com.interface21.web.servlet.mvc.multiaction
Class MultiActionController

java.lang.Object
  |
  +--com.interface21.context.support.ApplicationObjectSupport
        |
        +--com.interface21.web.servlet.mvc.WebContentGenerator
              |
              +--com.interface21.web.servlet.mvc.multiaction.MultiActionController

All Implemented Interfaces:

ApplicationContextAware, Controller, LastModified

public class MultiActionController

extends WebContentGenerator

implements Controller, LastModified

Controller implementation that allows multiple request types to be handled by the same class.
Subclasses of this class can handle several different types of request with methods of the form ModelAndView actionName(HttpServletRequest request, HttpServletResponse response); May take a third parameter HttpSession in which an existing session will be required, or a third parameter of an arbitrary class that gets treated as command (i.e. an instance of the class gets created, and request parameters get bound to it)
These methods can throw any kind of exception, but should only let propagate those that they consider fatal, or which their class or superclass is prepared to catch by implementing an exception handler.
This model allows for rapid coding, but loses the advantage of compile-time checking.

Inherits superclass bean properties. Adds methodNameResolver bean property. An implementation of the MethodNameResolver interface defined in this package should return a method name for a given request, based on any aspect of the request, such as its URL or an "action" or like attribute. The default behavior is URL based.
Also supports delegation to another object.

Subclasses can implement custom exception handler methods with names such as ModelAndView anyMeaningfulName(HttpServletRequest request, HttpServletResponse response, ExceptionClass exception); The third parameter can be any subclass or Exception or RuntimeException.
There can also be an optional lastModified method for handlers, of signature long anyMeaningfulNameLastModified(HttpServletRequest request) If such a method is present, it will be invoked. Default return from getLastModified() is -1, meaning that content must always be regenerated.
Like Struts 1.1 DispatchAction, but more sophisticated.
The mapping from requests to handler method names is parameterized in the MethodNameResolver interface.
Note that method overloading isn't allowed.

Author:

Rod Johnson

Field Summary

static java.lang.String

LAST_MODIFIED_METHOD_SUFFIX Prefix for last modified methods

Fields inherited from class com.interface21.context.support.ApplicationObjectSupport

logger

Constructor Summary

MultiActionController()
Constructor for MultiActionController that looks for handler methods in the present subclass.

MultiActionController(java.lang.Object delegate)
Constructor for MultiActionController that looks for handler methods in delegate, rather than a subclass of this class.

Method Summary

protected void	bind(javax.servlet.ServletRequest request, java.lang.Object command) Bind request parameters onto the given command bean
protected java.lang.reflect.Method	getExceptionHandler(java.lang.Throwable exception) Can return null if not found
long	getLastModified(javax.servlet.http.HttpServletRequest request) Try to find an XXXXLastModified method, where XXXX is the name of a handler.
MethodNameResolver	getMethodNameResolver() Get the MethodNameResolver used by this class
ModelAndView	handleRequest(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Process the request and return a ModelAndView object which the DispatcherServlet will render.
protected ModelAndView	invokeNamedMethod(java.lang.String method, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Invoke the named method.
protected java.lang.Object	newCommandObject(java.lang.Class clazz) Create a new command object of the given class.
void	setDelegate(java.lang.Object delegate) Set the delegate used by this class.
void	setMethodNameResolver(MethodNameResolver methodNameResolver) Sets the method name resolver used by this class.

Methods inherited from class com.interface21.web.servlet.mvc.WebContentGenerator

cacheForSeconds, preventCaching, setUseExpiresHeader

Methods inherited from class com.interface21.context.support.ApplicationObjectSupport

getApplicationContext, initApplicationContext, setApplicationContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LAST_MODIFIED_METHOD_SUFFIX

public static final java.lang.String LAST_MODIFIED_METHOD_SUFFIX

Prefix for last modified methods

Constructor Detail

MultiActionController

public MultiActionController()
                      throws ApplicationContextException

Constructor for MultiActionController that looks for handler methods in the present subclass. Caches methods for quick invocation later. This class's use of reflection will impose little overhead at runtime

Throws:

ApplicationContextException - if the class doesn't contain any action handler methods (and so could never handle any requests).

MultiActionController

public MultiActionController(java.lang.Object delegate)
                      throws ApplicationContextException

Constructor for MultiActionController that looks for handler methods in delegate, rather than a subclass of this class. Caches methds

Parameters:

delegate - handler class. This doesn't need to implement any particular interface, as everything is done using reflection.

Throws:

ApplicationContextException - if the class doesn't contain any handler methods

Method Detail

setMethodNameResolver

public final void setMethodNameResolver(MethodNameResolver methodNameResolver)

Sets the method name resolver used by this class. Allows parameterization of mappings.

Parameters:

methodNameResolver - the method name resolver used by this class

getMethodNameResolver

public final MethodNameResolver getMethodNameResolver()

Get the MethodNameResolver used by this class

Returns:

MethodNameResolver the method name resolver used by this class

setDelegate

public final void setDelegate(java.lang.Object delegate)
                       throws ApplicationContextException

Set the delegate used by this class. The default is "this", assuming that handler methods have been added by a subclass. This method is rarely invoked once the class is configured.

Parameters:

delegate - class containing methods, which may be the present class, the handler methods being in a subclass

Throws:

ApplicationContextException - if there aren't any valid request handling methods in the subclass.

getLastModified

public final long getLastModified(javax.servlet.http.HttpServletRequest request)

Try to find an XXXXLastModified method, where XXXX is the name of a handler. Return -1, indicating that content must be updated, if there's no such handler.

Specified by:

getLastModified in interface LastModified

See Also:

LastModified.getLastModified(HttpServletRequest)

handleRequest

public final ModelAndView handleRequest(javax.servlet.http.HttpServletRequest request,
                                        javax.servlet.http.HttpServletResponse response)
                                 throws javax.servlet.ServletException,
                                        java.io.IOException

Description copied from interface: Controller

Process the request and return a ModelAndView object which the DispatcherServlet will render. A null return is not an error. It indicates that this object completed request processing itself, thus there is no ModelAndView to render.

Specified by:

handleRequest in interface Controller

See Also:

AbstractController.handleRequestInternal(HttpServletRequest, HttpServletResponse)

invokeNamedMethod

protected final ModelAndView invokeNamedMethod(java.lang.String method,
                                               javax.servlet.http.HttpServletRequest request,
                                               javax.servlet.http.HttpServletResponse response)
                                        throws NoSuchRequestHandlingMethodException,
                                               javax.servlet.ServletException,
                                               java.io.IOException

Invoke the named method. Use a custom exception handler if possible; otherwise, throw an unchecked exception; wrap a checked exception or Throwable

newCommandObject

protected java.lang.Object newCommandObject(java.lang.Class clazz)
                                     throws javax.servlet.ServletException

Create a new command object of the given class.
Subclasses can override this implementation if they want. This implementation uses class.newInstance(), so commands need to have public no arg constructors.

bind

protected void bind(javax.servlet.ServletRequest request,
                    java.lang.Object command)
             throws javax.servlet.ServletException

Bind request parameters onto the given command bean

Parameters:

request - request from which parameters will be bound

command - command object, that must be a JavaBean

getExceptionHandler

protected java.lang.reflect.Method getExceptionHandler(java.lang.Throwable exception)

Can return null if not found

Parameters:

exception - Won't be a ServletException or IOException

Returns:

a handler for the given exception type