2009 coreservlets com 358548 - PDF document

© 2009 coreservlets.com HibtQi Hib erna e Originals of Slides and Source Code for Examples: Customized Java EE Training: http://courses.coreservlets.com/Servlets, JSP, Struts, JSF/MyFaces/Facelets, Aj © 2009 coreservlets.com For live Spring & Hibernate training, see thtt//lt/ courses a t t Taught by the experts that brought you this tutorial. Availableatpublicvenuesorcustomizedversions Available at venues can be held on-site at your organization. CdlddthtbMtHll an d t ht b y M H a Java 5, Java 6, intermediate/beginning servlets/JSP, advanced servlets/JSP, Struts, JSF, Ajax, GWT, custom mix of topicsCourses developed and taught by coreservlets.com experts (edited by Marty)Spring, Hibernate/JPA, EJB3, Ruby/RailsContact hall@coreservlets.com for details To ics in This Section p •Briefl y review SQL q uer in yqyg Discover Hibernate’s different approachestoqueryinga approaches a Getacquaintedwiththe‘Queryby Criteria’ technique •Introduce the ‘Query by Example’ offshoot © 2009 coreservlets.com Qi Q uery Customized Java EE Training: http://courses.coreservlets.com/Servlets, JSP, Struts, JSF/MyFaces/Facelets, Ajax, GWT, Spring, Hibernate/JPA, Java 5 & 6. Developed and taught by well-known author and developer. At public venues or onsite at Quer for Data yg •Pull back specific data from a database Retrieve a specific object Retrieve a collection of a specific object typeRetrieve a collection of different object types •In the database, handled through the Structured Query Language (SQL) SELECT statements for querying Quer Terminolo gy yggy •Restriction down the results ( rows based on s p ecified criteria g()p In SQL, accomplished with the use of conditions appearing in a FROMEBILL WHEREEBILLID=1 ; EBILL EBILL _ SELECT * FROM EBILL �BALANCE 1000 Nidthdt(l)t g d t co we re t In SQL, accomplished by identifying columns in the ‘select’ clause _ �FROM EBILL WHERE AMOUNT 1000 ; _ ; SELECT EBILL_ID, EBILLER_ID, BALANCE, DUE_DATEFROM EBILL WHERE EBILL_ID=1;• Groupingsimilarresultstogetherbasedoncommonattributes similar SELECT EBILLER_ID, AVG(BALANCE)FROM EBILL GROUP BY EBILLER_ID; Quer for data yg SQL statements can be simple… SELECT*FROMACCOUNT – * Returns all the records from the account table Returntherowofdatafortherecordwithaccountid1 account 1 …or more involvedSELECT AO ABALANCE ., ACCOUNT_OWNER AO, ACCOUNT A WHERE �A.BALANCE 500 AND AACCOUNTIDAAOACCOUNTIDAND _ AAO _ Returns a list of all the account owners who have accounts with a balance over $500 SQL Quer y O �// projection [ WHERE ] // restriction [ ORDER_BY ] // ordering [ GROUP BY ]// aggregation [ HAVING ]// group restriction diti() ) � Quer with Hibernate yg Provides multiple interfaces for querying QuerybyID – Query by Criteria–Query by Example Hibernate Query Language • Relievesthedeveloperofhavingtoknow • Relieves Hibernate understands the underlying database and knows how to write more • Flexible • Flexible data, it provides hooks for you to write your own © 2009 coreservlets.com QbID Q uery y Customized Java EE Training: http://courses.coreservlets.com/Servlets, JSP, Struts, JSF/MyFaces/Facelets, Ajax, GWT, Spring, Hibernate/JPA, Java 5 & 6. Developed and taught by well-known author and developer. At public venues or onsite at Quer Retrieve an object by its ID •Most common and easiest a roach to obtainin g ob j ects ppgj Fastest type of query, but can only return a sin g le ob j ect at a time gj –Assuming primary key index on the id column Account account = (Account)sessionget( (Account)session . © 2009 coreservlets.com QbCiti Q uery y a Customized Java EE Training: http://courses.coreservlets.com/Servlets, JSP, Struts, JSF/MyFaces/Facelets, Ajax, GWT, Spring, Hibernate/JPA, Java 5 & 6. Developed and taught by well-known author and developer. At public venues or onsite at Quer Criteria ( QBC ) yy() Build a query by defining multiple ‘Criterion’ – Specifyconstraintswithoutdirectstringmanipulations Specify May result in less readable code than other methodsRealized through four Hibernate interfaces Base object for QBC, created off the Session, Contains all the restriction/projection/aggregation/order – org.hibernate.DetachedCriteria org.hibernate.DetachedCriteria Same as Criteria, but created without the presence a Later, attached (like detached objects) to a session and executed executed Think of each Criterion as a ‘where’ clause addition Utility class used to create Criterion objects org.hibernate.Criteria Create by passing the session a ‘root’ class –session.createCriteria(String className); • Addrestrictions • Add addCriterion(Criterion criterion);•Think ‘where’ clause Join to an association, assigning the li(iiihili) – createA ng assoc i at , Str i ng a Still thinking ‘where’ clause Addorder Think ‘order by’ org.hibernate.Criteria Get results of the q uer as a List of qy root objects – list Get result of the query as a single root ob ect No session required to create –Created by calling static method, providing a ‘root’ class• DetachedCriteriaforClass(StringclassName); Contains most of the methods from the Criteriaclass Criteria list(), uniqueResult() etc… To execute, create regular Criteria instance off of detached version EblCii(Si) – C r i ) ; org.hibernate.criterion.Restrictions lt(String propertyName, String value); • gt(StringpropertyNameStringvalue); • gt(String eq(String properyName, String value); p Strin g value ); (gppy,g); like(String propertyName, String value);isEmpty(String propertyName, String value); isNotEmpty(String propertyName, String value);isNull(String propertyName, String value); • isNotNull(StringpropertyNameStringvalue); • isNotNull(String in(String propertyName, Collection values); Ma p q(pppy); between(String propertyName, Object lo, Object hi); Hibernate Criterion Interfaces •org.hibernate.criterion.Property Way to represent query restrictions orghibernatecriterionOrder • . . Order Data container used to represent an ordering scheme– SingleCriteriaobjectcancontainmultipleorders contain Created through static method, passing in attribute to sort Hibernate utility class to help identify returned columns CtdthhttithdiththPjti – d c me th o d s on e ith er e ro ec of Property classes Query Building Retrieve List of Ob j ects // retrieves list of all Savings Account ObjectsCriteria criteria = session.createCriteria(SavingsAccount.class);List savingAccounts = criteria.list(); RootEntity:SavingsAccount // order savings accounts by balance, ascendingCriteria criteria = sessioncreateCriteria(SavingsAccountclass) Root . List savingAccounts = criteria.list();Attribute Name // polymorphic query –Criteria criteria = itCiti(Atl) sess on.crea C r .c ass Root Entity: Account Retrieve Sin g le Ob j ect // retrieve an AccountOwner...Criteria criteria = session.createCriteria(AccountOwner.class);// ...with a specific email address CriterionrestrictByEmail = // add restrictByEmail to criteria criteriaadd(restrictByEmail); Attribute Name, Value criteria . // ...and we know there can be only oneAccountOwner marty = (AtO)itiiRlt() (A ccoun tO wner cr it er a.un que esu lt() // same commands -shortened to one line of code AccountOwner marty = (AccountOwner)session.createCriteria(AccountOwner.class) ueResult() Creating Criterion: RestrictionsandProperty Restrictions // shortened version from previous slide, // using Restrictions AccountOwner marty = (AccountOwner)session.createCriteria(AccountOwner.class) " , " " ) Restrictions.eq(email,hall@coreservlets) ________________________________________________// could also have written using the Property class AtOt(AtO)i A ccoun tO wner mar t y = (A ccoun tO wner sess on.createCriteria(AccountOwner.class)Property.forName("email").eq("hall@coreservlets.com") Usin Dot Notation on Ob j ects // can use dot notation to access component attributes Listaccounts=session List = .add(Restrictions.eq("address.zipCode","21045") // also valid with Property objectLi st n sess o n staccoutssesso Property.forName("address.zipCode").eq("21045") (); (); 'Between' and 'In' Clauses // using ‘ Listaccounts= = Restrictions.between("balance",100, 500) o n n t I 1L 2L 3 L og[]accoutds{,,3}; List accounts = session.createCriteria(Account.class) ert .forName "accountId" .in accountIds py()() Strin Matchin g ( like clause ) gg() // String matching ListaccountOwners = Restrictions.like("lastName","H%").ignoreCase() ________________________________________________ // Alternate String matching.// MatchMode.END and MatchMode.EXACT also availableList accountOwners = session.createCriteria(AccountOwner.class)Property.forName("lastName").like("H", MatchMode.START).ignoreCase() lit() . s ; g Multi p le Criterion gp // adding multiple criteria results in an ‘ ListaccountOwners= = Restrictions.ilike("lastName","H%") " , " " ) Restrictions.ilike(firstName,M%) Can also use 'ilike‘ for case insensitive ________________________________________________ wi h Pr ope t i a l //ostopetesaso List accountOwners = session.createCriteria(AccountOwner.class) ert .forName "lastName" .like "H%" py()() Property.forName("firstName").like("M%") Or’ing Multiple Criterion usingOr/And using Or/And //option1 