datanucleus

问题 I just tried to connect to hbase which is part of the cloudera-vm using a java client. (192.168.56.102 is the inet ip of the vm) I use virtual box with host only network setting. So I can access the webUI of the hbase master @ http://192.168.56.102:60010/master.jsp Also my java client (worked well on the vm itself) established connection to 192.168.56.102:2181 But when it calls getMaster I get connection refused see log: 11/09/14 11:19:30 INFO zookeeper.ZooKeeper: Initiating client connection

问题 I got an error when querying to the entity extended by mappedsuperclass on GAE/J. MappedSuperClass import java.sql.Timestamp; import javax.persistence.MappedSuperclass; @MappedSuperclass public abstract class AbstractModel { private String lastModifiedBy; private Timestamp createTimestamp; private Timestamp modifyTimestamp; private Integer version; // setters & getters } Entity import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table(name =

问题 What am I missing in the following configuration that my Datanucleus JPA 2 Level 2 cache is not using Google App Engine Memcache service? I am using the GAE 1.7.2 SDK. In the persistence.xml: <persistence-unit name="transactions-optional"> <provider>org.datanucleus.api.jpa.PersistenceProviderImpl</provider> <properties> <property name="datanucleus.NontransactionalRead" value="true"/> <property name="datanucleus.NontransactionalWrite" value="true"/> <property name="datanucleus.ConnectionURL"

问题 Is there a way to specify using JPA that there should be multiple unique constraints on different sets of columns? @Entity @Table(name="person", uniqueConstraints=@UniqueConstraint(columnNames={"code", "uid"})) public class Person { // Unique on code and uid public String code; public String uid; // Unique on username public String username; public String name; public String email; } I have seen a hibernate specific annotation but I am trying to avoid vendor specific solutions as we are still

问题 How can I generate metamodel classes (like QClient, QProduct, QInvoice) from a persistence model classes (like Client, Product, Invoice) so that a JDOQL typesafe queries can be employed? In particular, I'm interested on generating the metamodel classes and also run bytecode enhancement on persistence classes, via SBT and using DataNucleus with JDO annotations. This question is related to How can I run DataNucleus Bytecode Enhancer from SBT? 回答1: In a nutshell, you need to define functions in

问题 Entity class: public class CustomerSurvey implements Serializable { @Id @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="CUSTOMER_SURVEY_SEQUENCE") @Column(name = "SURVEYID", nullable = false) private String surveyId; @Column(name="ATTACHMENT") @Lob private byte[] attachment; .... Persistence class/logic: public List<CustomerSurvey> getSurveysByCustomer(String custNo) throws WorkServiceException { EntityManager em = entityManagerFactory.createEntityManager(); Query query = em

问题 According to this, Google App Engine's JDO implementation does not support JDO @Unique annotation. Is this still so? For example, I have this class: @PersistenceCapable public class User { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key key; @Persistent private String email; @Persistent private String sessionToken; ... } Obviously the key is unique, but I also wanted to have unique email and sessionToken . If @Unique is not supported, what's the best way to

问题 I am trying this JPA query "SELECT ml FROM MediaLibrary ml WHERE ml.media.id = :id" and I get this error message: "Cannot find type of (part of) ml.media.id since symbol has no type; implicit variable?" I realize that should probably be some kind of MEMBER OF query instead but I tried that with the same result. I am looking to find the media library containing the media with the id equal to the given value. Simplified code: @Entity( name = "MediaLibrary" ) @Table( name = "MediaLibrary" )

问题 any example on using memcache/general cache with jpa entitymanager on JGAE? or the only way to do it is manually put/set memcache on service layer? 回答1: DataNucleus docs define adequately how to use the JDO/JPA L2 cache. http://www.datanucleus.org/products/accessplatform_1_1/jpa/cache.html in the case of GAE/J memcache the L2 cache should be "javax.cache". 来源： https://stackoverflow.com/questions/1978428/example-using-memcache-with-jpa-entitymanager-on-jgae

问题 Is there a tool to generate JDO objects from an existing database? I prefer a awesome looking Eclipse plugin which i could use to generate and maintain the object but it seems that this is currently not existing. Are other, simple tools to generate the database objects? 回答1: JDO objects are not simple wrappers around database rows (although you can implement your JDO objects as simple wrappers around database rows if that is what you wish). As such, most automated tools will not know how the