driver.java

java 数据库编程源代码

/*
 * MM JDBC Drivers for MySQL
 *
 * $Id: Driver.java,v 1.3 1998/08/25 04:03:36 mmatthew Exp $
 *
 * Copyright (C) 1998 Mark Matthews <[e-mail]>
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA  02111-1307, USA.
 *
 * See the COPYING file located in the top-level-directory of
 * the archive of this library for complete text of license.
 */

/**
 * The Java SQL framework allows for multiple database drivers.  Each
 * driver should supply a class that implements the Driver interface
 *
 * <p>The DriverManager will try to load as many drivers as it can find and
 * then for any given connection request, it will ask each driver in turn
 * to try to connect to the target URL.
 *
 * <p>It is strongly recommended that each Driver class should be small and
 * standalone so that the Driver class can be loaded and queried without
 * bringing in vast quantities of supporting code.
 *
 * <p>When a Driver class is loaded, it should create an instance of itself
 * and register it with the DriverManager.  This means that a user can load
 * and register a driver by doing Class.forName("foo.bah.Driver")
 *
 * @see org.gjt.mm.mysql.Connection
 * @see java.sql.Driver
 * @author Mark Matthews <[e-mail]>
 * @version $Id$
 */

package org.gjt.mm.mysql;

import java.sql.*;
import java.util.*;

public class Driver implements java.sql.Driver
{
    //
    // Register ourselves with the DriverManager
    //
    
    static
    {
	try {
	    java.sql.DriverManager.registerDriver(new Driver());
	} 
	catch (java.sql.SQLException E) {
	    E.printStackTrace();
	}
    }
    
    private Properties _Props      = null;
    
    //
    // Version Info
    //

    static final int _MAJORVERSION = 1;
    static final int _MINORVERSION = 2;
    
    static final boolean debug = false;
    static final boolean trace = false;
    
    /**
     * Construct a new driver and register it with DriverManager
     *
     * @exception java.sql.SQLException
     */
    
    public Driver() throws java.sql.SQLException
    {
    }
    
    /**
     * Try to make a database connection to the given URL.  The driver
     * should return "null" if it realizes it is the wrong kind of
     * driver to connect to the given URL.  This will be common, as
     * when the JDBC driverManager is asked to connect to a given URL,
     * it passes the URL to each loaded driver in turn.
     *
     * <p>The driver should raise an java.sql.SQLException if it is the right driver
     * to connect to the given URL, but has trouble connecting to the
   * database.
   *
   * <p>The java.util.Properties argument can be used to pass arbitrary
   * string tag/value pairs as connection arguments.
   *
   * My protocol takes the form:
   * <PRE>
   *    jdbc:mysql://host:port/database
   * </PRE>
   *
   * @param url the URL of the database to connect to
   * @param info a list of arbitrary tag/value pairs as connection
   *    arguments
   * @return a connection to the URL or null if it isnt us
   * @exception java.sql.SQLException if a database access error occurs
   * @see java.sql.Driver#connect
   */

    public synchronized java.sql.Connection connect(String Url, Properties Info) 
	throws java.sql.SQLException
    {
		if ((_Props = parseURL(Url, Info)) == null) {
		    return null;
		}
		else {
		    return new Connection (host(), port(), _Props, database(), Url, this);
		}
    }
 
    /**
     * Returns true if the driver thinks it can open a connection to the
     * given URL.  Typically, drivers will return true if they understand
     * the subprotocol specified in the URL and false if they don't.  This 
     * driver's protocols start with jdbc:mysql:
     *
     * @see java.sql.Driver#acceptsURL
     * @param url the URL of the driver
     * @return true if this driver accepts the given URL
     * @exception java.sql.SQLException if a database-access error occurs
     */

    public synchronized boolean acceptsURL(String Url) throws java.sql.SQLException
    {
	if (parseURL(Url, null) == null) {
	    return false;
	}
	else {
	    return true;
	}
    }

