Created with colorer-take5 library. Type 'xml' <filter> <filter-name>Path Mapped Filter</filter-name> <filter-class>filters.ExampleFilter</filter-class> <init-param> <param-name>attribute</param-name> <param-value>filters.ExampleFilter.PATH_MAPPED</param-value> </init-param> </filter>
Created with colorer-take5 library. Type 'xml' <!-- Define filter mappings for the defined filters -->
<filter-mapping> <filter-name>Path Mapped Filter</filter-name> <url-pattern>/servlet/*</url-pattern> </filter-mapping>
Created with colorer-take5 library. Type 'xml' <init-param> <param-name>attribute</param-name> <param-value>filters.ExampleFilter.SERVLET_MAPPED</param-value> </init-param>
Created with colorer-take5 library. Type 'java' /* * Copyright 2004 The Apache Software Foundation * * Licensed 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 filters; import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; /** * Example filter that can be attached to either an individual servlet * or to a URL pattern. This filter performs the following functions: * <ul> * <li>Attaches itself as a request attribute, under the attribute name * defined by the value of the <code>attribute</code> initialization * parameter.</li> * <li>Calculates the number of milliseconds required to perform the * servlet processing required by this request, including any * subsequently defined filters, and logs the result to the servlet * context log for this application. * </ul> * * @author Craig McClanahan * @version $Revision: 267129 $ $Date: 2004-03-18 11:40:35 -0500 (Thu, 18 Mar 2004) $ */ public final class ExampleFilter implements Filter { // ----------------------------------------------------- Instance Variables /** * The request attribute name under which we store a reference to ourself. */ private String attribute = null; /** * The filter configuration object we are associated with. If this value * is null, this filter instance is not currently configured. */ private FilterConfig filterConfig = null; // --------------------------------------------------------- Public Methods /** * Take this filter out of service. */ public void destroy() { this.attribute = null; this.filterConfig = null; } /** * Time the processing that is performed by all subsequent filters in the * current filter stack, including the ultimately invoked servlet. * * @param request The servlet request we are processing * @param result The servlet response we are creating * @param chain The filter chain we are processing * * @exception IOException if an input/output error occurs * @exception ServletException if a servlet error occurs */ public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { // Store ourselves as a request attribute (if requested) if (attribute != null) request.setAttribute(attribute, this); // Time and log the subsequent processing long startTime = System.currentTimeMillis(); chain.doFilter(request, response); long stopTime = System.currentTimeMillis(); filterConfig.getServletContext().log (this.toString() + ": " + (stopTime - startTime) + " milliseconds"); } /** * Place this filter into service. * * @param filterConfig The filter configuration object */ public void init(FilterConfig filterConfig) throws ServletException { this.filterConfig = filterConfig; this.attribute = filterConfig.getInitParameter("attribute"); } /** * Return a String representation of this object. */ public String toString() { if (filterConfig == null) return ("InvokerFilter()"); StringBuffer sb = new StringBuffer("InvokerFilter("); sb.append(filterConfig); sb.append(")"); return (sb.toString()); } }
Created with colorer-take5 library. Type 'java' /* * Copyright 2004 The Apache Software Foundation * * Licensed 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 javax.servlet; import java.io.IOException; /** * 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><br> * Filters perform filtering in the <code>doFilter</code> 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><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</code> 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</strong> invoke the next entity in the chain using the FilterChain object (<code>chain.doFilter()</code>), <br> ** 4. b) <strong>or</strong> not pass on the request/response pair to the next entity in the filter chain to block the request processing<br> ** 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><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(); }
Created with colorer-take5 library. Type 'java' public void init(FilterConfig filterConfig) throws ServletException { this.filterConfig = filterConfig; this.attribute = filterConfig.getInitParameter("attribute"); }
Created with colorer-take5 library. Type 'java' public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { // Store ourselves as a request attribute (if requested) if (attribute != null) request.setAttribute(attribute, this); // Time and log the subsequent processing long startTime = System.currentTimeMillis(); chain.doFilter(request, response); long stopTime = System.currentTimeMillis(); filterConfig.getServletContext().log (this.toString() + ": " + (stopTime - startTime) + " milliseconds"); }
Created with colorer-take5 library. Type 'java' public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { PrintWriter out = response.getWriter(); CharResponseWrapper wrapper = new CharResponseWrapper( (HttpServletResponse)response); chain.doFilter(request, wrapper); String strAvant = wrapper.toString(); String strApres = avant.replace("bonjour", "good morning"); out.write(strApres); out.close(); }
Created with colorer-take5 library. Type 'java' import java.io.CharArrayWriter; import java.io.PrintWriter; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpServletResponseWrapper; public class CharResponseWrapper extends HttpServletResponseWrapper { private CharArrayWriter output; public String toString() { return output.toString(); } public CharResponseWrapper(HttpServletResponse response){ super(response); output = new CharArrayWriter(); } public PrintWriter getWriter(){ return new PrintWriter(output); } }