Addressbook/src/org/mxchange/addressbook/database/backend/mysql/MySqlDatabaseBackend.java

   1 /*
   2  * Copyright (C) 2015 Roland Haeder
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17 package org.mxchange.addressbook.database.backend.mysql;
  18
  19 import java.io.IOException;
  20 import java.sql.Connection;
  21 import java.sql.DriverManager;
  22 import java.sql.PreparedStatement;
  23 import java.sql.ResultSet;
  24 import java.sql.SQLException;
  25 import java.text.MessageFormat;
  26 import java.util.Iterator;
  27 import org.mxchange.addressbook.database.backend.BaseDatabaseBackend;
  28 import org.mxchange.addressbook.database.backend.DatabaseBackend;
  29 import org.mxchange.addressbook.database.storage.Storeable;
  30 import org.mxchange.addressbook.exceptions.BadTokenException;
  31 import org.mxchange.addressbook.exceptions.UnsupportedDatabaseDriverException;
  32
  33 /**
  34  * A backend class for MySQL connections
  35  *
  36  * @author Roland Haeder
  37  */
  38 public class MySqlDatabaseBackend extends BaseDatabaseBackend implements DatabaseBackend {
  39         /**
  40          * An instance of a datbase connection
  41          */
  42         private static Connection connection;
  43
  44         /**
  45          * Prepared statement for full row count
  46          */
  47         private PreparedStatement totalRowCount;
  48
  49         /**
  50          * Constructor with table name
  51          *
  52          * @param tableName Table to access
  53          * @throws org.mxchange.addressbook.exceptions.UnsupportedDatabaseDriverException
  54          */
  55         public MySqlDatabaseBackend (final String tableName) throws UnsupportedDatabaseDriverException {
  56                 // Validate driver
  57                 this.validateDriver("mysql"); //NOI18N
  58
  59                 // Now that the driver is there, set the table name
  60                 this.setTableName(tableName);
  61         }
  62
  63         @Override
  64         public void connectToDatabase () throws SQLException {
  65                 // Trace message
  66                 this.getLogger().trace("CALLED!"); //NOI18N
  67
  68                 // Is the connection already there?
  69                 if (MySqlDatabaseBackend.connection instanceof Connection) {
  70                         // Already connected
  71                         this.getLogger().debug("Connection is already established."); //NOI18N
  72
  73                         // No need to connect
  74                         return;
  75                 }
  76
  77                 // Generate connection string
  78                 String connect = String.format("jdbc:mysql://%s/%s", //NOI18N
  79                                 this.getProperty("database.mysql.host"), //NOI18N
  80                                 this.getProperty("database.mysql.dbname") //NOI18N
  81                 );
  82
  83                 // Debug message
  84                 this.getLogger().debug(MessageFormat.format("Attempting to connect to {0} ...", connect)); //NOI18N
  85
  86                 // Now get a connection instance back
  87                 MySqlDatabaseBackend.connection = DriverManager.getConnection(
  88                                 connect,
  89                                 this.getProperty("database.mysql.login"), //NOI18N
  90                                 this.getProperty("database.mysql.password") //NOI18N
  91                 );
  92
  93                 // Is the connection really up?
  94                 if (MySqlDatabaseBackend.connection.isClosed()) {
  95                         // Connection is closed again
  96                         throw new SQLException("Connection is closed."); //NOI18N
  97                 }
  98
  99                 // Debug message
 100                 this.getLogger().debug("Connection is up, preparing some statements ..."); //NOI18N
 101
 102                 // Here, the connection is established, so prepare some statements
 103                 this.totalRowCount = MySqlDatabaseBackend.connection.prepareStatement(String.format("SELECT COUNT(`id`) AS `cnt` FROM `%s` LIMIT 1", this.getTableName())); //NOI18N
 104
 105                 // Trace message
 106                 this.getLogger().trace("EXIT!"); //NOI18N
 107         }
 108
 109         @Override
 110         public void doShutdown () {
 111                 // This should not happen:
 112                 assert(MySqlDatabaseBackend.connection instanceof Connection) : MessageFormat.format("connection is not valid: {0}", MySqlDatabaseBackend.connection); //NOI18N
 113
 114                 try {
 115                         // Close down database connection
 116                         MySqlDatabaseBackend.connection.close();
 117                 } catch (final SQLException ex) {
 118                         // Something happened during close()
 119                         this.abortProgramWithException(ex);
 120                 }
 121         }
 122
 123         @Override
 124         public int getTotalCount () throws SQLException {
 125                 // Trace message
 126                 this.getLogger().trace(MessageFormat.format("tableName={0} - CALLED!", this.getTableName())); //NOI18N
 127
 128                 // Nothing counted by default
 129                 int count = 0;
 130
 131                 // Prepared statements are cool ...
 132                 if (this.totalRowCount.execute()) {
 133                         // Did fully work, so get result set
 134                         ResultSet set = this.totalRowCount.getResultSet();
 135
 136                         // First rewind it
 137                         assert(set.last()) : ": last() failed"; //NOI18N
 138
 139                         // Get integer from 'cnt' alias (see statement)
 140                         count = set.getInt("cnt"); //NOI18N
 141
 142                         // Debug message
 143                         this.getLogger().debug(MessageFormat.format("count={0}", count)); //NOI18N
 144
 145                         // Go back to beginning
 146                         set.beforeFirst();
 147                 } else {
 148                         // Empty result
 149                         this.getLogger().warn(MessageFormat.format("COUNT() query didn't return any result on table {0}.", this.getTableName())); //NOI18N
 150                 }
 151
 152                 // Trace message
 153                 this.getLogger().trace(MessageFormat.format("count={0} - EXIT!", count)); //NOI18N
 154
 155                 // Return result
 156                 return count;
 157         }
 158
 159         /**
 160          * Checks whether at least one row is found with given boolean value.
 161          *
 162          * @param columnName Column to check for boolean value
 163          * @param bool Boolean value to check
 164          * @return Whether boolean value is found and returns at least one row
 165          */
 166         @Override
 167         public boolean isRowFound (final String columnName, final boolean bool) throws SQLException {
 168                 // Is at least one entry found?
 169                 if (this.getTotalCount() == 0) {
 170                         // No entry found at all
 171                         return false;
 172                 }
 173                 throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
 174         }
 175
 176         @Override
 177         public Iterator<?> iterator () throws BadTokenException {
 178                 throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
 179         }
 180
 181         @Override
 182         public long length () {
 183                 throw new UnsupportedOperationException("Not implemented for this backend."); //NOI18N
 184         }
 185
 186         @Override
 187         public void rewind () {
 188                 throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
 189         }
 190
 191         @Override
 192         public void store (final Storeable object) throws IOException {
 193                 throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
 194         }
 195 }