Object/Relational Mapping with Hibernate

1. Object/Relational Mapping with Hibernate Practical ORM

2. 基础配置 • Managed environment—池资源像database connections和 允许transaction,security 靠指定的声明 • Non-managed environment—提供基本的并发管理通过线程池,不提供自动transaction or resource management or 安全机制. 自己管理database connections和划分transaction边界

3. 非管理环境的配置 • Using a connection pool • C3P0,Apache DBCP and Proxool.

4. Using hibernate.properties for C3P0 connection pool settings hibernate.connection.driver_class = org.postgresql.Driver hibernate.connection.url = jdbc:postgresql://localhost/auctiondb hibernate.connection.username = auctionuser hibernate.connection.password = secret hibernate.dialect = net.sf.hibernate.dialect.PostgreSQLDialect hibernate.c3p0.min_size=5 hibernate.c3p0.max_size=20 hibernate.c3p0.timeout=300 hibernate.c3p0.max_statements=50（缓存中最大的prepared statements 数） hibernate.c3p0.idle_test_period=3000（释放连接）

5. 管理环境的配置

6. Sample hibernate.properties for a container-provided datasource hibernate.connection.datasource =java:/comp/env/jdbc/AuctionDB hibernate.transaction.factory_class = \ net.sf.hibernate.transaction.JTATransactionFactory（CMT） hibernate.transaction.manager_lookup_class = \ net.sf.hibernate.transaction.JBossTransactionManagerLookup hibernate.dialect = net.sf.hibernate.dialect.PostgreSQLDialect

7. Using XML-based configuration <?xml version='1.0'encoding='utf-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN" "http://hibernate.sourceforge.net/hibernate-configuration-2.0.dtd"> <hibernate-configuration> <session-factory name="java:/hibernate/HibernateFactory"> <property name="show_sql">true</property> <property name="connection.datasource">java:/comp/env/jdbc/AuctionDB</property> <property name="dialect">net.sf.hibernate.dialect.PostgreSQLDialect</property> <property name="transaction.manager_lookup_class"> net.sf.hibernate.transaction.JBossTransactionManagerLookup </property> <mapping resource="auction/Item.hbm.xml"/> <mapping resource="auction/Category.hbm.xml"/> <mapping resource="auction/Bid.hbm.xml"/> </session-factory> </hibernate-configuration>

8. JNDI-bound SessionFactory hibernate.connection.datasource = java:/comp/env/jdbc/AuctionDB hibernate.transaction.factory_class = \ net.sf.hibernate.transaction.JTATransactionFactory hibernate.transaction.manager_lookup_class = \ net.sf.hibernate.transaction.JBossTransactionManagerLookup hibernate.dialect = net.sf.hibernate.dialect.PostgreSQLDialect hibernate.session_factory_name = hibernate/HibernateFactory hibernate.jndi.class = com.sun.jndi.fscontext.RefFSContextFactory hibernate.jndi.url = file:/auction/jndi

9. log4j.properties ### direct log messages to stdout ### log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.Target=System.out log4j.appender.stdout.layout=org.apache.log4j.PatternLayout log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} ➾ %5p %c{1}:%L - %m%n ### root logger option ### log4j.rootLogger=warn, stdout ### Hibernate logging options ### log4j.logger.net.sf.hibernate=info ### log JDBC bind parameters ### log4j.logger.net.sf.hibernate.type=info ### log PreparedStatement cache activity ### log4j.logger.net.sf.hibernate.ps.PreparedStatementCache=info

10. POJO implementation of the User class public class User implements Serializable { private String username; private Address address; public User() {} public String getUsername() { return username;} public void setUsername(String username) { this.username = username;} public Address getAddress() { return address;} public void setAddress(Address address) { this.address = address;} public MonetaryAmount calcShippingCosts(Address fromLocation) { } }

11. Implementing POJO associations Category aParent = new Category(); Category aChild = new Category(); aChild.setParentCategory(aParent); aParent.getChildCategories().add(aChild);

12. many-to-many association

13. Hibernate XML mapping of the Category class

14. Basic property and class mappings <property name="description" column="DESCRIPTION" type="string"/> <property name="description" column="DESCRIPTION"/> 以上配置是等同的，以下配置是等同的 <property name="description" column="DESCRIPTION" type="string"/> <property name="description" type="string"> <column name="DESCRIPTION"/> </property> <property name="initialPrice" column="INITIAL_PRICE" not-null="true"/>

