| -----------------------------xyzzyx | |
| Content-Disposition: form-data; name="service" | |
| direct/0/Home/$Form | |
| -----------------------------xyzzyx | |
| Content-Disposition: form-data; name="sp" | |
| S0 | |
| -----------------------------xyzzyx | |
| Content-Disposition: form-data; name="$Upload"; filename="context19/long.html" | |
| Content-Type: text/html | |
| <html><head> | |
| <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> | |
| <title>Manual Persistent Component Properties</title><link rel="stylesheet" href="Tapestry.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.59.2"><link rel="home" href="TapestryUsersGuide.html" title="Tapestry User's Guide"><link rel="up" href="state.html" title="Chapter 2. Managing Server-Side State"><link rel="previous" href="state.manual-page-properties.html" title="Implementing Persistent Page Properties Manually"><link rel="next" href="state.stateless.html" title="Stateless Applications"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Manual Persistent Component Properties</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="state.manual-page-properties.html"><img src="common-images/prev.png" alt="Prev"></a> </td><th width="60%" align="center">Chapter 2. Managing Server-Side State</th><td width="20%" align="right"> <a accesskey="n" href="state.stateless.html"><img src="common-images/next.png" alt="Next"></a></td></tr></table><hr></div><div class="section" lang="en"><div class="titlepage"><div><h2 class="title" style="clear: both"><a name="state.manual-component-properties"></a>Manual Persistent Component Properties</h2></div></div><p> | |
| Implementing transient and persistent properties inside components involves more work. | |
| The <tt>fireObservedChange()</tt> | |
| method is available to components as well as pages, but the initialization of | |
| the component is more complicated. | |
| </p><p> | |
| Components do not have the equivalent of the <tt>initialize()</tt> method. Instead, | |
| they must register for an event notification to tell them when the page is being <span class="emphasis"><em>detached</em></span> | |
| from the engine (prior to be stored back into the page pool). This event is generated by the page itself. | |
| </p><p> | |
| The Java interface <a href="../api/net/sf/tapestry/event/PageDetachListener.html" target="_self"><tt>PageDetachListener</tt></a> is the event listener interface for this purpose. | |
| By simply implementing this interface, Tapestry will register the component as a listener and ensure that | |
| it receives event notifications at the right time (this works for the two other | |
| page event interfaces, <a href="../api/net/sf/tapestry/event/PageRenderListener.html" target="_self"><tt>PageRenderListener</tt></a> and <a href="../api/net/sf/tapestry/event/PageCleanupListener.html" target="_self"><tt>PageCleanupListener</tt></a> as well; simply | |
| implement the interface and leave the rest to the framework). | |
| </p><p> | |
| Tapestry provides a method, <tt>finishLoad()</tt>, for just this purpose: late initialization. | |
| </p><div class="example"><a name="d0e593"></a><p class="title"><b>Example 2.7. Manual Persistent Component Properties</b></p><table border="0" bgcolor="#E0E0E0"><tr><td><pre class="programlisting"> | |
| public class MyComponent extends <a href="../api/net/sf/tapestry/BaseComponent.html" target="_self"><tt>BaseComponent</tt></a> implements <a href="../api/net/sf/tapestry/event/PageDetachListener.html" target="_self"><tt>PageDetachListener</tt></a> | |
| { | |
| private String _myProperty; | |
| public void setMyProperty(String myProperty) | |
| { | |
| _myProperty = myProperty; | |
| fireObservedChange("myProperty", myProperty); | |
| } | |
| public String getMyProperty() | |
| { | |
| return _myProperty; | |
| } | |
| protected void initialize() | |
| { | |
| _myProperty = "<span class="emphasis"><em>a default value</em></span>"; | |
| } | |
| protected void finishLoad() | |
| { | |
| initialize(); | |
| } | |
| /** | |
| * The method specified by <a href="../api/net/sf/tapestry/event/PageDetachListener.html" target="_self"><tt>PageDetachListener</tt></a>. | |
| * | |
| **/ | |
| public void pageDetached(PageEvent event) | |
| { | |
| initialize(); | |
| } | |
| } | |
| </pre></td></tr></table></div><p> | |
| Again, there is no particular need to do all this; using the | |
| <a href="spec.property-specification.html" title="property-specification element"><tt class="sgmltag-starttag"><property-specification></tt></a> element is far, far simpler. | |
| </p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="state.manual-page-properties.html"><img src="common-images/prev.png" alt="Prev"></a> </td><td width="20%" align="center"><a accesskey="u" href="state.html"><img src="common-images/up.png" alt="Up"></a></td><td width="40%" align="right"> <a accesskey="n" href="state.stateless.html"><img src="common-images/next.png" alt="Next"></a></td></tr><tr><td width="40%" align="left" valign="top">Implementing Persistent Page Properties Manually </td><td width="20%" align="center"><a accesskey="h" href="TapestryUsersGuide.html"><img src="common-images/home.png" alt="Home"></a></td><td width="40%" align="right" valign="top"> Stateless Applications</td></tr></table></div></body></html> | |
| -----------------------------xyzzyx | |
| Content-Disposition: form-data; name="Form0" | |
| $Upload | |
| -----------------------------xyzzyx-- |