翻译文献-制作一个oracle实体项目

外文原文UNDERSTANDINGTHEORADATAINTERFACEONEOFTHECHOICESINMAKINGANORACLEOBJECTANDITSATTRIBUTEDATAAVAILABLETOJAVAAPPLICATIONSISTOCREATEACUSTOMOBJECTCLASSTHATIMPLEMENTSTHEORACLESQLORADATAANDORACLESQLORADATAFACTORYINTERFACESORYOUCANIMPLEMENTORADATAFACTORYINASEPARATECLASSTHEORADATAANDORADATAFACTORYINTERFACESARESUPPLIEDBYORACLEANDARENOTAPARTOFTHEJDBCSTANDARDUNDERSTANDINGORADATAFEATURESTHEORADATAINTERFACEHASTHESEADVANTAGESITRECOGNIZESORACLEEXTENSIONSTOTHEJDBCORADATAUSESORACLESQLDATUMTYPESDIRECTLYITDOESNOTREQUIREATYPEMAPTOSPECIFYTHENAMESOFTHEJAVACUSTOMCLASSESYOUWANTTOCREATEITPROVIDESBETTERPERFORMANCEORADATAWORKSDIRECTLYWITHDATUMTYPES,THEINTERNALFORMATTHEDRIVERUSESTOHOLDORACLEOBJECTSTHEORADATAANDORADATAFACTORYINTERFACESDOTHEFOLLOWINGTHETODATUMMETHODOFTHEORADATACLASSTRANSFORMSTHEDATAINTOANORACLESQLREPRESENTATIONORADATAFACTORYSPECIFIESACREATEMETHODEQUIVALENTTOACONSTRUCTORFORYOURCUSTOMOBJECTCLASSITCREATESANDRETURNSAORADATAINSTANCETHEJDBCDRIVERUSESTHECREATEMETHODTORETURNANINSTANCEOFTHECUSTOMOBJECTCLASSTOYOURJAVAAPPLICATIONORAPPLETITTAKESASINPUTANORACLESQLDATUMOBJECTANDANINTEGERINDICATINGTHECORRESPONDINGSQLTYPECODEASSPECIFIEDINTHEORACLETYPESCLASSORADATAANDORADATAFACTORYHAVETHEFOLLOWINGDEFINITIONSPUBLICINTERFACEORADATADATUMTODATUMORACLECONNECTIONCONNTHROWSSQLEXCEPTIONPUBLICINTERFACEORADATAFACTORYNOTETHEJPUBLISHERUTILITYSUPPORTSTHEGENERATIONOFCLASSESTHATIMPLEMENTTHEORADATAANDORADATAFACTORYINTERFACESSEE“USINGJPUBLISHERTOCREATECUSTOMOBJECTCLASSES“ONPAGE945ORADATACREATEDATUMD,INTSQL_TYPE_CODETHROWSSQLEXCEPTIONWHERECONNREPRESENTSTHECONNECTIONOBJECT,DREPRESENTSANOBJECTOFTYPEORACLESQLDATUM,ANDSQL_TYPE_CODEREPRESENTSTHESQLTYPECODEFROMTHESTANDARDTYPESORORACLETYPESCLASSOFTHEDATUMOBJECTRETRIEVINGANDINSERTINGOBJECTDATATHEJDBCDRIVERSPROVIDETHEFOLLOWINGMETHODSTORETRIEVEANDINSERTOBJECTDATAASINSTANCESOFORADATATORETRIEVEOBJECTDATAUSETHEORACLESPECIFICORACLERESULTSETCLASSGETORADATAMETHODASSUMEANORACLERESULTSETOBJECTORSORSGETORADATAINTCOL_INDEX,ORADATAFACTORYFACTORYTHISMETHODTAKESASINPUTTHECOLUMNINDEXOFTHEDATAINYOURRESULTSET,ANDAORADATAFACTORYINSTANCEFOREXAMPLE,YOUCANIMPLEMENTAGETORAFACTORYMETHODINYOURCUSTOMOBJECTCLASSTOPRODUCETHEORADATAFACTORYINSTANCETOINPUTTOGETORADATATHETYPEMAPISNOTREQUIREDWHENUSINGJAVACLASSESTHATIMPLEMENTORADATAORUSETHESTANDARDGETOBJECTINDEX,MAPMETHODSPECIFIEDBYTHERESULTSETINTERFACETORETRIEVEDATAASINSTANCESOFORADATAINTHISCASE,YOUMUSTHAVEANENTRYINTHETYPEMAPTHATIDENTIFIESTHEFACTORYCLASSTOBEUSEDFORTHEGIVENOBJECTTYPE,ANDITSCORRESPONDINGSQLTYPENAMETOINSERTOBJECTDATAUSETHEORACLESPECIFICORACLEPREPAREDSTATEMENTCLASSSETORADATAMETHODASSUMEANORACLEPREPAREDSTATEMENTOBJECTOPSOPSSETORADATAINTBIND_INDEX,ORADATACUSTOM_OBJTHISMETHODTAKESASINPUTTHEPARAMETERINDEXOFTHEBINDVARIABLEANDTHENAMEOFTHEOBJECTCONTAININGTHEVARIABLEORUSETHESTANDARDSETOBJECTMETHODSPECIFIEDBYTHEPREPAREDSTATEMENTINTERFACEYOUCANALSOUSETHISMETHOD,INITSDIFFERENTFORMS,TOINSERTORADATAINSTANCESWITHOUTREQUIRINGATYPEMAPTHEFOLLOWINGSECTIONSDESCRIBETHEGETORADATAANDSETORADATAMETHODSTOCONTINUETHEEXAMPLEOFANORACLEOBJECTEMPLOYEE,YOUMIGHTHAVESOMETHINGLIKETHEFOLLOWINGINYOURJAVAAPPLICATIONORADATADATUMORSGETORADATA1,EMPLOYEEGETORAFACTORYINTHISEXAMPLE,ORSISANORACLERESULTSET,GETORADATAISAMETHODINTHEORACLERESULTSETCLASSUSEDTORETRIEVEAORADATAOBJECT,ANDTHEEMPLOYEEISINCOLUMN1OFTHERESULTSETTHESTATICEMPLOYEEGETORAFACTORYMETHODWILLRETURNAORADATAFACTORYTOTHEJDBCDRIVERTHEJDBCDRIVERWILLCALLCREATEFROMTHISOBJECT,RETURNINGTOYOURJAVAAPPLICATIONANINSTANCEOFTHEEMPLOYEECLASSPOPULATEDWITHDATAFROMTHERESULTSETREADINGANDWRITINGDATAWITHAORADATAIMPLEMENTATIONTHISSECTIONDESCRIBESHOWTOREADDATAFROMANORACLEOBJECTORWRITEDATATOANORACLEOBJECTIFYOURCORRESPONDINGJAVACLASSIMPLEMENTSORADATAREADINGDATAFROMANORACLEOBJECTUSINGAORADATAIMPLEMENTATIONTHISSECTIONSUMMARIZESTHESTEPSINREADINGDATAFROMANORACLEOBJECTINTOYOURJAVAAPPLICATIONTHESESTEPSAPPLYWHETHERYOUIMPLEMENTORADATAMANUALLYORUSEJPUBLISHERTOPRODUCEYOURCUSTOMOBJECTCLASSESTHESESTEPSASSUMEYOUHAVEALREADYDEFINEDTHEORACLEOBJECTTYPE,CREATEDTHECORRESPONDINGCUSTOMOBJECTCLASSORHADJPUBLISHERCREATEITFORYOU,ANDDEFINEDASTATEMENTOBJECTSTMTNOTESORADATAANDORADATAFACTORYAREDEFINEDASSEPARATEINTERFACESSOTHATDIFFERENTJAVACLASSESCANIMPLEMENTTHEMIFYOUWISHSUCHASANEMPLOYEECLASSANDANEMPLOYEEFACTORYCLASSTOUSETHEORADATAINTERFACE,YOURCUSTOMOBJECTCLASSESMUSTIMPORTORACLESQLORATLEASTORADATA,ORADATAFACTORY,ANDDATUM1QUERYTHEDATABASETOREADTHEORACLEOBJECTINTOARESULTSET,CASTINGTOANORACLERESULTSETORACLERESULTSETORSORACLERESULTSETSTMTEXECUTEQUERY“SELECTEMP_COLFROMPERSONNEL“WHEREPERSONNELISAONECOLUMNTABLETHECOLUMNNAMEISEMP_COLOFTYPEEMPLOYEE_OBJECT2USETHEGETORADATAMETHODOFYOURORACLERESULTSETTOPOPULATEANINSTANCEOFYOURCUSTOMOBJECTCLASSWITHDATAFROMONEROWOFTHERESULTSETTHEGETORADATAMETHODRETURNSANORACLESQLORADATAOBJECT,WHICHYOUCANCASTTOYOURSPECIFICCUSTOMOBJECTCLASSIFORSNEXTEMPLOYEEEMPEMPLOYEEORSGETORADATA1,EMPLOYEEGETORAFACTORYORIFORSNEXTORADATADATUMORSGETORADATA1,EMPLOYEEGETORAFACTORYTHISEXAMPLEASSUMESTHATEMPLOYEEISTHENAMEOFYOURCUSTOMOBJECTCLASSANDORSISTHENAMEOFYOURORACLERESULTSETOBJECTINCASEYOUDONOTWANTTOUSEGETORADATA,THEJDBCDRIVERSLETYOUUSETHEGETOBJECTMETHODOFASTANDARDJDBCRESULTSETTORETRIEVEORADATADATAHOWEVER,YOUMUSTHAVEANENTRYINTHETYPEMAPTHATIDENTIFIESTHEFACTORYCLASSTOBEUSEDFORTHEGIVENOBJECTTYPE,ANDITSCORRESPONDINGSQLTYPENAMEFOREXAMPLE,IFTHESQLTYPENAMEFORYOUROBJECTISEMPLOYEE,THENTHECORRESPONDINGJAVACLASSISEMPLOYEE,WHICHWILLIMPLEMENTORADATATHECORRESPONDINGFACTORYCLASSISEMPLOYEEFACTORY,WHICHWILLIMPLEMENTORADATAFACTORYUSETHISSTATEMENTTODECLARETHEEMPLOYEEFACTORYENTRYFORYOURTYPEMAPMAPPUT“EMPLOYEE“,CLASSFORNAME“EMPLOYEEFACTORY“THENUSETHEFORMOFGETOBJECTWHEREYOUSPECIFYTHEMAPOBJECTEMPLOYEEEMPEMPLOYEERSGETOBJECT1,MAPIFTHECONNECTIONSDEFAULTTYPEMAPALREADYHASANENTRYTHATIDENTIFIESTHEFACTORYCLASSTOBEUSEDFORTHEGIVENOBJECTTYPE,ANDITSCORRESPONDINGSQLTYPENAME,THENYOUCANUSETHISFORMOFGETOBJECTEMPLOYEEEMPEMPLOYEERSGETOBJECT13IFYOUHAVEGETMETHODSINYOURCUSTOMOBJECTCLASS,USETHEMTOREADDATAFROMYOUROBJECTATTRIBUTESINTOJAVAVARIABLESINYOURAPPLICATIONFOREXAMPLE,IFEMPLOYEEHASEMPNAMEOFTYPECHARANDEMPNUMEMPLOYEENUMBEROFTYPENUMBER,PROVIDEAGETEMPNAMEMETHODTHATRETURNSAJAVASTRINGANDAGETEMPNUMMETHODTHATRETURNSANINTEGERTHENINVOKETHEMINYOURJAVAAPPLICATIONASFOLLOWSSTRINGEMPNAMEEMPGETEMPNAMEINTEMPNUMBEREMPGETEMPNUMWRITINGDATATOANORACLEOBJECTUSINGAORADATAIMPLEMENTATIONTHISSECTIONSUMMARIZESTHESTEPSINWRITINGDATATOANORACLEOBJECTFROMYOURJAVAAPPLICATIONTHESESTEPSAPPLYWHETHERYOUIMPLEMENTORADATAMANUALLYORUSEJPUBLISHERTOPRODUCEYOURCUSTOMOBJECTCLASSESTHESESTEPSASSUMEYOUHAVEALREADYDEFINEDTHEORACLEOBJECTTYPEANDCREATEDTHECORRESPONDINGCUSTOMOBJECTCLASSORHADJPUBLISHERCREATEITFORYOU1IFYOUHAVESETMETHODSINYOURCUSTOMOBJECTCLASS,THENUSETHEMTOWRITEDATAFROMJAVAVARIABLESINYOURAPPLICATIONTOATTRIBUTESOFYOURJAVADATATYPEOBJECTEMPSETEMPNAMEEMPNAMEEMPSETEMPNUMEMPNUMBERTHISSTATEMENTUSESTHEEMPOBJECTANDTHEEMPNAMEANDEMPNUMBERVARIABLESDEFINEDIN“READINGDATAFROMANORACLEOBJECTUSINGAORADATAIMPLEMENTATION“ONPAGE9232WRITEANORACLEPREPAREDSTATEMENTTHATUPDATESANORACLEOBJECTINAROWOFADATABASETABLE,ASAPPROPRIATE,USINGTHEDATAPROVIDEDINYOURJAVADATATYPEOBJECTNOTEALTERNATIVELY,YOUCANFETCHDATAINTOACALLABLESTATEMENTOBJECTTHEORACLECALLABLESTATEMENTCLASSALSOHASAGETORADATAMETHODNOTETHETYPEMAPISNOTUSEDWHENYOUAREPERFORMINGDATABASEINSERTANDUPDATEOPERATIONSORACLEPREPAREDSTATEMENTOPSTMTCONNPREPARESTATEMENT“UPDATEPERSONNELSETEMPLOYEEWHEREEMPLOYEEEMPNUM28959THISASSUMESCONNISYOURCONNECTIONOBJECT3USETHESETORADATAMETHODOFTHEORACLEPREPAREDSTATEMENTTOBINDYOURJAVADATATYPEOBJECTTOTHEPREPAREDSTATEMENTOPSTMTSETORADATA1,EMPTHESETORADATAMETHODCALLSTHETODATUMMETHODOFTHECUSTOMOBJECTCLASSINSTANCETORETRIEVEANORACLESQLSTRUCTOBJECTTHATCANBEWRITTENTOTHEDATABASEINTHISSTEPYOUCOULDALSOUSETHESETOBJECTMETHODTOBINDTHEJAVADATATYPEFOREXAMPLEOPSTMTSETOBJECT1,EMPADDITIONALUSESFORORADATATHEORADATAINTERFACEOFFERSFARMOREFLEXIBILITYTHANTHESQLDATAINTERFACETHESQLDATAINTERFACEISDESIGNEDTOLETYOUCUSTOMIZETHEMAPPINGOFONLYORACLEOBJECTTYPESSQLOBJECTTYPESTOJAVATYPESOFYOURCHOICEIMPLEMENTINGTHESQLDATAINTERFACELETSTHEJDBCDRIVERPOPULATEFIELDSOFACUSTOMJAVACLASSINSTANCEFROMTHEORIGINALSQLOBJECTDATA,ANDTHEREVERSE,AFTERPERFORMINGTHEAPPROPRIATECONVERSIONSBETWEENJAVAANDSQLTYPESTHEORADATAINTERFACEGOESBEYONDSUPPORTINGTHECUSTOMIZATIONOFORACLEOBJECTTYPESTOJAVATYPESITLETSYOUPROVIDEAMAPPINGBETWEENJAVAOBJECTTYPESANDANYSQLTYPESUPPORTEDBYTHEORACLESQLPACKAGEITMIGHTBEUSEFULTOPROVIDECUSTOMJAVACLASSESTOWRAPORACLESQLTYPESANDPERHAPSIMPLEMENTCUSTOMIZEDCONVERSIONSORFUNCTIONALITYASWELLTHEFOLLOWINGARESOMEPOSSIBLESCENARIOSTOPERFORMENCRYPTIONANDDECRYPTIONORVALIDATIONOFDATATOPERFORMLOGGINGOFVALUESTHATHAVEBEENREADORAREBEINGWRITTENTOPARSECHARACTERCOLUMNSSUCHASCHARACTERFIELDSCONTAININGURLINFORMATIONINTOSMALLERCOMPONENTSNOTEYOUCANUSEYOURJAVADATATYPEOBJECTSASEITHERINOROUTBINDVARIABLESTOMAPCHARACTERSTRINGSINTONUMERICCONSTANTSTOMAPDATAINTOMOREDESIRABLEJAVAFORMATSSUCHASMAPPINGADATEFIELDTOJAVAUTILDATEFORMATTOCUSTOMIZEDATAREPRESENTATIONFOREXAMPLE,DATAINATABLECOLUMNISINFEETBUTYOUWANTITREPRESENTEDINMETERSAFTERITISSELECTEDTOSERIALIZEANDDESERIALIZEJAVAOBJECTSINTOOROUTOFRAWFIELDS,FOREXAMPLEFOREXAMPLE,USEORADATATOSTOREINSTANCESOFJAVAOBJECTSTHATDONOTCORRESPONDTOAPARTICULARSQLORACLE9OBJECTTYPEINTHEDATABASEINCOLUMNSOFSQLTYPERAWTHECREATEMETHODINORADATAFACTORYWOULDHAVETOIMPLEMENTACONVERSIONFROMANOBJECTOFTYPEORACLESQLRAWTOTHEDESIREDJAVAOBJECTTHETODATUMMETHODINORADATAWOULDHAVETOIMPLEMENTACONVERSIONFROMTHEJAVAOBJECTTOANORACLESQLRAWOBJECTTHISCANBEDONE,FOREXAMPLE,BYUSINGJAVASERIALIZATIONUPONRETRIEVAL,THEJDBCDRIVERTRANSPARENTLYRETRIEVESTHERAWBYTESOFDATAINTHEFORMOFANORACLESQLRAWANDCALLSTHEORADATAFACTORYSCREATEMETHODTOCONVERTTHEORACLESQLRAWOBJECTTOTHEDESIREDJAVACLASSWHENYOUINSERTTHEJAVAOBJECTINTOTHEDATABASE,YOUCANSIMPLYBINDITTOACOLUMNOFTYPERAWTOSTOREITTHEDRIVERTRANSPARENTLYCALLSTHEORADATATODATUMMETHODTOCONVERTTHEJAVAOBJECTTOANORACLESQLRAWOBJECTTHISOBJECTISTHENSTOREDINACOLUMNOFTYPERAWINTHEDATABASESUPPORTFORTHEORADATAINTERFACESISALSOHIGHLYEFFICIENTBECAUSETHECONVERSIONSAREDESIGNEDTOWORKUSINGORACLESQLFORMATS,WHICHHAPPENTOBETHEINTERNALFORMATSUSEDBYTHEJDBCDRIVERSMOREOVER,THETYPEMAP,WHICHISNECESSARYFORTHESQLDATAINTERFACE,ISNOTREQUIREDWHENUSINGJAVACLASSESTHATIMPLEMENTORADATAFORMOREINFORMATIONONWHYCLASSESTHATIMPLEMENTORADATADONOTNEEDATYPEMAP,SEE“UNDERSTANDINGTHEORADATAINTERFACE“ONPAGE921THEDEPRECATEDCUSTOMDATUMINTERFACEASARESULTOFTHEORACLEJDBCINTERFACESBEINGINTRODUCEDINORACLE9IASANALTERNATIVETOTHEORACLEJDBCDRIVERCLASSES,THEORACLESQLCUSTOMDATUMANDORACLESQLCUSTOMDATUMFACTORYINTERFACES,FORMERLYUSEDTOACCESSCUSTOMIZEDOBJECTS,HAVEBEENDEPRECATEDBYTHENEWINTERFACESORACLESQLORADATAANDORACLESQLORADATAFACTORYTHEFOLLOWINGARETHESPECIFICATIONSFORTHECUSTOMDATUMANDCUSTOMDATUMFACTORYINTERFACESPUBLICINTERFACECUSTOMDATUMORACLESQLDATUMTODATUMORACLEJDBCDRIVERORACLECONNECTIONCTHROWSSQLEXCEPTION/THEFOLLOWINGISEXPECTEDTOBEPRESENTINAN/IMPLEMENTATION/DEFINITIONOFPUBLICSTATICFIELDSFOR/_SQL_TYPECODE,_SQL_NAMEAND_SQL_BASETYPE/SEEORACLEJDBCDOCUMENTATIONFORDETAILS/DEFINITIONOF/PUBLICSTATICCUSTOMDATUMFACTORY/GETFACTORY/PUBLICINTERFACECUSTOMDATUMFACTORYORACLESQLCUSTOMDATUMCREATEORACLESQLDATUMD,INTSQLTYPETHROWSSQLEXCEPTIONOBJECTTYPEINHERITANCEOBJECTTYPEINHERITANCEISANORACLE9IFEATUREWHICHALLOWSANEWOBJECTTYPETOBECREATEDBYEXTENDINGANOTHEROBJECTTYPEWHILEORACLE9IDOESNOTYETSUPPORTJDBC30,OBJECTTYPEINHERITANCEISSUPPORTEDANDDOCUMENTEDTHENEWOBJECTTYPEISTHENASUBTYPEOFTHEOBJECTTYPEFROMWHICHITEXTENDSTHESUBTYPEAUTOMATICALLYINHERITSALLTHEATTRIBUTESANDMETHODSDEFINEDINTHESUPERTYPETHESUBTYPECANADDATTRIBUTESANDMETHODS,ANDOVERLOADOROVERRIDEMETHODSINHERITEDFROMTHESUPERTYPEOBJECTTYPEINHERITANCEINTRODUCESSUBSTITUTABILITYSUBSTITUTABILITYISTHEABILITYOFASLOTDECLAREDTOHOLDAVALUEOFTYPETTODOSOINADDITIONTOANYSUBTYPEOFTYPETORACLE9IJDBCDRIVERSHANDLESUBSTITUTABILITYTRANSPARENTLYADATABASEOBJECTISRETURNEDWITHITSMOSTSPECIFICTYPEWITHOUTLOSINGINFORMATIONFOREXAMPLE,IFTHESTUDENT_TOBJECTISSTOREDINAPERSON_TSLOT,THEORACLEJDBCDRIVERRETURNSAJAVAOBJECTTHATREPRESENTSTHESTUDENT_TOBJECTCREATINGSUBTYPESCREATECUSTOMOBJECTCLASSESIFYOUWANTTOHAVEJAVACLASSESTHATEXPLICITLYCORRESPONDTOTHEORACLEOBJECTTYPESSEE“CREATINGANDUSINGCUSTOMOBJECTCLASSESFORORACLEOBJECTS“ONPAGE910IFYOUHAVEAHIERARCHYOFOBJECTTYPES,YOUMAYWANTACORRESPONDINGHIERARCHYOFJAVACLASSESTHEMOSTCOMMONWAYTOCREATEADATABASESUBTYPEINJDBCISTOPASSTHEEXTENDEDSQLCREATETYPECOMMANDTOTHEEXECUTEMETHODOFTHEJAVASQLSTATEMENTINTERFACEFOREXAMPLE,TOCREATEATYPEINHERITANCEHIERARCHYFORPERSON_T|STUDENT_T|PARTTIMESTUDENT_TTHEJDBCCODECANBESTATEMENTSCONNCREATESTATEMENTSEXECUTE“CREATETYPEPERSON_TSSNNUMBER,NAMEVARCHAR230,ADDRESSVARCHAR2255“SEXECUTE“CREATETYPESTUDENT_TUNDERPERSON_TDEPTIDNUMBER,MAJORVARCHAR2100“SEXECUTE“CREATETYPEPARTTIMESTUDENT_TUNDERSTUDENT_TNUMHOURSNUMBER“INTHEFOLLOWINGCODE,THE“FOO“MEMBERPROCEDUREINTYPESTISOVERLOADEDANDTHEMEMBERPROCEDURE“PRINT“OVERWRITESTHECOPYITINHERITSFROMTYPETCREATETYPETASOBJECT,MEMBERPROCEDUREFOOXNUMBER,MEMBERPROCEDUREPRINT,NOTFINALCREATETYPESTUNDERT,MEMBERPROCEDUREFOOXDATE,OVERLOAD“FOO“OVERRIDINGMEMBERPROCEDUREPRINT,OVERRIDE“PRINT“STATICFUNCTIONBARONCETHESUBTYPESHAVEBEENCREATED,THEYCANBEUSEDASBOTHCOLUMNSOFABASETABLEASWELLASATTRIBUTESOFAOBJECTTYPEFORCOMPLETEDETAILSONTHESYNTAXTOCREATESUBTYPES,SEETHEORACLE9IAPPLICATIONDEVELOPERSGUIDEOBJECTRELATIONALFEATURESFORDETAILSIMPLEMENTINGCUSTOMIZEDCLASSESFORSUBTYPESINMOSTCASES,ACUSTOMIZEDJAVACLASSREPRESENTSADATABASEOBJECTTYPEWHENYOUCREATEACUSTOMIZEDJAVACLASSFORASUBTYPE,THEJAVACLASSCANEITHERMIRRORTHEDATABASEOBJECTTYPEHIERARCHYORNOTYOUCANUSEEITHERTHEORADATAORSQLDATASOLUTIONINCREATINGCLASSESTOMAPTOTHEHIERARCHYOFOBJECTTYPESUSEOFORADATAFORTYPEINHERITANCEHIERARCHYCUSTOMIZEDMAPPINGWHEREJAVACLASSESIMPLEMENTTHEORACLESQLORADATAINTERFACEISTHERECOMMENDEDMAPPINGSEE“RELATIVEADVANTAGESOFORADATAVERSUSSQLDATA“ONPAGE911ORADATAMAPPINGREQUIRESTHEJDBCAPPLICATIONTOIMPLEMENTTHEORADATAANDORADATAFACTORYINTERFACESTHECLASSIMPLEMENTINGTHEORADATAFACTORYINTERFACECONTAINSAFACTORYMETHODTHATPRODUCESOBJECTSEACHOBJECTREPRESENTSADATABASEOBJECTTHEHIERARCHYOFTHECLASSIMPLEMENTINGTHEORADATAINTERFACECANMIRRORTHEDATABASEOBJECTTYPEHIERARCHYFOREXAMPLE,THEJAVACLASSESMAPPINGTOPERSON_TANDSTUDENT_TAREASFOLLOWSPERSONJAVAUSINGORADATACODEFORTHEPERSONJAVACLASSWHICHIMPLEMENTSTHEORADATAANDORADATAFACTORYINTERFACESCLASSPERSONIMPLEMENTSORADATA,ORADATAFACTORYSTATICFINALPERSON_PERSONFACTORYNEWPERSONPUBLICNUMBERSSNPUBLICCHARNAMEPUBLICCHARADDRESSPUBLICSTATICORADATAFACTORYGETORADATAFACTORYRETURN_PERSONFACTORYPUBLICPERSONPUBLICPERSONNUMBERSSN,CHARNAME,CHARADDRESSTHISSSNSSNTHISNAMENAMETHISADDRESSADDRESSPUBLICDATUMTODATUMORACLECONNECTIONCTHROWSSQLEXCEPTIONSTRUCTDESCRIPTORSDSTRUCTDESCRIPTORCREATEDESCRIPTOR“SCOTTPERSON_T“,COBJECTATTRIBUTESSSN,NAME,ADDRESSRETURNNEWSTRUCTSD,C,ATTRIBUTESPUBLICORADATACREATEDATUMD,INTSQLTYPETHROWSSQLEXCEPTIONIFDNULLRETURNNULLOBJECTATTRIBUTESSTRUCTDGETORACLEATTRIBUTESRETURNNEWPERSONNUMBERATTRIBUTES0,CHARATTRIBUTES1,CHARATTRIBUTES2STUDENTJAVAEXTENDINGPERSONJAVACODEFORTHESTUDENTJAVACLASSWHICHEXTENDSTHEPERSONJAVACLASSCLASSSTUDENTEXTENDSPERSONSTATICFINALSTUDENT_STUDENTFACTORYNEWSTUDENTPUBLICNUMBERDEPTIDPUBLICCHARMAJORPUBLICSTATICORADATAFACTORYGETORADATAFACTORYRETURN_STUDENTFACTORYPUBLICSTUDENTPUBLICSTUDENTNUMBERSSN,CHARNAME,CHARADDRESS,NUMBERDEPTID,CHARMAJORSUPERSSN,NAME,ADDRESSTHISDEPTIDDEPTIDTHISMAJORMAJORPUBLICDATUMTODATUMORACLECONNECTIONCTHROWSSQLEXCEPTIONSTRUCTDESCRIPTORSDSTRUCTDESCRIPTORCREATEDESCRIPTOR“SCOTTSTUDENT_T“,COBJECTATTRIBUTESSSN,NAME,ADDRESS,DEPTID,MAJORRETURNNEWSTRUCTSD,C,ATTRIBUTESPUBLICCUSTOMDATUMCREATEDATUMD,INTSQLTYPETHROWSSQLEXCEPTIONIFDNULLRETURNNULLOBJECTATTRIBUTESSTRUCTDGETORACLEATTRIBUTESRETURNNEWSTUDENTNUMBERATTRIBUTES0,CHARATTRIBUTES1,CHARATTRIBUTES2,NUMBERATTRIBUTES3,CHARATTRIBUTES4CUSTOMIZEDCLASSESTHATIMPLEMENTTHEORADATAINTERFACEDONOTHAVETOMIRRORTHEDATABASEOBJECTTYPEHIERARCHYFOREXAMPLE,YOUCOULDHAVEDECLAREDTHEABOVECLASS,STUDENT,WITHOUTASUPERCLASSINTHISCASE,STUDENTWOULDCONTAINFIELDSTOHOLDTHEINHERITEDATTRIBUTESFROMPERSON_TASWELLASTHEATTRIBUTESDECLAREDBYSTUDENT_TORADATAFACTORYIMPLEMENTATIONTHEJDBCAPPLICATIONUSESTHEFACTORYCLASSINQUERYINGTHEDATABASETORETURNINSTANCESOFPERSONORITSSUBCLASSES,ASINTHEFOLLOWINGEXAMPLERESULTSETRSETSTMTEXECUTEQUERY“SELECTPERSONFROMTAB1“WHILERSETNEXTOBJECTSRSETGETORADATA1,PERSONFACTORYGETORADATAFACTORYACLASSIMPLEMENTINGTHEORADATAFACTORYINTERFACESHOULDBEABLETOPRODUCEINSTANCESOFTHEASSOCIATEDCUSTOMOBJECTTYPE,ASWELLASINSTANCESOFANYSUBTYPE,ORATLEASTALLTHETYPESYOUEXPECTTOSUPPORTINTHEFOLLOWINGEXAMPLE,THEPERSONFACTORYGETORADATAFACTORYMETHODRETURNSAFACTORYTHATCANHANDLEPERSON_T,STUDENT_T,ANDPARTTIMESTUDENT_TOBJECTSBYRETURNINGPERSON,STUDENT,ORPARTTIMESTUDENTJAVAINSTANCESCLASSPERSONFACTORYIMPLEMENTSORADATAFACTORYSTATICFINALPERSONFACTORY_FACTORYNEWPERSONFACTORYPUBLICSTATICORADATAFACTORYGETORADATAFACTORYRETURN_FACTORYPUBLICORADATACREATEDATUMD,INTSQLTYPETHROWSSQLEXCEPTIONSTRUCTSSTRUCTDIFSGETSQLTYPENAMEEQUALS“SCOTTPERSON_T“RETURNPERSONGETORADATAFACTORYCREATED,SQLTYPEELSEIFSGETSQLTYPENAMEEQUALS“SCOTTSTUDENT_T“RETURNSTUDENTGETORADATAFACTORYCREATED,SQLTYPEELSEIFSGETSQLTYPENAMEEQUALS“SCOTTPARTTIMESTUDENT_T“RETURNPARTTIMESTUDENTGETORADATAFACTORYCREATED,SQLTYPEELSERETURNNULLTHEFOLLOWINGEXAMPLEASSUMESATABLETAB1,SUCHASTHEFOLLOWINGCREATETABLETAB1IDXNUMBER,PERSONPERSON_TINSERTINTOTABL1VALUES1,PERSON_T1000,SCOTT,100ORACLEPARKWAYINSERTINTOTABL1VALUES2,STUDENT_T1001,PETER,200ORACLEPARKWAY,101,CSINSERTINTOTABL1VALUES3,PARTTIMESTUDENT_T1002,DAVID,300ORACLEPARKWAY,102,EEUSEOFSQLDATAFORTYPEINHERITANCEHIERARCHYTHECUSTOMIZEDCLASSESTHATIMPLEMENTTHEJAVASQLSQLDATAINTERFACECANMIRRORTHEDATABASEOBJECTTYPEHIERARCHYTHEREADSQLANDWRITESQLMETHODSOFASUBCLASSCASCADEEACHCALLTOTHECORRESPONDINGMETHODSINTHESUPERCLASSINORDERTOREADORWRITETHESUPERCLASSATTRIBUTESBEFOREREADINGORWRITINGTHESUBCLASSATTRIBUTESFOREXAMPLE,THEJAVACLASSESMAPPINGTOPERSON_TANDSTUDENT_TAREASFOLLOWSPERSONJAVAUSINGSQLDATACODEFORTHEPERSONJAVACLASSWHICHIMPLEMENTSTHESQLDATAINTERFACEIMPORTJAVASQLPUBLICCLASSPERSONIMPLEMENTSSQLDATAPRIVATESTRINGSQL_TYPEPUBLICINTSSNPUBLICSTRINGNAMEPUBLICSTRINGADDRESSPUBLICPERSONPUBLICSTRINGGETSQLTYPENAMETHROWSSQLEXCEPTIONRETURNSQL_TYPEPUBLICVOIDREADSQLSQLINPUTSTREAM,STRINGTYPENAMETHROWSSQLEXCEPTIONSQL_