org.finra.herd.dao

Class Log4jOverridableConfigurer.JdbcOperation<T>

java.lang.Object

org.finra.herd.dao.Log4jOverridableConfigurer.JdbcOperation<T>

Type Parameters:

T - the type of the results produced by a JDBC operation

Enclosing class:

Log4jOverridableConfigurer

protected abstract class Log4jOverridableConfigurer.JdbcOperation<T>
extends Object

An internally used helper class for simplifying database access through plain JDBC. This class provides a simple framework for creating and executing a JDBC statement. It especially takes care of proper handling of JDBC resources even in case of an error. This code was mostly taken from the Commons Configuration DatabaseConfiguration class:

 https://apache.googlesource.com/commons-configuration/+/trunk/src/main/java/org/apache/commons/configuration2/DatabaseConfiguration.java
 

Using a simple low level JDBC class such as this as opposed to a higher level abstraction such as JPA/Hibernate is preferred since we want logging initialized before as many other technologies as possible. That way, we will be able to capture higher level technology logging in our Log4J logs and not lose it.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	JdbcOperation(DataSource dataSource) Creates a new instance of JdbcOperation.

Method Summary

Modifier and Type	Method and Description
protected void	close(Connection connection, Statement statement, ResultSet resultSet) Close the specified database objects.
T	execute() Executes this operation.
protected Connection	getConnection() Returns the current connection.
protected PreparedStatement	initStatement(String sql, Object... parameters) Creates an initializes a PreparedStatement object for executing an SQL statement.
protected ResultSet	openResultSet(String sql, Object... params) Creates a PreparedStatement for a query, initializes it and executes it.
protected abstract T	performOperation() Performs the JDBC operation.

Methods inherited from class java.lang.Object

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

Constructor Detail

JdbcOperation

protected JdbcOperation(DataSource dataSource)

Creates a new instance of JdbcOperation.

Parameters:

dataSource - the data source to the database.

Method Detail

performOperation

protected abstract T performOperation()
                               throws SQLException

Performs the JDBC operation. This method is called by execute() after this object has been fully initialized. Here the actual JDBC logic has to be placed.

Returns:

the result of the operation

Throws:

SQLException - if an SQL error occurs

execute

public T execute()
          throws SQLException

Executes this operation. This method obtains a database connection and then delegates to performOperation(). Afterwards it performs the necessary clean up.

Returns:

the result of the operation.

Throws:

SQLException - if there was a problem executing the operation.

openResultSet

protected ResultSet openResultSet(String sql,
                                  Object... params)
                           throws SQLException

Creates a PreparedStatement for a query, initializes it and executes it. The resulting ResultSet is returned.

Parameters:

sql - the statement to be executed.

params - the parameters for the statement.

Returns:

the ResultSet produced by the query.

Throws:

SQLException - if an SQL error occurs.

initStatement

protected PreparedStatement initStatement(String sql,
                                          Object... parameters)
                                   throws SQLException

Creates an initializes a PreparedStatement object for executing an SQL statement.

Parameters:

sql - the statement to be executed

parameters - the parameters for the statement

Returns:

the initialized statement object

Throws:

SQLException - if an SQL error occurs

getConnection

protected Connection getConnection()

Returns the current connection. This method can be called while execute() is running. It returns null otherwise.

Returns:

the current connection

close

protected void close(Connection connection,
                     Statement statement,
                     ResultSet resultSet)

Close the specified database objects. Avoid closing if null and hide any SQLExceptions that occur.

Parameters:

connection - The database connection to close

statement - The statement to close

resultSet - the result set to close