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/*
 * 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
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package org.apache.tomcat.jdbc.pool;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.util.Map;

import org.apache.tomcat.jdbc.pool.PoolProperties.InterceptorProperty;

/**
 * Abstract class that is to be extended for implementations of interceptors.
 * Everytime an operation is called on the {@link java.sql.Connection} object the
 * {@link #invoke(Object, Method, Object[])} method on the interceptor will be called.
 * Interceptors are useful to change or improve behavior of the connection pool.
* Interceptors can receive a set of properties. Each sub class is responsible for parsing the properties during runtime when they * are needed or simply override the {@link #setProperties(Map)} method. * Properties arrive in a key-value pair of Strings as they were received through the configuration. * This method is called once per cached connection object when the object is first configured. * * @version 1.0 */ public abstract class JdbcInterceptor implements InvocationHandler { /** * {@link java.sql.Connection#close()} method name */ public static final String CLOSE_VAL = "close"; /** * {@link Object#toString()} method name */ public static final String TOSTRING_VAL = "toString"; /** * {@link java.sql.Connection#isClosed()} method name */ public static final String ISCLOSED_VAL = "isClosed"; /** * {@link javax.sql.PooledConnection#getConnection()} method name */ public static final String GETCONNECTION_VAL = "getConnection"; /** * {@link java.sql.Wrapper#unwrap(Class)} method name */ public static final String UNWRAP_VAL = "unwrap"; /** * {@link java.sql.Wrapper#isWrapperFor(Class)} method name */ public static final String ISWRAPPERFOR_VAL = "isWrapperFor"; /** * {@link java.sql.Connection#isValid(int)} method name */ public static final String ISVALID_VAL = "isValid"; /** * {@link java.lang.Object#equals(Object)} */ public static final String EQUALS_VAL = "equals"; /** * {@link java.lang.Object#hashCode()} */ public static final String HASHCODE_VAL = "hashCode"; /** * Properties for this interceptor. */ protected Map properties = null; /** * The next interceptor in the chain */ private volatile JdbcInterceptor next = null; /** * Property that decides how we do string comparison, default is to use * {@link String#equals(Object)}. If set to false then the * equality operator (==) is used. */ private boolean useEquals = true; /** * Public constructor for instantiation through reflection */ public JdbcInterceptor() { // NOOP } /** * Gets invoked each time an operation on {@link java.sql.Connection} is invoked. * {@inheritDoc} */ @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { if (getNext()!=null) return getNext().invoke(proxy,method,args); else throw new NullPointerException(); } /** * Returns the next interceptor in the chain * @return the next interceptor in the chain */ public JdbcInterceptor getNext() { return next; } /** * configures the next interceptor in the chain * @param next The next chain item */ public void setNext(JdbcInterceptor next) { this.next = next; } /** * Performs a string comparison, using references unless the useEquals property is set to true. * @param name1 The first name * @param name2 The second name * @return true if name1 is equal to name2 based on {@link #useEquals} */ public boolean compare(String name1, String name2) { if (isUseEquals()) { return name1.equals(name2); } else { return name1==name2; } } /** * Compares a method name (String) to a method (Method) * {@link #compare(String,String)} * Uses reference comparison unless the useEquals property is set to true * @param methodName The method name * @param method The method * @return true if the name matches */ public boolean compare(String methodName, Method method) { return compare(methodName, method.getName()); } /** * Gets called each time the connection is borrowed from the pool * This means that if an interceptor holds a reference to the connection * the interceptor can be reused for another connection. *
* This method may be called with null as both arguments when we are closing down the connection. * @param parent - the connection pool owning the connection * @param con - the pooled connection */ public abstract void reset(ConnectionPool parent, PooledConnection con); /** * Called when {@link java.sql.Connection#close()} is called on the underlying connection. * This is to notify the interceptors, that the physical connection has been released. * Implementation of this method should be thought through with care, as no actions should trigger an exception. * @param parent - the connection pool that this connection belongs to * @param con - the pooled connection that holds this connection * @param finalizing - if this connection is finalizing. True means that the pooled connection will not reconnect the underlying connection */ public void disconnected(ConnectionPool parent, PooledConnection con, boolean finalizing) { } /** * Returns the properties configured for this interceptor * @return the configured properties for this interceptor */ public Map getProperties() { return properties; } /** * Called during the creation of an interceptor * The properties can be set during the configuration of an interceptor * Override this method to perform type casts between string values and object properties * @param properties The properties */ public void setProperties(Map properties) { this.properties = properties; final String useEquals = "useEquals"; InterceptorProperty p = properties.get(useEquals); if (p!=null) { setUseEquals(Boolean.parseBoolean(p.getValue())); } } /** * @return true if the compare method uses the Object.equals(Object) method * false if comparison is done on a reference level */ public boolean isUseEquals() { return useEquals; } /** * Set to true if string comparisons (for the {@link #compare(String, Method)} and {@link #compare(String, String)} methods) should use the Object.equals(Object) method * The default is false * @param useEquals true if equals will be used for comparisons */ public void setUseEquals(boolean useEquals) { this.useEquals = useEquals; } /** * This method is invoked by a connection pool when the pool is closed. * Interceptor classes can override this method if they keep static * variables or other tracking means around. * This method is only invoked on a single instance of the interceptor, and not on every instance created. * @param pool - the pool that is being closed. */ public void poolClosed(ConnectionPool pool) { // NOOP } /** * This method is invoked by a connection pool when the pool is first started up, usually when the first connection is requested. * Interceptor classes can override this method if they keep static * variables or other tracking means around. * This method is only invoked on a single instance of the interceptor, and not on every instance created. * @param pool - the pool that is being closed. */ public void poolStarted(ConnectionPool pool) { // NOOP } }




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