Hibernate retrieval method and the explanation of criteria query

Hibernate framework 5 ways to retrieve

1. Navigation object Graph retrieval Method : Navigating to other objects based on objects that have already been loaded

2.OID Retrieval method : Retrieving Objects by the OID of the object

3.HQL Retrieval method : Using object-oriented HQL Query Language

     4. QBC Retrieval method : using qbc (Query by Criteria) API api encapsulates query statements based on string form, providing a more object-oriented query interface

5. local sql Retrieval method : SQL query statement using local database focus on the criteria query this time , let's first look at it. The criteria query encapsulates the SQL statement by encapsulating the query condition in object-oriented way, also called object Query.
By using the method of object to combine various query conditions , the criteria for generating SQL query statements automatically by Hibernate is created by hibernate Session .
0. the code for the Hibernateutil helper class is as follows

 packageentity;Importorg.hibernate.Session;Importorg.hibernate.SessionFactory;Importorg.hibernate.cfg.Configuration; public classHibernateutil {Private Static FinalThreadLocal sessiontl=NewThreadLocal ();Private StaticConfiguration conf;Private Final Staticsessionfactory sf;Static{    Try{conf=NewConfiguration (). Configure (); SF=conf.buildsessionfactory (); } Catch(Exception Ex) {ex.printstacktrace (); Throw NewExceptionininitializererror (ex); }    } public Staticsession Currentsession () {session session=(Session) Sessiontl.get (); if(session==NULL) {session=sf.opensession ();    Sessiontl.set (session); }    returnsession; } public Static voidCloseSession () {session session=(Session) Sessiontl.get (); Sessiontl.set (NULL);    Session.close (); }}

1. Unconditional Inquiry

    /*      * Unconditional query      */ @Testpublicvoid  critest ()    {=  Hibernateutil.currentsession ();     = session.begintransaction ();     = Session.createcriteria (Dept.class);    List<Dept> list=criteria.list ();      for (Dept dept:list) {        System.out.println (dept.getdeptname ());    }    Tx.commit ();     Hibernateutil.closesession ();    }

2.

 /*   * comparison operation * Conditional query  */  @Test  public  void   critestbyname () {session session  = = session.begintransaction (); List  <Dept> list = Session.createcriteria (dept.class ). Add ( Restrictions. eq     ("deptname", "test department"  for   (Dept dept:list) {System.out.print    ln (dept.getdeptname ());     } tx.commit ();    Hibernateutil.closesession (); }   

3. alias Query

/** Alias Query*/@Test public voidCrinamedtest () {session session=hibernateutil.currentsession (); Transaction TX=session.begintransaction (); criteria Criteria= Session.createcriteria (Emp.class); Criteria. CreateAlias ("dept", "d");//Name the Dept property in EMP as Dlist<emp> list=criteria.add (restrictions.eq ("d.deptname", "test Department")) . List ();  for(Emp emp:list) {System.out.println (emp.getempname ());         } tx.commit ();            Hibernateutil.closesession (); }

4. Range Arithmetic

/** Range Operations * restrictions.in Query*/@Test public voidCriintest () {session session=hibernateutil.currentsession (); Transaction TX=session.begintransaction (); criteria Criteria= Session.createcriteria (Emp.class); List<String> loclist=NewArraylist<>(); Loclist.add ("bj"); List<Emp> List=criteria.add (restrictions.inch("loc", loclist)).        List ();  for(Emp emp:list) {System.out.println (emp.getempname ());         } tx.commit ();            Hibernateutil.closesession (); }

5. Fuzzy Query

/** String pattern matching (fuzzy query)*/@Test public voidCriliketest () {session session=hibernateutil.currentsession (); Transaction TX=session.begintransaction (); criteria Criteria= Session.createcriteria (Emp.class); List<Emp> list= Criteria.add (restrictions. like("loc", "%b%") . List (); //The following function is the same as above, except that the case is ignored//list<emp> list= criteria.add (restrictions.  ilike("loc", "b", matchmode.anywhere)). list ();         for(Emp emp:list) {System.out.println (emp.getempname ());         } tx.commit ();            Hibernateutil.closesession (); }

6. Logical Operation

/** Logical operation and OR not*/@Test public voidCriandtest () {session session=hibernateutil.currentsession (); Transaction TX=session.begintransaction (); criteria Criteria= Session.createcriteria (Emp.class). Add (restrictions. and(restrictions.eq ("empname", "little music"), restrictions.like ("loc", "%b%"))); List<Emp> list =criteria.list ();  for(Emp emp:list) {System.out.println (emp.getempno ());         } tx.commit ();    Hibernateutil.closesession (); }

7. Dynamic Query

/** Dynamic Query*/@Test public voidCridynamictest () {session session=hibernateutil.currentsession (); Transaction TX=session.begintransaction (); EMP EMPCRI=NewEMP (); Empcri.setempname ("little music"); Empcri.setempno (0); criteria Criteria= Session.createcriteria (Emp.class); if(empcri.getempname ()! =NULL) {            //the user fills in the name as the conditionCriteria.add (restrictions.eq ("empname", Empcri.getempname ())); }        if(empcri.getloc ()! =NULL) {criteria.add (restrictions.gt ("empNo", Empcri.getempno ())); } List<Emp> list =criteria.list ();  for(Emp emp:list) {System.out.println (emp.getempno ());         } tx.commit ();    Hibernateutil.closesession (); }

8. Sorting

/** Sort*/@Test public voidCriordertest () {session session=hibernateutil.currentsession (); Transaction TX=session.begintransaction (); criteria Criteria= Session.createcriteria (Emp.class); List<Emp> list = Criteria.AddOrder(ORDER.ASC("empNo") . List ();  for(Emp emp:list) {System.out.println (emp.getempname ());         } tx.commit ();    Hibernateutil.closesession (); }

9. Paging

/** Paging*/@Test public voidCripagetest () {session session=hibernateutil.currentsession (); Transaction TX=session.begintransaction (); criteria Criteria= Session.createcriteria (Emp.class); intpageindex=2;//Current page number        intpagesize=2;//the amount of data displayed per pageCriteria.Setfirstresult((pageIndex-1) *pageSize); Criteria. Setmaxresults        (pageSize); List<Emp> list =criteria.list ();  for(Emp emp:list) {System.out.println (emp.getempname ());         } tx.commit ();            Hibernateutil.closesession (); }

Detachedcriteria Query

/** Detachedcriteria Query*/@Test public voidDetachedcritest () {session session=hibernateutil.currentsession (); Detachedcriteria DC=detachedcriteria.forclass (Emp.class, "e"); Dc.createalias ("e.dept", "d"). Add (restrictions.eq ("d.deptname", "test department")); List<Emp> list=Dc.getexecutablecriteria (session). List ();  for(Emp emp:list) {System.out.println (emp.getempname ());             } hibernateutil.closesession (); }

Hibernate retrieval method and the explanation of criteria query