at org.hibernate.shards.session.ShardedSessionImpl.getShardIdOfRelatedObject(ShardedSessionImpl.java:697)
               at org.hibernate.shards.session.ShardedSessionImpl.selectShardIdForNewObject(ShardedSessionImpl.java:660)
               at org.hibernate.shards.session.ShardedSessionImpl.save(ShardedSessionImpl.java:637)
               at org.hibernate.shards.session.ShardedSessionImpl.save(ShardedSessionImpl.java:767)
               at com.cmc.hibernate.shards.main.HibernateShardsMain.main(HibernateShardsMain.java:36)
               at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
               at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
               at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
               at java.lang.reflect.Method.invoke(Method.java:597)

ShardId getShardIdOfRelatedObject(Object obj) {
    ClassMetadata cmd = getClassMetadata(obj.getClass());
    Type[] types = cmd.getPropertyTypes();

   
public static void main(String[] args) {
        HibernateUtil util = new HibernateUtil();
        SessionFactory sessionFactory = util.createSessionFactory();
        Session session = sessionFactory.openSession();
        Transaction transaction = session.getTransaction();
        transaction.begin();
        WeatherReport weatherReport = new WeatherReport();
        weatherReport.setContinent("ASIA");
        weatherReport.setLatitude(BigDecimal.valueOf(44.43));
        weatherReport.setLatitude(BigDecimal.valueOf(44.43));
        weatherReport.setTemperature(25);
        weatherReport.setReportTime(new Date(new GregorianCalendar().getTimeInMillis()));
        session.save(weatherReport);
        transaction.commit();
        session.close();
    }

public class HibernateUtil {

    public SessionFactory createSessionFactory() {
        AnnotationConfiguration prototypeConfig = new AnnotationConfiguration().configure("shard0.hibernate.cfg.xml");
        Properties props = prototypeConfig.getProperties();
        props.entrySet();
        prototypeConfig.addAnnotatedClass(WeatherReport.class);
        List<ShardConfiguration> shardConfigs = new ArrayList<ShardConfiguration>();
        ShardConfiguration shardConfiguration0 = buildShardConfig("shard0.hibernate.cfg.xml");
        ShardConfiguration shardConfiguration1 = buildShardConfig("shard1.hibernate.cfg.xml");
        shardConfigs.add(shardConfiguration0);
        shardConfigs.add(shardConfiguration1);

        ShardStrategyFactory shardStrategyFactory = buildShardStrategyFactory();
        ShardedConfiguration shardedConfig = new ShardedConfiguration(
                prototypeConfig,
                shardConfigs,
                shardStrategyFactory);
        return shardedConfig.buildShardedSessionFactory();
    }

    ShardConfiguration buildShardConfig(String configFile) {
        Configuration config = new Configuration().configure(configFile);
        return new ConfigurationToShardConfigurationAdapter(config);
    }

    ShardStrategyFactory buildShardStrategyFactory() {
        ShardStrategyFactory shardStrategyFactory = new ShardStrategyFactory() {
            public ShardStrategy newShardStrategy(List<ShardId> shardIds) {
                RoundRobinShardLoadBalancer loadBalancer = new RoundRobinShardLoadBalancer(shardIds);
                ShardSelectionStrategy pss = new RoundRobinShardSelectionStrategy(loadBalancer);
                ShardResolutionStrategy prs = new AllShardsShardResolutionStrategy(shardIds);
                ShardAccessStrategy pas = new SequentialShardAccessStrategy();
                return new ShardStrategyImpl(pss, prs, pas);
            }
        };
        return shardStrategyFactory;
    }

@Entity
@Table(name = "WeatherReport")
public class WeatherReport {
    @Id
    @GeneratedValue(generator = "WeatherReportIdGenerator")
    @GenericGenerator(name = "WeatherReportIdGenerator", strategy = "org.hibernate.shards.id.ShardedUUIDGenerator")
    @Column(name = "reportId")
    private Integer reportId;
    @Column(name = "continent")
    private String continent;
    @Column(name = "latitude")
    private BigDecimal latitude;
    @Column(name = "longitude")
    private BigDecimal longitude;
    @Column(name = "temperature")
    private int temperature;
    @Column(name = "reportTime")
    private Date reportTime;
//... getters & setters