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| Version: 9.4.28-SNAPSHOT</span></td><td style="width: 50%"></td></tr></table><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Working with Annotations</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="annotations.html"><i class="fa fa-chevron-left" aria-hidden="true"></i> Previous</a> </td><th width="60%" align="center">Chapter 13. Annotations<br><a accesskey="p" href="index.html"><i class="fa fa-home" aria-hidden="true"></i> Home</a></th><td width="20%" align="right"> <a accesskey="n" href="using-annotations-embedded.html">Next <i class="fa fa-chevron-right" aria-hidden="true"></i></a></td></tr></table><hr></div><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="jetty-callout"><h5 class="callout"><a href="http://www.webtide.com/">Contact the core Jetty developers at |
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| </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="using-annotations"></a>Working with Annotations</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="using-annotations.html#_which_annotations_are_supported">Which Annotations Are Supported</a></span></dt><dt><span class="section"><a href="using-annotations.html#discoverable_introspectable_annotations">Discovered vs Introspected Annotations</a></span></dt><dt><span class="section"><a href="using-annotations.html#jars-scanned-for-annotations">Which Jar Files Are Scanned For Discovered Annotations</a></span></dt><dt><span class="section"><a href="using-annotations.html#_multi_threaded_annotation_scanning">Multi-threaded Annotation Scanning</a></span></dt><dt><span class="section"><a href="using-annotations.html#servlet-container-initializers">ServletContainerInitializers</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_which_annotations_are_supported"></a>Which Annotations Are Supported</h3></div></div></div><p>Jetty supports interpretation and application of the following annotations:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">@Resource</li><li class="listitem">@Resources</li><li class="listitem">@PostConstruct</li><li class="listitem">@PreDestroy</li><li class="listitem">@DeclaredRoles</li><li class="listitem">@RunAs</li><li class="listitem">@MultipartConfig</li><li class="listitem">@WebServlet</li><li class="listitem">@WebFilter</li><li class="listitem">@WebListener</li><li class="listitem">@WebInitParam</li><li class="listitem">@ServletSecurity, @HttpConstraint, @HttpMethodConstraint</li><li class="listitem">@HandlesTypes (on ServletContainerInitializers)</li></ul></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="discoverable_introspectable_annotations"></a>Discovered vs Introspected Annotations</h3></div></div></div><p>Some types of annotation can be placed on any class, not necessarily just those with which the container interacts directly. |
| These type of annotations are referred to as "discovered" to indicate that the container must take proactive action to go out and find them. |
| The other type of annotation is call "introspected", meaning that they occur on classes with which the container interacts during their lifecycle (e.g. <code class="literal">javax.servlet.Servlet</code>, <code class="literal">javax.servlet.Filter</code>, …​etc.), and hence can be found by simple inspection of the class at that point.</p><p>Some examples of discovered annotations are:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">@WebServlet</li><li class="listitem">@WebFilter</li><li class="listitem">@WebListener</li></ul></div><p>Some examples of introspected annotations are:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">@PostConstruct</li><li class="listitem">@PreDestroy</li><li class="listitem">@Resource</li></ul></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="jars-scanned-for-annotations"></a>Which Jar Files Are Scanned For Discovered Annotations</h3></div></div></div><p>The web.xml file can contain the attribute <code class="literal">metadata-complete</code>. |
| If this is set to <code class="literal">true</code>, then <span class="emphasis"><em>no</em></span> scanning of discoverable annotations takes place. |
| However, scanning of classes may <span class="emphasis"><em>still</em></span> occur because of <a class="link" href="http://docs.oracle.com/javaee/6/api/javax/servlet/ServletContainerInitializer.html" target="_top">javax.servlet.ServletContainerInitializer</a>s. |
| Classes implementing this interface are found by Jetty using the <a class="link" href="http://docs.oracle.com/javase/6/docs/api/java/util/ServiceLoader.html" target="_top">javax.util.ServiceLoader</a> mechanism, and if one is present <span class="emphasis"><em>and</em></span> it includes the @HandlesTypes annotation, then Jetty must scan the class hierarchy of the web application. |
| This may be very time-consuming if you have many jars in the container’s path or in the webapp’s WEB-INF/lib.</p><p>If scanning is to take place - because either <code class="literal">metadata-complete</code> is <code class="literal">false</code> or missing, or because there are one or more <a class="link" href="http://docs.oracle.com/javaee/6/api/javax/servlet/ServletContainerInitializer.html" target="_top">javax.servlet.ServletContainerIntializer</a>s with @HandlesTypes - then Jetty must consider both the container’s classpath and the webapp’s classpath.</p><p>By default, Jetty will <span class="emphasis"><em>not</em></span> scan any classes that are on the container’s classpath. |
