ResultSets. This class is thread safe.
*
* @see ResultSetHandler
*
* @author Henri Yandell
* @author Juozas Baliuka
* @author Steven Caswell
* @author David Graham
*/
public class QueryRunner {
/**
* The DataSource to retrieve connections from.
*/
protected DataSource ds = null;
/**
* Constructor for QueryRunner.
*/
public QueryRunner() {
super();
}
/**
* Constructor for QueryRunner. Methods that do not take a
* Connection parameter will retrieve connections from this
* DataSource.
*
* @param ds The DataSource to retrieve connections from.
*/
public QueryRunner(DataSource ds) {
super();
this.ds = ds;
}
/**
* Fill the PreparedStatement replacement parameters with
* the given objects.
* @param stmt
* @param params Query replacement parameters; null is a valid
* value to pass in.
* @throws SQLException
*/
protected void fillStatement(PreparedStatement stmt, Object[] params)
throws SQLException {
if (params == null) {
return;
}
for (int i = 0; i < params.length; i++) {
if (params[i] != null) {
stmt.setObject(i + 1, params[i]);
} else {
stmt.setNull(i + 1, Types.OTHER);
}
}
}
/**
* Returns the DataSource this runner is using.
*/
public DataSource getDataSource() {
return this.ds;
}
/**
* Factory method that creates and initializes a
* PreparedStatement object for the given SQL.
* QueryRunner methods always call this method to prepare
* statements for them. Subclasses can override this method to provide
* special PreparedStatement configuration if needed. This implementation
* simply calls conn.prepareStatement(sql).
*
* @param conn The Connection used to create the
* PreparedStatement
* @param sql The SQL statement to prepare.
* @return An initialized PreparedStatement.
* @throws SQLException
*/
protected PreparedStatement prepareStatement(Connection conn, String sql)
throws SQLException {
return conn.prepareStatement(sql);
}
/**
* Execute an SQL SELECT query with a single replacement parameter. The
* caller is responsible for connection cleanup.
*
* @param conn The connection to execute the query in.
* @param sql The query to execute.
* @param param The replacement parameter.
* @param rsh The handler that converts the results into an object.
* @return The object returned by the handler.
* @throws SQLException
*/
public Object query(
Connection conn,
String sql,
Object param,
ResultSetHandler rsh)
throws SQLException {
return this.query(conn, sql, new Object[] { param }, rsh);
}
/**
* Execute an SQL SELECT query with replacement parameters. The
* caller is responsible for connection cleanup.
*
* @param conn The connection to execute the query in.
* @param sql The query to execute.
* @param params The replacement parameters.
* @param rsh The handler that converts the results into an object.
* @return The object returned by the handler.
* @throws SQLException
*/
public Object query(
Connection conn,
String sql,
Object[] params,
ResultSetHandler rsh)
throws SQLException {
PreparedStatement stmt = null;
ResultSet rs = null;
Object result = null;
try {
stmt = this.prepareStatement(conn, sql);
this.fillStatement(stmt, params);
rs = this.wrap(stmt.executeQuery());
result = rsh.handle(rs);
} catch (SQLException e) {
this.rethrow(e, sql, params);
} finally {
DbUtils.close(rs);
DbUtils.close(stmt);
}
return result;
}
/**
* Execute an SQL SELECT query without any replacement parameters. The
* caller is responsible for connection cleanup.
*
* @param conn The connection to execute the query in.
* @param sql The query to execute.
* @param rsh The handler that converts the results into an object.
* @return The object returned by the handler.
* @throws SQLException
*/
public Object query(Connection conn, String sql, ResultSetHandler rsh)
throws SQLException {
return this.query(conn, sql, (Object[]) null, rsh);
}
/**
* Executes the given SELECT SQL with a single replacement parameter.
* The Connection is retrieved from the
* DataSource set in the constructor.
*
* @param sql The SQL statement to execute.
* @param param The replacement parameter.
* @param rsh The handler used to create the result object from
* the ResultSet.
*
* @return An object generated by the handler.
* @throws SQLException
*/
public Object query(String sql, Object param, ResultSetHandler rsh)
throws SQLException {
return this.query(sql, new Object[] { param }, rsh);
}
/**
* Executes the given SELECT SQL query and returns a result object.
* The Connection is retrieved from the
* DataSource set in the constructor.
*
* @param sql The SQL statement to execute.
* @param params Initialize the PreparedStatement's IN parameters with
* this array.
*
* @param rsh The handler used to create the result object from
* the ResultSet.
*
* @return An object generated by the handler.
* @throws SQLException
*/
public Object query(String sql, Object[] params, ResultSetHandler rsh)
throws SQLException {
Connection conn = this.ds.getConnection();
try {
return this.query(conn, sql, params, rsh);
} finally {
DbUtils.close(conn);
}
}
/**
* Executes the given SELECT SQL without any replacement parameters.
