在Hibernate中将两个类映射到一个DB表

Question

I have 2 class Class1.java and Class2.java. Both are mapped to Class Table.

@Entity
@Table(name = "Class")
public class Class1 {
 String name;
}

@Entity
@Table(name = "Class")
public class Class2 {
  String name;
}

Now when my sessionfactory will be created at that time both the class will be scanned and both will consume memory.

But in my application when it boot up we are deciding at runtime which class will be used in whole application either Class1.java or Class2.java by looking into database.

So I want hibernate to use either of the class Class1.java or Class2.java so that I can save memory. Please help with this issue.

Answer 1

We are able to do it in following way.

We are using Spring so used the concept of creating bean by annotation ie JavaConfig.

for eg

@Configuration
public class BeanFactory {

@Bean(name = "sessionFactory")
public LocalSessionFactoryBean sessionFactory() {
    LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
    sessionFactory.setDataSource(dataSource); // datasource injected using @Autowire
    Connection connection = null;
    Statement statement = null;
    ResultSet resultSet = null;
    String[] packageToScan = new String[] {"your package"};
    try {
        Class.forName("com.mysql.jdbc.Driver");
        connection = DriverManager.getConnection("", "", "");
        statement = connection.createStatement();
        resultSet = statement.executeQuery("query to get packagetoscan property.");
        if (resultSet.next()){
            packageToScan[0] = resultSet.getString(1);
        }
    }catch (Exception e){
        e.printStackTrace();
    }
    sessionFactory.setPackagesToScan(packageToScan);
    sessionFactory.setHibernateProperties(hibernateProperties()); // hibernateProperties() method will return properties.
    return sessionFactory;
}

so this way we can change packagetoscan property in database and when our application is booting up it will get this property from database and we are able to save memory.