Mapping One To Many Set : Relation One to Many « Hibernate « Java
Mapping One To Many Set
/////////////////////////////////////////////////////////////////////////
import java.io.Serializable;
import java.util.*;
import org.hibernate.*;
import org.hibernate.cfg.*;
import org.hibernate.criterion.*;
import org.hibernate.event.*;
import org.hibernate.event.def.*;
public class Main {
public static void main(String[] args) throws Exception {
HibernateUtil.setup("create table HighScores (id int,name varchar);");
HibernateUtil.setup("create table gamescores (id int,name varchar,score int,parent_id int);");
Session session = HibernateUtil.currentSession();
HighScores sp = new HighScores("HighScores Name");
HashSet set = new HashSet();
set.add(new GameScore("GameScore Name 1", 3));
set.add(new GameScore("GameScore Name 2", 2));
sp.setGames(set);
session.save(sp);
session.flush();
session.close();
HibernateUtil.checkData("select * from HighScores");
HibernateUtil.checkData("select * from gamescores");
}
}
/////////////////////////////////////////////////////////////////////////
public class GameScore {
private int id;
private String name;
private int score;
public GameScore() {
}
public GameScore(String name, int score) {
this.name = name;
this.score = score;
}
public void setId(int i) {
id = i;
}
public int getId() {
return id;
}
public void setName(String s) {
name = s;
}
public String getName() {
return name;
}
public void setScore(int i) {
score = i;
}
public int getScore() {
return score;
}
public boolean equals(Object obj) {
if (obj == null) return false;
if (!this.getClass().equals(obj.getClass())) return false;
GameScore obj2 = (GameScore)obj;
if ((this.id == obj2.getId()) &&
(this.name.equals(obj2.getName())) &&
(this.score == obj2.getScore())
) {
return true;
}
return false;
}
public int hashCode() {
int tmp = 0;
tmp = (id + name + score).hashCode();
return tmp;
}
}
/////////////////////////////////////////////////////////////////////////
import java.util.*;
public class HighScores {
private int id;
private String name;
private Set games;
public HighScores() {
}
public HighScores(String name) {
this.name = name;
}
public void setId(int i) {
id = i;
}
public int getId() {
return id;
}
public void setName(String n) {
name = n;
}
public String getName() {
return name;
}
public void setGames(Set games) {
this.games = games;
}
public Set getGames() {
return games;
}
}
/////////////////////////////////////////////////////////////////////////
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="HighScores" table="highscores">
<id name="id" unsaved-value="0">
<generator class="increment"/>
</id>
<set name="games" cascade="all">
<key column="parent_id"/>
<one-to-many class="GameScore"/>
</set>
<property name="name" type="string"/>
</class>
<class name="GameScore" table="gamescores">
<id name="id" unsaved-value="0">
<generator class="increment"/>
</id>
<property name="name"/>
<property name="score"/>
</class>
</hibernate-mapping>
/////////////////////////////////////////////////////////////////////////
<?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>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- Mapping files -->
<mapping resource="HighScores.hbm.xml"/>
</session-factory>
</hibernate-configuration>
/////////////////////////////////////////////////////////////////////////
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateUtil {
public static final SessionFactory sessionFactory;
static {
try {
// Create the SessionFactory from hibernate.cfg.xml
sessionFactory = new Configuration().configure().buildSessionFactory();
} catch (Throwable ex) {
// Make sure you log the exception, as it might be swallowed
System.err.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
}
public static final ThreadLocal session = new ThreadLocal();
public static Session currentSession() throws HibernateException {
Session s = (Session) session.get();
// Open a new Session, if this thread has none yet
if (s == null) {
s = sessionFactory.openSession();
// Store it in the ThreadLocal variable
session.set(s);
}
return s;
}
public static void closeSession() throws HibernateException {
Session s = (Session) session.get();
if (s != null)
s.close();
session.set(null);
}
static Connection conn;
static Statement st;
public static void setup(String sql) {
try {
// Step 1: Load the JDBC driver.
Class.forName("org.hsqldb.jdbcDriver");
System.out.println("Driver Loaded.");
// Step 2: Establish the connection to the database.
String url = "jdbc:hsqldb:data/tutorial";
conn = DriverManager.getConnection(url, "sa", "");
System.out.println("Got Connection.");
st = conn.createStatement();
st.executeUpdate(sql);
} catch (Exception e) {
System.err.println("Got an exception! ");
e.printStackTrace();
System.exit(0);
}
}
public static void checkData(String sql) {
try {
HibernateUtil.outputResultSet(st
.executeQuery(sql));
// conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void outputResultSet(ResultSet rs) throws Exception{
ResultSetMetaData metadata = rs.getMetaData();
int numcols = metadata.getColumnCount();
String[] labels = new String[numcols];
int[] colwidths = new int[numcols];
int[] colpos = new int[numcols];
int linewidth;
for (int i = 0; i < numcols; i++) {
labels[i] = metadata.getColumnLabel(i + 1); // get its label
System.out.print(labels[i]+" ");
}
System.out.println("------------------------");
while (rs.next()) {
for (int i = 0; i < numcols; i++) {
Object value = rs.getObject(i + 1);
if(value == null){
System.out.print(" ");
}else{
System.out.print(value.toString().trim()+" ");
}
}
System.out.println(" ");
}
}
}
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