org.wandora.modules.servlet

Class AbstractAction

java.lang.Object

org.wandora.modules.AbstractModule

org.wandora.modules.ScriptModule

org.wandora.modules.servlet.AbstractAction

All Implemented Interfaces:

Module, ActionHandler, ServletModule.RequestListener

Direct Known Subclasses:

AbstractWebApp, BrowserPluginService, CachedAction, ChainedAction, GetUserLogAction, RecaptchaAction, RedirectAction, StaticContentAction, UserLoggerAction

public abstract class AbstractAction
extends ScriptModule
implements ServletModule.RequestListener, ActionHandler

The base class for action modules, that is modules that respond to an HTTP request and return some content. It implements ServletModule.RequestListener which makes it possible to register itself to ServletModules. In addition, it also implements ActionHandler which is needed if the action is used inside one of the context classes.

If you extend this class directly, your main point of extension is the only abstract method, handleAction, and the basic Module initialisation methods. If you wish to be notified of every HTTP request without any filtering, override the handleRequest instead.

This action reads parameters with following names from the initialisation parameters. actionParamKey can be used to specify the HTTP request parameter which contains the action id, this defaults to "action". action parameter contains the id of this action, alternatively, you can use parameter actions and provide a comma separated list of multiple ids, the default is to have no id associated with this action. defaultAction parameter can be set to "true" to make this a default action. If the action id is not specified in the request and this is a default action, it'll try to handle the action. Any parameter with its name prefixed with "httpheader." will be used to add custom HTTP headers in the response. The part following this prefix in the parameter name is not important, it only needs to be unique in the module. The actual header name and value are parsed from the contents of the element. It should contain the header name followed by a colon character (:) followed by the value.

Note that custom HTTP headers can be added in the initialisation parameters but they don't get automatically in the response. Instead, you will need to call setHttpHeaders in your handleAction code to have them added.

Author:

olli

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.String	actionParamKey
protected java.util.Collection<java.lang.String>	handledActions
protected java.util.HashMap<java.lang.String,java.lang.String>	httpHeaders
protected boolean	isDefaultAction
protected ReplacementsModule	replacements
protected boolean	replacementsInitialized
protected ServletModule	servletModule

Fields inherited from class org.wandora.modules.ScriptModule

engine, initScript, persistentObjects, scriptManager, startScript, stopScript

Fields inherited from class org.wandora.modules.AbstractModule

autoStart, isInitialized, isRunning, logging, loggingModule, moduleManager

Constructor Summary

Constructors

Constructor and Description
AbstractAction()

Method Summary

Modifier and Type	Method and Description
protected void	addHandledAction(java.lang.String action)
java.lang.String	doReplacements(java.lang.String value, javax.servlet.http.HttpServletRequest req, ModulesServlet.HttpMethod method, java.lang.String action, User user) Performs basic string replacement using a ReplacementsModule if one is available.
java.util.Collection<Module>	getDependencies(ModuleManager manager) Returns all the modules this module depends on.
abstract boolean	handleAction(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp, ModulesServlet.HttpMethod method, java.lang.String action, User user) Handles this action.
boolean	handleRequest(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp, ModulesServlet.HttpMethod method, User user) Handles the request, if this is the type of request the listener is interested in.
void	init(ModuleManager manager, java.util.HashMap<java.lang.String,java.lang.Object> settings) Initialises the module.
boolean	isHandleAction(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp, ModulesServlet.HttpMethod method) Checks if this action handler will try to handle the given action without handling it yet or causing any side effects.
protected void	setActionParamKey(java.lang.String key)
protected void	setHttpHeaders(javax.servlet.http.HttpServletResponse resp, java.util.Map<java.lang.String,java.lang.String> headers) Sets HTTP headers from a Map of key value pairs.
void	start(ModuleManager manager) Starts the module.
void	stop(ModuleManager manager) Stops the module.

Methods inherited from class org.wandora.modules.ScriptModule

getScriptEngine

Methods inherited from class org.wandora.modules.AbstractModule

isInitialized, isRunning, requireLogging, toString

Methods inherited from class java.lang.Object

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

Field Detail

isDefaultAction

protected boolean isDefaultAction

servletModule

protected ServletModule servletModule

actionParamKey

protected java.lang.String actionParamKey

handledActions

protected final java.util.Collection<java.lang.String> handledActions

httpHeaders

protected final java.util.HashMap<java.lang.String,java.lang.String> httpHeaders

replacementsInitialized

protected boolean replacementsInitialized

replacements

protected ReplacementsModule replacements

Constructor Detail

AbstractAction

public AbstractAction()

Method Detail

addHandledAction

protected void addHandledAction(java.lang.String action)

setActionParamKey

protected void setActionParamKey(java.lang.String key)

getDependencies

public java.util.Collection<Module> getDependencies(ModuleManager manager)
                                             throws ModuleException

Description copied from interface: Module

Returns all the modules this module depends on. This method will be called after init and the dependencies are allowed to depend on the parameters passed to init. The modules that this module depends on must be returned as a collection. In addition, if any required module is not present, a MissingDependencyException should be thrown. Typically you will use the requireModule and optionalModule methods of the manager to make sure that the modules exist and add them to the collection. requireModule will automatically throw the exception too if the module is not found whereas optionalModule does not.

Specified by:

getDependencies in interface Module

Overrides:

getDependencies in class AbstractModule

Parameters:

manager - The module manager handling this module.

Returns:

A collection of modules this module depends on.

Throws:

ModuleException

doReplacements

public java.lang.String doReplacements(java.lang.String value,
                                       javax.servlet.http.HttpServletRequest req,
                                       ModulesServlet.HttpMethod method,
                                       java.lang.String action,
                                       User user)

Performs basic string replacement using a ReplacementsModule if one is available. Otherwise returns the value as is. See ReplacementsModule for more information. Adds certain things from the request in the context that will be passed to the replacements module. Context variable user contains the user, req contains the request and action contains the action name.

