com.ibm.wsspi.webcontainer.servlet
Class GenericServletWrapper

java.lang.Object
  extended by com.ibm.wsspi.webcontainer.servlet.GenericServletWrapper
All Implemented Interfaces:
RequestProcessor, IServletWrapper

public abstract class GenericServletWrapper
extends java.lang.Object
implements IServletWrapper

A convenience class that implements IServletWrapper. This class must be subclassed if IServletWrapper implementations want to leverage the webcontainer's handling of the following: -> Servlet lifecycle management -> Event generation and firing -> Request handling leveraging sessions and security Subclasses usually override the handleRequest() method wherein they implement logic specific to the container they are part of, and at the end call on super.handleRequest() which then handles the actual dispatch to the servlet and invokes the Servlet's service() method.

Since:
WAS6.0

Constructor Summary
GenericServletWrapper(IServletContext parent)
          Public constructor.
 
Method Summary
 void addServletReferenceListener(ServletReferenceListener listener)
          Add a listener which will listen to the invalidation events for this wrapper instance.
 void destroy()
          This method will be invoked when the parent container wishes to destroy this IServletWrapper instance.
 long getLastAccessTime()
          This method will be called by the webcontainer's reaper mechanism which polls for the access times of the wrappers in its datastructures, and invalidates them if they have been inactive for a preconfigured amount of time.
 java.lang.String getName()
           
 IServletConfig getServletConfig()
          Returns the ServletConfig associated with the target
 javax.servlet.ServletContext getServletContext()
          Returns the servlet context associated with this servlet wrapper.
 java.lang.String getServletName()
          Returns the servlet name of the target
 javax.servlet.Servlet getTarget()
          Returns the target Servlet instance
 java.lang.ClassLoader getTargetClassLoader()
          Returns the current classloader which loaded (or will, in the future, load) the target.
 void handleRequest(javax.servlet.ServletRequest req, javax.servlet.ServletResponse res)
          Method that processes the request, and ultimately invokes the service() on the Servlet target.
 void initialize(IServletConfig config)
          Method that handles the initialization of this IServletWrapper instance.
 boolean isAvailable()
          Returns whether the requested wrapper resource exists.
 boolean isInternal()
           
 void load()
          Loads the servlet and calls the Servlet's init method with the previously passed IServletConfig.
 void loadOnStartupCheck()
          Initializes this wrapper with the specified config.
 void modifyTarget(javax.servlet.Servlet s)
           
 void nameSpacePostInvoke()
           
 void nameSpacePreInvoke()
           
 void prepareForReload()
          Gracefully invalidates the target by overseeing its lifecycle (destroy()) This method must be called before the target is invalidated for reload.
 void service(javax.servlet.ServletRequest request, javax.servlet.ServletResponse response)
           
 void setParent(IServletContext parent)
          Sets the parent context for this servletwrapper
 void setTarget(javax.servlet.Servlet target)
          Sets the target for this IServletWrapper.
 void setTargetClassLoader(java.lang.ClassLoader loader)
          Instructs the underlying implementation to use the supplied class loader to instantiate the target instance.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

GenericServletWrapper

public GenericServletWrapper(IServletContext parent)
                      throws java.lang.Exception
Public constructor. This contructor must be invoked from within the constructor of the subclass passing in the IServletContext so that the parent object can be constructed correctly.

Parameters:
parent - The IServletContext that this IServletWrapper will be a part of
Throws:
java.lang.Exception
Method Detail

initialize

public void initialize(IServletConfig config)
                throws java.lang.Exception
Method that handles the initialization of this IServletWrapper instance. Subclasses must call this by invoking super.initialize(config), so that the underlying target Servlet can be setup and initialized by calling its init() method (if specified in the config as loadAtStartUp).

Specified by:
initialize in interface IServletWrapper
Parameters:
config - the IServletConfig associated with this IServletWrapper
Throws:
java.lang.Exception
See Also:
IServletConfig

handleRequest

public void handleRequest(javax.servlet.ServletRequest req,
                          javax.servlet.ServletResponse res)
                   throws java.lang.Exception
Method that processes the request, and ultimately invokes the service() on the Servlet target. Subclasses may override this method to put in additional logic (eg., reload/retranslation logic in the case of JSP containers). Subclasses must call this method by invoking super.handleRequest() if they want the webcontainer to handle initialization and servicing of the target in a proper way. An example scenario: class SimpleJSPServletWrapper extends GenericServletWrapper { ... public void handleRequest(ServletRequest req, ServletResponse res) { String jspFile = getFileFromRequest(req); // get the JSP target if (hasFileChangedOnDisk(jspFile)) { prepareForReload(); // invalidate the target and targetClassLoader setTargetClassLoader(null); setTarget(null); JSPServlet jsp = compileJSP(jspFile); ClassLoader loader = getLoaderForServlet(jsp); setTarget(jsp.getClassName()); setTargetClassLoader(loader); } super.handleRequest(req, res); } ... }

Specified by:
handleRequest in interface RequestProcessor
Specified by:
handleRequest in interface IServletWrapper
Throws:
java.lang.Exception

prepareForReload

public void prepareForReload()
Gracefully invalidates the target by overseeing its lifecycle (destroy()) This method must be called before the target is invalidated for reload.