useRestrictionsorandRestrictionsand // 1 – . . // retrieve accounts where: //1)lastnamestartswith ‘ H ’ andfirstnamewith ‘ M ’ H M // OR// 2) email address ends in ‘ ListaccountOwners Restrictions.or( ct o n n estctos.ad( ) Or’ing Multiple Criterion usingDisjunction/Conjuction using // option 2 – u // Restrictions.disjunction// retrieve accounts where: //1)lastnamestartswith ‘ H ’ andfirstnamewith ‘ M ’ H M // OR// 2) email address ends in ‘List accountOwners = sessioncreateCriteria(AccountOwnerclass) session . . Restrictions.disjunction().add(Restrictions.conjunction() dd(Rtitilik("ltN""H%")) .a dd(R es i c lik tN ame Restrictions.like("email","%coreservlets.com") Adding Your Own SQL – UsingDatabaseFunctions Using // use the sql ‘ //withlastnamesgreaterthen10characters // List accountOwners = session.createCriteria(AccountOwner.class).add( Hibernate.INTEGER Hibernate.INTEGER Need to put an ‘alias’ place holder for the table name, which will come from the root entitiy, AccountOwner Adding Your Own SQL – JoiningTables Joining // retrieve accounts where all the transactions made //bytheaccounthavebeenlessthan$500 // List accounts = session.createCriteria(Account.class).add( whereatx.accountid = {alias}.accountid) " where _ ) Again, ‘alias’ place holder for the table namewhichwillcomefromtheroot Oracle and Derby evaluate ‘all’ to ‘true’ iftdithblt name , entitiy, Account if no rows are re t urne i e su b se Creating Detached Criteria Queries DetachedCriteria detachedCriteria = DetachedCriteria.forClass(AccountOwner.class) DetachedCriteria.forClass(AccountOwner.class) .add(Restrictions.ilike("lastName","H%"));Session session = HibernateUtilgetSessionFactory() HibernateUtil . Criteria regularCriteria = detachedCriteria.getExecutableCriteria(session);List accountOwners = regularCriteria.list(); _______________________________________________________// can also be combined into one lineList accountOwners = detachedCriteria.getExecutableCriteria(session) Data with Joins g ebIllers is the name of the association that appears In the root entity’s mapping file session.createCriteria(EBill.class);// build the EBiller criteria off the EBill criteria CriteriaebillerCriteria = ebillerCriteria.add(Restrictions.like("name","VISA")); // return all the EBills issued from VISAList ebills = ebillCriteria.list(); ______________________________________// can be combined into a single like of codeCriteria ebillCriteria = session.createCriteria(EBill.class) session.createCriteria(EBill.class) .createCriteria("ebiller" Restricting Data with Joins – UsinganAlias Using Alternate approach using an alias and only creatingoneCriteriaobject creating // single line approach from previous// slide using two Criteria objects CriteriaebillCriteria= Criteria = createCriteria(EBill.class)("ebiller").add(Restrictions.like("name", "VISA")); ebIllers is the name of the association that ears In the root entit y ’s ma pp in file // use an alias , and create a sin le Criteria ob ect ppyppg //,gj Criteria ebillCrit = session.createCriteria(EBill.class)("ebillers", "eb").add(Restrictions.like("eb.name", "VISA")); Criteria Ob j ect Joinin g jg Currently, only joining of associations td are suppor t e d &#xmany;&#x-to-;&#xmany; Cjiii i n i s no at this time – Receive failure that the property you want to reference does not represent an entity association Thiftlikltbdddithft – Thi s l y t o b e a dd e d i n e near f u t Forcin Ea g er Loadin g ggg Indicate in the Criteria to fully load all bjd i o ects, an d to use prox i esIf already setup to fully load in the object mapping file (ienolazy =" etc)thisisunnecessary . e lazyfalse … ) also unnecessary. Hibernate will automatically load bjfdiii o ects re f erence i n restr i ct Listebillers List ebillers .setFetchMode("ebills", FetchMode.JOIN) .list(); Indicates that the “ebills” collection should be fully loaded for each EBiller instance Result Transformers – DefaultBehavior Default Transformers map the returned result sets Jbj to ava o bj ectsBy default, maps returned result sets to the Root Entity object object // this…List accounts = session.createCriteria(Account.class) Default results transformer maps the result set into the Root Entity indicated in the // …is the same as thisList accounts = session.createCriteria(Account.class) Result Transformers – DistinctEntityResults Distinct • Eliminates any duplicate objects // transformer eliminates any duplicate objectsList accounts = session.createCriteria(Account.class) Result Transformers – ReturnMultipleObjectTypes Return • Returnsalistofmapswhereeachmaphasaninstanceof a all