Date: 2004-10-19T04:51:50
Editor: KurtHoehn <[EMAIL PROTECTED]>
Wiki: Jakarta HiveMind Wiki
Page: PluggingIntoStruts
URL: http://wiki.apache.org/jakarta-hivemind/PluggingIntoStruts
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= Plugging into Struts =
!HiveMind does offer a servlet filter for initializing the registry but if your
servlet engine does not support filters or you want to control the registry
from Struts then a plugin is the way to go. This is not an example of how to
configure !HiveMind but how to configure a plugin to use !HiveMind. It's a
quick and easy way to get !HiveMind into your Struts application.
= The Interface (StrutsHive.java) =
{{{
public interface StrutsHive
{
public static final String STRUTSHIVE_REGISTRY =
"org.apache.struts.hivemind.STRUTSHIVE_REGISTRY";
Object lookup( String name, Class type );
Object lookup( Class type );
List getConfiguration( String configuration );
void cleanupThread();
}
}}}
= The PlugIn (StrutsHivePlugIn.java) =
{{{
public class StrutsHivePlugIn implements StrutsHive, PlugIn
{
private static final Log _log = LogFactory.getLog( StrutsHivePlugIn.class );
private Registry _registry;
private String _errorHandler;
private String _classResolver;
private String _language;
private String _country = "";
private String _variant = "";
public void setLanguage(String language)
{
this._language = language;
}
public void setCountry(String country)
{
this._country = country;
}
public void setVariant(String variant)
{
this._variant = variant;
}
public void setErrorHandler( String errorHandler )
{
_errorHandler = errorHandler;
}
public void setClassResolver( String classResolver )
{
_classResolver = classResolver;
}
public void init(ActionServlet actionServlet, ModuleConfig moduleConfig)
throws ServletException
{
ClassResolver resolver;
RegistryBuilder builder;
if( _log.isDebugEnabled() )
{
_log.debug("Initializing StrutsHivePlugIn.");
}
if( _classResolver == null )
{
if( _log.isDebugEnabled() )
{
_log.debug( "No class resolver was defined using HiveMinds
default class resolver." );
}
resolver = new DefaultClassResolver();
}
else
{
try
{
resolver = initializeClassResolver();
}
catch( Exception e )
{
throw new ServletException( e.getMessage() );
}
}
if( _errorHandler == null )
{
builder = new RegistryBuilder();
}
else
{
try
{
ErrorHandler errorHandler = initializeErrorHandler();
builder = new RegistryBuilder( errorHandler );
}
catch( Exception e )
{
throw new ServletException( e.getMessage() );
}
}
builder.processModules( resolver );
_registry = builder.constructRegistry( getLocale() );
actionServlet.getServletContext().setAttribute( STRUTSHIVE_REGISTRY,
this );
if( _log.isDebugEnabled() )
{
_log.debug("StrutsHivePlugIn initialized.");
}
}
public Object lookup( String name, Class type )
{
if( _registry.containsService( name, type ) )
{
return _registry.getService( name, type );
}
throw new IllegalArgumentException( type.getName() + " service was not
found in the registry");
}
public Object lookup( Class type )
{
if( _registry.containsService( type ) )
{
return _registry.getService( type );
}
throw new IllegalArgumentException( type.getName() + " service was not
found in the registry");
}
public List getConfiguration( String configuration )
{
if( _registry.containsConfiguration( configuration ) )
{
return _registry.getConfiguration( configuration );
}
throw new IllegalArgumentException( configuration + " configuration was
not found in the registry");
}
public void cleanupThread()
{
_registry.cleanupThread();
}
public void destroy()
{
if( _log.isDebugEnabled() )
{
_log.debug("Shutting down StrutsHivePlugIn");
}
_registry.shutdown();
}
protected Locale getLocale()
{
if( _language != null )
{
return new Locale( _language, _country, _variant );
}
else
{
return Locale.getDefault();
}
}
protected ErrorHandler initializeErrorHandler() throws Exception
{
Thread thread = Thread.currentThread();
ClassLoader loader = thread.getContextClassLoader();
Class clazz = loader.loadClass( _errorHandler);
return (ErrorHandler) clazz.newInstance();
}
protected ClassResolver initializeClassResolver() throws Exception
{
Thread thread = Thread.currentThread();
ClassLoader loader = thread.getContextClassLoader();
Class clazz = loader.loadClass( _classResolver);
return (ClassResolver) clazz.newInstance();
}
}
}}}
= Configuration (struts-config.xml) =
The plugin has multiple set-properties but all are optional
|| Property || Optional || Description ||
|| language ||<:> Y || define a locale different from the default ||
|| country ||<:> Y || used in conjunction with the language property but not
mandatory ||
|| variant ||<:> Y || used in conjunction with the country property but not
mandatory ||
|| errorHandler ||<:> Y || include your own !HiveMind error handler ||
|| classResolver ||<:> Y || include your own !HiveMind class resolver ||
{{{
<plug-in className="<your package name goes here>.StrutsHivePlugIn">
<set-property property="language" value="en"/>
</plug-in>
}}}
= Using it in your application =
{{{
public MyAction extends Action
{
...
public Object getService( String service, Class type )
{
StrutsHive hive = (StrutsHive)
getServlet().getServletContext().getAttribute( StrutsHive.STRUTSHIVE_REGISTRY );
return hive.lookup( service, type );
}
...
}
}}}
= Conclusion =
Not much to talk about here but if you want to use it, go nuts! If you have
improvements let me know or add to the Wiki.
Contributed by KurtHoehn
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