    /**
     * The getPropertyInfo method is intended to allow a generic GUI
     * tool to discover what properties it should prompt a human for
     * in order to get enough information to connect to a database.
     *
     * <p>Note that depending on the values the human has supplied so
     * far, additional values may become necessary, so it may be necessary
     * to iterate through several calls to getPropertyInfo
     *
     * @param url the Url of the database to connect to
     * @param info a proposed list of tag/value pairs that will be sent on
     *    connect open.
     * @return An array of DriverPropertyInfo objects describing
     *    possible properties.  This array may be an empty array if
     *    no properties are required
     * @exception java.sql.SQLException if a database-access error occurs
     * @see java.sql.Driver#getPropertyInfo
     */

    public DriverPropertyInfo[] getPropertyInfo(String Url, Properties Info) 
	throws java.sql.SQLException
    {
		if (_Props == null) {
			_Props = new Properties();
		}
		
	DriverPropertyInfo HostProp =
	    new DriverPropertyInfo("HOST", _Props.getProperty("HOST"));
	HostProp.required = true;
	
	HostProp.description = "Hostname of MySQL Server";

	DriverPropertyInfo PortProp =
	    new DriverPropertyInfo("PORT", _Props.getProperty("PORT", "3306"));
	PortProp.required = false;
	PortProp.description = "Port number of MySQL Server";
	
	DriverPropertyInfo DBProp = 
	    new DriverPropertyInfo("DBNAME", _Props.getProperty("DBNAME"));
	DBProp.required = false;
	DBProp.description = "Database name"; 

	DriverPropertyInfo UserProp = 
	    new DriverPropertyInfo("user", Info.getProperty("user"));
	UserProp.required = true;
	UserProp.description = "Username to authenticate as";

	DriverPropertyInfo PasswordProp =
	    new DriverPropertyInfo("password", Info.getProperty("password"));
	PasswordProp.required = true;
	PasswordProp.description =  "Password to use for authentication";

	DriverPropertyInfo AutoReconnect =
	    new DriverPropertyInfo("autoReconnect", Info.getProperty("autoReconnect", "false"));
	AutoReconnect.required = false;
	AutoReconnect.choices = new String[] {"true", "false"};
	AutoReconnect.description = "Should the driver try to re-establish bad connections?";

	DriverPropertyInfo MaxReconnects =
	    new DriverPropertyInfo("maxReconnects", Info.getProperty("maxReconnects", "3"));
	MaxReconnects.required = false;
	MaxReconnects.description = "Maximum number of reconnects to attempt if autoReconnect is true"; ;

	DriverPropertyInfo InitialTimeout =
	    new DriverPropertyInfo("initialTimeout", Info.getProperty("initialTimeout", "2"));
	InitialTimeout.required = false;
	InitialTimeout.description = "Initial timeout (seconds) to wait between failed connections"; 
       
	DriverPropertyInfo Dpi[] = {HostProp,
				    PortProp,
				    DBProp,
				    UserProp,
				    PasswordProp,
				    AutoReconnect,
				    MaxReconnects,
				    InitialTimeout};
	return Dpi;
    }
  
    /**
     * Gets the drivers major version number
     *
     * @return the drivers major version number
     */

    public int getMajorVersion()
    {
	return _MAJORVERSION;
    }

    /**
     * Get the drivers minor version number
     *
     * @return the drivers minor version number
     */

    public int getMinorVersion()
    {
	return _MINORVERSION;
    }

    /**
     * Report whether the driver is a genuine JDBC compliant driver.  A
     * driver may only report "true" here if it passes the JDBC compliance
     * tests, otherwise it is required to return false.  JDBC compliance
     * requires full support for the JDBC API and full support for SQL 92
     * Entry Level.
     *
     * <p>MySQL is not SQL92 compliant
     */

    public boolean jdbcCompliant()
    {
	return false;
    }

    /**
     * Constructs a new DriverURL, splitting the specified URL into its
     * component parts
     * @param url JDBC URL to parse
     * @param defaults Default properties
     * @return Properties with elements added from the url
     * @exception java.sql.SQLException
     */

    //
    // This is a new URL-parser. This file no longer contains any
    // Postgresql code.
    //

    Properties parseURL(String Url, Properties Defaults) throws java.sql.SQLException
    {
	Properties URLProps = new Properties(Defaults);
    
 
    