15. 使用合成属性 <property name="totalIncludingTax" formula="TOTAL + TAX_RATE * TOTAL" type="big_decimal"/> <property name="averageBidAmount" formula="( select AVG(b.AMOUNT) from BID b ➾where b.ITEM_ID = ITEM_ID )" type="big_decimal"/>

16. Property access strategies <property name="name" column="NAME" type="string" access=“field”/>(这种配置不需要get()/set()) • Default uses the property accessors(get/set method pair) • The field strategy uses reflection to access the instance variable directly

17. 控制插入和更新 • <property name="name" column="NAME" type="string" insert="false" update="false"/> • immutable=“false”设置改属性为只读 • <class name="org.hibernate.auction.model.User" dynamic-insert="true" dynamic-update="true"> ... </class> • 只插入\更新需要的属性

18. Using quoted SQL identifiers • <property name="description" column="`Item Description`"/>

19. SQL schemas <hibernate-mapping> <class name="org.hibernate.auction.model.Category" table="CATEGORY" schema="AUCTION"> ... </class> </hibernate-mapping> 在整个文档中声明: <hibernate-mapping default-schema="AUCTION"> .. </hibernate-mapping>

20. <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd"> <hibernate-mapping> <class name="org.hibernate.auction.model.Category" table="CATEGORY"> ... </class> </hibernate-mapping> <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd"> <hibernate-mapping package="org.hibernate.auction.model"> <class name="Category" table="CATEGORY"> ... </class> </hibernate-mapping> Declaring class names

21. // Get the existing mapping for User from Configuration PersistentClass userMapping = cfg.getClassMapping(User.class); // Define a new column for the USER table Column column = new Column(); column.setType(Hibernate.STRING); column.setName("MOTTO"); column.setNullable(false); column.setUnique(true); userMapping.getTable().addColumn(column); // Wrap the column in a Value SimpleValue value = new SimpleValue(); value.setTable( userMapping.getTable() ); value.addColumn(column); value.setType(Hibernate.STRING); // Define a new property of the User class Property prop = new Property(); prop.setValue(value); prop.setName("motto"); userMapping.addProperty(prop); // Build a new session factory, using the new mapping SessionFactory sf = cfg.buildSessionFactory(); Manipulating metadata at runtime

22. 持久化实例的identifier property的值 这个值通过调用Session.getIdentifier(Object o)返回 Database identity with Hibernate public class Category { private Long id; ... public Long getId() { return this.id; } private void setId(Long id) { this.id = id; } ... } <class name="Category" table="CATEGORY"> <id name="id" column="CATEGORY_ID" type="long"> <generator class="native"/> </id> ... </class> <id column="CATEGORY_ID"> <generator class="native"/> </id> Long catId = (Long) session.getIdentifier(category); category.getId()；

23. 使用components

24. <component name="homeAddress" class="Address"> <parent name="user"/> <property name="street" type="string" column="HOME_STREET"/> <property name="city" type="string" column="HOME_CITY"/> <property name="zipcode" type="short" column="HOME_ZIPCODE"/> </component> 使用components-2

25. 表对应具体的类—在关系模型中放弃多态和继承（<class>）表对应具体的类—在关系模型中放弃多态和继承（<class>） 表对应类的继承关系—能在关系模型中使用多态,使用一个类型描述的列保持数据类型信息（<subclass>） 表对应子类—把 “is a” (inheritance) 关系作为 “has a”(foreign key) 关系（<joined-subclass>） 映射类的继承

26. 表对应具体的类

27. select CREDIT_CARD_ID, OWNER, NUMBER, CREATED, TYPE, ... from CREDIT_CARD where CREATED = ? select BANK_ACCOUNT_ID, OWNER, NUMBER, CREATED, BANK_NAME, ... from BANK_ACCOUNT where CREATED = ? select CREDIT_CARD_ID, TYPE, EXP_MONTH, EXP_YEAR from CREDIT_CARD where CREATED = ? SQL SELECTs

28. 表对应类的继承关系

29. XML Mapping

30. 1.querying the BillingDetails class select BILLING_DETAILS_ID, BILLING_DETAILS_TYPE, OWNER, ..., CREDIT_CARD_TYPE, from BILLING_DETAILS where CREATED = ? 2. query the CreditCard subclass select BILLING_DETAILS_ID, CREDIT_CARD_TYPE, CREDIT_CARD_EXP_MONTH, ... from BILLING_DETAILS where BILLING_DETAILS_TYPE='CC' and CREATED = ? SQL SELECTs

