Encapsulate the Connection-related operations that every JDBC program seems to use : Connection « Database SQL JDBC « Java

1. Java
2. Database SQL JDBC
3. Connection

Encapsulate the Connection-related operations that every JDBC program seems to use

    
/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

/** Encapsulate the Connection-related operations that every 
 * JDBC program seems to use.
 */
public class ConnectionUtil {
  /** The default config filename, relative to ${user.home} */
  public static final String DEFAULT_NAME = ".db.properties";
  
  /** The current config filename */
  private static String configFileName =
    System.getProperty("user.home") + File.separator + DEFAULT_NAME;

  /** Get a Connection for the given config using the default or set property file name */
  public static Connection getConnection(String config) throws Exception {
    try {
      Properties p = new Properties();
      p.load(new FileInputStream(configFileName));
      return getConnection(p, config);
    } catch (IOException ex) {
      throw new Exception(ex.toString());
    }
  }
  
  /** Get a Connection for the given config name from a provided Properties */
  public static Connection getConnection(Properties p,  String config) throws Exception {
    try {
      String db_driver = p.getProperty(config  + "." + "DBDriver");
      String db_url = p.getProperty(config  + "." + "DBURL");
      String db_user = p.getProperty(config  + "." + "DBUser");
      String db_password = p.getProperty(config  + "." + "DBPassword");
      if (db_driver == null || db_url == null) {
        throw new IllegalStateException("Driver or URL null: " + config);
      }
      return createConnection(db_driver, db_url, db_user, db_password);
    } catch (ClassNotFoundException ex) {
      throw new Exception(ex.toString());
  
    } catch (SQLException ex) {
      throw new Exception(ex.toString());
    }
  }

  public static Connection createConnection(String db_driver, String db_url, 
          String db_user, String db_password)
      throws ClassNotFoundException, SQLException {


    // Load the database driver
    System.out.println("Loading driver " + db_driver);
    Class.forName(db_driver);

    System.out.println("Connecting to DB " + db_url);
    return DriverManager.getConnection(
      db_url, db_user, db_password);
  }
  
  /** Returns the full path of the configuration file being used.
   * @return Returns the configFileName.
   */
  public static String getConfigFileName() {
    return configFileName;
  }
  
  /** Sets the full path of the config file to read.
   * @param configFileNam The FileName of the configuration file to use.
   */
  public static void setConfigFileName(String configFileNam) {
    configFileName = configFileNam;
    File file = new File(configFileName);
    if (!file.canRead()) {
      throw new IllegalArgumentException("Unreadable: " + configFileName);
    }
    try {
      ConnectionUtil.configFileName = file.getCanonicalPath();
    } catch (IOException ex) {
      System.err.println("Warning: IO error checking path: " + configFileName);
      ConnectionUtil.configFileName = configFileName;
    }
  }
}


           
         
    
    
    
  

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