entitymanager merge

for the current o-r mappings, each entitymanagerfactory, which can be called a Persistence unit (persistenceunit), Each persistence unit can be considered a mapping of a data source (the so-called data source, can be understood as a database, we can configure multiple data sources in the application server, while using different persistenceunit to map these data sources, which makes it easy to implement transactional operations across multiple databases! --jta do not explain)2, Persistenceconte

Package Com. Persia. JPA. onetable; Import Java. Io. serializable; Import Javax. Persistence. column; Import Javax. Persistence. entity; Import Javax. Persistence. generatedvalue; Import Javax. Persistence. ID; Import Javax. Persistence. Table; @ entity @ table (name =" Person ") Public Class Person Implements Serializable { Private Integer ID; Private String name; Private Short age; @ ID @ generatedvalue Public Integer GETID (){ Return ID ;} Public Void Setid (integer ID ){ This . ID = ID;}

find the corresponding instance by ID. This requirement can be easily implemented using map in STL. Entitymanager classHere we encapsulate it as the entitymanager class. The entitymanager class saves a map and provides the getentitybyid method. Here, I also deliver the new and delete responsibilities of the entity instance to the

1. In the container, entitymanager is managed by the container, and its transactions are managed by JTA. When entitymanager is called, the container first checks whether it is in the persistent context. If yes, entitymanager uses the persistent context and associated transactions; If no persistence context is associated, a new persistence context is created a

Configure the entitymanager via a persistence. xml file Notice thatMovieEntity is listed viaElement. This is not required, But can help when testing or whenMovieClass is located in a different jar than the jar containingpersistence.xmlFile. If persistence. xml and entity are in the same jar package, class elements are not required. Injection via @ persistencecontext TheEntityManagerItself is created by the container using the information inpersistenc

Today encountered a strange thing, using the Entitymanager.remove (entity) method to delete an entity, deleted, and do not error. Later through the multi-checks to solve the problem.ERD650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M00/7F/49/wKioL1cY4PXDaMjhAAA3p6ZllUk448.png "title=" Image 1.png "alt=" Wkiol1cy4pxdamjhaaa3p6zlluk448.png "/>Entity definition------------- First entitya---------------@Entitypublic classA{ @Id privateLongid; @Column (nullable=false,unique=true,length=60)

;import org.hibernate.envers.auditreaderfactory;publicclassenversillustrationtestextends Testcase{privateloggerlogger=logger.getlogger ( EnversIllustrationTest.class.getName ());p rivateentitymanagerfactoryentitymanagerfactory;@ Overrideprotectedvoidsetup () throwsException{entityManagerFactory= Persistence.createentitymanagerfactory ("Org.hibernate.tutorial.envers");} @Overrideprotected voidteardown () throwsexception{entitymanagerfactory.close ();} PublicvoidtestbAsicusage () {// Here is the m

Similarities Both methods take the class of the object and the object representing the primary key of the object as the parameter. Because they use Java generic methods, they can obtain object objects of specific types without any explicit type conversion. Specifically, autoboxing (automatic packing) of Java 5 is widely used in primarykey. In addition, both of them are thrown when entitymanager is disabled.IllegalStateException-If this

Hibernate Entitymanager is a wrapper around the hibernate core that provides the JPA programming interface, supports the lifecycle of JPA entity instances, and allows you to write queries in a standard Java Persistence Query language.1. Basic JPA configuration (ENTITYMANAGERFACTORY--EMF configuration)Persistence.xml, the file must be placed in the Meta-inf directory of the persistent unit being deployed, because I am building Java project here, so I p

I encountered a small problem when I used JPA yesterday. entitymanager was injected through the @ persistcontext method. There is no problem in using entitymanager to query objects, but data cannot be saved to the database during persistence,ProgramNo exception is thrown. After a day, I always thought it was persistence. where is the XML file going wrong? Finally, I checked the information online and found

Org.springframework.transaction.CannotCreateTransactionException:Could not open JPA Entitymanager forTransaction Nested exception is Java.lang.NoSuchMethodError:org.hibernate.Session.getFlushMode () lorg/hibernate/Flushmode; At Org.springframework.orm.jpa.JpaTransactionManager.doBegin (Jpatransactionmanager.java:431) at Org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction ( Abstractplatformtransactionmanager.java:3

Jpaquery.getresultlist the value method after SQL text execution The return value may be a collection of objects or an array of objects 1, String sql = "SELECT * from T_order where ..." Entitymanager Emread; Query qr = emread.createnativequery (sqlres); return list Use List For (object[] objects:listo) {Vo vo=new vo ();int i=0;Vo.setxxx (Integer.parseint (objects[i++].tostring ())); //.... List.add (VO); } 2, String sql = "Select SUM (Money) Monery

+ V] =sorted[v];} Public Static voidMerge_sort (int[] unsorted,intFirstintLastint[] sorted) { if(First + 1 Last ) { intMid = (first + last)/2; Merge_sort (unsorted, first, Mid, sorted);//Left OrderMerge_sort (unsorted, Mid, last, sorted);//Right Ordermerge (unsorted, first, mid, last, sorted);//two numeric merges }} Public Static voidMain (string[] args) {int[] Array = {6, 2, 4, 1, 5, 9};//Original Array int[] sorted =New int[Array.Length];//new array, sorted valuesmerge_sort (A