ide/usersguide/javahelp/org/netbeans/modules/usersguide/f1_web_apps002.htm - netbeans - Git at Google

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 <head>
 <title>web.xml Visual Editor: Context Parameters</title>
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 <p><a id="dd_multiview_overview_contextParamsNode" name="dd_multiview_overview_contextParamsNode"></a></p>
 <div id="NBCSH3773"><!-- infolevel="all" infotype="General" --><a id="sthref512" name="sthref512"></a>
 <h1>web.xml Visual Editor: Context Parameters</h1>
 <a name="BEGIN" id="BEGIN"></a>
 <p>Use the Context Parameters section in the <code dir="ltr">web.xml</code>Visual Editor to add, remove, and view the web application's context parameters. Context parameters are initialization parameters that are available throughout a web application. You can use them, for example, to provide configuration information to all servlets and JSP pages in a web application.
 <object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
 <param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG1114">
 <param name="text" value="<html><u>How?</u></html>">
 <param name="textFontSize" value="medium">
 <param name="textColor" value="blue">
 </object>
 </p>
 <p>You can access context parameters in your code using the <code dir="ltr">javax.servlet.ServletContext.getInitParameter()</code> and <code dir="ltr">javax.servlet.ServletContext.getInitParameterNames()</code> methods, as shown in <a href="#CHDDHBHI">Example: Methods to access context parameters in code</a>.</p>
 <div id="NBCSH3774"><a id="CHDDHBHI" name="CHDDHBHI"></a>
 <p>Example: Methods to access context parameters in code</p>
 <pre xml:space="preserve" dir="ltr">
 ServletContext context = this.getServletContext();
 String mainPage = context.getInitParameter("mainPage");
 </pre>
 <!-- -->
 <p>If a company name changes frequently, you can define its value as a context parameter in the <code dir="ltr">web.xml</code> file instead of hard-coding it in all your JSP files and servlets. Then define and declare a listener that reads the value and stores it in the servlet context. Next, define and declare another listener that monitors changes to the name.</p>
 <p>To declare a context parameter, you must register it in the <code dir="ltr">web.xml</code> file. When you do this, you provide information needed by the server to use the parameter. You tell the server which value should be returned when a context parameter is referred to in the web application.</p>
 <p>In the Visual Editor, click <b>General</b> at the top of the editor to open the General section, then click the Context Parameters header to open the Context Parameters section.</p>
 <p>Click <b>Add</b> to define the context parameter element with the following properties:</p>

 <table summary="User interface elements and descriptions" dir="ltr" border="1" width="100%" frame="hsides" rules="groups" cellpadding="3" cellspacing="0">
 <col width="24%" />
 <col width="*" />
 <thead>
 <tr align="left" valign="top">
 <th align="left" valign="bottom" id="r1c1-t4">Element</th>
 <th align="left" valign="bottom" id="r1c2-t4">Description</th>
 </tr>
 </thead>
 <tbody>
 <tr align="left" valign="top">
 <td align="left" id="r2c1-t4" headers="r1c1-t4">
 <p>Param Name</p>
 </td>
 <td align="left" headers="r2c1-t4 r1c2-t4">Specifies the parameter's name, such as <code dir="ltr">MyCompanyName</code>.
 <object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
 <param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG1114">
 <param name="text" value="<html><u>How?</u></html>">
 <param name="textFontSize" value="medium">
 <param name="textColor" value="blue">
 </object>
 </td>
 </tr>
 <tr align="left" valign="top">
 <td align="left" id="r3c1-t4" headers="r1c1-t4">
 <p>Param Value</p>
 </td>
 <td align="left" headers="r3c1-t4 r1c2-t4">Specifies the parameter's value, such as <code dir="ltr">Sand For Africa Inc</code>.
 <object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
 <param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG114">
 <param name="text" value="<html><u>How?</u></html>">
 <param name="textFontSize" value="medium">
 <param name="textColor" value="blue">
 </object>
 </td>
 </tr>
 <tr align="left" valign="top">
 <td align="left" id="r4c1-t4" headers="r1c1-t4">
 <p>Description</p>
 </td>
 <td align="left" headers="r4c1-t4 r1c2-t4">Specifies a description, such as <code dir="ltr">Current name of my company</code>.
 <object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
 <param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG1114">
 <param name="text" value="<html><u>How?</u></html>">
 <param name="textFontSize" value="medium">
 <param name="textColor" value="blue">
 </object>
 </td>
 </tr>
 </tbody>
 </table>
 <br />
 <!-- -->
 <a id="NBCSH3778" name="NBCSH3778"></a>
 <hr><p><b>Related Topics</b></p>
 <p><i>Developing Applications with NetBeans IDE</i>,
 <object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
 <param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG2810">
 <param name="text" value="<html><u>&quot;Using Annotations and Deployment Descriptors&quot;</u></html>">
 <param name="textFontSize" value="medium">
 <param name="textColor" value="blue">
 </object>
 </p>
 <p><i>Developing Applications with NetBeans IDE</i>,
 <object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
 <param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG1111">
 <param name="text" value="<html><u>&quot;Configuring a Web Application&quot;</u></html>">
 <param name="textFontSize" value="medium">
 <param name="textColor" value="blue">
 </object>
 </p>

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 <td align="left" width="86%"><a href="legal_notice.htm">
 Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements; and to You under the Apache License, Version 2.0.</a>
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	Licensed to the Apache Software Foundation (ASF) under one
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	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,
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	<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" dir="ltr">
	<head>
	<title>web.xml Visual Editor: Context Parameters</title>
	<link rel="stylesheet" href="ide.css" title="Oracle BLAFDoc" type="text/css"/>
	</head>

