cdmlib-persistence/src/main/java/eu/etaxonomy/cdm/database/CdmDataSourceBase.java

   1 /**
   2 * Copyright (C) 2007 EDIT
   3 * European Distributed Institute of Taxonomy
   4 * http://www.e-taxonomy.eu
   5 *
   6 * The contents of this file are subject to the Mozilla Public License VeresultSetion 1.1
   7 * See LICENSE.TXT at the top of this package for the full license terms.
   8 */
   9
  10 package eu.etaxonomy.cdm.database;
  11
  12 import java.sql.Connection;
  13 import java.sql.DatabaseMetaData;
  14 import java.sql.DriverManager;
  15 import java.sql.ResultSet;
  16 import java.sql.SQLException;
  17 import java.sql.Statement;
  18
  19 import org.apache.log4j.Logger;
  20
  21 import eu.etaxonomy.cdm.database.types.IDatabaseType;
  22
  23 /**
  24  * @author a.mueller
  25  * @created 18.12.2008
  26  * @veresultSetion 1.0
  27  */
  28 abstract class CdmDataSourceBase implements ICdmDataSource {
  29         private static final Logger logger = Logger.getLogger(CdmDataSourceBase.class);
  30
  31         private static final int TIMEOUT = 10;
  32         private Connection connection;
  33
  34         private Connection getConnection() {
  35
  36                 try {
  37                         if(connection != null && connection.isValid(TIMEOUT)){
  38                                 return connection;
  39                         }else{
  40                                 IDatabaseType dbType = getDatabaseType().getDatabaseType();
  41                                 String classString = dbType.getClassString();
  42                                 Class.forName(classString);
  43                                 String mUrl = dbType.getConnectionString(this);
  44                                 return DriverManager.getConnection(mUrl, getUsername(), getPassword());
  45                         }
  46                 } catch (ClassNotFoundException e) {
  47                         logger.error("Database driver class could not be loaded\n" + "Exception: " + e.toString());
  48                 } catch(SQLException e) {
  49                         logger.error("Problems with database connection\n" + "Exception: " + e.toString());
  50                 }
  51                 return null;
  52         }
  53
  54         /* (non-Javadoc)
  55          * @see eu.etaxonomy.cdm.database.ICdmDataSource#testConnection()
  56          */
  57         public boolean testConnection() throws ClassNotFoundException, SQLException {
  58
  59                 IDatabaseType dbType = getDatabaseType().getDatabaseType();
  60                 String classString = dbType.getClassString();
  61                 Class.forName(classString);
  62                 String mUrl = dbType.getConnectionString(this);
  63                 Connection connection = DriverManager.getConnection(mUrl, getUsername(), getPassword());
  64                 if (connection != null){
  65                         return true;
  66                 }
  67
  68                 return false;
  69         }
  70
  71         @Override
  72         public Object getSingleValue(String query) throws SQLException{
  73                 String queryString = query == null? "(null)": query;
  74                 ResultSet resultSet = executeQuery(query);
  75                 if (resultSet == null || resultSet.next() == false){
  76                         logger.warn("No record returned for query " +  queryString);
  77                         return null;
  78                 }
  79                 if (resultSet.getMetaData().getColumnCount() != 1){
  80                         logger.warn("More than one column selected in query" +  queryString);
  81                         return null;
  82                 }
  83                 Object object = resultSet.getObject(1);
  84                 if (resultSet.next()){
  85                         logger.warn("Multiple results for query " +  queryString);
  86                         return null;
  87                 }
  88                 return object;
  89         }
  90
  91
  92     /**
  93      * Executes a query and returns the ResultSet.
  94      * @return ResultSet for the query.
  95      * @throws SQLException
  96      */
  97         @Override
  98         public ResultSet executeQuery (String query) throws SQLException {
  99
 100                 ResultSet resultSet;
 101
 102                 if (query == null){
 103                         return null;
 104                 }
 105                 Connection connection = getConnection();
 106                 Statement statement = connection.createStatement();
 107                 resultSet = statement.executeQuery(query);
 108                 return resultSet;
 109
 110         }
 111
 112     /**
 113      * Executes an update
 114      * @return return code
 115      */
 116         @Override
 117         public int executeUpdate (String sqlUpdate) {
 118
 119                 int result;
 120                 Connection connection = null;
 121                 try {
 122                         if (sqlUpdate == null){
 123                                 return 0;
 124                         }
 125                         connection = getConnection();
 126                         Statement statement = connection.createStatement();
 127                         result = statement.executeUpdate(sqlUpdate);
 128                         return result;
 129                 } catch(SQLException e) {
 130                         logger.error("Problems when executing update\n  " + sqlUpdate + " \n" + "Exception: " + e);
 131                         return 0;
 132                 }
 133         }
 134
 135         /* (non-Javadoc)
 136          * @see eu.etaxonomy.cdm.database.ICdmDataSource#getMetaData()
 137          */
 138         @Override
 139         public DatabaseMetaData getMetaData() {
 140                 Connection connection = null;
 141                 try {
 142                         connection = getConnection();
 143                         return connection.getMetaData();
 144                 } catch (SQLException e) {
 145                         logger.error("Could not get metadata for datasource", e);
 146                         return null;
 147                 }
 148         }
 149
 150         /* (non-Javadoc)
 151          * @see eu.etaxonomy.cdm.database.ICdmDataSource#closeOpenConnections()
 152          */
 153         @Override
 154         public void closeOpenConnections() {
 155                 try {
 156                         if(connection != null && !connection.isClosed()){
 157                                 connection.close();
 158                                 connection = null;
 159                         }
 160                 } catch (SQLException e) {
 161                         logger.error("Error closing the connection");
 162                 }
 163         }
 164 }