt.executeUpdate();      

Answer 3

I am able to get date and time in EST datetime format with these 2 lines of codes:

TimeZone.setDefault(TimeZone.getTimeZone("America/New_York"));
Timestamp timestamp = new Timestamp(new Date().getTime());

I get the output as EST date and time: 2016-03-23 03:12:16.1216

Here is the working code including the code that I had provided while asking the question:

TimeZone.setDefault(TimeZone.getTimeZone("America/New_York"));
Timestamp timestamp = new Timestamp(new Date().getTime());

//Code to insert into database
dataSource = DataSourceFactoryUtil.initDataSource("net.sourceforge.jtds.jdbc.Driver",
PortletProps.get("exampledatabase.db.url"), PortletProps.get("exampledatabase.db.user"),
PortletProps.get("exampledatabase.db.password"), StringPool.BLANK);

connection = dataSource.getConnection();
stmt = connection.createStatement();
String insertQuery = "INSERT INTO [exampletable] ([Firstname], [Lastname], [address], [Time]) VALUES ('"
                        + firstname + "', '" + lastname + "', '" + address + "', '" + timestamp + "')";
stmt.executeUpdate(insertQuery);