Save linked objects twice : Save « Hibernate « Java Tutorial
File: Main.java
import java.util.HashSet;
import org.hibernate.Session;
public class Main {
public static void main(String[] args) throws Exception {
HibernateUtil hibernateUtil = new HibernateUtil();
hibernateUtil
.executeSQLCommand("create table speakers (uid int, firstName varchar,lastName varchar, event_id int);");
hibernateUtil
.executeSQLCommand("create table locations (uid int, name varchar, address varchar, event_id int);");
hibernateUtil
.executeSQLCommand("create table attendees (uid int, firstName varchar, lastName varchar, event_id int);");
hibernateUtil
.executeSQLCommand("create table events (uid int , name varchar, start_date date, duration integer,location_id int);");
Session session = hibernateUtil.getSession();
Event e = new Event();
e.setName("testSave");
Location l = new Location();
l.setName("building 1");
e.setLocation(l);
e.setSpeakers(new HashSet());
e.getSpeakers().add(new Speaker("John", "Doe"));
e.setAttendees(new HashSet());
e.getAttendees().add(new Attendee("John", "Smith"));
session.save(l);
session.save(e);
session.close();
hibernateUtil.checkData("select * from events");
hibernateUtil.checkData("select * from speakers");
hibernateUtil.checkData("select * from locations");
hibernateUtil.checkData("select * from attendees");
}
}
File: Location.java
public class Location {
private Long id;
private String name;
private String address;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
File: Location.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="Location" table="locations">
<id name="id" column="uid" type="long">
<generator class="native"/>
</id>
<property name="name" type="string"/>
<property name="address" type="string"/>
</class>
</hibernate-mapping>
File: Speaker.java
public class Speaker {
private Long id;
private String firstName;
private String lastName;
public Speaker() {
}
public Speaker(String firstName, String lastName) {
setFirstName(firstName);
setLastName(lastName);
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
File: Speaker.java
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="Speaker" table="speakers">
<id name="id" column="uid" type="long">
<generator class="native"/>
</id>
<property name="firstName" type="string" length="20"/>
<property name="lastName" type="string" length="20"/>
</class>
</hibernate-mapping>
File: Event.java
import java.util.Date;
import java.util.Set;
public class Event {
private Long id;
private String name;
private Date startDate;
private int duration;
private Set speakers;
private Set attendees;
private Location location;
public void setId(Long id) {
this.id = id;
}
public Long getId() {
return id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Date getStartDate() {
return startDate;
}
public void setStartDate(Date startDate) {
this.startDate = startDate;
}
public int getDuration() {
return duration;
}
public void setDuration(int duration) {
this.duration = duration;
}
public Location getLocation() {
return location;
}
public void setLocation(Location location) {
this.location = location;
}
public void setSpeakers(Set speakers) {
this.speakers = speakers;
}
public Set getSpeakers() {
return speakers;
}
public Set getAttendees() {
return attendees;
}
public void setAttendees(Set attendees) {
this.attendees = attendees;
}
}
File: Event.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="Event" table="events">
<id name="id" column="uid" type="long" unsaved-value="null">
<generator class="native"/>
</id>
<property name="name" type="string" length="100"/>
<property name="startDate" column="start_date"
type="date"/>
<property name="duration" type="integer"/>
<many-to-one name="location" column="location_id"
class="Location" cascade="all"/>
<set name="speakers" cascade="all">
<key column="event_id"/>
<one-to-many class="Speaker"/>
</set>
<set name="attendees" cascade="all">
<key column="event_id"/>
<one-to-many class="Attendee"/>
</set>
</class>
</hibernate-mapping>
File: Attendee.java
public class Attendee {
private Long id;
private String firstName;
private String lastName;
public Attendee() {
}
public Attendee(String firstName, String lastName) {
setFirstName(firstName);
setLastName(lastName);
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
File: Attendee.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="Attendee" table="attendees">
<id name="id" column="uid" type="long">
<generator class="native"/>
</id>
<property name="firstName" type="string" length="20"/>
<property name="lastName" type="string" length="20"/>
</class>
</hibernate-mapping>
File: HibernateUtil.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateUtil {
Session session;
Statement st;
public HibernateUtil() throws Exception{
SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
session = sessionFactory.openSession();
// Load the JDBC driver.
Class.forName("org.hsqldb.jdbcDriver");
System.out.println("Driver Loaded.");
// Establish the connection to the database.
String url = "jdbc:hsqldb:data/tutorial";
Connection conn = DriverManager.getConnection(url, "sa", "");
System.out.println("Got Connection.");
st = conn.createStatement();
}
public Session getSession(){
return session;
}
public void executeSQLCommand(String sql) throws Exception {
st.executeUpdate(sql);
}
public void checkData(String sql) throws Exception {
ResultSet rs = st.executeQuery(sql);
ResultSetMetaData metadata = rs.getMetaData();
for (int i = 0; i < metadata.getColumnCount(); i++) {
System.out.print("\t"+ metadata.getColumnLabel(i + 1));
}
System.out.println("\n----------------------------------");
while (rs.next()) {
for (int i = 0; i < metadata.getColumnCount(); i++) {
Object value = rs.getObject(i + 1);
if (value == null) {
System.out.print("\t ");
} else {
System.out.print("\t"+value.toString().trim());
}
}
System.out.println("");
}
}
}
File: hibernate.cfg.xml
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="connection.driver_class">org.hsqldb.jdbcDriver</property>
<property name="connection.url">jdbc:hsqldb:data/tutorial</property>
<property name="connection.username">sa</property>
<property name="connection.password"></property>
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.HSQLDialect</property>
<!-- Enable Hibernate's current session context -->
<property name="current_session_context_class">org.hibernate.context.ManagedSessionContext</property>
<property name="hibernate.cache.use_second_level_cache">false</property>
<property name="hibernate.cache.use_query_cache">false</property>
<!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- Mapping files -->
<mapping resource="Event.hbm.xml"/>
<mapping resource="Location.hbm.xml"/>
<mapping resource="Attendee.hbm.xml"/>
<mapping resource="Speaker.hbm.xml"/>
</session-factory>
</hibernate-configuration>
Download: HibernateSaveLinkedobjectsTwice.zip( 4,867 k)| 21.4.Save | ||||
| 21.4.1. | Save entity with Session | | ||
| 21.4.2. | Flush a Session | | ||
| 21.4.3. | Save linked objects twice | | ||
| 21.4.4. | Save date type data | | ||
| 21.4.5. | Get Row Count With Projection | | ||