31. 表对应子类

32. XML Mapping

33. 1.querying the BillingDetails class select BD.BILLING_DETAILS_ID, BD.OWNER, BD.NUMER, BD.CREATED, CC.TYPE, ..., BA.BANK_SWIFT, ... case when CC.CREDIT_CARD_ID is not null then 1 when BA.BANK_ACCOUNT_ID is not null then 2 when BD.BILLING_DETAILS_ID is not null then 0 end as TYPE from BILLING_DETAILS BD left join CREDIT_CARD CC on BD.BILLING_DETAILS_ID = CC.CREDIT_CARD_ID left join BANK_ACCOUNT BA on BD.BILLING_DETAILS_ID = BA.BANK_ACCOUNT_ID where BD.CREATED = ? SQL SELECTs(outerjoin)

34. SQL SELECTs(innerjoin) • select BD.BILLING_DETAILS_ID, BD.OWNER, BD.CREATED, CC.TYPE, ... from CREDIT_CARD CC inner join BILLING_DETAILS BD on BD.BILLING_DETAILS_ID = CC.CREDIT_CARD_ID where CC.CREATED = ?

35. Managed associations(CMP->CMR) public class Bid { ... private Item item; public void setItem(Item item) { this.item = item; } public Item getItem() { return item; } ... } bid.setItem(item)->item.getBids().add(item)双向 <class name="Bid" table="BID"> ... <many-to-one name="item" column="ITEM_ID" class="Item" not-null="true"/> </class> 单向

36. 双向关联关系 public class Item { ... private Set bids = new HashSet(); public void setBids(Set bids) { this.bids = bids; } public Set getBids() { return bids; } public void addBid(Bid bid) { bid.setItem(this); bids.add(bid); } ... } <class name="Item" table="ITEM"> ... <set name="bids"> <key column="ITEM_ID"/> <one-to-many class="Bid"/> </set> </class>

37. 表关联(one-many)

38. One-to-one associations <class name="Address" table="ADDRESS"> <id name="id" column="ADDRESS_ID"> <generator class="native"/> </id> <property name="street"/> <property name="city"/> <property name="zipcode"/> </class> <one-to-one name="user" class="User" property-ref="billingAddress"/>

39. 表关联（one-one） Address address = new Address(); address.setStreet("646 Toorak Rd"); address.setCity("Toorak"); address.setZipcode("3000"); Transaction tx = session.beginTransaction(); User user = (User) session.get(User.class, userId); address.setUser(user); user.setBillingAddress(address); tx.commit();

40. Using a primary key association 1.single address property address and map it with the User <one-to-one name="address" class="Address" cascade="save-update"/> 2.here’s the user of Address <one-to-one name="user" class="User" constrained="true"/>

41. XML Mapping <class name="Address" table="ADDRESS"> <id name="id" column="ADDRESS_ID"> <generator class="foreign"> <param name="property">user</param> </generator> </id> ... <one-to-one name="user" class="User" constrained="true"/> </class>

42. Many-to-many associations A unidirectional many-to-many association <set name="items" table="CATEGORY_ITEM" lazy="true" cascade="save-update"> <key column="CATEGORY_ID"/> <many-to-many class="Item" column="ITEM_ID"/> </set>

43. Many-to-many associations We can also use a bag with a separate primary key column: <idbag name="items" table="CATEGORY_ITEM” lazy="true" cascade="save-update"> <collection-id type="long" column="CATEGORY_ITEM_ID"> <generator class="sequence"/> </collection-id> <key column="CATEGORY_ID"/> <many-to-many class="Item" column="ITEM_ID"/> </idbag>

44. Many-to-many associations <list name="items" table="CATEGORY_ITEM” lazy="true" cascade="save-update"> <key column="CATEGORY_ID"/> <index column="DISPLAY_POSITION"/> <many-to-many class="Item" column="ITEM_ID"/> </list>

45. Many-to-many associations Transaction tx = session.beginTransaction(); Category cat = (Category) session.get(Category.class, categoryId); Item item = (Item) session.get(Item.class, itemId); cat.getItems().add(item); tx.commit();

46. Many-to-many associations • A bidirectional many-to-many association <class name="Category" table="CATEGORY"> ... < set name="items" table="CATEGORY_ITEM" lazy="true" cascade="save-update"> <key column="CATEGORY_ID"/> <many-to-many class="Item" column="ITEM_ID"/> </set> </class> • A bidirectional many-to-many association <class name="Item" table="ITEM"> ... <set name="categories" table="CATEGORY_ITEM" lazy="true" inverse="true" cascade="save-update"> <key column="ITEM_ID"/> <many-to-many class="Item" column="CATEGORY_ID"/> </set> </class>

47. Understanding the Hibernate type system Built-in mapping types Java primitive mapping types Using mapping types Creating custom mapping types