MySql和MyBatis日期时间小数秒

Question

I use mysql 5.6.14. Firsly I created

CREATE TABLE `TEST` (
  `id` tinyint(3) unsigned zerofill NOT NULL AUTO_INCREMENT,
  `dateTime` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB;

From mysql documentation

To define a column that includes a fractional seconds part, use the syntax type_name(fsp), where type_name is TIME, DATETIME, or TIMESTAMP, and fsp is the fractional seconds precision. For example:

CREATE TABLE t1 (t TIME(3), dt DATETIME(6));

The fsp value, if given, must be in the range 0 to 6. A value of 0 signifies that there is no fractional part. If omitted, the default precision is 0. (This differs from the standard SQL default of 6, for compatibility with previous MySQL versions.)

As I dont define fsp it means that fsp is zero - no fractional part.

This is my mybatis result mapper:

 <resultMap id="readItemsRM" type="com.Foo">
        <id property="id" column="id"/>
        <result property="dateTime" column="dateTime"/>
  </resultMap>

This is my Foo class

class Foo{
 private String id;
 private String dateTime
 //getters+setters
}

This is the result when I do foo.getDateTime()

2015-01-21 16:46:03.0

Why does this ".0" appear and how to avoid it?

Answer 1

The reason of .0 is that we told MySQL there is no fractional part. Specifying java variable as a String we make MyBatis do a getString() for that parameter, and that's how the MySQL JDBC driver formats the value.

Instead, it's necessary to set Java variable as java.util.Date, and format it for example using SimpleDateFormatter.