TEST-TAP: Experiment metadata extraction from the database.

test/tap/metadata/MetadataExtractionTest.java

+package tap.metadata;
+
+/*
+ * 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 Institute (ARI)
+ */
+
+import java.sql.Connection;
+import java.sql.DatabaseMetaData;
+import java.sql.DriverManager;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+/**
+ * @author Gr&eacute;gory Mantelet (ARI) - gmantele@ari.uni-heidelberg.de
+ * @version 1.1 (04/2014)
+ */
+public class MetadataExtractionTest {
+
+	public static void main(String[] args) throws Throwable{
+		MetadataExtractionTest extractor = new MetadataExtractionTest();
+		try{
+			extractor.connect();
+			extractor.printTableMetadata("gums");
+		}finally{
+			extractor.close();
+		}
+	}
+
+	private Connection connection = null;
+	private Statement statement = null;
+
+	public void connect(){
+		try{
+			Class.forName("org.postgresql.Driver");
+			connection = DriverManager.getConnection("jdbc:postgresql:gmantele", "gmantele", "pwd");
+			statement = connection.createStatement();
+			System.out.println("[OK] DB connection successfully established !");
+		}catch(ClassNotFoundException notFoundException){
+			notFoundException.printStackTrace();
+			System.err.println("[ERROR] Connection error !");
+		}catch(SQLException sqlException){
+			sqlException.printStackTrace();
+			System.err.println("[ERROR] Connection error !");
+		}
+	}
+
+	public ResultSet query(String requet){
+		ResultSet resultat = null;
+		try{
+			resultat = statement.executeQuery(requet);
+		}catch(SQLException e){
+			e.printStackTrace();
+			System.out.println("Erreur dans la requête: " + requet);
+		}
+		return resultat;
+
+	}
+
+	public TAPSchema printTableMetadata(final String table){
+		try{
+
+			DatabaseMetaData dbMeta = connection.getMetaData();
+			TAPSchema tapSchema = null;
+			TAPTable tapTable = null;
+
+			// Extract Table metadata (schema, table, type):
+			ResultSet rs = dbMeta.getTables(null, null, table, null);
+			rs.last();
+			if (rs.getRow() == 0)
+				System.err.println("[ERROR] No found table for \"" + table + "\" !");
+			else if (rs.getRow() > 1){
+				rs.first();
+				System.err.println("[ERROR] More than one match for \"" + table + "\":");
+				while(rs.next())
+					System.err.println(rs.getString(2) + "." + rs.getString(3) + " : " + rs.getString(4));
+			}else{
+				rs.first();
+				tapSchema = new TAPSchema(rs.getString(2));
+				tapTable = new TAPTable(rs.getString(3), rs.getString(4));
+				tapSchema.addTable(tapTable);
+				System.out.println("[OK] 1 table FOUND ! => " + tapTable + " : " + tapTable.getType());
+			}
+
+			// Extract all columns metadata (type, precision, scale):
+			rs = dbMeta.getColumns(null, tapSchema.getDBName(), tapTable.getDBName(), null);
+			String type;
+			while(rs.next()){
+				type = rs.getString(6);
+				if (type.endsWith("char") || type.equals("numeric")){
+					type += "(" + rs.getInt(7);
+					if (type.startsWith("numeric"))
+						type += "," + rs.getInt(9);
+					type += ")";
+				}
+				System.out.println("    * " + rs.getString(4) + " : " + type);
+			}
+
+			// Extract all indexed columns:
+			rs = dbMeta.getIndexInfo(null, tapSchema.getDBName(), tapTable.getDBName(), false, true);
+			while(rs.next()){
+				System.out.println("    # " + rs.getString(6) + " : " + rs.getShort(7) + " (unique ? " + (!rs.getBoolean(4)) + ") -> " + rs.getString(9) + " => " + rs.getInt(11) + " unique values in the index ; " + rs.getInt(12) + " pages");
+			}
+
+			return tapSchema;
+
+		}catch(SQLException e){
+			e.printStackTrace();
+			return null;
+		}
+	}
+
+	public void close(){
+		try{
+			connection.close();
+			statement.close();
+			System.out.println("[OK] Connection closed !");
+		}catch(SQLException e){
+			e.printStackTrace();
+			System.out.println("[ERROR] Connection CAN NOT be closed !");
+		}
+	}
+
+}