How to force Hibernate to return dates as java util Date instead of Timestamp

Question

Situation   I have a persistable class with variable of java util Date type   import java util Date    Entity  Table name    prd period    Cache usage   CacheConcurrencyStrategy NONSTRICT READ WRITE  public class Period extends ManagedEntity implements Interval        Column name    startdate    nullable   false     private Date startDate       Corresponding table in DB   CREATE TABLE  prd period       id   bigint 20  NOT NULL AUTO INCREMENT          startdate   datetime NOT NULL     Then I save my Period object to DB   Period p   new Period    Date d   new Date    p setStartDate    myDao save p     After then if I m trying to extract my object from DB  it is returned with variable startDate of Timestamp type - and all the places where I m trying to use equals      are returning false   Question  are there any means to force Hibernate to return dates as object of java util Date type instead of Timestamp without explicit modification of every such variable  e g it must be able just work  without explicit modification of existed variables of java util Date type    NOTE   I found number of explicit solutions  where annotations are used or setter is modified - but I have many classes with Date-variables - so I need some centralized solution and all that described below is not good enough    Using annotation  Type  - java sql Date will be returned   Column  Type type  date   private Date startDate   Using annotation  Temporal TemporalType DATE  - java sql Date will be returned   Temporal TemporalType DATE   Column name    CREATION DATE     private Date startDate   By modifying setter  deep copy  - java util Date will be returned  public void setStartDate Date startDate        if  startDate    null            this startDate   new Date startDate getTime           else           this startDate   null           By creation of my own type  - java util Date will be returned   Details are given here   http   blogs sourceallies com 2012 02 hibernate-date-vs-timestamp

User · Answer

Approaches 1 and 2 obviously don t work  because you get java sql Date objects  per JPA Hibernate spec  and not java util Date  From approaches 3 and 4  I would rather choose the latter one  because it s more declarative  and will work with both field and getter annotations   You have already laid out the solution 4 in your referenced blog post  as  tscho was kind to point out  Maybe defaultForType  see below  should give you the centralized solution you were looking for  Of course will will still need to differentiate between date  without time  and timestamp fields   For future reference I will leave the summary of using your own Hibernate UserType here   To make Hibernate give you java util Date instances  you can use the  Type and  TypeDef annotations to define a different mapping of your java util Date java types to and from the database   See the examples in the core reference manual here    Implement a UserType to do the actual plumbing  conversion to from java util Date   named e g  TimestampAsJavaUtilDateType Add a  TypeDef annotation on one entity or in a package-info java - both will be available globally for the session factory  see manual link above   You can use defaultForType to apply the type conversion on all mapped fields of type java util Date    TypeDef   name    timestampAsJavaUtilDate     defaultForType   java util Date class     applied globally      typeClass   TimestampAsJavaUtilDateType class    Optionally  instead of defaultForType  you can annotate your fields getters with  Type individually    Entity public class MyEntity                Type type  timestampAsJavaUtilDate      private java util Date myDate                P S  To suggest a totally different approach  we usually just don t compare Date objects using equals   anyway  Instead we use a utility class with methods to compare e g  only the calendar date of two Date instances  or another resolution such as seconds   regardless of the exact implementation type  That as worked well for us

User · Answer

A simple alternative to using a custom UserType is to construct a new java util Date in the setter for the date property in your persisted bean  eg   import java util Date  import javax persistence Entity  import javax persistence Column    Entity public class Purchase        private Date date        Column     public Date getDate             return this date             public void setDate Date date               force java sql Timestamp to be set as a java util Date         this date   new Date date getTime