	<body>
	<p><a id="dd_multiview_overview_contextParamsNode" name="dd_multiview_overview_contextParamsNode"></a></p>
	<div id="NBCSH3773"><!-- infolevel="all" infotype="General" --><a id="sthref512" name="sthref512"></a>
	<h1>web.xml Visual Editor: Context Parameters</h1>
	<a name="BEGIN" id="BEGIN"></a>
	<p>Use the Context Parameters section in the <code dir="ltr">web.xml</code>Visual Editor to add, remove, and view the web application's context parameters. Context parameters are initialization parameters that are available throughout a web application. You can use them, for example, to provide configuration information to all servlets and JSP pages in a web application.
	<object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
	<param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG1114">
	<param name="text" value="<html><u>How?</u></html>">
	<param name="textFontSize" value="medium">
	<param name="textColor" value="blue">
	</object>
	</p>
	<p>You can access context parameters in your code using the <code dir="ltr">javax.servlet.ServletContext.getInitParameter()</code> and <code dir="ltr">javax.servlet.ServletContext.getInitParameterNames()</code> methods, as shown in <a href="#CHDDHBHI">Example: Methods to access context parameters in code</a>.</p>
	<div id="NBCSH3774"><a id="CHDDHBHI" name="CHDDHBHI"></a>
	<p>Example: Methods to access context parameters in code</p>
	<pre xml:space="preserve" dir="ltr">
	ServletContext context = this.getServletContext();
	String mainPage = context.getInitParameter("mainPage");
	</pre>
	<!-- -->
	<p>If a company name changes frequently, you can define its value as a context parameter in the <code dir="ltr">web.xml</code> file instead of hard-coding it in all your JSP files and servlets. Then define and declare a listener that reads the value and stores it in the servlet context. Next, define and declare another listener that monitors changes to the name.</p>
	<p>To declare a context parameter, you must register it in the <code dir="ltr">web.xml</code> file. When you do this, you provide information needed by the server to use the parameter. You tell the server which value should be returned when a context parameter is referred to in the web application.</p>
	<p>In the Visual Editor, click <b>General</b> at the top of the editor to open the General section, then click the Context Parameters header to open the Context Parameters section.</p>
	<p>Click <b>Add</b> to define the context parameter element with the following properties:</p>

	<table summary="User interface elements and descriptions" dir="ltr" border="1" width="100%" frame="hsides" rules="groups" cellpadding="3" cellspacing="0">
	<col width="24%" />
	<col width="*" />
	<thead>
	<tr align="left" valign="top">
	<th align="left" valign="bottom" id="r1c1-t4">Element</th>
	<th align="left" valign="bottom" id="r1c2-t4">Description</th>
	</tr>
	</thead>
	<tbody>
	<tr align="left" valign="top">
	<td align="left" id="r2c1-t4" headers="r1c1-t4">
	<p>Param Name</p>
	</td>
	<td align="left" headers="r2c1-t4 r1c2-t4">Specifies the parameter's name, such as <code dir="ltr">MyCompanyName</code>.
	<object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
	<param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG1114">
	<param name="text" value="<html><u>How?</u></html>">
	<param name="textFontSize" value="medium">
	<param name="textColor" value="blue">
	</object>
	</td>
	</tr>
	<tr align="left" valign="top">
	<td align="left" id="r3c1-t4" headers="r1c1-t4">
	<p>Param Value</p>
	</td>
	<td align="left" headers="r3c1-t4 r1c2-t4">Specifies the parameter's value, such as <code dir="ltr">Sand For Africa Inc</code>.
	<object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
	<param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG114">
	<param name="text" value="<html><u>How?</u></html>">
	<param name="textFontSize" value="medium">
	<param name="textColor" value="blue">
	</object>
	</td>
	</tr>
	<tr align="left" valign="top">
	<td align="left" id="r4c1-t4" headers="r1c1-t4">
	<p>Description</p>
	</td>
	<td align="left" headers="r4c1-t4 r1c2-t4">Specifies a description, such as <code dir="ltr">Current name of my company</code>.
	<object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
	<param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG1114">
	<param name="text" value="<html><u>How?</u></html>">
	<param name="textFontSize" value="medium">
	<param name="textColor" value="blue">
	</object>
	</td>
	</tr>
	</tbody>
	</table>
	<br />
	<!-- -->
	<a id="NBCSH3778" name="NBCSH3778"></a>
	<hr><p><b>Related Topics</b></p>
	<p><i>Developing Applications with NetBeans IDE</i>,
	<object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
	<param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG2810">
	<param name="text" value="<html><u>"Using Annotations and Deployment Descriptors"</u></html>">
	<param name="textFontSize" value="medium">
	<param name="textColor" value="blue">
	</object>
	</p>
	<p><i>Developing Applications with NetBeans IDE</i>,
	<object classid="java:org.netbeans.modules.javahelp.BrowserDisplayer">
	<param name="content" value="http://www.oracle.com/pls/topic/lookup?ctx=nb8200&id=NBDAG1111">
	<param name="text" value="<html><u>"Configuring a Web Application"</u></html>">
	<param name="textFontSize" value="medium">
	<param name="textColor" value="blue">
	</object>
	</p>

	<!-- -->
	<!-- Start Footer -->


	<table summary="" cellspacing="0" cellpadding="0" width="100%">
	<tr>
	<td align="left" width="86%"><a href="legal_notice.htm">
	Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements; and to You under the Apache License, Version 2.0.</a>
	</td>
	</tr>
	</table>
	<!-- -->
	</body>
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