| If you need to cause jars and classes that are on the container’s classpath to be scanned, then you can use the <a class="link" href="configuring-webapps.html#container-include-jar-pattern" title="org.eclipse.jetty.server.webapp.ContainerIncludeJarPattern"><code class="literal">org.eclipse.jetty.server.webapp.ContainerIncludeJarPattern</code></a> context attribute to specify a pattern for jars and directories from the container’s classpath to scan.</p><p>By default Jetty will scan <span class="emphasis"><em>all</em></span>classes from <code class="literal">WEB-INF/classes</code> and all jars from <code class="literal">WEB-INF/lib</code> according to the order, if any, established by absolute or relative ordering clauses in web.xml. |
| If your webapp contains many jar files, you can significantly speed up deployment by omitting them from scanning. |
| To do this, use the <a class="link" href="configuring-webapps.html#web-inf-include-jar-pattern" title="org.eclipse.jetty.server.webapp.WebInfIncludeJarPattern">org.eclipse.jetty.server.webapp.WebInfIncludeJarPattern</a> context attribute to define the patterns of jars that you specifically want to be scanned.</p><p>Note that if you have configured an <a class="link" href="jetty-classloading.html#using-extra-classpath-method" title="Using the extraClasspath() method">extraClasspath</a> for the webapp, then it participates in the scanning process too. |
| Any classes dirs are treated the same for scanning purposes as if they were in WEB-INF/classes and jars are treated as if they were in WEB-INF/lib.</p><p>See also the next section on <a class="link" href="using-annotations.html#servlet-container-initializers" title="ServletContainerInitializers">ServletContainerInitializers</a> if you need to <a class="link" href="using-annotations.html#servlet-container-initializers" title="ServletContainerInitializers">control the order in which they are applied</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_multi_threaded_annotation_scanning"></a>Multi-threaded Annotation Scanning</h3></div></div></div><p><a class="link" href="using-annotations.html#jars-scanned-for-annotations" title="Which Jar Files Are Scanned For Discovered Annotations">If annotation scanning is to be performed</a>, by default Jetty will do it in a multi-threaded manner in order to complete it in the minimum amount of time.</p><p>If for some reason you don’t want multi-threaded scanning, you can configure Jetty to revert to single-threaded scanning. |
| There are several ways to configure this:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">Set the context attribute <code class="literal">org.eclipse.jetty.annotations.multiThreaded</code> to <code class="literal">false</code></li><li class="listitem">Set the Server attribute <code class="literal">org.eclipse.jetty.annotations.multiThreaded</code> to <code class="literal">false</code></li><li class="listitem">Set the System property <code class="literal">org.eclipse.jetty.annotations.multiThreaded</code> to <code class="literal">false</code></li></ol></div><p>Method 1 will only affect the current webapp. |
| Method 2 will affect all webapps deployed to the same Server instance. |
| Method 3 will affect all webapps deployed in the same JVM.</p><p>By default, Jetty will wait a maximum of 60 seconds for all of the scanning threads to complete. |
| You can set this to a higher or lower number of seconds by doing one of the following:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">Set the context attribute <code class="literal">org.eclipse.jetty.annotations.maxWait</code></li><li class="listitem">Set the Server attribute <code class="literal">org.eclipse.jetty.annotations.maxWait</code></li><li class="listitem">Set the System property <code class="literal">org.eclipse.jetty.annotations.maxWait</code></li></ol></div><p>Method 1 will only affect the current webapp. |
| Method 2 will affect all webapps deployed to the same Server instance. |
| Method 3 will affect all webapps deployed in the same JVM.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="servlet-container-initializers"></a>ServletContainerInitializers</h3></div></div></div><p>The <a class="link" href="http://docs.oracle.com/javaee/6/api/javax/servlet/ServletContainerInitializer.html" target="_top">javax.servlet.ServletContainerInitializer</a> class can exist in: the container’s classpath, the webapp’s <code class="literal">WEB-INF/classes</code> directory, the webapp’s <code class="literal">WEB-INF/lib</code> jars, or any external <a class="link" href="jetty-classloading.html#using-extra-classpath-method" title="Using the extraClasspath() method">extraClasspath</a> that you have configured on the webapp.</p><p>The <a class="link" href="http://jcp.org/aboutJava/communityprocess/final/jsr340/" target="_top">Servlet Specification</a> does not define any order in which a <code class="literal">ServletContainerInitializer</code> must be called when the webapp starts. |
