| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| |
| package org.apache.catalina.loader; |
| |
| import java.sql.Driver; |
| import java.sql.DriverManager; |
| import java.sql.SQLException; |
| import java.util.ArrayList; |
| import java.util.Enumeration; |
| import java.util.HashSet; |
| import java.util.List; |
| |
| /** |
| * This class is loaded by the {@link WebappClassLoader} to enable it to |
| * deregister JDBC drivers forgotten by the web application. There are some |
| * classloading hacks involved - see {@link WebappClassLoader#clearReferences()} |
| * for details - but the short version is do not just create a new instance of |
| * this class with the new keyword. |
| * |
| * Since this class is loaded by {@link WebappClassLoader}, it can not refer to |
| * any internal Tomcat classes as that will cause the security manager to |
| * complain. |
| */ |
| public class JdbcLeakPrevention { |
| |
| public List<String> clearJdbcDriverRegistrations() throws SQLException { |
| List<String> driverNames = new ArrayList<>(); |
| |
| /* |
| * DriverManager.getDrivers() has a nasty side-effect of registering |
| * drivers that are visible to this class loader but haven't yet been |
| * loaded. Therefore, the first call to this method a) gets the list |
| * of originally loaded drivers and b) triggers the unwanted |
| * side-effect. The second call gets the complete list of drivers |
| * ensuring that both original drivers and any loaded as a result of the |
| * side-effects are all de-registered. |
| */ |
| HashSet<Driver> originalDrivers = new HashSet<>(); |
| Enumeration<Driver> drivers = DriverManager.getDrivers(); |
| while (drivers.hasMoreElements()) { |
| originalDrivers.add(drivers.nextElement()); |
| } |
| drivers = DriverManager.getDrivers(); |
| while (drivers.hasMoreElements()) { |
| Driver driver = drivers.nextElement(); |
| // Only unload the drivers this web app loaded |
| if (driver.getClass().getClassLoader() != |
| this.getClass().getClassLoader()) { |
| continue; |
| } |
| // Only report drivers that were originally registered. Skip any |
| // that were registered as a side-effect of this code. |
| if (originalDrivers.contains(driver)) { |
| driverNames.add(driver.getClass().getCanonicalName()); |
| } |
| DriverManager.deregisterDriver(driver); |
| } |
| return driverNames; |
| } |
| } |