Parameters:

value - The value in which replacement is to be done.

req - The HTTP request where this call originated.

method - The method of the HTTP request.

action - The parsed action.

user - The logged in user, or null if not applicable.

Returns:

The value after replacements have been done.

init

public void init(ModuleManager manager,
                 java.util.HashMap<java.lang.String,java.lang.Object> settings)
          throws ModuleException

Description copied from interface: Module

Initialises the module. After constructor, this is the first method called in the life cycle of a module. It should not perform anything time consuming or anything with notable outside side effects. It should only read the parameters and initialise the module so that it can later be started. Note that a module being initialised doesn't mean that it necessarily will ever be started.

A ModuleException may be thrown if something vital is missing from the parameters or they are not sensible. In some cases you may not want to throw an exception even if vital initialisation information is missing. If, for example, it is possible that the module is initialised in some other way between the init and the start method calls. A ModuleException may also be thrown at the start method if the module is still not initialised.

Specified by:

init in interface Module

Overrides:

init in class ScriptModule

Parameters:

manager - The module manager handling this module. You may keep a reference to it if needed.

Throws:

ModuleException

start

public void start(ModuleManager manager)
           throws ModuleException

Description copied from interface: Module

Starts the module. This will be called after init and getDependencies and signals that the module should now begin to perform whatever it was designed to do. This method call however should not block for long, so any time consuming tasks should be started in their own threads. You will typically get references to the required modules again in start using the findModule method of the manager and then store those references to instance variables for later use. You may throw a ModuleException if the module is not in a state where it can be started or it immediately becomes obvious that it cannot be started with the provided settings.

Specified by:

start in interface Module

Overrides:

start in class ScriptModule

Parameters:

manager - The module manager handling this module.

Throws:

ModuleException

stop

public void stop(ModuleManager manager)

Description copied from interface: Module

Stops the module. Should stop all threads used by the module, free any large data structures and perform other cleanup. It is possible that the module will be started again later with a start method call (and foregoing init and getDependencies calls). The module should be left in a state where this is possible.

Specified by:

stop in interface Module

Overrides:

stop in class ScriptModule

Parameters:

manager - The module manager handling this module.

setHttpHeaders

protected void setHttpHeaders(javax.servlet.http.HttpServletResponse resp,
                              java.util.Map<java.lang.String,java.lang.String> headers)

Sets HTTP headers from a Map of key value pairs. You typically pass the field httpHeaders to this method if you wish to add them in the response.

Parameters:

resp - The HTTP response object.

headers - A Map containing the headers to be added.

handleAction

public abstract boolean handleAction(javax.servlet.http.HttpServletRequest req,
                                     javax.servlet.http.HttpServletResponse resp,
                                     ModulesServlet.HttpMethod method,
                                     java.lang.String action,
                                     User user)
                              throws javax.servlet.ServletException,
                                     java.io.IOException,
                                     ActionException

Handles this action. Prior to calling this action, it's already been determined that this action should try to handle the action by either matching the action request parameter with the action id of this action, or this being the default action. Perform any operations needed here and then write the response into the response object. You will typically want to call setHttpHeaders to set the HTTP headers in the response after you know that you definitely will handle the request but before you write anything else into the response stream. If for whatever reason this method shouldn't handle the request after all, return false. Otherwise return true.

Parameters:

req - The HTTP Request.

resp - The HTTP response.

method - The HTTP method of the request.

action - The parsed action id.

user - The logged in user, or null if not applicable.

Returns:

True if the action was handled and a response sent. False otherwise in which case other actions may try to handle this action.

Throws:

javax.servlet.ServletException

java.io.IOException

ActionException

isHandleAction

public boolean isHandleAction(javax.servlet.http.HttpServletRequest req,
                              javax.servlet.http.HttpServletResponse resp,
                              ModulesServlet.HttpMethod method)

Description copied from interface: ActionHandler

Checks if this action handler will try to handle the given action without handling it yet or causing any side effects. Returning true means that the action handler will try to handle it, not necessarily that the action will succeed. You may also return false from the handleRequest method even if you return true here. The return value should be your best guess as to whether you will handle it without spending too much time checking.

Specified by:

isHandleAction in interface ActionHandler

Parameters:

req - The HTTP request.

resp - The HTTP response.

method - The HTTP method of the request.

Returns:

handleRequest

public boolean handleRequest(javax.servlet.http.HttpServletRequest req,
                             javax.servlet.http.HttpServletResponse resp,
                             ModulesServlet.HttpMethod method,
                             User user)
                      throws javax.servlet.ServletException,
                             java.io.IOException,
                             ActionException

Description copied from interface: ServletModule.RequestListener

Handles the request, if this is the type of request the listener is interested in. If the listener does not wish to handle the request, it should return false. False return value indicates that the request should be passed to other listeners, a true return value indicates that this should not happen and a response to the request has been sent. Thus it is possible that you perform some action and still return false and let some other action write the response.

However, keep in mind that some other listener may grab any request before your listener and your listener will then never even see the request. Thus, you will not necessarily be notified of every single request. If this is your goal, you should probably make a separate context that all requests will pass through before they are passed on to other actions, see GenericContext.

Specified by:

handleRequest in interface ServletModule.RequestListener

Parameters:

req - The HTTP request.

resp - The HTTP response.

method - The HTTP method of the request.

user - The logged in user if applicable or null.

Returns:

True if a response has been sent and no further listener should try to process the request. False if the request can be forwarded to other listeners for processing.

Throws:

javax.servlet.ServletException

java.io.IOException

ActionException