com.interface21.web.servlet
Interface HandlerAdapter

All Superinterfaces:
ApplicationContextAware
All Known Implementing Classes:
SimpleControllerHandlerAdapter

public interface HandlerAdapter
extends ApplicationContextAware

MVC framework SPI interface, allowing parameterization of core MVC workflow.

Interface that must be implemented for each handler type to handle a request. This interface is used to allow the DispatcherServlet to be indefinitely extensible. The DispatcherServlet accesses all installed handlers through this interface, meaning that it does not contain code specific to any handler type.

Note that a handler can be of type Object. This is to enable handlers from other frameworks to be integrated with this framework without custom coding.

This interface is not intended for application developers. It is available to handlers who want to develop their own web workflow.

Note: Implementations can implement the Ordered interface to be able to specify a sorting order and thus a priority for getting applied by DispatcherServlet. Non-Ordered instances get treated as lowest priority.

Author:
Rod Johnson

Method Summary
 long getLastModified(javax.servlet.http.HttpServletRequest request, java.lang.Object handler)
          Same contract as for HttpServlet.getLastModified.
 ModelAndView handle(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, java.lang.Object handler)
          Use the given handler to handle this request.
 boolean supports(java.lang.Object handler)
          Given a handler instance, return whether or not this HandlerAdapter can support it.
 
Methods inherited from interface com.interface21.context.ApplicationContextAware
setApplicationContext
 

Method Detail

supports

public boolean supports(java.lang.Object handler)
Given a handler instance, return whether or not this HandlerAdapter can support it. Usually HandlerAdapters will base the decision on the handler type. HandlerAdapters will normally support only one handler type.

A typical implementation: return handler != null && MyHandler.class.isAssignableFrom(handler.getClass());

Parameters:
handler - handler object to check
Returns:
whether or not this object can use the given handler

handle

public ModelAndView handle(javax.servlet.http.HttpServletRequest request,
                           javax.servlet.http.HttpServletResponse response,
                           java.lang.Object handler)
                    throws javax.servlet.ServletException,
                           java.io.IOException
Use the given handler to handle this request. The workflow that is required may vary widely. Can also perform authorization checks.
Parameters:
request - current HTTP request
response - current HTTP response
handler - handler to use. This object must have previously been passed to the supports() method of this interface, which must have returned true. Implementations that generate output themselves (and return null from this method) may encounter IOExceptions.
Returns:
ModelAndView object with the name of the view and the required model data, or null if the request has been handled directly.
Throws:
javax.servlet.ServletException - if there is a general error
java.io.IOException - in case of I/O errors

getLastModified

public long getLastModified(javax.servlet.http.HttpServletRequest request,
                            java.lang.Object handler)
Same contract as for HttpServlet.getLastModified. Can simply return -1 if there's no support in the handler class.
Parameters:
request - current HTTP request
handler - handler to use
Returns:
the lastModified value for the given handler
See Also:
HttpServlet.getLastModified(javax.servlet.http.HttpServletRequest)


Rod Johnson and Spring contributors 2001-2003.