Collection Mapping: TreeMap
///////////////////////////////////////////////////////////////////////// <?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="Console" table="console"> <id name="id" unsaved-value="0"> <generator class="increment"/> </id> <map name="games" table="game_instructions" sort="GameComparator" cascade="all"> <key column="parent_id"/> <index-many-to-many column="game_id" class="Game"/> <many-to-many column="instructions_id" class="Instructions"/> </map> <property name="name" type="string"/> </class> <class name="Game" table="game"> <id name="id" unsaved-value="0"> <generator class="increment"/> </id> <property name="name" type="string"/> </class> <class name="Instructions" table="instructions"> <id name="id" unsaved-value="0"> <generator class="increment"/> </id> <property name="info" type="string"/> </class> </hibernate-mapping> ///////////////////////////////////////////////////////////////////////// import java.util.*; public class Console { private int id; private String name; private Map games; public Console() { } public Console(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(Map m) { games = m; } public Map getGames() { return games; } } ///////////////////////////////////////////////////////////////////////// public class Game { private int id; private String name; public Game() { } public Game(String name) { this.name = name; } 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 boolean equals(Object obj) { if (obj == null) return false; if (!this.getClass().equals(obj.getClass())) return false; Game obj2 = (Game)obj; if ((this.id == obj2.getId()) && this.name.equals(obj2.getName())) { return true; } return false; } public int hashCode() { int tmp = 0; tmp = (id + name).hashCode(); return tmp; } } ///////////////////////////////////////////////////////////////////////// import java.util.*; public class GameComparator implements Comparator { public int compare(Object o1, Object o2) { Game game1 = (Game)o1; Game game2 = (Game)o2; return game1.getName().compareTo(game2.getName()); } public boolean equals(Object obj) { if (obj == null) return false; if (!this.getClass().equals(obj.getClass())) return false; return true; } } ///////////////////////////////////////////////////////////////////////// <?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="Console.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(" "); } } } ///////////////////////////////////////////////////////////////////////// public class Instructions { private int id; private String info; public Instructions() { } public Instructions(String info) { this.info = info; } public void setId(int i) { id = i; } public int getId() { return id; } public void setInfo(String s) { info = s; } public String getInfo() { return info; } } ///////////////////////////////////////////////////////////////////////// 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 console (id int, name varchar);"); HibernateUtil.setup("create table game (id int, name varchar);"); HibernateUtil.setup("create table instructions (id int, info varchar );"); HibernateUtil.setup("create table game_instructions (parent_id int,game_id int,instructions_id int);"); Session session = HibernateUtil.currentSession(); Console sp = new Console("Console"); TreeMap p = new TreeMap(new GameComparator()); Game g = new Game("Game 1"); Game g2 = new Game("Game 2"); p.put(g, new Instructions("Instructions for Game 1")); p.put(g2, new Instructions("Instructions for Game 2")); sp.setGames(p); session.save(g); session.save(g2); session.flush(); session.save(sp); session.flush(); session.flush(); session.close(); HibernateUtil.checkData("select * from console"); HibernateUtil.checkData("select * from game"); HibernateUtil.checkData("select * from instructions"); HibernateUtil.checkData("select * from game_instructions"); } }
1. | Hibernate Collection Mapping Map | ![]() | |
2. | Collection Mapping: Map Key and Value are Both Objects | ![]() | |
3. | Collection Mapping: Many-To-Many map based on HashMap | ![]() |