Collection Mapping: Many-To-Many map based on HashMap : Relation Many to Many « Hibernate « Java
Collection Mapping: Many-To-Many map based on HashMap
/////////////////////////////////////////////////////////////////////////
public class Benefit {
private int id;
private int cost;
public Benefit() {
}
public Benefit(int c) {
cost = c;
}
public void setId(int i) {
id = i;
}
public int getId() {
return id;
}
public void setCost(int i) {
cost = i;
}
public int getCost() {
return cost;
}
}
/////////////////////////////////////////////////////////////////////////
<?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="Employee" table="employee">
<id name="id" unsaved-value="0">
<generator class="increment"/>
</id>
<map name="benefits" table="employee_benefit" cascade="all">
<key column="parent_id"/>
<index column="benefit_name" type="string"/>
<many-to-many column="benefit_id" class="Benefit"/>
</map>
<property name="name" type="string"/>
</class>
<class name="Benefit" table="benefit">
<id name="id" unsaved-value="0">
<generator class="increment"/>
</id>
<property name="cost" type="int"/>
</class>
</hibernate-mapping>
/////////////////////////////////////////////////////////////////////////
import java.util.*;
public class Employee {
private int id;
private String name;
private Map benefits;
public Employee() {
}
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 setBenefits(Map m) {
benefits = m;
}
public Map getBenefits() {
return benefits;
}
}
/////////////////////////////////////////////////////////////////////////
<?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="Employee.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(" ");
}
}
}
/////////////////////////////////////////////////////////////////////////
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 employee (id int,name varchar);");
HibernateUtil.setup("create table benefit (id int,cost int);");
HibernateUtil.setup("create table employee_benefit (parent_id int,benefit_name varchar,benefit_id int);");
Session session = HibernateUtil.currentSession();
Employee sp = new Employee();
Employee sp3 = new Employee();
sp.setName("Joe");
HashMap p = new HashMap();
p.put("health", new Benefit(200));
p.put("dental", new Benefit(300));
sp.setBenefits(p);
sp3.setName("Jim");
sp3.setBenefits(p);
session.save(sp);
session.save(sp3);
session.flush();
HibernateUtil.closeSession();
session = HibernateUtil.currentSession();
Employee sp2 = (Employee)session.load(Employee.class, new Integer(sp.getId()));
Map p2 = sp2.getBenefits();
System.out.println(((Benefit)p2.get("health")).getCost());
System.out.println(((Benefit)p2.get("dental")).getCost());
session.flush();
session.close();
HibernateUtil.checkData("select * from employee");
HibernateUtil.checkData("select * from benefit");
HibernateUtil.checkData("select * from employee_benefit");
}
}
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