Package org.apache.struts.dispatcher

Class AbstractDispatcher

java.lang.Object

org.apache.struts.dispatcher.AbstractDispatcher

All Implemented Interfaces:

Serializable, Dispatcher

Direct Known Subclasses:

AbstractMappingDispatcher, AbstractParameterDispatcher

public abstract class AbstractDispatcher
extends Object
implements Dispatcher, Serializable

This abstract class is the stock template for Dispatcher implementations.

Since:

Struts 1.4

Version:

$Rev$

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static final String	CANCELLED_METHOD_NAME	The name of the cancelled method.
static final String	EXECUTE_METHOD_NAME	The name of the execute method.

Constructor Summary

Constructors

Constructor	Description
AbstractDispatcher(MethodResolver methodResolver)	Constructs a new dispatcher with the specified method resolver.

Method Summary

Modifier and Type	Method	Description
Object	dispatch(ActionContext context)	Dispatches to the action referenced by the specified context.
protected final Object	dispatchMethod(ActionContext context, Method method, String name)	Dispatches to the specified method.
protected String	getDefaultMethodName()	Retrieves the name of the method to fallback upon if no method name can be resolved.
protected final Method	getMethod(ActionContext context, String methodName)	Introspects the action to identify a method of the specified name that will be the target of the dispatch.
protected final Object	invoke(Object target, Method method, Object[] args, String path)	Convenience method to help dispatch the specified method.
protected boolean	isCancelled(ActionContext context)	Determines whether the current form's cancel button was pressed.
protected Object	unspecified(ActionContext context)	Services the case when the dispatch fails because the method name cannot be resolved.

Methods inherited from class java.lang.Object

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

Field Details

CANCELLED_METHOD_NAME

public static final String CANCELLED_METHOD_NAME

The name of the cancelled method.

See Also:

• ActionContext.getCancelled()
• Constant Field Values

EXECUTE_METHOD_NAME

public static final String EXECUTE_METHOD_NAME

The name of the execute method.

See Also:

• Constant Field Values

Constructor Details

AbstractDispatcher

public AbstractDispatcher(MethodResolver methodResolver)

Constructs a new dispatcher with the specified method resolver.

Parameters:

methodResolver - the method resolver

Method Details

dispatch

public Object dispatch(ActionContext context)
                throws Exception

Description copied from interface: Dispatcher

Dispatches to the action referenced by the specified context.

Specified by:

dispatch in interface Dispatcher

Parameters:

context - the current action context

Returns:

the result type, null if the response was handled directly, or Void if the executed method has no return signature

Throws:

Exception - if an exception occurs

dispatchMethod

protected final Object dispatchMethod(ActionContext context,
 Method method,
 String name)
                               throws Exception

Dispatches to the specified method.

Parameters:

context - the current action context

method - The method to invoke

name - The name of the method to invoke

Returns:

the return value of the method

Throws:

Exception - if the dispatch fails with an exception

See Also:

• buildMethodArguments(ActionContext, Method)

getDefaultMethodName

protected String getDefaultMethodName()

Retrieves the name of the method to fallback upon if no method name can be resolved. The default implementation returns EXECUTE_METHOD_NAME.

Returns:

the fallback method name; can be null

See Also:

• resolveMethodName(ActionContext)
• EXECUTE_METHOD_NAME

getMethod

protected final Method getMethod(ActionContext context,
 String methodName)
                          throws NoSuchMethodException

Introspects the action to identify a method of the specified name that will be the target of the dispatch. This implementation caches the method instance for subsequent invocations.

Parameters:

context - the current action context

methodName - the name of the method to be introspected

Returns:

the method of the specified name

Throws:

NoSuchMethodException - if no such method can be found

See Also:

• resolveMethod(ActionContext, String)
• flushMethodCache()

invoke

protected final Object invoke(Object target,
 Method method,
 Object[] args,
 String path)
                       throws Exception

Convenience method to help dispatch the specified method. The method is invoked via reflection.

Parameters:

target - the target object

method - the method of the target object

args - the arguments for the method

path - the mapping path

Returns:

the return value of the method

Throws:

Exception - if the dispatch fails with an exception

isCancelled

protected boolean isCancelled(ActionContext context)

Determines whether the current form's cancel button was pressed. The default behavior method will check if the ActionContext.getCancelled() context property is set , which normally occurs if the cancel button generated by CancelTag was pressed by the user in the current request.

Parameters:

context - the current action context

Returns:

true if the request is cancelled; otherwise false

unspecified

protected Object unspecified(ActionContext context)
                      throws Exception

Services the case when the dispatch fails because the method name cannot be resolved. The default behavior throws an IllegalStateException. Subclasses should override this to provide custom handling such as sending an HTTP 404 error or dispatching elsewhere.

Parameters:

context - the current action context

Returns:

the return value of the dispatch

Throws:

Exception - if an error occurs

See Also:

• resolveMethodName(ActionContext)