the objects identified in the query (on a per-row basis) ListmapList = for (Object aResult : result) {Map map = (Map) aResult; Att accoun = (Account)map.get(Criteria.ROOT_ALIAS);AccountTransaction atx = (AccountTransaction) map.get("atx"); Hibernate Pro j ections j •Restricting returned columns Only bring back objects/columns you want to see Created off of either the Projections of Property Property.forName () Cltt d • an map resu lt s o a non-manage d Java class Hibernate Pro j ections j // retrieve id, balance and creation date //dtth ddt // an d se t th em on a non-manage d summary dt List summaryList = .as("accountId")) add( Projectionsproperty( " " ) add( property(creationDate) new AliasToBeanResultTransformer(AccountSummaryDTO.class) Hibernate Pro j ections j // can also be coded using Property class //insteadofProjectionsclass // instead of Projections class List summaryList = . .add(.as("accountId")) add( PropertyforName("balance") . add( new AliasToBeanResultTransformer( Sl) Account S and Grou p in gpg // Returns a collection of Objects[] with 4 fields// 1) Account id // 2) A single EBiller id on that account session.createCriteria(Account.class) session.createCriteria(Account.class) .createAlias("ebills", "e").add(Property.forName("accountId") .group() t() .avg())); No ‘Having’ feature available at this time – Planned for a future release © 2009 coreservlets.com QbEl Q uery y Customized Java EE Training: http://courses.coreservlets.com/Servlets, JSP, Struts, JSF/MyFaces/Facelets, Ajax, GWT, Spring, Hibernate/JPA, Java 5 & 6. Developed and taught by well-known author and developer. At public venues or onsite at Exam p le ) yyp() •Set u p exam p le ob j ect ) for ppj() Hibernate to use to generate a databasequery database query Create ‘Example’ criterion based on these objects objects • p Create by using static create(Object obj); – Creates an Exam p le ob j ect used for q uer for pjqyg the supplied object type Quer Exam p le yyp // setup an owner with last name 'Hall' AtOAtO() A ccoun tO wner owner = new A ccoun tO // create an ‘example’ criterion based on user Examplecreate(owner); Example . // use the criterion to execute the // query for owners named 'Hall'List hallList = sessioncreateCriteria(AccountOwnerclass) session . . .add(.list(); Exam p le Ob j ect gppj Certain fields ignored by default ObjectIdentifiers – Object Identifiers –Version property– Anynullvaluedproperties Can also specify: enableLike(MatchModemode); – enableLike(MatchMode mode); Enable ‘like’ matching for all String attributes g nore case for all Strin g attributes gg –Excludes zero-valued properties–excludeProperty(String name); Eldtildt • d e a par ti cu ar name d proper t Do not exclude null or zero-valued properties Combine Example and TraditionalCriterion Traditional = Example.create(owner); // execute the query for owners named 'Hall'// who also live in the state of Maryland List hallList = session.createCriteria(Acc add( ) .add(dress.state", "MD")).list(); Combine Multiple ExampleCriterion Example // account owners named Hall AccountOwnerowner=newAccountOwner(); AccountOwner = Example exampleOwner = Example.create(owner); // accounts with a balance of 1000Account account = new Account(); account.setBalance(1000); account.setBalance(1000); Example exampleAccount = Example.create(account); // r y r wn s ll' wi h ba a n o 000 //queyooesaedatbaaceso000 List hallList = session.createCriteria(AccountOwner.class) leOwner exampleAccount Great Place for QBE Applications with GUI pages that allow ltilttibt mu l e a tt r u t as search criteria Example: © 2009 coreservlets.com W W rap-up Customized Java EE Training: http://courses.coreservlets.com/Servlets, JSP, Struts, JSF/MyFaces/Facelets, Ajax, GWT, Spring, Hibernate/JPA, Java 5 & 6. Developed and taught by well-known author and developer. At public venues or onsite at Summar In this lecture, we: Reviewed traditional SQL querying and established terms – IdentifiedseveralapproachesprovidedbyHibernateto – Identified several query a databaseWalked through Query by Criteria (QBC) and Query by l()ihddldbh Examp query i ng met h o d s, an d l earne d out t h e core Hibernate classes involved in querying• • Preview of Next Sections •Hibernate Quer y Lan g ua ygg Calling native SQL through Hibernate Hibernate 53 © 2009 coreservlets.com Qti? Q ues ti ons Customized Java EE Training: http://courses.coreservlets.com/Servlets, JSP, Struts, JSF/MyFaces/Facelets, Ajax, GWT, Spring, Hibernate/JPA, Java 5 & 6. Developed and taught by well-known author and developer. At public venues or onsite at