详解Java的Hibernat框架中的Map映射与SortedMap映射

 import java.util.Comparator; public class MyClass implements Comparator { public int compare(String o1, String o2) { final int BEFORE = -1; final int AFTER = 1; /* To reverse the sorting order, multiple by -1 */ if (o2 == null) { return BEFORE * -1; } Comparable thisCertificate = o1; Comparable thatCertificate = o2; if(thisCertificate == null) { return AFTER * 1; } else if(thatCertificate == null) { return BEFORE * -1; } else { return thisCertificate.compareTo(thatCertificate) * -1; } } } 

 import java.util.*; import org.hibernate.HibernateException; import org.hibernate.Session; import org.hibernate.Transaction; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class ManageEmployee { private static SessionFactory factory; public static void main(String[] args) { try{ factory = new Configuration().configure().buildSessionFactory(); }catch (Throwable ex) { System.err.println("Failed to create sessionFactory object." + ex); throw new ExceptionInInitializerError(ex); } ManageEmployee ME = new ManageEmployee(); /* Let us have a set of certificates for the first employee */ TreeMap set1 = new TreeMap(); set1.put("ComputerScience", new Certificate("MCA")); set1.put("BusinessManagement", new Certificate("MBA")); set1.put("ProjectManagement", new Certificate("PMP")); /* Add employee records in the database */ Integer empID1 = ME.addEmployee("Manoj", "Kumar", 4000, set1); /* Another set of certificates for the second employee */ TreeMap set2 = new TreeMap(); set2.put("ComputerScience", new Certificate("MCA")); set2.put("BusinessManagement", new Certificate("MBA")); /* Add another employee record in the database */ Integer empID2 = ME.addEmployee("Dilip", "Kumar", 3000, set2); /* List down all the employees */ ME.listEmployees(); /* Update employee's salary records */ ME.updateEmployee(empID1, 5000); /* Delete an employee from the database */ ME.deleteEmployee(empID2); /* List down all the employees */ ME.listEmployees(); } /* Method to add an employee record in the database */ public Integer addEmployee(String fname, String lname, int salary, TreeMap cert){ Session session = factory.openSession(); Transaction tx = null; Integer employeeID = null; try{ tx = session.beginTransaction(); Employee employee = new Employee(fname, lname, salary); employee.setCertificates(cert); employeeID = (Integer) session.save(employee); tx.commit(); }catch (HibernateException e) { if (tx!=null) tx.rollback(); e.printStackTrace(); }finally { sess<em style="color:transparent">来源[email protected]搞@^&代*@码网</em>ion.close(); } return employeeID; } /* Method to list all the employees detail */ public void listEmployees( ){ Session session = factory.openSession(); Transaction tx = null; try{ tx = session.beginTransaction(); List employees = session.createQuery("FROM Employee").list(); for (Iterator iterator1 = employees.iterator(); iterator1.hasNext();){ Employee employee = (Employee) iterator1.next(); System.out.print("First Name: " + employee.getFirstName()); System.out.print(" Last Name: " + employee.getLastName()); System.out.println(" Salary: " + employee.getSalary()); SortedMap map = employee.getCertificates(); for(Map.Entry entry : map.entrySet()){ System.out.print("\tCertificate Type: " + entry.getKey()); System.out.println(", Name: " + (entry.getValue()).getName()); } } tx.commit(); }catch (HibernateException e) { if (tx!=null) tx.rollback(); e.printStackTrace(); }finally { session.close(); } } /* Method to update salary for an employee */ public void updateEmployee(Integer EmployeeID, int salary ){ Session session = factory.openSession(); Transaction tx = null; try{ tx = session.beginTransaction(); Employee employee = (Employee)session.get(Employee.class, EmployeeID); employee.setSalary( salary ); session.update(employee); tx.commit(); }catch (HibernateException e) { if (tx!=null) tx.rollback(); e.printStackTrace(); }finally { session.close(); } } /* Method to delete an employee from the records */ public void deleteEmployee(Integer EmployeeID){ Session session = factory.openSession(); Transaction tx = null; try{ tx = session.beginTransaction(); Employee employee = (Employee)session.get(Employee.class, EmployeeID); session.delete(employee); tx.commit(); }catch (HibernateException e) { if (tx!=null) tx.rollback(); e.printStackTrace(); }finally { session.close(); } } } 

 $java ManageEmployee 

 .......VARIOUS LOG MESSAGES WILL DISPLAY HERE........ First Name: Manoj Last Name: Kumar Salary: 4000 Certificate Type: ProjectManagement, Name: PMP Certificate Type: ComputerScience, Name: MCA Certificate Type: BusinessManagement, Name: MBA First Name: Dilip Last Name: Kumar Salary: 3000 Certificate Type: ComputerScience, Name: MCA Certificate Type: BusinessManagement, Name: MBA First Name: Manoj Last Name: Kumar Salary: 5000 Certificate Type: ProjectManagement, Name: PMP Certificate Type: ComputerScience, Name: MCA Certificate Type: BusinessManagement, Name: MBA 

 mysql> select * from EMPLOYEE; 

 +----+------------+-----------+--------+ | id | first_name | last_name | salary | +----+------------+-----------+--------+ | 74 | Manoj   | Kumar   |  5000 | +----+------------+-----------+--------+ 1 row in set (0.00 sec) 

 mysql> select * from CERTIFICATE; 

 +----+--------------------+------------------+-------------+ | id | certificate_type  | certificate_name | employee_id | +----+--------------------+------------------+-------------+ | 52 | BusinessManagement | MBA       |     74 | | 53 | ComputerScience  | MCA       |     74 | | 54 | ProjectManagement | PMP       |     74 | +----+--------------------+------------------+-------------+ 3 rows in set (0.00 sec)