* The Connection is retrieved from the
* DataSource set in the constructor.
*
* @param sql The SQL statement to execute.
* @param rsh The handler used to create the result object from
* the ResultSet.
*
* @return An object generated by the handler.
* @throws SQLException
*/
public Object query(String sql, ResultSetHandler rsh) throws SQLException {
return this.query(sql, (Object[]) null, rsh);
}
/**
* Throws a new exception with a more informative error message.
*
* @param cause The original exception that will be chained to the new
* exception when it's rethrown.
*
* @param sql The query that was executing when the exception happened.
*
* @param params The query replacement paramaters; null is a
* valid value to pass in.
*
* @throws SQLException
*/
protected void rethrow(SQLException cause, String sql, Object[] params)
throws SQLException {
StringBuffer msg = new StringBuffer(cause.getMessage());
msg.append(" Query: ");
msg.append(sql);
msg.append(" Parameters: ");
if (params == null) {
msg.append("[]");
} else {
msg.append(Arrays.asList(params));
}
SQLException e = new SQLException(msg.toString());
e.setNextException(cause);
throw e;
}
/**
* Sets the DataSource this runner will use to get
* database connections from. This should be called after creating a
* runner with the default constructor if you intend to use the
* execute methods without passing in a Connection.
*
* @param dataSource The DataSource to use.
*/
public void setDataSource(DataSource dataSource) {
this.ds = dataSource;
}
/**
* Execute an SQL INSERT, UPDATE, or DELETE query without replacement
* parameters.
*
* @param conn The connection to use to run the query.
* @param sql The SQL to execute.
* @return The number of rows updated.
* @throws SQLException
*/
public int update(Connection conn, String sql) throws SQLException {
return this.update(conn, sql, (Object[]) null);
}
/**
* Execute an SQL INSERT, UPDATE, or DELETE query with a single replacement
* parameter.
*
* @param conn The connection to use to run the query.
* @param sql The SQL to execute.
* @param param The replacement parameter.
* @return The number of rows updated.
* @throws SQLException
*/
public int update(Connection conn, String sql, Object param)
throws SQLException {
return this.update(conn, sql, new Object[] { param });
}
/**
* Execute an SQL INSERT, UPDATE, or DELETE query.
*
* @param conn The connection to use to run the query.
* @param sql The SQL to execute.
* @param params The query replacement parameters.
* @return The number of rows updated.
* @throws SQLException
*/
public int update(Connection conn, String sql, Object[] params)
throws SQLException {
PreparedStatement stmt = null;
int rows = 0;
try {
stmt = this.prepareStatement(conn, sql);
this.fillStatement(stmt, params);
rows = stmt.executeUpdate();
} catch (SQLException e) {
this.rethrow(e, sql, params);
} finally {
DbUtils.close(stmt);
}
return rows;
}
/**
* Executes the given INSERT, UPDATE, or DELETE SQL statement without
* any replacement parameters. The Connection is retrieved
* from the DataSource set in the constructor.
*
* @param sql The SQL statement to execute.
* @throws SQLException
* @return The number of rows updated.
*/
public int update(String sql) throws SQLException {
return this.update(sql, (Object[]) null);
}
/**
* Executes the given INSERT, UPDATE, or DELETE SQL statement with
* a single replacement parameter. The Connection is
* retrieved from the DataSource set in the constructor.
*
* @param sql The SQL statement to execute.
* @param param The replacement parameter.
* @throws SQLException
* @return The number of rows updated.
*/
public int update(String sql, Object param) throws SQLException {
return this.update(sql, new Object[] { param });
}
/**
* Executes the given INSERT, UPDATE, or DELETE SQL statement. The
* Connection is retrieved from the DataSource
* set in the constructor.
*
* @param sql The SQL statement to execute.
* @param params Initializes the PreparedStatement's IN (i.e. '?')
* parameters.
* @throws SQLException
* @return The number of rows updated.
*/
public int update(String sql, Object[] params) throws SQLException {
Connection conn = this.ds.getConnection();
try {
return this.update(conn, sql, params);
} finally {
DbUtils.close(conn);
}
}
/**
* Wrap the ResultSet in a decorator before processing it.
* This implementation returns the ResultSet it is given
* without any decoration.
*
* * Often, the implementation of this method can be done in an anonymous * inner class like this: *
*
* QueryRunner run = new QueryRunner() {
* protected ResultSet wrap(ResultSet rs) {
* return StringTrimmedResultSet.wrap(rs);
* }
* };
*
*
* @param rs The ResultSet to decorate; never
* null.
* @return The ResultSet wrapped in some decorator.
*/
protected ResultSet wrap(ResultSet rs) {
return rs;
}
}