/*

 *

 * Copyright 2000 Sun Microsystems, Inc. All Rights Reserved.

 * 

 * This software is the proprietary information of Sun Microsystems, Inc.  

 * Use is subject to license terms.

 * 

 */



import java.sql.*;

import javax.sql.*;

import java.util.*;

import javax.ejb.*;

import javax.naming.*;

import javax.rmi.PortableRemoteObject;



public class StudentEJB implements EntityBean {



   private String studentId;

   private String name;

   private ArrayList courseIds;

   private Connection con;

   private String dbName = "java:comp/env/jdbc/CollegeDB";

   private EntityContext context;

   private EnrollerHome enrollerHome;



   public ArrayList getCourseIds() {



      System.out.println("in getCourseIds");

      return courseIds;

   }



   public String getName() {



      return name;

   }



   public void setName(String name) {



      this.name = name;

   }



   public String ejbCreate(String studentId, String name)

       throws CreateException {

   

       System.out.println("in ejbCreate");

       try {

          insertStudent(studentId, name);

       } catch (Exception ex) {

           throw new EJBException("ejbCreate: " + 

              ex.getMessage());

       }



       this.studentId = studentId;

       this.name = name;

       System.out.println("about to leave ejbCreate");

       return studentId;

   }

     

   public String ejbFindByPrimaryKey(String primaryKey) 

      throws FinderException {



      boolean result;



      try {

         result = selectByPrimaryKey(primaryKey);

       } catch (Exception ex) {

           throw new EJBException("ejbFindByPrimaryKey: " + 

              ex.getMessage());

       }



      if (result) {

         return primaryKey;

      }

      else {

         throw new ObjectNotFoundException

            ("Row for id " + primaryKey + " not found.");

      }

   }



   public void ejbRemove() {



      try {

         deleteStudent(studentId);

       } catch (Exception ex) {

           throw new EJBException("ejbRemove: " + 

              ex.getMessage());

       }

   } 



   public void setEntityContext(EntityContext context) {



      System.out.println("in setEntityContext");

      this.context = context;

      courseIds = new ArrayList();

      try {

         makeConnection();

         Context initial = new InitialContext();

         Object objref = initial.lookup("java:comp/env/ejb/Enroller");

         enrollerHome =

             (EnrollerHome)PortableRemoteObject.narrow(objref,

                                           EnrollerHome.class);

      } catch (Exception ex) {

          throw new EJBException("setEntityContext: " +

             ex.getMessage());

      }

   }



   public void unsetEntityContext() {



      try {

         con.close();

      } catch (SQLException ex) {

          throw new EJBException("unsetEntityContext: " + ex.getMessage());

      }

   }



   public void ejbActivate() {



      studentId = (String)context.getPrimaryKey();

   }



   public void ejbPassivate() {



      studentId = null;

   }

   

   public void ejbLoad() {



      System.out.println("in ejbLoad");

      try {

         loadStudent();

         loadCourseIds();

       } catch (Exception ex) {

           throw new EJBException("ejbLoad: " +

              ex.getMessage());

       }

      System.out.println("leaving ejbLoad");

   }



   private void loadCourseIds() {



      System.out.println("in loadCourseIds");

      courseIds.clear();

      System.out.println("in loadCourseIds, about to try");



      try {

         Enroller enroller = enrollerHome.create();

         ArrayList a = enroller.getCourseIds(studentId);

         courseIds.addAll(a);



      } catch (Exception ex) {

          throw new EJBException("Exception in loadCourseIds: " +

             ex.getMessage());

       }

      System.out.println("leaving loadCourseIds");

   }



   public void ejbStore() {



      System.out.println("in ejbStore");

      try {

         storeStudent();

       } catch (Exception ex) {

           throw new EJBException("ejbStore: " +

              ex.getMessage());

       }

      System.out.println("leaving ejbStore");

   }



   public void ejbPostCreate(String studentId, String name) { }



/*********************** Database Routines *************************/



   private void makeConnection() throws NamingException, SQLException {



      InitialContext ic = new InitialContext();

      DataSource ds = (DataSource) ic.lookup(dbName);

      con =  ds.getConnection();

   }



   private void insertStudent (String studentId, String name)

       throws SQLException {



          String insertStatement =

                "insert into student values ( ? , ? )";

          PreparedStatement prepStmt = 

                con.prepareStatement(insertStatement);



          prepStmt.setString(1, studentId);

          prepStmt.setString(2, name);



          prepStmt.executeUpdate();

          prepStmt.close();

   }



   private boolean selectByPrimaryKey(String primaryKey) 

      throws SQLException {



      String selectStatement =

            "select studentid " +

            "from student where studentid = ? ";

      PreparedStatement prepStmt =

            con.prepareStatement(selectStatement);

      prepStmt.setString(1, primaryKey);



      ResultSet rs = prepStmt.executeQuery();

      boolean result = rs.next();

      prepStmt.close();

      return result;

   }



   private void deleteStudent(String studentId) throws SQLException {



      String deleteStatement =

            "delete from student  " +

            "where studentid = ?";

      PreparedStatement prepStmt =

            con.prepareStatement(deleteStatement);



      prepStmt.setString(1, studentId);

      prepStmt.executeUpdate();

      prepStmt.close();

   }



   private void loadStudent() throws SQLException {



      String selectStatement =

            "select name " +

            "from student where studentid = ? ";

      PreparedStatement prepStmt = 

            con.prepareStatement(selectStatement);



      prepStmt.setString(1, studentId);



      ResultSet rs = prepStmt.executeQuery();



      if (rs.next()) {

         name = rs.getString(1);

         prepStmt.close();

      }

      else {

         prepStmt.close();

         throw new NoSuchEntityException("Row for studentId " + studentId +

            " not found in database.");

      }

   }



   private void storeStudent() throws SQLException {



      String updateStatement =

            "update student set name =  ? " +

            "where studentid = ?";

      PreparedStatement prepStmt = 

            con.prepareStatement(updateStatement);



      prepStmt.setString(1, name);

      prepStmt.setString(2, studentId);

      int rowCount = prepStmt.executeUpdate();

      prepStmt.close();



      if (rowCount == 0) {

         throw new EJBException("Storing row for studentId " + 

            studentId + " failed.");

      }

   }





} // StudentEJB