THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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This example illustrates developing an enterprise application that uses JPA for persistence. The database used is the embedded derby shipped with apache geronimo. Here, we present a persistence deployment descriptor (persistence.xml) that contains database connectivity and other information for the application. The persistence.xml is placed under META-INF/ directory of the application archive. The application contains an ejb module and a web module. EJB module uses a stateless session bean ShareHolderBean that uses JPA to perform database operations on the table SHAREACCOUNT in the ShareDB derby database. The SHAREACCOUNT table contains information about each shareholder along with the information regarding number shares he or she possesses currently in the account. The ShareHolderBean has methods that retrieve shareholder information, buy/sell shares of a particular shareholder, close the shareholder account etc. The web application has a servlet that looks up the ShareHolderBean and trigger the operations on it. The deployment descriptor information for the EJB module is provided using Java EE annotations in the respective bean classes. However, the persistence deployment descriptor information is provided using META-INF/persistence.xml file.
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package sample.jpa;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.NamedQuery;
import javax.persistence.PostLoad;
import javax.persistence.PostUpdate;
import javax.persistence.PrePersist;
import javax.persistence.PreUpdate;
import javax.persistence.Version;
import javax.persistence.Table;
@Entity
@Table(name = "SHAREACCOUNT")
@NamedQuery(name="findThem", query="SELECT a FROM ShareAccount a")
public class ShareAccount implements Serializable {
@Id
private int shareAccountNo;
private String ownerName;
private int numberOfShares;
@Version
private int version;
public ShareAccount(int shareAccountNo,
String ownerName,
int numberOfShares) {
this.shareAccountNo = shareAccountNo;
this.ownerName = ownerName;
this.numberOfShares = numberOfShares;
}
public String toString() {
return "Acc.# " + shareAccountNo +
", owner" + ownerName +
", numberOfShares: " +
numberOfShares + " $";
}
@PrePersist
void prepersist() {
System.out.println("pre persist!!");
}
@PreUpdate
void preupdate() {
System.out.println("pre update!!");
}
@PostUpdate
void postupdate() {
System.out.println("post update!!");
}
@PostLoad
void postload() {
System.out.println("post load!!");
}
public int getShareAccountNo() {
return shareAccountNo;
}
public void setShareAccountNo(int shareAccountNo) {
this.shareAccountNo = shareAccountNo;
}
public String getOwnerName() {
return ownerName;
}
public void setOwnerName(String ownerName) {
this.ownerName = ownerName;
}
public int getNumberOfShares() {
return numberOfShares;
}
public void setNumberOfShares(int numberOfShares) {
this.numberOfShares = numberOfShares;
}
public int getVersion() {
return version;
}
public void setVersion(int version) {
this.version = version;
}
}
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