Siege Lion on the road (one) Hibernate (ix)---hibernate mapping type

Hibernate takes a mapping type as a bridge between Java type and SQL type, corresponding to the type attribute.
There are two types: the built-in mapping type and the custom mapping type.
One, built-in mapping type :
1,JaVA basic types of Hibernate mapping types :

Types of hibernate mappings for Java underlying types
Hibernate mapping Type	Java type	Standard SQL type	Size and range of values
Integer or int	int or Java.lang.Integer	INTEGER
Long	Long	BIGINT
Short	Short	SMALLINT
Byte	Byte	TINYINT
Float	Float	FLOAT
Double	Double	DOUBLE
Character	Char\string	CHAR (1)	Fixed-length characters
String	String	VARCHAR	Edge length string
Boolean	Boolean	BIT
Yes_no	Boolean	CHAR (1)
True_false	Boolean	CHAR (1)

2. Types of Hibernate mappings for Java time and date types :

Types of hibernate mappings for time-date types in Java
Mapping type	Java type	Standard SQL type	Describe
Date	Java.util.Date or Java.sql.Date	DATE	Date represented
Time	Java. Util.date or Java.sql.Time	Time	Representative time
Timestamp	Java. Util.date or Java.sql.Timpstamp	TIMESTAMP	Represent time and date
Calendar	Java. Util.calendar	TIMESTAMP	Ditto
Calendar_date	Java. Util.calendar	DATE	Date represented

3. Types of hibernate mappings for Java large object types :

Hibernate mapping types for Java large object types
Mapping type	Java type	Standard SQL type	MySQL type	Oracle Type
Binary	Byte[]	VARBINARY (or BLOB)	Blob	Blob
Text	Java.lang.String	Clob	TEXT	Clob
Serializable	Classes that implement the Serializable interface	VARBINARY (or BLOB)	Blob	Blob
Clob	Java.sql.Clob	Clob	TEXT	Clob
Blob	Java.sql.Blob	Blob	Blob	Blob

4.The Hibernate mapping type of the individual Java classes that the JDK comes with :

Hibernate mapping types for individual classes that are brought from the JDK
Mapping type	Java type	Standard SQL type
Class	Java.lang.Class	VARCHAR
Locale	Java.util.Locale	VARCHAR
TimeZone	Java.util.TimeZone	VARCHAR
Currency	Java.util.Currency	VARCHAR

Ii. Customized mapping type :
By implementing the Org.hibernate.usertype.UserType interface, it is possible to map a Java type to a SQL type.
1, Several methods of the interface description :

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sqlTypes()：设置该类型的字段对应的SQL类型。比如VARCHAR。 returnClass()：设置该类型的字段对应的Java类型。 isMutabel()：判断对应的Java类型是否为可变类。 deepCopy(Object value)：该方法用于生成对应属性的快照。对于可变类，必须返回参数的复制值。 equals(Object x, Object y):比较对应属性的当前值和它的快照是否相同。 hashCode(Object x):不做解释。 nullSaveGet(ResultSet resultSet,String[] names, Ojbect owner): 　　当Hibernate从数据库加载对象时，调用该方法来取得该客户化类型的属性值。resultSet为JDBC的结果集，names为存放了表字段名的数组。在该方法内部实现从数据库字段到Java字段的转化。 nullSafeSet(PreparedStatement statement, Object value, int index): 　　当Hibernate将对象持久化到数据库时，调用该方法把对应的属性值添加到SQL insert语句中。在该方法内部完成SQL语句的参数指定。 assemble(Serializable cached, Object owner): 　　当Hibernate把二级缓存中的对象加载到Session缓存中时，调用该方法来获取对应属性的反序列化数据。如果参数cached为可变类型，则应该返回参数cached的快照（即调用deepCopy(cached)） disassemble(Object value): 　　当Hibernate把Session缓存中的对象保存到二级缓存中时，调用该方法获取对应属性的序列化数据。如果参数value为可变类型，则应该返回参数cached的快照（即调用deepCopy(value)） replace(Object original, Object target, Object owner): 　　当Session的merge()方法把一个游离对象A融合到持久化对象B时，会调用该方法来获得用于替代对象B对应属性的值。如果参数original为可变类型，则应该返回参数cached的快照（即调用deepCopy(original)）

2. configuration file Use :

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1	<property name="phone" type="xx.xx.MyType"column="PHONE"/>

3. Use this method instead of Hibernate components : The method is to encapsulate multiple SQL fields in an interface implementation as an address object.

4. Example code :

 Public classAddressusertypeImplementsusertype {Private Static Final int[] Sql_types ={Types.varchar,types.varchar,types.varchar,types.varchar};  Public int[] SqlTypes () {returnSql_types;}  PublicClass Returnedclass () {returnAddress.class; }  Public BooleanIsmutable () {return false; }  PublicObject Deepcopy (object value) {returnValue//Address is immutable  }   Public Booleanequals (object x, Object y) {if(x = = y)return true; if(x = =NULL|| y = =NULL)return false; returnx.equals (y); }   Public inthashcode (Object x) {returnX.hashcode (); }     PublicObject Nullsafeget (ResultSet resultset,string[] names, object owner)throwshibernateexception, SQLException {String province= Resultset.getstring (names[0]); String City= Resultset.getstring (names[1]); String Street= Resultset.getstring (names[2]); String ZipCode= Resultset.getstring (names[3]); if(Province = =NULL&& city==NULL&& street==NULL&& zipcode==NULL)      return NULL; return NewAddress (Province,city,street,zipcode); }   Public voidNullsafeset (PreparedStatement statement,object value,intindex)throwshibernateexception, SQLException {if(Value = =NULL) {statement.setnull (index, Types.varchar); Statement.setnull (Index+1, Types.varchar); Statement.setnull (Index+2, Types.varchar); Statement.setnull (Index+3, Types.varchar); } Else{Address Address=(Address) value;      Statement.setstring (Index, address.getprovince ()); Statement.setstring (Index+1, Address.getcity ()); Statement.setstring (Index+2, Address.getstreet ()); Statement.setstring (Index+3, Address.getzipcode ()); }  }   Publicobject Assemble (Serializable cached, object owner) {returncached; }   PublicSerializable disassemble (Object value) {return(Serializable) value; }     PublicObject Replace (object Original,object target,object owner) {returnoriginal; }}

manipulating BLOBs and CLOB type data :
In a persisted class, a binary large object can be declared as byte[] or java.sql.Blob; A string large object can be declared as a java.lang.String or a java.sql.Clob type.
No explanation at this stage.

( Disclaimer: This article is all from "proficient Hibernate:java object Persistence technology detailed" [Sun Weichen Electronic Industry Press] a book. The purpose of this article is only as a study note. If you need to reprint, please indicate the original book related information. )