Java tutorial
/** * '$RCSfile: SimpleDatabaseLoader.java,v $' * * '$Author: leinfelder $' * '$Date: 2008-06-23 23:43:01 $' * '$Revision: 1.1 $' * * For Details: http://ecoinformatics.org * * Copyright (c) 2008 The Regents of the University of California. * All rights reserved. * * Permission is hereby granted, without written agreement and without * license or royalty fees, to use, copy, modify, and distribute this * software and its documentation for any purpose, provided that the * above copyright notice and the following two paragraphs appear in * all copies of this software. * * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY * FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN * IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY * OF SUCH DAMAGE. * * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE * PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY * OF CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, * UPDATES, ENHANCEMENTS, OR MODIFICATIONS. */ package edu.lternet.pasta.dml.database; import java.io.InputStream; import java.io.OutputStream; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.SQLException; import java.util.Vector; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import edu.lternet.pasta.dml.DataManager; import edu.lternet.pasta.dml.download.DataSourceNotFoundException; import edu.lternet.pasta.dml.download.DataStorageInterface; import edu.lternet.pasta.dml.parser.AttributeList; import edu.lternet.pasta.dml.parser.Entity; /** * This is a very bare-bones class for loading Entity data into a table * * * @author Ben Leinfelder (based on Jing Tao's DatabaseLoader) * */ public class SimpleDatabaseLoader implements DataStorageInterface, Runnable { /* * Class fields */ private static TableMonitor tableMonitor = null; public static Log log = LogFactory.getLog(SimpleDatabaseLoader.class); /* * Instance fields */ private Entity entity = null; private TextDataReader dataReader = null; private DatabaseAdapter databaseAdapter = null; private boolean completed = false; private boolean success = false; private Exception exception = null; /* * Constructors */ /** * Constructor of this class. Sets up the necessary components for loading data * * @param dbAdapter * Database adapter name * @param entity * Metadata information associated with the loader * @param dataReader * the data for the loader */ public SimpleDatabaseLoader(String databaseAdapterName, Entity entity, TextDataReader dataReader) { //the description this.entity = entity; //the data this.dataReader = dataReader; /* Initialize the databaseAdapter and tableMonitor fields */ this.databaseAdapter = DataManager.getDatabaseAdapterObject(databaseAdapterName); try { tableMonitor = new TableMonitor(databaseAdapter); } catch (SQLException e) { log.error("problem setting table monitor: " + e.getMessage()); e.printStackTrace(); } } /** * */ public void run() { if (entity == null) { success = false; completed = true; return; } //don't reload data if we have it if (doesDataExist(entity.getEntityIdentifier())) { return; } AttributeList attributeList = entity.getAttributeList(); String tableName = entity.getDBTableName(); String insertSQL = ""; Vector rowVector = new Vector(); Connection connection = null; try { rowVector = this.dataReader.getOneRowDataVector(); connection = DataManager.getConnection(); if (connection == null) { success = false; exception = new Exception("The connection to db is null"); completed = true; return; } connection.setAutoCommit(false); while (!rowVector.isEmpty()) { insertSQL = databaseAdapter.generateInsertSQL(attributeList, tableName, rowVector); if (insertSQL != null) { PreparedStatement statement = connection.prepareStatement(insertSQL); statement.execute(); } rowVector = this.dataReader.getOneRowDataVector(); } connection.commit(); success = true; } catch (Exception e) { log.error("problem while loading data into table. Error message: " + e.getMessage()); e.printStackTrace(); log.error("SQL string to insert row:\n" + insertSQL); success = false; exception = e; try { connection.rollback(); } catch (Exception ee) { System.err.println(ee.getMessage()); } } finally { try { connection.setAutoCommit(true); } catch (Exception ee) { log.error(ee.getMessage()); } DataManager.returnConnection(connection); } } /** * Determines whether the data table * already exists in the database and is loaded with data. This method is * mandated by the DataStorageInterface. * * First, check that the data table exists. Second, check that the row count * is greater than zero. (We want to make sure that the table has not only * been created, but has also been loaded with data.) * * @param identifier * the identifier for the data table * @return true if the data table has been loaded into the database, else * false */ public boolean doesDataExist(String identifier) { boolean doesExist = false; try { String tableName = tableMonitor.identifierToTableName(identifier); doesExist = tableMonitor.isTableInDB(tableName); if (doesExist) { int rowCount = tableMonitor.countRows(tableName); doesExist = (rowCount > 0); } } catch (SQLException e) { log.error(e.getMessage()); e.printStackTrace(); } return doesExist; } /** * Gets the completion status of the serialize process. * * @param identifier * Identifier of the entity which is being serialized * @return true if complete, false if not complete */ public boolean isCompleted(String identifier) { return completed || doesDataExist(identifier); } /** * Gets the success status of the serialize process - success or failure * * @param identifier * Identifier of the entity which has been serialized * @return true if success, else false */ public boolean isSuccess(String identifier) { return success || doesDataExist(identifier); } public Exception getException() { return exception; } public void finishSerialize(String indentifier, String errorCode) { log.warn("unimplemented method called"); return; } public InputStream load(String identifier) throws DataSourceNotFoundException { log.warn("unimplemented method called"); return null; } public OutputStream startSerialize(String identifier) { log.warn("unimplemented method called"); return null; } }