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package com.sun.s1asdev.ejb.bmp.finder.ejb;
import java.rmi.RemoteException;
import javax.ejb.*;
import java.sql.*;
import javax.sql.*;
import java.util.*;
import javax.naming.*;
import javax.rmi.PortableRemoteObject;
import java.io.*;
public class EnrollerBean implements SessionBean {
private Connection con;
private String dbName = "java:comp/env/jdbc/bmp-finderDB";
private SessionContext context;
/**
* Enrolls a Student in a course
* @param studentId primary key of the student object
* @param courseId primary key of the course object
* @exception RemoteException
*/
public void enroll(String studentId, String courseId) {
try {
insertEntry(studentId, courseId);
} catch (Exception ex) {
throw new EJBException("enroll: " + ex.getMessage());
}
}
/**
* Un-Enrolls a Student in a course
* @param studentId primary key of the student object
* @param courseId primary key of the course object
* @exception RemoteException
*/
public void unEnroll(String studentId, String courseId) {
try {
deleteEntry(studentId, courseId);
} catch (Exception ex) {
throw new EJBException("unEnroll: " + ex.getMessage());
}
}
/**
* Deletes a Student
* @param studentId primary key of the student object
* @exception RemoteException
*/
public void deleteStudent(String studentId) {
try {
deleteStudentEntries(studentId);
} catch (Exception ex) {
throw new EJBException("deleteStudent: " + ex.getMessage());
}
}
/**
* Deletes a Course
* @param courseId primary key of the course object
* @exception RemoteException
*/
public void deleteCourse(String courseId) {
try {
deleteCourseEntries(courseId);
} catch (Exception ex) {
throw new EJBException("deleteCourse: " + ex.getMessage());
}
}
/**
* Returns an Arraylist of StudentsIds enrolled in a course
* @param courseId primary key of the course object
* @exception RemoteException
*/
public ArrayList getStudentIds(String courseId) {
try {
return selectStudent(courseId);
} catch (Exception ex) {
throw new EJBException("getStudentIds: " + ex.getMessage());
}
}
/**
* Return an ArrayList of CourseIds that student is enroller in
* @param studentId primary key of the student object
* @exception RemoteException
*/
public ArrayList getCourseIds(String studentId) {
try {
return selectCourse(studentId);
} catch (Exception ex) {
throw new EJBException("getCourseIds: " + ex.getMessage());
}
}
public void ejbCreate() {
try {
makeConnection();
} catch (Exception ex) {
throw new EJBException("Unable to connect to database. " +
ex.getMessage());
}
}
public void ejbRemove() {
try {
con.close();
} catch (SQLException ex) {
throw new EJBException("ejbRemove: " + ex.getMessage());
}
}
public void ejbActivate() {
try {
makeConnection();
} catch (Exception ex) {
throw new EJBException("ejbActivate Exception: " + ex.getMessage());
}
}
public void ejbPassivate() {
try {
con.close();
} catch (SQLException ex) {
throw new EJBException("ejbPassivate Exception: " + ex.getMessage());
}
}
public void setSessionContext(SessionContext context) {
this.context = context;
}
public EnrollerBean() {}
/*********************** Database Routines *************************/
private void makeConnection() throws NamingException, SQLException {
InitialContext ic = new InitialContext();
DataSource ds = (DataSource) ic.lookup(dbName);
con = ds.getConnection();
}
private void insertEntry(String studentId, String courseId)
throws SQLException {
String insertStatement =
"insert into FinderEnrollment values ( ? , ? )";
PreparedStatement prepStmt =
con.prepareStatement(insertStatement);
prepStmt.setString(1, studentId);
prepStmt.setString(2, courseId);
prepStmt.executeUpdate();
prepStmt.close();
}
private void deleteEntry(String studentId, String courseId)
throws SQLException {
String deleteStatement =
"delete from FinderEnrollment " +
"where studentid = ? and courseid = ?";
PreparedStatement prepStmt =
con.prepareStatement(deleteStatement);
prepStmt.setString(1, studentId);
prepStmt.setString(2, courseId);
prepStmt.executeUpdate();
prepStmt.close();
}
private void deleteStudentEntries(String studentId)
throws SQLException {
String deleteStatement =
"delete from FinderEnrollment " +
"where studentid = ?";
PreparedStatement prepStmt =
con.prepareStatement(deleteStatement);
prepStmt.setString(1, studentId);
prepStmt.executeUpdate();
prepStmt.close();
}
private void deleteCourseEntries(String courseId)
throws SQLException {
String deleteStatement =
"delete from FinderEnrollment " +
"where courseid = ?";
PreparedStatement prepStmt =
con.prepareStatement(deleteStatement);
prepStmt.setString(1, courseId);
prepStmt.executeUpdate();
prepStmt.close();
}
private ArrayList selectStudent(String courseId)
throws SQLException {
String selectStatement =
"select studentid " +
"from FinderEnrollment where courseid = ? ";
PreparedStatement prepStmt =
con.prepareStatement(selectStatement);
prepStmt.setString(1, courseId);
ResultSet rs = prepStmt.executeQuery();
ArrayList a = new ArrayList();
while (rs.next()) {
String id = rs.getString(1);
a.add(id);
}
prepStmt.close();
return a;
}
private ArrayList selectCourse(String studentId)
throws SQLException {
String selectStatement =
"select courseid " +
"from FinderEnrollment where studentid = ? ";
PreparedStatement prepStmt =
con.prepareStatement(selectStatement);
prepStmt.setString(1, studentId);
ResultSet rs = prepStmt.executeQuery();
ArrayList a = new ArrayList();
while (rs.next()) {
String id = rs.getString(1);
a.add(id);
}
prepStmt.close();
return a;
}
}