| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.jdbc.EmbeddedDriver |
| 4 | |
| 5 | Copyright 1997, 2004 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.jdbc; |
| 22 | |
| 23 | import java.sql.DriverManager; |
| 24 | import java.sql.Driver; |
| 25 | import java.sql.Connection; |
| 26 | import java.sql.DriverPropertyInfo; |
| 27 | import java.sql.SQLException; |
| 28 | |
| 29 | import java.io.PrintStream; |
| 30 | import java.util.Properties; |
| 31 | |
| 32 | import org.apache.derby.iapi.reference.MessageId; |
| 33 | import org.apache.derby.iapi.reference.Attribute; |
| 34 | import org.apache.derby.iapi.services.i18n.MessageService; |
| 35 | import org.apache.derby.iapi.jdbc.JDBCBoot; |
| 36 | |
| 37 | |
| 38 | /** |
| 39 | The embedded JDBC driver (Type 4) for Derby. |
| 40 | <P> |
| 41 | The driver automatically supports the correct JDBC specification version |
| 42 | for the Java Virtual Machine's environment. |
| 43 | <UL> |
| 44 | <LI> JDBC 3.0 - Java 2 - JDK 1.4, J2SE 5.0 |
| 45 | <LI> JDBC 2.0 - Java 2 - JDK 1.2,1.3 |
| 46 | </UL> |
| 47 | |
| 48 | <P> |
| 49 | Loading this JDBC driver boots the database engine |
| 50 | within the same Java virtual machine. |
| 51 | <P> |
| 52 | The correct code to load the Derby engine using this driver is |
| 53 | (with approriate try/catch blocks): |
| 54 | <PRE> |
| 55 | Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance(); |
| 56 | |
| 57 | // or |
| 58 | |
| 59 | new org.apache.derby.jdbc.EmbeddedDriver(); |
| 60 | |
| 61 | |
| 62 | </PRE> |
| 63 | When loaded in this way, the class boots the actual JDBC driver indirectly. |
| 64 | The JDBC specification recommends the Class.ForName method without the .newInstance() |
| 65 | method call, but adding the newInstance() guarantees |
| 66 | that Derby will be booted on any Java Virtual Machine. |
| 67 | |
| 68 | <P> |
| 69 | Any initial error messages are placed in the PrintStream |
| 70 | supplied by the DriverManager. If the PrintStream is null error messages are |
| 71 | sent to System.err. Once the Derby engine has set up an error |
| 72 | logging facility (by default to derby.log) all subsequent messages are sent to it. |
| 73 | <P> |
| 74 | By convention, the class used in the Class.forName() method to |
| 75 | boot a JDBC driver implements java.sql.Driver. |
| 76 | |
| 77 | This class is not the actual JDBC driver that gets registered with |
| 78 | the Driver Manager. It proxies requests to the registered Derby JDBC driver. |
| 79 | |
| 80 | @see java.sql.DriverManager |
| 81 | @see java.sql.DriverManager#getLogStream |
| 82 | @see java.sql.Driver |
| 83 | @see java.sql.SQLException |
| 84 | */ |
| 85 | |
| 86 | public class EmbeddedDriver implements Driver { |
| 87 | |
| 88 | static { |
| 89 | |
| 90 | EmbeddedDriver.boot(); |
| 91 | } |
| 92 | |
| 93 | // Boot from the constructor as well to ensure that |
| 94 | // Class.forName(...).newInstance() reboots Derby |
| 95 | // after a shutdown inside the same JVM. |
| 96 | public EmbeddedDriver() { |
| 97 | EmbeddedDriver.boot(); |
| 98 | } |
| 99 | |
| 100 | /* |
| 101 | ** Methods from java.sql.Driver. |
| 102 | */ |
| 103 | /** |
| 104 | Accept anything that starts with <CODE>jdbc:derby:</CODE>. |
| 105 | @exception SQLException if a database-access error occurs. |
| 106 | @see java.sql.Driver |
| 107 | */ |
| 108 | public boolean acceptsURL(String url) throws SQLException { |
| 109 | return getRegisteredDriver().acceptsURL(url); |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | Connect to the URL if possible |
| 114 | @exception SQLException illegal url or problem with connectiong |
| 115 | @see java.sql.Driver |
| 116 | */ |
| 117 | public Connection connect(String url, Properties info) |
| 118 | throws SQLException |
| 119 | { |
| 120 | return getRegisteredDriver().connect(url, info); |
| 121 | } |
| 122 | |
| 123 | /** |
| 124 | * Returns an array of DriverPropertyInfo objects describing possible properties. |
| 125 | @exception SQLException if a database-access error occurs. |
| 126 | @see java.sql.Driver |
| 127 | */ |
| 128 | public DriverPropertyInfo[] getPropertyInfo(String url, Properties info) |
| 129 | throws SQLException |
| 130 | { |
| 131 | return getRegisteredDriver().getPropertyInfo(url, info); |
| 132 | } |
| 133 | |
| 134 | /** |
| 135 | * Returns the driver's major version number. |
| 136 | @see java.sql.Driver |
| 137 | */ |
| 138 | public int getMajorVersion() { |
| 139 | try { |
| 140 | return (getRegisteredDriver().getMajorVersion()); |
| 141 | } |
| 142 | catch (SQLException se) { |
| 143 | return 0; |
| 144 | } |
| 145 | } |
| 146 | /** |
| 147 | * Returns the driver's minor version number. |
| 148 | @see java.sql.Driver |
| 149 | */ |
| 150 | public int getMinorVersion() { |
| 151 | try { |
| 152 | return (getRegisteredDriver().getMinorVersion()); |
| 153 | } |
| 154 | catch (SQLException se) { |
| 155 | return 0; |
| 156 | } |
| 157 | } |
| 158 | |
| 159 | /** |
| 160 | * Report whether the Driver is a genuine JDBC COMPLIANT (tm) driver. |
| 161 | @see java.sql.Driver |
| 162 | */ |
| 163 | public boolean jdbcCompliant() { |
| 164 | try { |
| 165 | return (getRegisteredDriver().jdbcCompliant()); |
| 166 | } |
| 167 | catch (SQLException se) { |
| 168 | return false; |
| 169 | } |
| 170 | } |
| 171 | |
| 172 | private static void boot() { |
| 173 | PrintStream ps = DriverManager.getLogStream(); |
| 174 | |
| 175 | if (ps == null) |
| 176 | ps = System.err; |
| 177 | |
| 178 | new JDBCBoot().boot(Attribute.PROTOCOL, ps); |
| 179 | } |
| 180 | |
| 181 | /* |
| 182 | ** Retrieve the actual Registered Driver, |
| 183 | ** probe the DriverManager in order to get it. |
| 184 | */ |
| 185 | private Driver getRegisteredDriver() throws SQLException { |
| 186 | |
| 187 | try { |
| 188 | return DriverManager.getDriver(Attribute.PROTOCOL); |
| 189 | } |
| 190 | catch (SQLException se) { |
| 191 | // Driver not registered |
| 192 | throw new SQLException(MessageService.getTextMessage(MessageId.CORE_JDBC_DRIVER_UNREGISTERED)); |
| 193 | } |
| 194 | } |
| 195 | } |