Hibernate 2005

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Introduction to the object to relational mapping framework called Hibernate.

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Hibernate 2005

  1. 1. Hibernate:the short versionBjörn Granvik, Jayway
  2. 2. Overview• Dry run: Theory• Wet run: Lab– Tutorial part 1: Store two tables with straight Hibernateand do the same using Spring.– Tutorial part 2: More relationships
  3. 3. Write the SQLCREATE TABLE users (LogonID varchar(20) NOT NULL default 0,Name varchar(40) default NULL,Password varchar(20) default NULL,EmailAddress varchar(40) default NULL,LastLogon datetime default NULL,PRIMARY KEY (LogonID));
  4. 4. Create the Pojopublic class User {private String userID;private String userName;private String password;...public String getID() {return userID;}public void setID(String newUserID) {userID = newUserID;}...}
  5. 5. Write the hbm file<hibernate-mapping><class name=”dbdemo.User" table="users"><id name="ID" column="LogonId" type="string"><generator class=”native"/></id><property name="userName"column="Name” type="string"/><property name="password" type="string"/><property name="emailAddress" type="string"/><property name="lastLogon" type=”java.util.Date"/></class></hibernate-mapping>
  6. 6. Property filehibernate.connection.driver_class=org.gjt.mm.mysql.Driverhibernate.connection.url=jdbc:mysql://localhost/testdbhibernate.connection.username = gsmithhibernate.connection.password = sesame...caches etc
  7. 7. So far• User.java - Java bean object to persist• User.hbm.xml - Hibernate mapping file• hibernate.properties - properties file with JDBCconnection info• SQL User table in your database
  8. 8. What to do• Create a Pojo• Tell the DB about the type of objects you want tostore• Create a Session to your database of choice• Load, Save and Query your objects• flush() your Session back to the database
  9. 9. Example: Setup// Set up configuration... conf// Then build a session to the databaseSessionFactory sf = conf.buildSessionFactory();session = sf.openSession();
  10. 10. Example: Save// Create new User and store it in dbUser newUser = new User();newUser.setID("joe_cool");newUser.setUserName("Joseph Cool");...// And call Hibernate to store itsession.save(newUser);
  11. 11. Example: Get single userUser newUser = (User)session.load(User.class, suserId);
  12. 12. Example: Get usersList myUsers = session.find("from User");for (Iterator i = myUsers.iterator(); i.hasNext();) {User nextUser = (User) i.next();System.out.println("Resetting password for User: "+ nextUser.getUserName());nextUser.setPassword("secret");}...
  13. 13. Example: flush// close our session and release resourcessession.flush();session.close();
  14. 14. OR vs. Relational model• Java object identity, equality, primary keysa == ba.equals(b)• Polymorphism• Joining tables vs. navigating associations– (bi)birectional relations• Detach
  15. 15. Detached objectsRetrieve an AuctionItem and change the description:Session session = sessionFactory.openSession();Transaction tx = session.beginTransaction();AuctionItem item =(AuctionItem) session.get(ActionItem.class, itemId);tx.commit();session.close();Bid bid = new Bid();bid.setAmount(bidAmount);bid.setItem(item);item.getBids().add(bid);Session session2 = sessionFactory.openSession();Transaction tx = session2.beginTransaction();session2.update(item);tx.commit();session2.close();
  16. 16. One-to-OneJava usage:Bar myBar = Foo.getBar();Mapping file: Mapping file:<class name=“Foo”>...<one-to-one name=“bar” class=“Bar” /></class>Schema:Foo Barid id
  17. 17. One-to-ManyJava usage:Set myBars = Foo.getBars();Mapping file: Mapping file:<class name=“Foo”> ”>...<set role=“bars” table=“bar” inverse=“true”><key column=”foo_id” /><one-to-many class=“Bar”></set></class>Schema:Foo Barid id, foo_id
  18. 18. One-to-ManyJava usage:Set myBars = Foo.getBars();Mapping file: Mapping file:<class name=“Foo”> ”>...<set role=“bars” table=“bar” inverse=“true” lazy=“true”cascade=”orphan-delete”><key column=”foo_id” /><one-to-many class=“Bar”></set></class>Schema:Foo Barid id, foo_id
  19. 19. Many-to-ManyJava usage:Set myBars = Foo.getBars();Mapping file: Mapping file:<class name=“Foo”> ”>...<set role=“bars” table=“Foo_Bar”><key column=”foo_id” /><many-to-many column=“bar_id” class=“Bar”></set></class>Schema:Foo Bar Foo_Barid id foo_id, bar_idNo relationalclass FooBar!
  20. 20. Much more• Criteria• Query by example• Composites• Version 3.0
  21. 21. CriteriaList cats = sess.createCriteria(Cat.class).add( Expression.like("name", "Fritz%") ).add( Expression.between("weight",minWeight, maxWeight) ).list();
  22. 22. Query by exampleExample example = Example.create(cat.excludeZeroes() //exclude zero valued properties.excludeProperty("color") //exclude the property "color".ignoreCase(.enableLike(); //use like for string comparisonsList results = session.createCriteria(Cat.class).add(example).list();

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