User · Answer

Here is solution for Hibernate 4 3 7 Final   pacakge-info java contains   TypeDefs                 TypeDef                  name    javaUtilDateType                   defaultForType   java util Date class                  typeClass   JavaUtilDateType class                  package some pack  import org hibernate annotations TypeDef  import org hibernate annotations TypeDefs    And JavaUtilDateType   package some other or same pack   import java sql Timestamp  import java util Comparator  import java util Date  import org hibernate HibernateException  import org hibernate dialect Dialect  import org hibernate engine spi SessionImplementor  import org hibernate type AbstractSingleColumnStandardBasicType  import org hibernate type LiteralType  import org hibernate type StringType  import org hibernate type TimestampType  import org hibernate type VersionType  import org hibernate type descriptor WrapperOptions  import org hibernate type descriptor java JdbcTimestampTypeDescriptor  import org hibernate type descriptor sql TimestampTypeDescriptor          Note  Depends on hibernate implementation details hibernate-core-4 3 7 Final         see     lt a href  http   docs jboss org hibernate orm 4 3 manual en-US html ch06 html types-custom  gt Hibernate    Documentation lt  a gt      see TimestampType     public class JavaUtilDateType         extends AbstractSingleColumnStandardBasicType lt Date gt          implements VersionType lt Date gt   LiteralType lt Date gt         public static final TimestampType INSTANCE   new TimestampType         public JavaUtilDateType             super                  TimestampTypeDescriptor INSTANCE                  new JdbcTimestampTypeDescriptor                           Override                     public Date fromString String string                            return new Date super fromString string  getTime                                                 Override                     public  lt X gt  Date wrap X value  WrapperOptions options                            return new Date super wrap value  options  getTime                                                                     Override     public String getName             return  timestamp               Override     public String   getRegistrationKeys             return new String   getName    Timestamp class getName    java util Date class getName                 Override     public Date next Date current  SessionImplementor session            return seed session               Override     public Date seed SessionImplementor session            return new Timestamp System currentTimeMillis                 Override     public Comparator lt Date gt  getComparator             return getJavaTypeDescriptor   getComparator                Override     public String objectToSQLString Date value  Dialect dialect  throws Exception           final Timestamp ts   Timestamp class isInstance value                     Timestamp  value                   new Timestamp value getTime                TODO   use JDBC date literal escape syntax  - gt   d  date-string   in yyyy-mm-dd hh mm ss  f     format         return StringType INSTANCE objectToSQLString ts toString    dialect               Override     public Date fromStringValue String xml  throws HibernateException           return fromString xml             This solution mostly relies on TimestampType implementation with adding additional behaviour through anonymous class of type JdbcTimestampTypeDescriptor

User · Answer

There are some classes in the Java platform libraries that do extend an instantiable class and add a value component  For example  java sql Timestamp extends java util Date and adds a nanoseconds field  The equals implementation for Timestamp does violate symmetry and can cause erratic behavior if Timestamp and Date objects are used in the same collection or are otherwise intermixed  The Timestamp class has a disclaimer cautioning programmers against mixing dates and timestamps  While you won   t get into trouble as long as you keep them separate  there   s nothing to prevent you from mixing them  and the resulting errors can be hard to debug  This behavior of the Timestamp class was a mistake and should not be emulated   check out this link  http   blogs sourceallies com 2012 02 hibernate-date-vs-timestamp

User · Answer

I ran into a problem with this as well as my JUnit assertEquals were failing comparing Dates to Hibernate emitted  java util Date  types  which as described in the question are really Timestamps   It turns out that by changing the mapping to  date  rather than  java util Date  Hibernate generates java util Date members  I am using an XML mapping file with Hibernate version 4 1 12   This version emits  java util Timestamp     lt property name  date  column  DAY  type  java util Date  unique-key  KONSTRAINT DATE IDX  unique  false  not-null  true    gt    This version emits  java util Date     lt property name  date  column  DAY  type  date  unique-key  KONSTRAINT DATE IDX  unique  false  not-null  true    gt    Note  however  if Hibernate is used to generate the DDL  then these will generate different SQL types  Date for  date  and Timestamp for  java util Date