| By default Jetty will call them in the following order:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">ServletContainerInitializers from the container’s classpath</li><li class="listitem">ServletContainerInitializers from WEB-INF/classes</li><li class="listitem">ServletContainerInitializers from WEB-INF/lib jars <span class="emphasis"><em>in the order established in web.xml</em></span>, or in the order that the SCI is returned by the <a class="link" href="http://docs.oracle.com/javase/6/docs/api/java/util/ServiceLoader.html" target="_top">javax.util.ServiceLoader</a> if there is <span class="emphasis"><em>no</em></span> ordering</li></ol></div><p>As is the case with annotation scanning, the <a class="link" href="jetty-classloading.html#using-extra-classpath-method" title="Using the extraClasspath() method">extraClasspath</a> is fully considered for <code class="literal">ServletContainerInitializer</code> callbacks. <code class="literal">ServletContainerInitializer</code> derived from a classes directory on the <code class="literal">extraClasspath</code> and jars from an <code class="literal">extraClasspath</code> for the webapp are called in step 2 and 3, respectively.</p><div class="blockquote"><blockquote class="blockquote"><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><i class="fa fa-asterisk" aria-hidden="true"></i> Note</h3><p>As of Jetty-9.4.4, unless the <code class="literal">web.xml</code> is version 3.0 or greater, only <code class="literal">ServletContainerInitializers</code> that are on the container classpath will be discovered. |
| Users wishing to use <code class="literal">ServletContainerInitializers</code> from within the webapp with older versions of <code class="literal">web.xml</code> must either upgrade their <code class="literal">web.xml</code> version, or call <code class="literal">WebAppContext.setConfigurationDiscovered(true)</code> either programmatically or in xml. |
| Upgrading the <code class="literal">web.xml</code> version is preferable.</p></div></blockquote></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a name="_controlling_the_order_of_servletcontainerinitializer_invocation"></a>Controlling the order of ServletContainerInitializer invocation</h4></div></div></div><p>If you need <code class="literal">ServletContainerInitializer</code> classes called in a specific order that is different from that outlined above, you can use the context attribute <code class="literal">org.eclipse.jetty.containerInitializerOrder</code>. |
| Set them to a list of comma separated class names of <code class="literal">ServletContainerInitializers</code> in the order that you want them applied. |
| You may optionally use the wildcard character "<span class="strong"><strong>" *once</strong></span> in the list. |
| It will match all <code class="literal">ServletContainerInitializer</code> classed not explicitly named in the list.</p><p>Here is an example, setting the context attribute in code (although you can also do the <a class="link" href="quickstart-config-what.html#intro-jetty-configuration-webapps" title="Configuring Web Applications">same in xml</a>):</p><pre xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times"><code>WebAppContext context = new WebAppContext(); |
| context.setAttribute("org.eclipse.jetty.containerInitializerOrder", |
| "org.eclipse.jetty.websocket.jsr356.server.deploy.WebSocketServerContainerInitializer, com.acme.Foo.MySCI, *");</code></pre><p>In this example, we ensure that the <code class="literal">WebSocketServerContainerInitializer</code> is the very first <code class="literal">ServletContainerInitializer</code> that is called, followed by MySCI and then any other <code class="literal">ServletContainerInitializer</code> instances that were discovered but not yet called.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a name="excluding-scis"></a>Excluding ServletContainerInitializers</h4></div></div></div><p>By default, as according to the Servlet Specification, all <code class="literal">ServletContainerInitializer</code> that are discovered are invoked (see above for how to control the invocation order). |
| Sometimes, depending on your requirements, you may need to prevent some being called at all.</p><p>In this case, you can define the <code class="literal">org.eclipse.jetty.containerInitializerExclusionPattern</code> context attribute. |
| This is a regular expression that defines <a class="link" href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html" target="_top">patterns</a> of classnames that you want to exclude. |
| Here’s an example, setting the context attribute in code, although you may do exactly the <a class="link" href="quickstart-config-what.html#intro-jetty-configuration-webapps" title="Configuring Web Applications">same in xml</a>:</p><pre xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times"><code>WebAppContext context = new WebAppContext(); |
| context.setAttribute("org.eclipse.jetty.containerInitializerExclusionPattern", |
| "com.acme.*|com.corp.SlowContainerInitializer");</code></pre><p>In this example we exclude <span class="strong"><strong>all</strong></span> <code class="literal">ServletContainerInitializer</code> instances in the com.acme package, and the <code class="literal">SlowContainerInitializer</code>.</p><p>It is possible to use exclusion and ordering together to control <code class="literal">ServletContainerInitializer</code> invocation - the exclusions will be applied before the ordering.</p></div></div></div><script type="text/javascript"> |
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