📄 jsp-applications.xtp
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<document> <header> <product>resin</product> <title>Applications</title> <description> <p> An application collects servlets, JSP pages, scripts and Java Beans into a self-contained web application. Applications are just generalized virtual hosts, only based on the URL instead of the host name. </p> </description> </header> <body><summary/><s1 title="Introduction"><p>An application collects servlets, JSP pages, scripts and Java Beans into aself-contained web application. Applications are just generalized virtualhosts, only based on the URL instead of the host name.</p><p>For example, abulletin board application groups pages for article reading, grouplisting, user registration, and new article posting into a singleapplication.</p><p>Applications can keep track of user sessions, giving the users theillusion of a single application out of disjoint pages.</p><ul><li>Resin organizes applications with an application <a href="#dir">directory</a>, WEB-INF</li><li><a href="#session">Sessions</a> share state for a user's visit tothe site.</li></ul><p>Many, if not most sites, will only use the default application.</p></s1><s1 name="dir" title="Applications"><deftable title="application contents"><tr><th>File/Directory</th><th>Contents</th></tr><tr><td>.</td><td>JSP, HTML and GIF files</td></tr><tr><td>WEB-INF/classes</td><td>Java class files</td></tr><tr><td>WEB-INF/lib</td><td>Java jars</td></tr><tr><td>WEB-INF/tmp</td><td>Temporary servlet files</td></tr><tr><td>WEB-INF/work</td><td>Generated java for JSP and XSLT</td></tr></deftable><ul><li><img src="folder.gif"/> example<ul> <li><img src="file.gif"/> index.html </li><li><img src="file.gif"/> folder.gif </li><li><img src="file.gif"/> article.gif </li><li><img src="jsp.gif"/> post-article.xtp </li><li><img src="folder.gif"/> jsp-interest <ul> <li><img src="jsp.gif"/> index.jsp </li><li><img src="jsp.gif"/> article1.jsp </li><li><img src="jsp.gif"/> article2.jsp </li></ul> </li><li><img src="folder.gif"/> WEB-INF <ul> <li><img src="folder.gif"/> lib <ul> <li><img src="bean.gif"/> bulletin-board.jar </li></ul> </li><li><img src="folder.gif"/> classes <ul> <li><img src="bean.gif"/> Navigation.class </li><li><img src="bean.gif"/> HelloWorld.class </li></ul> </li><li><img src="folder.gif"/> xsl <ul> <li><img src="style.gif"/> default.xsl </li><li><img src="style.gif"/> article.xsl </li></ul> </li></ul></li></ul></li></ul></s1><s1 name="beans" title="JSP Beans"><p>Java Beans get first class treatment in JSP 1.0. Beans can becreated for a page, across a session, or for the entire application.</p><p>The classes and lib directories can contain application beans used by <a href="jsp-actions.xtp#usebean">jsp:useBean</a>. These are simply Javaclasses implementing the bitmechanic work of an application.</p><p>For example, a shopping cart application may have a set of Javaclasses that perform the security necessary for credit cardprocessing. The application can put those classes in the beansdirectory and access them from the JSP page.</p><p>Beans can be created with different lifetimes.</p><ul><li>Application beans last the lifetime of an application.</li><li>Session beans last for a user's session.</li><li>Request beans last for a single request.</li><li>Page beans only last for a single page.</li></ul><p>Requests and pages often last the same lifetime, but may differ if onepage <a href="jsp-actions.xtp#forward">forwards</a>or <a href="jsp-actions.xtp#include">includes</a> another page. </p><s2 title="Accessing Beans"><p>Each bean is defined with a <a href="jsp-actions.xtp#usebean">jsp:useBean</a>directive.</p><p>JSP assigns the created bean object to the JavaScript variablenamed by jsp:useBean.</p><p>In addition, the created beans are stored in JSP variables: pagebeans are stored in <code>request</code>, session beans are stored in<code>session</code>, and application beans are stored in<code>application</code>. Storing the beans in the JSP variables letsother beans and functions retrieve the beans.</p><example title="Beans in variables: test.jsp"><jsp:useBean id='test' class='java.util.Hashtable'>&lt% test.put("a", 1); %>&lt%= test.get("a"); %></example><example title="Page beans in request: test.jsp"><jsp:useBean id='test' class='java.util.Hashtable'><% var t = request.attributes.test t.put("a", 1);%>&lt%= test.get("a"); %></example><results>1</results></s2></s1><s1 name="session" title="Sessions"><p>Session variables let applications keep track of the user as she movesthrough the site. Any e-commerce site needs this capability to keeptrack of the user's purchases.</p><p>JSP sessions start when the page accesses the <a href="jsp-variables.xtp#session">session</a> variable.</p><p>Sessions end when the session times out, when the session isinvalidated, or when the application ends.</p></s1> </body></document>⌨️ 快捷键说明
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