[TAP] Add the interface TableIterator (whose implementations let iterate over...

package tap.data;

import tap.TAPException;

/**

 * Exception that occurs when reading a data input (can be an InputStream, a ResultSet, a SavotTable, ...).

 * 

 * @author Grégory Mantelet (ARI) - gmantele@ari.uni-heidelberg.de

 * @version 2.0 (06/2014)

 * @since 2.0

 * 

 * @see TableIterator

 */

public class DataReadException extends TAPException {

	private static final long serialVersionUID = 1L;

	public DataReadException(final String message){

		super(message);

	}

	public DataReadException(Throwable cause){

		super(cause);

	}

	public DataReadException(String message, Throwable cause){

		super(message, cause);

	}

}

package tap.data;

/*

 * This file is part of TAPLibrary.

 * 

 * TAPLibrary is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 * 

 * TAPLibrary is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU Lesser General Public License for more details.

 * 

 * You should have received a copy of the GNU Lesser General Public License

 * along with TAPLibrary.  If not, see <http://www.gnu.org/licenses/>.

 * 

 * Copyright 2014 - Astronomisches Rechen Institut (ARI)

 */

import java.sql.ResultSet;

import java.sql.ResultSetMetaData;

import java.sql.SQLException;

import java.util.NoSuchElementException;

/**

 * <p>{@link TableIterator} which lets iterate over a SQL {@link ResultSet}.</p>

 * 

 * <p>{@link #getColType()} will return the type declared in the {@link ResultSetMetaData} object.</p>

 * 

 * @author Grégory Mantelet (ARI) - gmantele@ari.uni-heidelberg.de

 * @version 2.0 (06/2014)

 * @since 2.0

 */

public class ResultSetTableIterator implements TableIterator {

	/** ResultSet/Dataset to read. */

	private final ResultSet data;

	/** Number of columns to read. */

	private final int nbColumns;

	/** Type of all columns. */

	private final String[] colTypes;

	/** Indicate whether the row iteration has already started. */

	private boolean iterationStarted = false;

	/** Indicate whether the last row has already been reached. */

	private boolean endReached = false;

	/** Index of the last read column (=0 just after {@link #nextRow()} and before {@link #nextCol()}, ={@link #nbColumns} after the last column has been read). */

	private int colIndex;

	/**

	 * Build a TableIterator able to read rows and columns of the given ResultSet.

	 * 

	 * @param dataSet	Dataset over which this iterator must iterate.

	 * 

	 * @throws NullPointerException	If NULL is given in parameter.

	 * @throws DataReadException	If the given ResultSet is closed

	 *                              or if the metadata (columns count and types) can not be fetched.

	 */

	public ResultSetTableIterator(final ResultSet dataSet) throws NullPointerException, DataReadException{

		// A dataset MUST BE provided:

		if (dataSet == null)

			throw new NullPointerException("Missing ResultSet object over which to iterate!");

		// It MUST also BE OPEN:

		try{

			if (dataSet.isClosed())

				throw new DataReadException("Closed ResultSet: impossible to iterate over it!");

		}catch(SQLException se){

			throw new DataReadException("Can not know whether the ResultSet is open!", se);

		}

		// Keep a reference to the ResultSet:

		data = dataSet;

		// Count columns and determine their type:

		try{

			// get the metadata:

			ResultSetMetaData metadata = data.getMetaData();

			// count columns:

			nbColumns = metadata.getColumnCount();

			// determine their type:

			colTypes = new String[nbColumns];

			for(int i = 1; i <= nbColumns; i++)

				colTypes[i - 1] = metadata.getColumnTypeName(i);

		}catch(SQLException se){

			throw new DataReadException("Can not get the column types of the given ResultSet!", se);

		}

	}

	@Override

	public boolean nextRow() throws DataReadException{

		try{

			// go to the next row:

			boolean rowFetched = data.next();

			endReached = !rowFetched;

			// prepare the iteration over its columns:

			colIndex = 0;

			iterationStarted = true;

			return rowFetched;

		}catch(SQLException e){

			throw new DataReadException("Unable to read a result set row!", e);

		}

	}

	/**

	 * <p>Check the row iteration state. That's to say whether:</p>

	 * <ul>

	 * 	<li>the row iteration has started = the first row has been read = a first call of {@link #nextRow()} has been done</li>

