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Tomcat example source code file (

This example Tomcat source code file ( is included in the "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

filter, filter, filterchain, filterchain, io, ioexception, servletexception, servletexception, servletrequest, servletrequest, servletresponse

The Tomcat source code

* 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
* Unless required by applicable law or agreed to in writing, software
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package javax.servlet;


	* A filter is an object that performs filtering tasks on either the request to a resource (a servlet or static content), or on the response from a resource, or both.
        * <br>
* Filters perform filtering in the <code>doFilter method. Every Filter has access to ** a FilterConfig object from which it can obtain its initialization parameters, a ** reference to the ServletContext which it can use, for example, to load resources ** needed for filtering tasks. ** <p> ** Filters are configured in the deployment descriptor of a web application ** <p> ** Examples that have been identified for this design are<br> ** 1) Authentication Filters <br> ** 2) Logging and Auditing Filters <br> ** 3) Image conversion Filters <br> ** 4) Data compression Filters <br> ** 5) Encryption Filters <br> ** 6) Tokenizing Filters <br> ** 7) Filters that trigger resource access events <br> ** 8) XSL/T filters <br> ** 9) Mime-type chain Filter <br> * @since Servlet 2.3 */ public interface Filter { /** * Called by the web container to indicate to a filter that it is being placed into * service. The servlet container calls the init method exactly once after instantiating the * filter. The init method must complete successfully before the filter is asked to do any * filtering work. <br>
* The web container cannot place the filter into service if the init method either<br> * 1.Throws a ServletException <br> * 2.Does not return within a time period defined by the web container */ public void init(FilterConfig filterConfig) throws ServletException; /** * The <code>doFilter method of the Filter is called by the container * each time a request/response pair is passed through the chain due * to a client request for a resource at the end of the chain. The FilterChain passed in to this * method allows the Filter to pass on the request and response to the next entity in the * chain.<p> * A typical implementation of this method would follow the following pattern:- <br> * 1. Examine the request<br> * 2. Optionally wrap the request object with a custom implementation to * filter content or headers for input filtering <br> * 3. Optionally wrap the response object with a custom implementation to * filter content or headers for output filtering <br> * 4. a) <strong>Either invoke the next entity in the chain using the FilterChain object (chain.doFilter()),
** 4. b) <strong>or not pass on the request/response pair to the next entity in the filter chain to block the request processing
** 5. Directly set headers on the response after invocation of the next entity in the filter chain. **/ public void doFilter ( ServletRequest request, ServletResponse response, FilterChain chain ) throws IOException, ServletException; /** * Called by the web container to indicate to a filter that it is being taken out of service. This * method is only called once all threads within the filter's doFilter method have exited or after * a timeout period has passed. After the web container calls this method, it will not call the * doFilter method again on this instance of the filter. <br>
* * This method gives the filter an opportunity to clean up any resources that are being held (for * example, memory, file handles, threads) and make sure that any persistent state is synchronized * with the filter's current state in memory. */ public void destroy(); }

Other Tomcat examples (source code examples)

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