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