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SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Object | +--javax.servlet.GenericServlet | +--javax.servlet.http.HttpServlet | +--org.apache.struts.action.ActionServlet
ActionServlet provides the "controller" in the Model-View-Controller (MVC) design pattern for web applications that is commonly known as "Model 2". This nomenclature originated with a description in the JavaServerPages Specification, version 0.92, and has persisted ever since (in the absence of a better name).
Generally, a "Model 2" application is architected as follows:
RequestProcessor
object. This component
represents the "controller" component of an MVC architecture.RequestProcessor
selects and invokes an Action
class to perform
the requested business logic, or delegates the response to another resource.Action
classes can manipulate the state of the application's
interaction with the user, typically by creating or modifying JavaBeans
that are stored as request or session attributes (depending on how long
they need to be available). Such JavaBeans represent the "model"
component of an MVC architecture.Action
classes generally return an ActionForward
to indicate
which resource should handle the response. If the Action
does not return null, the RequestProcessor
forwards or
redirects to the specified resource (by utilizing
RequestDispatcher.forward
or Response.sendRedirect
)
so as to produce the next page of the user interface.The standard version of RequestsProcessor
implements the
following logic for each incoming HTTP request. You can override
some or all of this functionality by subclassing this object and
implementing your own version of the processing.
Action
interface).
Action
class,
instantiate an instance of that class and cache it for future use.ActionForm
bean
associated with this mapping.execute
method of this Action
class, passing
on a reference to the mapping that was used, the relevant form-bean
(if any), and the request and the response that were passed to the
controller by the servlet container (thereby providing access to any
specialized properties of the mapping itself as well as to the
ServletContext).
The standard version of ActionServlet
is configured based
on the following servlet initialization parameters, which you will specify
in the web application deployment descriptor (/WEB-INF/web.xml
)
for your application. Subclasses that specialize this servlet are free to
define additional initialization parameters.
ModuleConfigFactory
used to create the implementation of the
ModuleConfig
interface.
[org.apache.struts.config.impl.DefaultModuleConfigFactory]
java.lang.Integer
) will default to null (rather than 0).
(Since Struts 1.1) [false] org.apache.commons.digester.RuleSet
instances that should be added to the Digester
that will
be processing struts-config.xml
files. By default, only
the RuleSet
for the standard configuration elements is
loaded. (Since Struts 1.1)
Field Summary | |
protected java.lang.String |
config
Comma-separated list of context-relative path(s) to our configuration resource(s) for the default module. |
protected org.apache.commons.digester.Digester |
configDigester
The Digester used to produce ModuleConfig objects from a Struts configuration file. |
protected boolean |
convertNull
The flag to request backwards-compatible conversions for form bean properties of the Java wrapper class types. |
protected org.apache.commons.collections.FastHashMap |
dataSources
The JDBC data sources that has been configured for this module, if any, keyed by the servlet context attribute under which they are stored. |
protected MessageResources |
internal
The resources object for our internal resources. |
protected java.lang.String |
internalName
The Java base name of our internal resources. |
protected static org.apache.commons.logging.Log |
log
Commons Logging instance. |
protected RequestProcessor |
processor
The RequestProcessor instance we will use to process
all incoming requests. |
protected java.lang.String[] |
registrations
The set of public identifiers, and corresponding resource names, for the versions of the configuration file DTDs that we know about. |
protected java.lang.String |
servletMapping
The URL pattern to which we are mapped in our web application deployment descriptor. |
protected java.lang.String |
servletName
The servlet name under which we are registered in our web application deployment descriptor. |
Fields inherited from class javax.servlet.http.HttpServlet |
HEADER_IFMODSINCE, HEADER_LASTMOD, LSTRING_FILE, lStrings, METHOD_DELETE, METHOD_GET, METHOD_HEAD, METHOD_OPTIONS, METHOD_POST, METHOD_PUT, METHOD_TRACE |
Constructor Summary | |
ActionServlet()
|
Method Summary | |
private void |
addRuleSets()
Add any custom RuleSet instances to configDigester that have been specified in the rulesets init parameter. |
void |
addServletMapping(java.lang.String servletName,
java.lang.String urlPattern)
Remember a servlet mapping from our web application deployment descriptor, if it is for this servlet. |
void |
destroy()
Gracefully shut down this controller servlet, releasing any resources that were allocated at initialization. |
protected void |
destroyConfigDigester()
Gracefully release any configDigester instance that we have created. |
protected void |
destroyInternal()
Gracefully terminate use of the internal MessageResources. |
protected void |
destroyModules()
Gracefully terminate use of any modules associated with this application (if any). |
void |
doGet(javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response)
Process an HTTP "GET" request. |
void |
doPost(javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response)
Process an HTTP "POST" request. |
MessageResources |
