A client JDBC application can receive a Java object from the database in a result set or as the value of an output parameter returned from a stored procedure. If a result set contains a Java object as column data, use one of the following getObject methods in the ResultSet interface to retrieve the object:
Object getObject(int columnIndex) throws SQLException;
Object getObject(String columnName) throws SQLException;
If an output parameter from a stored procedure contains a Java object, use the following getObject method in the CallableStatement interface to retrieve the object:
Object getObject(int parameterIndex) throws SQLException;
The following example illustrates the use of ResultSet.getObject(int parameterIndex) to assign an object received in a result set to a class variable. The example uses the Address class and Friends table used in the previous section and presents a simple application that prints a name and address on an envelope.
/*
** This application takes a first and last name, gets the
** specified person’s address from the Friends table in the
** database, and addresses an envelope using the name and
** retrieved address.
*/
public class Envelope
{
Connection conn = null;
String firstName = null;
String lastName = null;
String street = null;
String city = null;
String zip = null;
public static void main(String[] args)
{
if (args.length < 2)
{
System.out.println("Usage: Envelope <firstName>
<lastName>");
System.exit(1);
}
// create a 4" x 10" envelope
Envelope e = new Envelope(4, 10);
try
{
// connect to the database with the Friends table.
conn = DriverManager.getConnection(
"jdbc:sybase:Tds:localhost:5000", "username",
"password");
// look up the address of the specified person
firstName = args[0];
lastName = args[1];
PreparedStatement ps = conn.prepareStatement(
"SELECT address FROM friends WHERE " +
"firstname = ? AND lastname = ?");
ps.setString(1, firstName);
ps.setString(2, lastName);
ResultSet rs = ps.executeQuery();
if (rs.next())
{
Address a = (Address) rs.getObject(1);
// set the destination address on the envelope
e.setAddress(firstName, lastName, a);
}
conn.close();
}
catch (SQLException sqe)
{
sqe.printStackTrace();
System.exit(2);
}
// if everything was successful, print the envelope
e.print();
}
private void setAddress(String fname, String lname, Address a)
{
street = a.streetNumber + " " + a.street + " " +
a.apartmentNumber;
city = a.city;
zip = "" + a.zipCode;
}
private void print()
{
// Print the name and address on the envelope.
...
}
}
You can find a more detailed example of HandleObject.java in the sample2 subdirectory under your jConnect installation directory.