User · Answer

So  I spent some time with this issue and found a solution  It is not pretty one  but at least a start point - maybe someone will supplement this with some useful comments   Some info about mapping that I found in process    Class that contains basic mapping of Hibernate types to property types is org hibernate type TypeFactory  All this mappings are stored in unmodifiable map    private static final Map BASIC TYPES      basics put  java util Date class getName    Hibernate TIMESTAMP        BASIC TYPES   Collections unmodifiableMap  basics       As you can see with java util Date type assosited with Hibernate type org hibernate type TimestampType   Next interesting moment - creation of Hibernate org hibernate cfg Configuration - object that contains all info about mapped classes  This classes and their properties can be extracted like this   Iterator clsMappings   cfg getClassMappings    while clsMappings hasNext         PersistentClass mapping    PersistentClass  clsMappings next        handleProperties mapping getPropertyIterator    map      Vast majority of properties are the objects of org hibernate mapping SimpleValue types  Our point of interest is the method SimpleValue getType   - in this method is defined what type will be used to convert properties values back-and-forth while working with DB  Type result   TypeFactory heuristicType typeName  typeParameters      At this point I understand that I am unable to modify BASIC TYPES - so the only way - to replace SimpleValue object to the properties of java util Date types to my custom Object that will be able to know the exact type to convert   The solution    Create custom container entity manager factory by extending HibernatePersistence class and overriding its method createContainerEntityManagerFactory   public class HibernatePersistenceExtensions extends HibernatePersistence         Override     public EntityManagerFactory createContainerEntityManagerFactory PersistenceUnitInfo info  Map map             if   true  equals map get  hibernate use custom entity manager factory                   return CustomeEntityManagerFactoryFactory createCustomEntityManagerFactory info  map             else               return super createContainerEntityManagerFactory info  map                      Create Hibernate configuration object  modify value ojects for java util Date properties and then create custom entity manager factory   public class ReattachingEntityManagerFactoryFactory          SuppressWarnings  rawtypes       public static EntityManagerFactory createContainerEntityManagerFactory      PersistenceUnitInfo info  Map map            Ejb3Configuration cfg   new Ejb3Configuration             Ejb3Configuration configured   cfg configure  info  map             handleClassMappings cfg  map            return configured    null   configured buildEntityManagerFactory     null              SuppressWarnings  rawtypes       private static void handleClassMappings Ejb3Configuration cfg  Map map            Iterator clsMappings   cfg getClassMappings            while clsMappings hasNext                  PersistentClass mapping    PersistentClass  clsMappings next                 handleProperties mapping getPropertyIterator    map                           private static void handleProperties Iterator props  Map map             while props hasNext                  Property prop    Property  props next                 Value value   prop getValue                 if  value instanceof Component                     Component c    Component  value                   handleProperties c getPropertyIterator    map                  else                     handleReturnUtilDateInsteadOfTimestamp prop  map                                   private static void handleReturnUtilDateInsteadOfTimestamp Property prop  Map map            if   true  equals map get  hibernate return date instead of timestamp                   Value value   prop getValue                 if  value instanceof SimpleValue                    SimpleValue simpleValue    SimpleValue  value                  String typeName   simpleValue getTypeName                    if   java util Date  equals typeName                         UtilDateSimpleValue udsv   new UtilDateSimpleValue simpleValue                       prop setValue udsv                                                         As you can see I just iterate over every property and substitute SimpleValue-object for UtilDateSimpleValue for properties of type java util Date  This is very simple class - it implements the same interface as SimpleValue object  e g org hibernate mapping KeyValue  In constructor original SimpleValue object is passed - so every call to UtilDateSimpleValue is redirected to the original object with one exception - method getType      return my custom Type   public class UtilDateSimpleValue implements KeyValue       private SimpleValue value       public UtilDateSimpleValue SimpleValue value            this value   value             public SimpleValue getValue             return value              Override     public int getColumnSpan             return value getColumnSpan                         Override     public Type getType   throws MappingException           final String typeName   value getTypeName             if  typeName    null                    throw new MappingException  No type name                       Type result   new UtilDateUserType             return result                     And the last step is implementation of UtilDateUserType  I just extend original org hibernate type TimestampType and override its method get   like this   public class UtilDateUserType extends TimestampType        Override     public Object get ResultSet rs  String name  throws SQLException           Timestamp ts   rs getTimestamp name            Date result   null          if ts    null               result   new Date ts getTime                        return result             That is all  A little bit tricky  but now every java util Date property is returned as java util Date without any additional modifications of existing code  annotations or modifying setters   As I find out in Hibernate 4 or above there is a much more easier way to substitute your own type  see details here  Hibernate TypeResolver   Any suggestions or criticism are welcome

User · Answer

Just add the this annotation  Temporal TemporalType DATE  for a java util Date field in your entity class   More information available in this stackoverflow answer

[java] How to force Hibernate to return dates as java.util.Date instead of Timestamp?

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