如何将休眠时间戳映射到MySQL BIGINT？

问题描述

我使用Hibernate 3.x，MySQL 4.1.20和Java 1.6。我正在将Hibernate Timestamp映射到MySQL TIMESTAMP。到现在为止还挺好。问题在于MySQL在几秒钟内存储了TIMESTAMP并丢弃了毫秒，现在我需要毫秒级的精度。我想我可以在我的表中使用BIGINT而不是TIMESTAMP，并在我的Java代码中转换类型。我试图找出是否有更好的方法来使用hibernate，mysql，JDBC或其他组合，所以我仍然可以在我的HSQL和/或SQL查询中使用日期函数？

  public class CalendarBigIntType extends org.hibernate.type.CalendarType {
 public Object get（ResultSet rs，String name）{
 return cal = new GregorianCalendar（rs.getLong（name））; 
} 
 public void set（PreparedStatement stmt，Object value，int index）{
 stmt.setParameter（index，（（Calendar）value）.getTime（））; 
 
 
 $ / code> 

然后，你需要映射你的新对象使用hibernate的TypeDef和Type映射。如果您使用的是Hibernate注释，则可以使用以下语句：



  @TypeDef（name =bigIntCalendar，typeClass = CalendarBigIntType .class）
 @Entity 
 public class MyEntity {
 @Type（type =bigIntCalendar）
私有日历myDate; 
} 
  




I am using Hibernate 3.x, MySQL 4.1.20 with Java 1.6. I am mapping a Hibernate Timestamp to a MySQL TIMESTAMP. So far so good. The problem is that MySQL stores the TIMESTAMP in seconds and discards the milliseconds and I now need millisecond precision. I figure I can use a BIGINT instead of TIMESTAMP in my table and convert the types in my Java code. I'm trying to figure out if there is a better way of doing this using hibernate, mysql, JDBC or some combination so I can still use date functions in my HSQL and/or SQL queries?

解决方案

Also, look at creating a custom Hibernate Type implementation. Something along the lines of (psuedocode as I don't have a handy environment to make it bulletproof):

public class CalendarBigIntType extends org.hibernate.type.CalendarType {
    public Object get(ResultSet rs, String name) {
        return cal = new GregorianCalendar(rs.getLong(name));
    }
    public void set(PreparedStatement stmt, Object value, int index) {
        stmt.setParameter(index, ((Calendar) value).getTime());
    }
}

Then, you'll need to map your new object using a hibernate TypeDef and Type mappings. If you are using Hibernate annotations, it be along the lines of:

@TypeDef (name="bigIntCalendar", typeClass=CalendarBigIntType.class)
@Entity
public class MyEntity {
    @Type(type="bigIntCalendar")
    private Calendar myDate;
}

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