getInternal()
Return the MessageResources instance containing our
internal message strings. |
protected ModuleConfig |
getModuleConfig(javax.servlet.http.HttpServletRequest request)
Return the module configuration object for the currently selected module. |
private RequestProcessor |
getProcessorForModule(ModuleConfig config)
Returns the RequestProcessor for the given module or null if one does not exist. |
protected RequestProcessor |
getRequestProcessor(ModuleConfig config)
Look up and return the RequestProcessor responsible for the
specified module, creating a new one if necessary. |
private void |
handleConfigException(java.lang.String path,
java.lang.Exception e)
Simplifies exception handling in the parseModuleConfigFile method. |
void |
init()
Initialize this servlet. |
protected org.apache.commons.digester.Digester |
initConfigDigester()
Create (if needed) and return a new Digester
instance that has been initialized to process Struts module
configuration files and configure a corresponding ModuleConfig
object (which must be pushed on to the evaluation stack before parsing
begins). |
protected void |
initInternal()
Initialize our internal MessageResources bundle. |
protected ModuleConfig |
initModuleConfig(java.lang.String prefix,
java.lang.String paths)
Initialize the module configuration information for the specified module. |
protected void |
initModuleConfigFactory()
Initialize the factory used to create the module configuration. |
protected void |
initModuleDataSources(ModuleConfig config)
Initialize the data sources for the specified module. |
protected void |
initModuleMessageResources(ModuleConfig config)
Initialize the application MessageResources for the specified
module. |
protected void |
initModulePlugIns(ModuleConfig config)
Initialize the plug ins for the specified module. |
protected void |
initModulePrefixes(javax.servlet.ServletContext context)
Saves a String[] of module prefixes in the ServletContext under Globals.MODULE_PREFIXES_KEY. |
protected void |
initOther()
Initialize other global characteristics of the controller servlet. |
protected void |
initServlet()
Initialize the servlet mapping under which our controller servlet is being accessed. |
private boolean |
isValidating()
Check the status of the validating initialization parameter. |
protected void |
parseModuleConfigFile(org.apache.commons.digester.Digester digester,
java.lang.String path)
Parses one module config file. |
protected void |
process(javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response)
Perform the standard request processing for this request, and create the corresponding response. |
Methods inherited from class javax.servlet.http.HttpServlet |
|
Methods inherited from class javax.servlet.GenericServlet |
getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, registerNatives, toString, wait, wait, wait |
Field Detail |
protected java.lang.String config
Comma-separated list of context-relative path(s) to our configuration resource(s) for the default module.
protected org.apache.commons.digester.Digester configDigester
The Digester used to produce ModuleConfig objects from a Struts configuration file.
protected boolean convertNull
The flag to request backwards-compatible conversions for form bean properties of the Java wrapper class types.
protected org.apache.commons.collections.FastHashMap dataSources
The JDBC data sources that has been configured for this module, if any, keyed by the servlet context attribute under which they are stored.
protected MessageResources internal
The resources object for our internal resources.
protected java.lang.String internalName
The Java base name of our internal resources.
protected static org.apache.commons.logging.Log log
Commons Logging instance.
protected RequestProcessor processor
The RequestProcessor
instance we will use to process
all incoming requests.
protected java.lang.String[] registrations
The set of public identifiers, and corresponding resource names, for the versions of the configuration file DTDs that we know about. There MUST be an even number of Strings in this list!
protected java.lang.String servletMapping
The URL pattern to which we are mapped in our web application deployment descriptor.
protected java.lang.String servletName
The servlet name under which we are registered in our web application deployment descriptor.
Constructor Detail |
public ActionServlet()
Method Detail |
public void destroy()
Gracefully shut down this controller servlet, releasing any resources that were allocated at initialization.
destroy
in class javax.servlet.GenericServlet
public void init() throws javax.servlet.ServletException
Initialize this servlet. Most of the processing has been factored into support methods so that you can override particular functionality at a fairly granular level.
init
in class javax.servlet.GenericServlet
javax.servlet.ServletException
- if we cannot configure ourselves correctlyprotected void initModulePrefixes(javax.servlet.ServletContext context)
Saves a String[] of module prefixes in the ServletContext under Globals.MODULE_PREFIXES_KEY. NOTE - the "" prefix for the default module is not included in this list.
context
- The servlet context.public void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws java.io.IOException, javax.servlet.ServletException
Process an HTTP "GET" request.
doGet
in class javax.servlet.http.HttpServlet
request
- The servlet request we are processingresponse
- The servlet response we are creatingjava.io.IOException
- if an input/output error occursjavax.servlet.ServletException
- if a servlet exception occurspublic void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws java.io.IOException, javax.servlet.ServletException
Process an HTTP "POST" request.