	 * 	<li>AND the row iteration is not finished = the last row has been read.</li>

	 * </ul>

	 * @throws IllegalStateException

	 */

	private void checkReadState() throws IllegalStateException{

		if (!iterationStarted)

			throw new IllegalStateException("No row has yet been read!");

		else if (endReached)

			throw new IllegalStateException("End of ResultSet already reached!");

	}

	@Override

	public boolean hasNextCol() throws IllegalStateException, DataReadException{

		// Check the read state:

		checkReadState();

		// Determine whether the last column has been reached or not:

		return (colIndex < nbColumns);

	}

	@Override

	public Object nextCol() throws NoSuchElementException, IllegalStateException, DataReadException{

		// Check the read state and ensure there is still at least one column to read:

		if (!hasNextCol())

			throw new NoSuchElementException("No more column to read!");

		// Get the column value:

		try{

			return data.getObject(++colIndex);

		}catch(SQLException se){

			throw new DataReadException("Can not read the value of the " + colIndex + "-th column!", se);

		}

	}

	@Override

	public String getColType() throws IllegalStateException, DataReadException{

		// Basically check the read state (for rows iteration):

		checkReadState();

		// Check deeper the read state (for columns iteration):

		if (colIndex <= 0)

			throw new IllegalStateException("No column has yet been read!");

		else if (colIndex > nbColumns)

			throw new IllegalStateException("All columns have already been read!");

		// Return the column type:

		return colTypes[colIndex - 1];

	}

}

package tap.data;

/*

 * This file is part of TAPLibrary.

 * 

 * TAPLibrary is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 * 

 * TAPLibrary is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU Lesser General Public License for more details.

 * 

 * You should have received a copy of the GNU Lesser General Public License

 * along with TAPLibrary.  If not, see <http://www.gnu.org/licenses/>.

 * 

 * Copyright 2014 - Astronomisches Rechen Institut (ARI)

 */

import java.util.NoSuchElementException;

/**

 * <p>Let's iterate on each row and then on each column over a table dataset.</p>

 * 

 * <p>Initially, no rows are loaded and the "cursor" inside the dataset is set before the first row.

 * Thus, a first call to {@link #nextRow()} is required to read each of the column values of the first row.</p>

 * 

 * <p>Example of an expected usage:</p>

 * <pre>

 * 	TableIterator it = ...;

 * 	try{

 * 		while(it.nextRow()){

 * 			while(it.hasNextCol()){

 * 				Object colValue = it.nextCol();

 * 				String colType = it.getColType();

 * 				...

 * 			}

 * 		}

 * 	}catch(DataReadException dre){

 * 		...

 * 	}

 * </pre>

 * 

 * @author Grégory Mantelet (ARI) - gmantele@ari.uni-heidelberg.de

 * @version 2.0 (06/2014)

 * @since 2.0

 */

public interface TableIterator {

	/**

	 * <p>Go to the next row if there is one.</p>

	 * 

	 * <p><i>Note: After a call to this function the columns must be fetched individually using {@link #nextCol()}

	 * <b>IF</b> this function returned </i>true<i>.</i></p>

	 * 

	 * @return	<i>true</i> if the next row has been successfully reached,

	 *          <i>false</i> if no more rows can be read.

	 * 

	 * @throws DataReadException	If an error occurs while reading the table dataset.

	 */

	public boolean nextRow() throws DataReadException;

	/**

	 * Tell whether another column is available.

	 * 

	 * @return	<i>true</i> if {@link #nextCol()} will return the value of the next column with no error,

	 *          <i>false</i> otherwise.

	 * 

	 * @throws IllegalStateException	If {@link #nextRow()} has not yet been called.

	 * @throws DataReadException	If an error occurs while reading the table dataset.

	 */

	public boolean hasNextCol() throws IllegalStateException, DataReadException;

	/**

	 * <p>Return the value of the next column.</p>

	 * 

	 * <p><i>Note: The column type can be fetched using {@link #getColType()} <b>after</b> a call to {@link #nextCol()}.</i></p>

	 * 

	 * @return	Get the value of the next column.

