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 <title>Creating Filters</title>
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 <body id="twfltwiz">
 <a name="twfltwiz"><!-- --></a>


 <h1 class="topictitle1">Creating Filters</h1>

 <div>

 	<p>The filter wizard helps you create Java servlet filters by walking
 you through the creation process and by providing you with output files
 that you can use or that you can modify for use with your Web
 application. The filters can run on Java EE-compliant Web servers.</p>

 	<div class="section">
 	<p>To create a filter, complete the following steps:</p>
 	</div>

 	<ol>
 		<li class="stepexpand"><span>In the Java EE perspective,
 		expand your <a href="ccwebprj.html" title="">dynamic project</a> in the
 		Project Explorer view.</span></li>

 		<li class="stepexpand"><span>Right click on the <strong>Filter</strong>
 		icon, and select <span class="menucascade"> <span
 			class="uicontrol">New</span> &gt; <span class="uicontrol">Filter</span></span>
 		from the pop-up menu.</span> The <span class="uicontrol">Create Filter</span>
 		wizard appears.</li>

 		<li class="stepexpand"><span>Follow the project wizard
 		prompts.</span></li>

 	</ol>

 <div class="section">
 <p><strong>General Information</strong></p>
 <dl>

 	<p><dt class="dlterm">Modifiers</dt></p>

 	<dd>The <cite>Sun Microsystems Java Servlet Specification</cite> states that a
 	Servlet class must be <b>public</b> and not <b>abstract</b>. Therefore,
 	you cannot change these modifiers. The only one available for change is
 	the <b>final</b> modifier. </dd>


 	<p><dt class="dlterm">Interfaces</dt></p>

 	<dd>There is one obligatory interface that filter classes must
 	implement: <strong>javax.servlet.Filter</strong>. This interface is
 	provided by javax.servlet package and is used to represent the
 	life-cycle of the filter. This interface has three methods: init,
 	doFilter and destroy.
 	<ul>
 		<li>The <strong>init</strong> method is called by the servlet
 		container only once, when it finishes instantiating the filter.</li>
 		<li>The <strong>doFilter</strong> method is where the filtering
 		is performed and is called every time a user requests a resource, such
 		as a servlet, to which the filter is mapped.</li>
 		<li>The <strong>destroy</strong> method is called by the servlet
 		container to tell the filter that it will be taken out of service.</li>
 	</ul>
 	You can add additional interfaces to implement by using the <strong>Add</strong>
 	button.</dd>


 	<p>
 	<dt class="dlterm">Interfaces dialog</dt>
 	</p>

 	<dd>This dialog appears if you select to add an interface to your
 	filter. As you type the name of the interface that you are adding, a
 	list of available interfaces listed in the <b>Matching items</b> list box
 	updates dynamically to display only the interfaces that match the
 	pattern. Choose an interface to see the qualifier, and then
 	click <b>OK</b> when finished.</dd>


 	<p><dt class="dlterm">Filter Mappings</dt></p>

 	<dd>For a filter to intercept a request to a servlet, you must:
 	<ol>
 		<li>declare the filter with a <b>&lt;filter&gt;</b> element in
 		the deployment descriptor</li>
 		<li>map the filter to the servlet using the <b>&lt;filter-mapping&gt;</b>
 		element.</li>
 	</ol>
 	Sometimes you want a filter to work on multiple servlets. You can do
 	this by mapping a filter to a URL pattern so that any request that
 	matches that URL pattern will be filtered. All this is made
 	automatically if you use the <b>Filter Mappings</b> field.</dd>

 	<p><dt class="dlterm">Method stubs</dt></p>
 	<dd>Because each filter must implement the javax.servlet.Filter
 	interface, the <b>Inherited abstract methods</b> option is always
 	checked and cannot be changed.</dd>

