The findInDate() method retrieves instances between two timestamps. Like any home method
implementation, it cannot use any data specific to a particular instance:
public Collection ejbFindInDate(Date from,
Date to) throws FinderException {
Connection con = null;
try {
InitialContext initial = new InitialContext();
DataSource ds =
(DataSource) initial.lookup
("java:comp/env/jdbc/DefaultDS");
con = ds.getConnection();
PreparedStatement ps =
con.prepareStatement
("SELECT id FROM measurements " +
"WHERE eventTimestamp >= ? " +
"AND eventTimestamp <= ?");
ps.setTimestamp
(1, new java.sql.Timestamp(from.getTime()));
ps.setTimestamp
(2, new java.sql.Timestamp(to.getTime()));
ResultSet rs = ps.executeQuery();
LinkedList results = new LinkedList();
while (rs.next()) {
results.add(new Long(rs.getLong(1)));
}
return results;
} catch (java.sql.SQLException sqle) {
sqle.printStackTrace();
throw new EJBException(sqle);
} catch (javax.naming.NamingException ne) {
ne.printStackTrace();
throw new EJBException(ne);
} finally {
if (con != null) {
try {
con.close();
} catch (Exception ex) {}
}
}
}
Note: Color coded lines should be on one line, they were split for formatting purposes.
The ejbCreate() method is the only method in this class that modifies the database:
public Long ejbCreate(long measurementId, Date timestamp,
String eventName,
double magnitude) throws CreateException {
if ((timestamp == null) || (eventName == null)) {
throw new CreateException
("Null values not allowed.");
}
this.id = measurementId;
this.eventTimestamp = timestamp;
this.eventName = eventName;
this.eventMagnitude = magnitude;
Connection con = null;
try {
InitialContext initial = new InitialContext();
DataSource ds =
(DataSource) initial.lookup
("java:comp/env/jdbc/DefaultDS");
con = ds.getConnection();
PreparedStatement ps =
con.prepareStatement
("INSERT INTO measurements (id, " +
"eventTimestamp, eventName, eventMagnitude) " +
"VALUES (?,?,?,?)");
ps.setLong(1, id);
ps.setTimestamp
(2, new java.sql.Timestamp(eventTimestamp.getTime()));
ps.setString(3, eventName);
ps.setDouble(4, eventMagnitude);
ps.executeUpdate();
return new Long(measurementId);
} catch (Exception e) {
e.printStackTrace();
throw new CreateException();
} finally {
if (con != null) {
try {
con.close();
} catch (Exception ex) {}
}
}
}
public void ejbPostCreate(long measurementId, Date timestamp,
String eventName,
double magnitude) throws CreateException {}
Note: Color coded lines should be on one line, they were split for formatting purposes.
This is a fairly standard ejbLoad() method. However, we do not implement ejbStore() because
there are no circumstances in which we modify the bean instance:
public void ejbLoad() {
Connection con = null;
Long tmpId = (Long) ctx.getPrimaryKey();
id = tmpId.longValue();
try {
InitialContext initial = new InitialContext();
DataSource ds =
(DataSource) initial.lookup
("java:comp/env/jdbc/DefaultDS");
con = ds.getConnection();
PreparedStatement ps =
con.prepareStatement
("SELECT eventTimestamp, eventName, " +
"eventMagnitude " +
"FROM measurements where id = ?");
ps.setLong(1, id);
ResultSet rs = ps.executeQuery();
if (!rs.next()) {
throw new EJBException
("Object not found");
}
eventTimestamp =
new Date(rs.getTimestamp(1).getTime());
if (rs.wasNull()) {
throw new EJBException
("Null in database not allowed.");
}
eventName = rs.getString(2);
if (rs.wasNull()) {
throw new EJBException
("Null in database not allowed.");
}
eventMagnitude = rs.getDouble(3);
if (rs.wasNull()) {
throw new EJBException
("Null in database not allowed.");
}
} catch (java.sql.SQLException sqle) {
sqle.printStackTrace();
throw new EJBException(sqle);
} catch (javax.naming.NamingException ne) {
ne.printStackTrace();
throw new EJBException(ne);
} finally {
if (con != null) {
try {
con.close();
} catch (Exception ex) {}
}
}
}
public void ejbStore() {}
public void ejbRemove() {}
public void ejbActivate() {}
public void ejbPassivate() {}
public void setEntityContext(EntityContext ctx) {
this.ctx = ctx;
}
public void unsetEntityContext() {
this.ctx = null;
}
}
Note: Color coded lines should be on one line, they were split for formatting purposes.
New on the Java Boutique:
New Review:
Time Management Made Easy with the Quartz Enterprise Job Scheduler
Why not just use the Java timer API? This open source scheduling
API boasts simplicity, ease-of-integration, a well-rounded feature
set, and it's free!
New Applet:
Reverse Complement
Reverse Complement is a simple applet that converts DNA or RNA
sequences into three useful formats.
Elsewhere on internet.com:
WebDeveloper Java
Lots of Java information on webdeveloper.com
WDVL Java
Thorough Java resource at the Web Developer's Virtual Library.
ScriptSearch Java
Hundreds of free Java code files to download.
jGuru: Your View of the Java Universe
Customizable portal with online training, FAQs, regular news updates, and tutorials.