	 * 

	 * @throws NoSuchElementException	If no more column value is available.

	 * @throws IllegalStateException	If {@link #nextRow()} has not yet been called.

	 * @throws DataReadException	If an error occurs while reading the table dataset.

	 */

	public Object nextCol() throws NoSuchElementException, IllegalStateException, DataReadException;

	/**

	 * <p>Get the type of the current column value.</p>

	 * 

	 * <p><i>Note: "Current column value" means here "the value last returned by {@link #nextCol()}".</i></p>

	 * 

	 * @return	Type of the current column value,

	 *          or NULL if this information is not available or if this function is not implemented. 

	 * 

	 * @throws IllegalStateException	If {@link #nextCol()} has not yet been called.

	 * @throws DataReadException	If an error occurs while reading the table dataset.

	 */

	public String getColType() throws IllegalStateException, DataReadException;

}

package tap.data;

import static org.junit.Assert.assertEquals;

import static org.junit.Assert.assertTrue;

import static org.junit.Assert.fail;

import java.sql.Connection;

import java.sql.ResultSet;

import org.junit.AfterClass;

import org.junit.BeforeClass;

import org.junit.Test;

import testtools.DBTools;

public class ResultSetTableIteratorTest {

	private static Connection conn;

	@BeforeClass

	public static void setUpBeforeClass() throws Exception{

		conn = DBTools.createConnection("postgresql", "127.0.0.1", null, "gmantele", "gmantele", "pwd");

	}

	@AfterClass

	public static void tearDownAfterClass() throws Exception{

		DBTools.closeConnection(conn);

	}

	@Test

	public void testWithRSNULL(){

		try{

			new ResultSetTableIterator(null);

			fail("The constructor should have failed, because: the given ResultSet is NULL.");

		}catch(Exception ex){

			assertEquals(ex.getClass().getName(), "java.lang.NullPointerException");

		}

	}

	@Test

	public void testWithData(){

		try{

			ResultSet rs = DBTools.select(conn, "SELECT id, ra, deg, gmag FROM gums LIMIT 10;");

			TableIterator it = new ResultSetTableIterator(rs);

			final int expectedNbLines = 10, expectedNbColumns = 4;

			int countLines = 0, countColumns = 0;

			while(it.nextRow()){

				// count lines:

				countLines++;

				// reset columns count:

				countColumns = 0;

				while(it.hasNextCol()){

					it.nextCol();

					// count columns

					countColumns++;

					// TEST the column type is set (not null):

					assertTrue(it.getColType() != null);

				}

				// TEST that all columns have been read:

				assertEquals(expectedNbColumns, countColumns);

			}

			// TEST that all lines have been read: 

			assertEquals(expectedNbLines, countLines);

		}catch(Exception ex){

			ex.printStackTrace(System.err);

			fail("An exception occurs while reading a correct ResultSet (containing some valid rows).");

		}

	}

	@Test

	public void testWithEmptySet(){

		try{

			ResultSet rs = DBTools.select(conn, "SELECT * FROM gums WHERE id = 'foo';");

			TableIterator it = new ResultSetTableIterator(rs);

			int countLines = 0;

			// count lines:

			while(it.nextRow())

				countLines++;

			// TEST that no line has been read: 

			assertEquals(countLines, 0);

		}catch(Exception ex){

			ex.printStackTrace(System.err);

			fail("An exception occurs while reading a correct ResultSet (containing some valid rows).");

		}

	}

	@Test

	public void testWithClosedSet(){

		try{

			// create a valid ResultSet:

			ResultSet rs = DBTools.select(conn, "SELECT * FROM gums WHERE id = 'foo';");

			// close the ResultSet:

			rs.close();

			// TRY to create a TableIterator with a closed ResultSet:

			new ResultSetTableIterator(rs);

			fail("The constructor should have failed, because: the given ResultSet is closed.");

		}catch(Exception ex){

			assertEquals(ex.getClass().getName(), "tap.data.DataReadException");

		}

	}

}

package testtools;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.HashMap;

public final class DBTools {

	public static int count = 0;

	public final static void main(final String[] args) throws Throwable{

		for(int i = 0; i < 3; i++){

			Thread t = new Thread(new Runnable(){

				@Override

				public void run(){

					count++;

					try{

						Connection conn = DBTools.createConnection("postgresql", "127.0.0.1", null, "gmantele", "gmantele", "pwd");