 </dl>
 </div>

 </div>
 </body>
 </html>
	<?xml version="1.0" encoding="UTF-8"?>
	<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
	<html lang="en-us" xml:lang="en-us">
	<head>
	<meta content="text/html; charset=utf-8" http-equiv="Content-Type" />
	<meta name="copyright"
	content="Copyright (c) 2000, 2006 IBM Corporation and others. All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse Public License v1.0 which accompanies this distribution, and is available at http://www.eclipse.org/legal/epl-v10.html. Contributors: IBM Corporation - initial API and implementation" />
	<meta name="DC.rights.owner" content="(C) Copyright 2000, 2006" />
	<meta content="public" name="security" />
	<meta content="index,follow" name="Robots" />
	<meta http-equiv="PICS-Label"
	content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
	<meta content="task" name="DC.Type" />
	<meta name="DC.Title" content="Creating Filters" />
	<meta content="filters, creating" name="DC.subject" />
	<meta content="filters, creating" name="keywords" />
	<meta content="XHTML" name="DC.Format" />
	<meta content="twfltwiz" name="DC.Identifier" />
	<meta content="en-us" name="DC.Language" />
	<link href="../../org.eclipse.wst.doc.user/common.css" type="text/css"
	rel="stylesheet" />
	<title>Creating Filters</title>
	</head>
	<body id="twfltwiz">
	<a name="twfltwiz"><!-- --></a>


	<h1 class="topictitle1">Creating Filters</h1>

	<div>

	<p>The filter wizard helps you create Java servlet filters by walking
	you through the creation process and by providing you with output files
	that you can use or that you can modify for use with your Web
	application. The filters can run on Java EE-compliant Web servers.</p>

	<div class="section">
	<p>To create a filter, complete the following steps:</p>
	</div>

	<ol>
	<li class="stepexpand"><span>In the Java EE perspective,
	expand your <a href="ccwebprj.html" title="">dynamic project</a> in the
	Project Explorer view.</span></li>

	<li class="stepexpand"><span>Right click on the <strong>Filter</strong>
	icon, and select <span class="menucascade"> <span
	class="uicontrol">New</span> > <span class="uicontrol">Filter</span></span>
	from the pop-up menu.</span> The <span class="uicontrol">Create Filter</span>
	wizard appears.</li>

	<li class="stepexpand"><span>Follow the project wizard
	prompts.</span></li>

	</ol>

	<div class="section">
	<p><strong>General Information</strong></p>
	<dl>

	<p><dt class="dlterm">Modifiers</dt></p>

	<dd>The <cite>Sun Microsystems Java Servlet Specification</cite> states that a
	Servlet class must be <b>public</b> and not <b>abstract</b>. Therefore,
	you cannot change these modifiers. The only one available for change is
	the <b>final</b> modifier. </dd>


	<p><dt class="dlterm">Interfaces</dt></p>

	<dd>There is one obligatory interface that filter classes must
	implement: <strong>javax.servlet.Filter</strong>. This interface is
	provided by javax.servlet package and is used to represent the
	life-cycle of the filter. This interface has three methods: init,
	doFilter and destroy.
	<ul>
	<li>The <strong>init</strong> method is called by the servlet
	container only once, when it finishes instantiating the filter.</li>
	<li>The <strong>doFilter</strong> method is where the filtering
	is performed and is called every time a user requests a resource, such
	as a servlet, to which the filter is mapped.</li>
	<li>The <strong>destroy</strong> method is called by the servlet
	container to tell the filter that it will be taken out of service.</li>
	</ul>
	You can add additional interfaces to implement by using the <strong>Add</strong>
	button.</dd>


	<p>
	<dt class="dlterm">Interfaces dialog</dt>
	</p>

	<dd>This dialog appears if you select to add an interface to your
	filter. As you type the name of the interface that you are adding, a
	list of available interfaces listed in the <b>Matching items</b> list box
	updates dynamically to display only the interfaces that match the
	pattern. Choose an interface to see the qualifier, and then
	click <b>OK</b> when finished.</dd>


	<p><dt class="dlterm">Filter Mappings</dt></p>

	<dd>For a filter to intercept a request to a servlet, you must:
	<ol>
	<li>declare the filter with a <b><filter></b> element in
	the deployment descriptor</li>
	<li>map the filter to the servlet using the <b><filter-mapping></b>
	element.</li>
	</ol>
	Sometimes you want a filter to work on multiple servlets. You can do
	this by mapping a filter to a URL pattern so that any request that
	matches that URL pattern will be filtered. All this is made
	automatically if you use the <b>Filter Mappings</b> field.</dd>

	<p><dt class="dlterm">Method stubs</dt></p>
	<dd>Because each filter must implement the javax.servlet.Filter
	interface, the <b>Inherited abstract methods</b> option is always
	checked and cannot be changed.</dd>

	</dl>
	</div>

	</div>
	</body>
	</html>