snaq.db

Class QueryValidator

java.lang.Object

snaq.db.QueryValidator

All Implemented Interfaces:

ConnectionValidator

Direct Known Subclasses:

SimpleQueryValidator

public abstract class QueryValidator
extends Object
implements ConnectionValidator

Abstract ConnectionValidator implementation that validates database connections by issuing a SQL query.

To create a simple ConnectionValidator implementation which validates using a SQL query, extend this class and implement the abstract methods.

For example, the getQueryString() method could be implemented to return the string:

SELECT * FROM test WHERE test_id < 10;

This would cause this SQL query to be issued to the database whenever a connection needs validating. If the query causes a SQLException to be thrown then the validation automatically fails. If the query completes successfully, the generated ResultSet is then passed to the checkResults(ResultSet) method.

This class is provided as a convenience for providing connection validation.

Author:

Giles Winstanley

Constructor Summary

Constructors

Constructor and Description
QueryValidator()

Method Summary

Modifier and Type	Method and Description
abstract boolean	checkResults(ResultSet results) Checks the results of the SQL query to see if it indicates a valid connection.
abstract String	getQueryString() Returns the SQL query string to be issued to the database.
boolean	isValid(Connection con) Determines whether the specified connection is good to use.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

QueryValidator

public QueryValidator()

Method Detail

isValid

public final boolean isValid(Connection con)
                      throws SQLException

Determines whether the specified connection is good to use.

Specified by:

isValid in interface ConnectionValidator

Parameters:

con - Connection instance to check for validity

Returns:

true if the specified connection is good to use, false otherwise

Throws:

SQLException - if the connection is invalid

getQueryString

public abstract String getQueryString()

Returns the SQL query string to be issued to the database.

Returns:

query string in SQL syntax

checkResults

public abstract boolean checkResults(ResultSet results)
                              throws SQLException

Checks the results of the SQL query to see if it indicates a valid connection.

Parameters:

results - ResultSet instance produced from SQL query

Returns:

boolean indicating whether checked results indicated a valid connection

Throws:

SQLException - if checking the results throws such an exception