Specified by:
prepareForReload in interface IServletWrapper

getServletName

public java.lang.String getServletName()
Returns the servlet name of the target

Specified by:
getServletName in interface IServletWrapper
Returns:

getServletConfig

public IServletConfig getServletConfig()
Returns the ServletConfig associated with the target

Specified by:
getServletConfig in interface IServletWrapper
Returns:

getServletContext

public javax.servlet.ServletContext getServletContext()
Description copied from interface: IServletWrapper
Returns the servlet context associated with this servlet wrapper.

Specified by:
getServletContext in interface IServletWrapper
Returns:

setTargetClassLoader

public void setTargetClassLoader(java.lang.ClassLoader loader)
Instructs the underlying implementation to use the supplied class loader to instantiate the target instance. Calling this method with a null, accompanied with a setTarget(null) will result in the current classloader being destroyed and garbage collected along with the target instance.

Specified by:
setTargetClassLoader in interface IServletWrapper

getTarget

public javax.servlet.Servlet getTarget()
Returns the target Servlet instance

Specified by:
getTarget in interface IServletWrapper
Returns:

getTargetClassLoader

public java.lang.ClassLoader getTargetClassLoader()
Returns the current classloader which loaded (or will, in the future, load) the target.

Specified by:
getTargetClassLoader in interface IServletWrapper

setTarget

public void setTarget(javax.servlet.Servlet target)
Sets the target for this IServletWrapper.

Specified by:
setTarget in interface IServletWrapper

addServletReferenceListener

public void addServletReferenceListener(ServletReferenceListener listener)
Add a listener which will listen to the invalidation events for this wrapper instance. The invalidate() event will be fired only when the wrapper itself (not the target) is about to be destroyed by the parent container.

Specified by:
addServletReferenceListener in interface IServletWrapper

getLastAccessTime

public long getLastAccessTime()
This method will be called by the webcontainer's reaper mechanism which polls for the access times of the wrappers in its datastructures, and invalidates them if they have been inactive for a preconfigured amount of time. Wrapper subclasses that do not want to be 'reaped' may override this method by returning the current system time.

Specified by:
getLastAccessTime in interface IServletWrapper
Returns:

destroy

public void destroy()
This method will be invoked when the parent container wishes to destroy this IServletWrapper instance. Thew subclasses may override this method to implement any resource clean up, but must invoke this method by calling super.destroy() inorder to correctly destroy the underlying target.

Specified by:
destroy in interface IServletWrapper

service

public void service(javax.servlet.ServletRequest request,
                    javax.servlet.ServletResponse response)
             throws java.io.IOException,
                    javax.servlet.ServletException
Specified by:
service in interface IServletWrapper
Throws:
java.io.IOException
javax.servlet.ServletException

setParent

public void setParent(IServletContext parent)
Description copied from interface: IServletWrapper
Sets the parent context for this servletwrapper

Specified by:
setParent in interface IServletWrapper

isAvailable

public boolean isAvailable()
Returns whether the requested wrapper resource exists.

Specified by:
isAvailable in interface IServletWrapper

nameSpacePostInvoke

public void nameSpacePostInvoke()

nameSpacePreInvoke

public void nameSpacePreInvoke()

getName

public java.lang.String getName()
Specified by:
getName in interface RequestProcessor

isInternal

public boolean isInternal()
Specified by:
isInternal in interface RequestProcessor
Returns:
boolean Returns true if this request processor is for internal use only

loadOnStartupCheck

public void loadOnStartupCheck()
                        throws java.lang.Exception
Description copied from interface: IServletWrapper
Initializes this wrapper with the specified config. Depending on the startup weight specified in the config, the underlying target Servlet will either be initialized within this call. NOTE: This initialization behaviour of the target Servlet can be controlled by calling the setStartUpWeight() method on the IServletConfig

Specified by:
loadOnStartupCheck in interface IServletWrapper
Throws:
java.lang.Exception
See Also:
IServletConfig

load

public void load()
          throws java.lang.Exception
Description copied from interface: IServletWrapper
Loads the servlet and calls the Servlet's init method with the previously passed IServletConfig. One component that calls this is SIP.

Specified by:
load in interface IServletWrapper
Throws:
java.lang.Exception

modifyTarget

public void modifyTarget(javax.servlet.Servlet s)
Specified by:
modifyTarget in interface IServletWrapper