						System.out.println("Start - " + count + ": ");

						String query = "SELECT * FROM gums.smc WHERE magg BETWEEN " + (15 + count) + " AND " + (20 + count) + ";";

						System.out.println(query);

						ResultSet rs = DBTools.select(conn, query);

						try{

							rs.last();

							System.out.println("Nb rows: " + rs.getRow());

						}catch(SQLException e){

							e.printStackTrace();

						}

						if (DBTools.closeConnection(conn))

							System.out.println("[DEBUG] Connection closed!");

					}catch(DBToolsException e){

						e.printStackTrace();

					}

					System.out.println("End - " + count);

					count--;

				}

			});

			t.start();

		}

	}

	public static class DBToolsException extends Exception {

		private static final long serialVersionUID = 1L;

		public DBToolsException(){

			super();

		}

		public DBToolsException(String message, Throwable cause){

			super(message, cause);

		}

		public DBToolsException(String message){

			super(message);

		}

		public DBToolsException(Throwable cause){

			super(cause);

		}

	}

	public final static HashMap<String,String> VALUE_JDBC_DRIVERS = new HashMap<String,String>(4);

	static{

		VALUE_JDBC_DRIVERS.put("oracle", "oracle.jdbc.OracleDriver");

		VALUE_JDBC_DRIVERS.put("postgresql", "org.postgresql.Driver");

		VALUE_JDBC_DRIVERS.put("mysql", "com.mysql.jdbc.Driver");

		VALUE_JDBC_DRIVERS.put("sqlite", "org.sqlite.JDBC");

	}

	private DBTools(){}

	public final static Connection createConnection(String dbms, final String server, final String port, final String dbName, final String user, final String passwd) throws DBToolsException{

		// 1. Resolve the DBMS and get its JDBC driver:

		if (dbms == null)

			throw new DBToolsException("Missing DBMS (expected: oracle, postgresql, mysql or sqlite)!");

		dbms = dbms.toLowerCase();

		String jdbcDriver = VALUE_JDBC_DRIVERS.get(dbms);

		if (jdbcDriver == null)

			throw new DBToolsException("Unknown DBMS (\"" + dbms + "\")!");

		// 2. Load the JDBC driver:

		try{

			Class.forName(jdbcDriver);

		}catch(ClassNotFoundException e){

			throw new DBToolsException("Impossible to load the JDBC driver: " + e.getMessage(), e);

		}

		// TODO DEBUG MSG

		System.out.println("[DEBUG] " + dbms + " JDBC Driver Registered!");

		// 3. Establish the connection:

		Connection connection = null;

		try{

			connection = DriverManager.getConnection("jdbc:" + dbms + "://" + server + ((port != null && port.trim().length() > 0) ? (":" + port) : "") + "/" + dbName, user, passwd);

		}catch(SQLException e){

			throw new DBToolsException("Connection failed: " + e.getMessage(), e);

		}

		if (connection == null)

			throw new DBToolsException("Failed to make connection!");

		// TODO DEBUG MSG

		System.out.println("[DEBUG] Connection to " + dbName + " established!");

		return connection;

	}

	public final static boolean closeConnection(final Connection conn) throws DBToolsException{

		try{

			if (conn != null && !conn.isClosed()){

				conn.close();

				try{

					Thread.sleep(200);

				}catch(InterruptedException e){

					System.err.println("WARNING: can't wait/sleep before testing the connection close status! [" + e.getMessage() + "]");

				}

				return conn.isClosed();

			}else

				return true;

		}catch(SQLException e){

			throw new DBToolsException("Closing connection failed: " + e.getMessage(), e);

		}

	}

	public final static ResultSet select(final Connection conn, final String selectQuery) throws DBToolsException{

		if (conn == null || selectQuery == null || selectQuery.trim().length() == 0)

			throw new DBToolsException("One parameter is missing!");

		try{

			Statement stmt = conn.createStatement();

			return stmt.executeQuery(selectQuery);

		}catch(SQLException e){

			throw new DBToolsException("Can't execute the given SQL query: " + e.getMessage(), e);

		}

	}

}