svn commit: r582231 - /myfaces/orchestra/trunk/core/src/main/java/org/apache/myfaces/orchestra/frameworkAdapter/jsf/JsfFrameworkAdapter.java

[sk...@apache.org]

Author: skitching
Date: Fri Oct  5 05:42:22 2007
New Revision: 582231

URL: http://svn.apache.org/viewvc?rev=582231&view=rev
Log:
Implement "magic beans" in order to provide framework-specific default objects.

Modified:
    myfaces/orchestra/trunk/core/src/main/java/org/apache/myfaces/orchestra/frameworkAdapter/jsf/JsfFrameworkAdapter.java

Modified: myfaces/orchestra/trunk/core/src/main/java/org/apache/myfaces/orchestra/frameworkAdapter/jsf/JsfFrameworkAdapter.java
URL: http://svn.apache.org/viewvc/myfaces/orchestra/trunk/core/src/main/java/org/apache/myfaces/orchestra/frameworkAdapter/jsf/JsfFrameworkAdapter.java?rev=582231&r1=582230&r2=582231&view=diff
==============================================================================
--- myfaces/orchestra/trunk/core/src/main/java/org/apache/myfaces/orchestra/frameworkAdapter/jsf/JsfFrameworkAdapter.java (original)
+++ myfaces/orchestra/trunk/core/src/main/java/org/apache/myfaces/orchestra/frameworkAdapter/jsf/JsfFrameworkAdapter.java Fri Oct  5 05:42:22 2007
@@ -19,6 +19,8 @@
 package org.apache.myfaces.orchestra.frameworkAdapter.jsf;
 
 import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
 
 import javax.faces.context.FacesContext;
 import javax.servlet.ServletRequest;
@@ -28,8 +30,11 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.myfaces.orchestra.conversation.ConversationMessager;
+import org.apache.myfaces.orchestra.conversation.jsf.JsfConversationMessager;
 import org.apache.myfaces.orchestra.frameworkAdapter.FrameworkAdapter;
 import org.apache.myfaces.orchestra.frameworkAdapter.FrameworkAdapterInterface;
+import org.apache.myfaces.orchestra.lib.OrchestraException;
 
 /**
  * An implementation of the FrameworkAdapter for JSF environments.
@@ -44,6 +49,16 @@
 	private final static ThreadLocal httpServletResponse = new ThreadLocal();
 
 	private final Log log = LogFactory.getLog(JsfFrameworkAdapter.class);
+	private final Map magicBeans = new HashMap();
+
+	public JsfFrameworkAdapter()
+	{
+		// Define magic bean names that cause an instance to be created even when it
+		// is not defined in the IOC configuration.
+		magicBeans.put(
+			ConversationMessager.class.getName(),
+			JsfConversationMessager.class);
+	}
 
 	protected FacesContext getFacesContext()
 	{
@@ -270,9 +285,62 @@
 		}
 
 		Object bean = context.getApplication()
-	        .getVariableResolver().resolveVariable(context, name);		
+	        	.getVariableResolver().resolveVariable(context, name);
+
+		if (bean == null)
+		{
+			bean = createMagicBean(name);
+		}
 
 		return bean;
+	}
+
+	/**
+	 * If the bean requested has one of the special "magic" names, then create an instance
+	 * from the corresponding hard-wired defaults in this class.
+	 * <p>
+	 * This provides a kind of "hard wired IOC default". This method is called when the
+	 * getBean method cannot locate an instance anywhere else.
+	 * <p>
+	 * Code throughout Orchestra generally locates resources by calling the getBean method
+	 * passing a bean name which is the classname of the implementation required. The user
+	 * can then configure an appropriate instance to be returned. If the user does not 
+	 * define a matching bean then the calling code uses "new" to create an instance of a
+	 * suitable default type. Unfortunately that doesn't work when the default type depends
+	 * upon what UI framework is being used. Intercepting calls here solves that issue by
+	 * ensuring that a suitable default object is returned for this framework but only if
+	 * the user has not mapped that name to their own definition.
+	 */
+	protected Object createMagicBean(String name)
+	{
+		Class beanClass; 
+		synchronized(magicBeans)
+		{
+			beanClass = (Class) magicBeans.get(name);
+		}
+
+		if (beanClass == null)
+		{
+			return null;
+		}
+		
+		// Ok, this is indeed a magic bean. Create an instance.
+		// Note that magic beans are always "prototypes"; a new instance
+		// is created for each call to getBean().
+		try
+		{
+			return beanClass.newInstance();
+		}
+		catch(InstantiationException e)
+		{
+			throw new OrchestraException(
+				"Internal error: unable to create instance of special bean " + name, e);
+		}
+		catch(IllegalAccessException e)
+		{
+			throw new OrchestraException(
+					"Internal error: unable to create instance of special bean " + name, e);
+		}
 	}
 
 	public void invokeNavigation(String navigationName)