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1
27
28 package enroller;
29
30 import java.sql.*;
31 import javax.sql.*;
32 import java.util.*;
33 import javax.ejb.*;
34 import javax.naming.*;
35 import javax.rmi.PortableRemoteObject  ;
36
37
38 public class CourseBean implements EntityBean, CourseRemoteBusiness {
39 private static final String dbName = "jdbc/pointbase";
40 private String courseId;
41 private String name;
42 private ArrayList studentIds;
43 private Connection con;
44 private EntityContext context;
45 private EnrollerRemoteHome enrollerHome;
46
47 public ArrayList getStudentIds() {
48 System.out.println("in getStudentIds");
49
50 return studentIds;
51 }
52
53 public String getName() {
54 return name;
55 }
56
57 public void setName(String name) {
58 this.name = name;
59 }
60
61 public String ejbCreate(String courseId, String name)
62 throws CreateException {
63 System.out.println("in ejbCreate");
64
65 try {
66 insertCourse(courseId, name);
67 } catch (Exception ex) {
68 throw new EJBException("ejbCreate: " + ex.getMessage());
69 }
70
71 this.courseId = courseId;
72 this.name = name;
73 System.out.println("about to leave ejbCreate");
74
75 return courseId;
76 }
77
78 public String ejbFindByPrimaryKey(String primaryKey)
79 throws FinderException {
80 boolean result;
81
82 try {
83 result = selectByPrimaryKey(primaryKey);
84 } catch (Exception ex) {
85 throw new EJBException("ejbFindByPrimaryKey: " + ex.getMessage());
86 }
87
88 if (result) {
89 return primaryKey;
90 } else {
91 throw new ObjectNotFoundException("Row for id " + primaryKey +
92 " not found.");
93 }
94 }
95
96 public void ejbRemove() {
97 try {
98 deleteCourse(courseId);
99 } catch (Exception ex) {
100 throw new EJBException("ejbRemove: " + ex.getMessage());
101 }
102 }
103
104 public void setEntityContext(EntityContext context) {
105 System.out.println("in setEntityContext");
106 this.context = context;
107 studentIds = new ArrayList();
108
109 try {
110 enrollerHome = lookupEnrollerBean();
111 } catch (Exception ex) {
112 throw new EJBException("Unable to connect to database. " +
113 ex.getMessage());
114 }
115 }
116
117 public void unsetEntityContext() {
118 }
119
120 public void ejbActivate() {
121 courseId = (String ) context.getPrimaryKey();
122 }
123
124 public void ejbPassivate() {
125 courseId = null;
126 }
127
128 public void ejbLoad() {
129 System.out.println("in ejbLoad");
130
131 try {
132 loadCourse();
133 loadStudentIds();
134 } catch (Exception ex) {
135 throw new EJBException("ejbLoad: " + ex.getMessage());
136 }
137
138 System.out.println("leaving ejbLoad");
139 }
140
141 private void loadStudentIds() {
142 System.out.println("in loadStudentIds");
143 studentIds.clear();
144
145 try {
146 EnrollerRemote enroller = enrollerHome.create();
147 ArrayList a = enroller.getStudentIds(courseId);
148
149 studentIds.addAll(a);
150 } catch (Exception ex) {
151 throw new EJBException("loadStudentIds: " + ex.getMessage());
152 }
153
154 System.out.println("leaving loadStudentIds");
155 }
156
157 public void ejbStore() {
158 System.out.println("in ejbStore");
159
160 try {
161 storeCourse();
162 } catch (Exception ex) {
163 throw new EJBException("ejbStore: " + ex.getMessage());
164 }
165
166 System.out.println("leaving ejbStore");
167 }
168
169 public void ejbPostCreate(String courseId, String name) {
170 }
171
172
173 private void makeConnection() {
174 try {
175 InitialContext ic = new InitialContext();
176 DataSource ds = (DataSource) ic.lookup(dbName);
177
178 con = ds.getConnection();
179 } catch (Exception ex) {
180 throw new EJBException("Unable to connect to database. " +
181 ex.getMessage());
182 }
183 }
184
185 private void releaseConnection() {
186 try {
187 con.close();
188 } catch (SQLException ex) {
189 throw new EJBException("releaseConnection: " + ex.getMessage());
190 }
191 }
192
193 private void insertCourse(String courseId, String name)
194 throws SQLException {
195 makeConnection();
196
197 String insertStatement = "insert into course values ( ? , ? )";
198 PreparedStatement prepStmt = con.prepareStatement(insertStatement);
199
200 prepStmt.setString(1, courseId);
201 prepStmt.setString(2, name);
202
203 prepStmt.executeUpdate();
204 prepStmt.close();
205 releaseConnection();
206 }
207
208 private boolean selectByPrimaryKey(String primaryKey)
209 throws SQLException {
210 makeConnection();
211
212 String selectStatement =
213 "select courseid " + "from course where courseid = ? ";
214 PreparedStatement prepStmt = con.prepareStatement(selectStatement);
215
216 prepStmt.setString(1, primaryKey);
217
218 ResultSet rs = prepStmt.executeQuery();
219 boolean result = rs.next();
220
221 prepStmt.close();
222 releaseConnection();
223
224 return result;
225 }
226
227 private void deleteCourse(String courseId) throws SQLException {
228 makeConnection();
229
230 String deleteStatement = "delete from course " + "where courseid = ?";
231 PreparedStatement prepStmt = con.prepareStatement(deleteStatement);
232
233 prepStmt.setString(1, courseId);
234 prepStmt.executeUpdate();
235 prepStmt.close();
236 releaseConnection();
237 }
238
239 private void loadCourse() throws SQLException {
240 makeConnection();
241
242 String selectStatement =
243 "select name " + "from course where courseid = ? ";
244 PreparedStatement prepStmt = con.prepareStatement(selectStatement);
245
246 prepStmt.setString(1, courseId);
247
248 ResultSet rs = prepStmt.executeQuery();
249
250 if (rs.next()) {
251 name = rs.getString(1);
252 prepStmt.close();
253 } else {
254 prepStmt.close();
255 throw new NoSuchEntityException("Row for courseId " + courseId +
256 " not found in database.");
257 }
258
259 releaseConnection();
260 }
261
262 private void storeCourse() throws SQLException {
263 makeConnection();
264
265 String updateStatement =
266 "update course set name = ? " + "where courseid = ?";
267 PreparedStatement prepStmt = con.prepareStatement(updateStatement);
268
269 prepStmt.setString(1, name);
270 prepStmt.setString(2, courseId);
271
272 int rowCount = prepStmt.executeUpdate();
273
274 prepStmt.close();
275
276 if (rowCount == 0) {
277 throw new EJBException("Storing row for courseId " + courseId +
278 " failed.");
279 }
280
281 releaseConnection();
282 }
283
284 private enroller.EnrollerRemoteHome lookupEnrollerBean() {
285 try {
286 javax.naming.Context c = new javax.naming.InitialContext ();
287 Object remote = c.lookup("ejb/SimpleEnroller");
288 enroller.EnrollerRemoteHome rv = (enroller.EnrollerRemoteHome) javax.rmi.PortableRemoteObject.narrow(remote, enroller.EnrollerRemoteHome.class);
289 return rv;
290 }
291 catch(javax.naming.NamingException ne) {
292 java.util.logging.Logger.getLogger(getClass().getName()).log(java.util.logging.Level.SEVERE,"exception caught" ,ne);
293 throw new RuntimeException (ne);
294 }
295
296 }
297 }
298 |
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