Interface JdbcRowSet

public interface JdbcRowSet extends RowSet, Joinable

The standard interface that all standard implementations of JdbcRowSet must implement.

1.0 Overview

A wrapper around a ResultSet object that makes it possible to use the result set as a JavaBeans component. Thus, a JdbcRowSet object can be one of the Beans that a tool makes available for composing an application. Because a JdbcRowSet is a connected rowset, that is, it continually maintains its connection to a database using a JDBC technology-enabled driver, it also effectively makes the driver a JavaBeans component.

Because it is always connected to its database, an instance of JdbcRowSet can simply take calls invoked on it and in turn call them on its ResultSet object. As a consequence, a result set can, for example, be a component in a Swing application.

Another advantage of a JdbcRowSet object is that it can be used to make a ResultSet object scrollable and updatable. All RowSet objects are by default scrollable and updatable. If the driver and database being used do not support scrolling and/or updating of result sets, an application can populate a JdbcRowSet object with the data of a ResultSet object and then operate on the JdbcRowSet object as if it were the ResultSet object.

2.0 Creating a JdbcRowSet Object

The reference implementation of the JdbcRowSet interface, JdbcRowSetImpl, provides an implementation of the default constructor. A new instance is initialized with default values, which can be set with new values as needed. A new instance is not really functional until its execute method is called. In general, this method does the following:

• establishes a connection with a database
• creates a PreparedStatement object and sets any of its placeholder parameters
• executes the statement to create a ResultSet object

If the execute method is successful, it will set the appropriate private JdbcRowSet fields with the following:

• a Connection object -- the connection between the rowset and the database
• a PreparedStatement object -- the query that produces the result set
• a ResultSet object -- the result set that the rowset's command produced and that is being made, in effect, a JavaBeans component

If these fields have not been set, meaning that the execute method has not executed successfully, no methods other than execute and close may be called on the rowset. All other public methods will throw an exception.

Before calling the execute method, however, the command and properties needed for establishing a connection must be set. The following code fragment creates a JdbcRowSetImpl object, sets the command and connection properties, sets the placeholder parameter, and then invokes the method execute.

    JdbcRowSetImpl jrs = new JdbcRowSetImpl();
    jrs.setCommand("SELECT * FROM TITLES WHERE TYPE = ?");
    jrs.setURL("jdbc:myDriver:myAttribute");
    jrs.setUsername("cervantes");
    jrs.setPassword("sancho");
    jrs.setString(1, "BIOGRAPHY");
    jrs.execute();

The variable jrs now represents an instance of JdbcRowSetImpl that is a thin wrapper around the ResultSet object containing all the rows in the table TITLES where the type of book is biography. At this point, operations called on jrs will affect the rows in the result set, which is effectively a JavaBeans component.

The implementation of the RowSet method execute in the JdbcRowSet reference implementation differs from that in the CachedRowSet reference implementation to account for the different requirements of connected and disconnected RowSet objects.