	/*
	 * Parse parameters after the ? in the URL and remove
	 * them from the original URL.
	 */
     
	int index = Url.indexOf("?");
    
	if (index != -1) {
	    String ParamString = Url.substring(index + 1, Url.length());
	    Url = Url.substring(0, index);
        
	    StringTokenizer QueryParams = new StringTokenizer(ParamString, "&");
        
	    while (QueryParams.hasMoreTokens()) {
        
		StringTokenizer VP = new StringTokenizer(QueryParams.nextToken(), "=");
            
		String Param = "";
            
		if (VP.hasMoreTokens()) {
		    Param = VP.nextToken();
		}
            
		String Value = "";
            
		if (VP.hasMoreTokens()) {
		    Value = VP.nextToken();
		}
                       
		if (Value.length() > 0 && Param.length() > 0) {
		    URLProps.put(Param, Value);
		}
	    }
	}
     
	StringTokenizer ST = new StringTokenizer(Url, ":/", true);
    
	if (ST.hasMoreTokens()) {
	    String Protocol = ST.nextToken();
	    if (Protocol != null) {
		if (!Protocol.toLowerCase().equals("jdbc"))
		    return null;
	    }
	    else {
		return null;
	    }
	}
	else {
	    return null;
	}

	// Look for the colon following 'jdbc'

	if (ST.hasMoreTokens()) {
	    String Colon = ST.nextToken();
	    if (Colon != null) {
		if (!Colon.equals(":"))
		    return null;
	    }
	    else {
		return null;
	    }
	}
	else {
	    return null;
	}

	// Look for sub-protocol to be mysql

	if (ST.hasMoreTokens()) {
	    String SubProto = ST.nextToken();
	    if (SubProto != null) {
		if (!SubProto.toLowerCase().equals("mysql"))
		    return null; // We only handle mysql sub-protocol
	    } 
	    else {
		return null;
	    }
	}
	else {
	    return null;
	}

	// Look for the colon following 'mysql'

	if (ST.hasMoreTokens()) {
	    String Colon = ST.nextToken();
	    if (Colon != null) {
		if (!Colon.equals(":"))
		    return null;
	    }
	    else {
		return null;
	    }
	}
	else {
	    return null;
	}

	// Look for the "//" of the URL

	if (ST.hasMoreTokens()) {
	    String Slash = ST.nextToken();
	    String Slash2 = "";
	    if (ST.hasMoreTokens()) {
		Slash2 = ST.nextToken();
	    }
	    if (Slash != null && Slash2 != null) {
		if (!Slash.equals("/") && !Slash2.equals("/"))
		    return null;
	    }
	    else {
		return null;
	    }
      
	}
	else {
	    return null;
	}

	// Okay the next one is a candidate for many things
	if (ST.hasMoreTokens()) {
	    String Token = ST.nextToken();
	    if (Token != null) {
		if (!Token.equals(":") && !Token.equals("/")) {
		    // Must be hostname
		    URLProps.put("HOST", Token);
		    if (ST.hasMoreTokens()) {
			Token = ST.nextToken();
		    }
		    else {
			return null;
		    }
		}
		// Check for Port spec
		if (Token.equals(":")) {
		    if (ST.hasMoreTokens()) {
			Token = ST.nextToken();
			URLProps.put("PORT", Token);
                        if (ST.hasMoreTokens()) {
			    Token = ST.nextToken();
			}
		    }
		}
		if (Token.equals("/")) {
		    if (ST.hasMoreTokens()) {
			Token = ST.nextToken();
			URLProps.put("DBNAME", Token);
          
			// We're done
			return URLProps;
		    }
		    else {
			return null;
		    }
		} 
	    }
	    else {
		return null;
	    }
	}
	else {
	    return null;
	}
    
	return URLProps;
    }
                  
    //
    // return the hostname property
    //

    public String host()
    {
	return _Props.getProperty("HOST","localhost");
    }

    //
    // return the port number property
    //

    public int port()
    {
	return Integer.parseInt(_Props.getProperty("PORT","3306"));
    }

    //
    // return the database name property
    //

    public String database()
    {
	return _Props.getProperty("DBNAME");
    }

    //
    // return the value of any property this driver knows about
    //
 
    public String property(String Name)
    {
	return _Props.getProperty(Name);
    }
}