doPost
in class javax.servlet.http.HttpServlet
request
- The servlet request we are processingresponse
- The servlet response we are creatingjava.io.IOException
- if an input/output error occursjavax.servlet.ServletException
- if a servlet exception occurspublic void addServletMapping(java.lang.String servletName, java.lang.String urlPattern)
Remember a servlet mapping from our web application deployment descriptor, if it is for this servlet.
servletName
- The name of the servlet being mappedurlPattern
- The URL pattern to which this servlet is mappedpublic MessageResources getInternal()
Return the MessageResources
instance containing our
internal message strings.
protected void destroyModules()
Gracefully terminate use of any modules associated with this application (if any).
protected void destroyConfigDigester()
Gracefully release any configDigester instance that we have created.
protected void destroyInternal()
Gracefully terminate use of the internal MessageResources.
protected ModuleConfig getModuleConfig(javax.servlet.http.HttpServletRequest request)
Return the module configuration object for the currently selected module.
request
- The servlet request we are processingprotected RequestProcessor getRequestProcessor(ModuleConfig config) throws javax.servlet.ServletException
Look up and return the RequestProcessor
responsible for the
specified module, creating a new one if necessary.
config
- The module configuration for which to
acquire and return a RequestProcessor.javax.servlet.ServletException
- if we cannot instantiate a RequestProcessor
instanceprivate RequestProcessor getProcessorForModule(ModuleConfig config)
Returns the RequestProcessor for the given module or null if one does not exist. This method will not create a RequestProcessor.
config
- The ModuleConfig.protected void initModuleConfigFactory()
Initialize the factory used to create the module configuration.
protected ModuleConfig initModuleConfig(java.lang.String prefix, java.lang.String paths) throws javax.servlet.ServletException
Initialize the module configuration information for the specified module.
prefix
- Module prefix for this modulepaths
- Comma-separated list of context-relative resource path(s)
for this modules's configuration resource(s)javax.servlet.ServletException
- if initialization cannot be performedprotected void parseModuleConfigFile(org.apache.commons.digester.Digester digester, java.lang.String path) throws javax.servlet.UnavailableException
Parses one module config file.
digester
- Digester instance that does the parsingpath
- The path to the config file to parse.javax.servlet.UnavailableException
- if file cannot be read or parsedprivate void handleConfigException(java.lang.String path, java.lang.Exception e) throws javax.servlet.UnavailableException
Simplifies exception handling in the parseModuleConfigFile
method.
path
- e
- javax.servlet.UnavailableException
- as a wrapper around Exceptionprotected void initModuleDataSources(ModuleConfig config) throws javax.servlet.ServletException
Initialize the data sources for the specified module.
config
- ModuleConfig information for this modulejavax.servlet.ServletException
- if initialization cannot be performedprotected void initModulePlugIns(ModuleConfig config) throws javax.servlet.ServletException
Initialize the plug ins for the specified module.
config
- ModuleConfig information for this modulejavax.servlet.ServletException
- if initialization cannot be performedprotected void initModuleMessageResources(ModuleConfig config) throws javax.servlet.ServletException
Initialize the application MessageResources
for the specified
module.
config
- ModuleConfig information for this modulejavax.servlet.ServletException
- if initialization cannot be performedprotected org.apache.commons.digester.Digester initConfigDigester() throws javax.servlet.ServletException
Create (if needed) and return a new Digester
instance that has been initialized to process Struts module
configuration files and configure a corresponding ModuleConfig
object (which must be pushed on to the evaluation stack before parsing
begins).
javax.servlet.ServletException
- if a Digester cannot be configuredprivate void addRuleSets() throws javax.servlet.ServletException
Add any custom RuleSet instances to configDigester that have
been specified in the rulesets
init parameter.
javax.servlet.ServletException
- private boolean isValidating()
Check the status of the validating
initialization parameter.
protected void initInternal() throws javax.servlet.ServletException
Initialize our internal MessageResources bundle.
javax.servlet.ServletException
- if we cannot initialize these resourcesprotected void initOther() throws javax.servlet.ServletException
Initialize other global characteristics of the controller servlet.
javax.servlet.ServletException
- if we cannot initialize these resourcesprotected void initServlet() throws javax.servlet.ServletException
Initialize the servlet mapping under which our controller servlet
is being accessed. This will be used in the &html:form>
tag to generate correct destination URLs for form submissions.
javax.servlet.ServletException
- if error happens while scanning web.xmlprotected void process(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws java.io.IOException, javax.servlet.ServletException
Perform the standard request processing for this request, and create the corresponding response.
request
- The servlet request we are processingresponse
- The servlet response we are creatingjava.io.IOException
- if an input/output error occursjavax.servlet.ServletException
- if a servlet exception is thrown
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