| <html><head> |
| <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> |
| <title>4.3 The controller</title><link rel="stylesheet" href="css/stylesheet.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.74.0"><link rel="home" href="index.html" title="Creating an application with EclipseRT Virgo Web Server"><link rel="up" href="ch04.html" title="4. The Web Module"><link rel="prev" href="ch04s02.html" title="4.2 GreenPages set up"><link rel="next" href="ch04s04.html" title="4.4 Deploying a bundle"><!--Begin Google Analytics code--><script type="text/javascript"> |
| var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); |
| document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); |
| </script><script type="text/javascript"> |
| var pageTracker = _gat._getTracker("UA-2728886-3"); |
| pageTracker._setDomainName("none"); |
| pageTracker._setAllowLinker(true); |
| pageTracker._trackPageview(); |
| </script><!--End Google Analytics code--></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">4.3 The controller</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch04s02.html">Prev</a> </td><th width="60%" align="center">4. The Web Module</th><td width="20%" align="right"> <a accesskey="n" href="ch04s04.html">Next</a></td></tr></table><hr></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="controller"></a>4.3 The controller</h2></div></div></div><p> |
| The Spring’s MVC style of web application development is used in which the central type |
| is the <code class="literal">Controller</code> class. |
| </p><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="import.greenpages.web"></a>Import the web project</h3></div></div></div><p> |
| The GreenPages application is divided into OSGi bundles that are represented as Eclipse |
| projects. In this step import the <code class="literal">greenpages.web</code> project. |
| </p><p> |
| Starting with no projects, import the web project by right-clicking in the <span class="emphasis"><em>Package Explorer</em></span> |
| view and selecting the <span class="emphasis"><em>Import…</em></span> menu item. |
| In the dialog that opens, choose <span class="guimenuitem">General</span> → <span class="guimenuitem">Existing Projects into Workspace</span> and select <span class="emphasis"><em>Next</em></span>. |
| In the following dialog set the <span class="emphasis"><em>root directory</em></span> to the value of |
| <code class="literal">$GREENPAGES_HOME/start/greenpages.web</code> and press <span class="emphasis"><em>Finish</em></span>. |
| </p><p> |
| (Initially this project may have compiler errors; |
| this is to be expected particularly if the Maven repository hasn’t yet been created.) |
| |
| |
| |
| |
| |
| |
| |
| |
| When this project is imported go to the next step. |
| </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="controller.controller"></a>The controller class</h3></div></div></div><p> |
| In the <code class="literal">src/main/java</code> source folder of the <code class="literal">greenpages.web</code> project |
| the package <code class="classname">greenpages.web</code> |
| should contain the controller class named |
| <code class="classname">GreenPagesController</code>. |
| Create this by right-clicking on the <code class="literal">greenpages.web</code> package in the |
| <code class="literal">src/main/java</code> source folder and selecting |
| <span class="guimenuitem">New</span> → <span class="guimenuitem">Class</span>. |
| (If <span class="emphasis"><em>Class</em></span> is not offered on the <span class="emphasis"><em>New</em></span> menu |
| the <span class="emphasis"><em>Java</em></span> perspective may not be being used, in which case look for |
| the <span class="emphasis"><em>Class</em></span> option under <span class="emphasis"><em>Other…</em></span> in the <span class="emphasis"><em>Java</em></span> section.) |
| </p><p> |
| Name the new class <code class="classname">GreenPagesController</code> and press <span class="emphasis"><em>Finish</em></span>. |
| </p><div class="mediaobject" align="center"><img src="images/web-module/new-greenpages-controller.png" align="middle"></div><p> |
| </p><p> |
| The code should be edited to look like this: |
| </p><pre class="programlisting">@Controller |
| <span class="hl-keyword">public</span> <span class="hl-keyword">class</span> GreenPagesController { |
| … |
| @RequestMapping(<span class="hl-string">"/home.htm"</span>) |
| <span class="hl-keyword">public</span> <span class="hl-keyword">void</span> home() { |
| } |
| … |
| </pre><p> |
| </p><p> |
| The annotations <code class="classname">Controller</code> and <code class="classname">RequestMapping</code> |
| are from Spring Framework and are imported by adding the lines: |
| </p><pre class="programlisting"><span class="hl-keyword">import</span> org.springframework.stereotype.Controller; |
| <span class="hl-keyword">import</span> org.springframework.web.bind.annotation.RequestMapping; |
| </pre><p> |
| </p><p> |
| STS will offer (as a <span class="emphasis"><em>Quick Fix</em></span>) to insert imports for these Spring Framework annotations |
| the first time they are used. |
| (Java 1.6 supports annotations, and the Spring Framework libraries are accessible by |
| linking to the correct Web Server runtime environment or generating the correct dependencies for the Maven plug-in.) |
| </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="controller.component.scanning"></a>Enabling component scanning</h3></div></div></div><p> |
| Spring will detect the <code class="classname">@Controller</code> annotation and create a bean of controller type, |
| <span class="emphasis"><em>provided that</em></span> it scans the classpath for these. |
| Spring’s component scanning is enabled by inserting a <code class="literal">context</code> tag |
| in one of the Spring bean definition files. |
| </p><p> |
| Open the <code class="filename">WEB-INF/greenpages-servlet.xml</code> file in the |
| <code class="literal">src/main/webapp</code> folder and ensure the following lines are present: |
| </p><pre class="programlisting"> <<span class="hl-comment">!-- enable classpath scanning --</span>> |
| <<span class="hl-tag">context:component-scan</span> <span class="hl-attribute">base-package</span>=<span class="hl-value">"greenpages.web"</span> /> |
| </pre><p> |
| </p><p> |
| Experiment by adding and removing this line, saving the file after each change. |
| (<span class="emphasis"><em>Easily done by commenting it—use the |
| <span class="emphasis"><em>Toggle Comment</em></span> |
| shortcut in STS.</em></span>) |
| Look in the <span class="emphasis"><em>Spring Explorer</em></span> view for a bean named <code class="literal">greenPagesController</code> |
| dynamically created by the <code class="literal">component-scan</code> tag. |
| </p></div></div><!--Begin LoopFuse code--><script src="http://loopfuse.net/webrecorder/js/listen.js" type="text/javascript"></script><script type="text/javascript"> |
| _lf_cid = "LF_48be82fa"; |
| _lf_remora(); |
| </script><!--End LoopFuse code--><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch04s02.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch04.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch04s04.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">4.2 GreenPages set up </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 4.4 Deploying a bundle</td></tr></table></div></body></html> |
