ActionServlet

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org.apache.struts.action
Class ActionServlet

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          org.apache.struts.action.ActionServlet

All Implemented Interfaces:: java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public class ActionServlet
extends javax.servlet.http.HttpServlet

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:

The user interface will generally be created with server pages, which will not themselves contain any business logic. These pages represent the "view" component of an MVC architecture.
Forms and hyperlinks in the user interface that require business logic to be executed will be submitted to a request URI that is mapped to this servlet.
There can be one instance of this servlet class, which receives and processes all requests that change the state of a user's interaction with the application. The servlet delegates the handling of a request to a RequestProcessor object. This component represents the "controller" component of an MVC architecture.
The RequestProcessor selects and invokes an Action class to perform the requested business logic, or delegates the response to another resource.
The 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.
Instead of producing the next page of the user interface directly, 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.

Identify, from the incoming request URI, the substring that will be used to select an action procedure.
Use this substring to map to the Java class name of the corresponding action class (an implementation of the Action interface).
If this is the first request for a particular Action class, instantiate an instance of that class and cache it for future use.
Optionally populate the properties of an ActionForm bean associated with this mapping.
Call the 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.

config - Comma-separated list of context-relative path(s) to the XML resource(s) containing the configuration information for the default module. (Multiple files support since Struts 1.1) [/WEB-INF/struts-config.xml].
config/${module} - Comma-separated list of Context-relative path(s) to the XML resource(s) containing the configuration information for the module that will use the specified prefix (/${module}). This can be repeated as many times as required for multiple modules. (Since Struts 1.1)
configFactory - The Java class name of the ModuleConfigFactory used to create the implementation of the ModuleConfig interface. [org.apache.struts.config.impl.DefaultModuleConfigFactory]
convertNull - Force simulation of the Struts 1.0 behavior when populating forms. If set to true, the numeric Java wrapper class types (like java.lang.Integer) will default to null (rather than 0). (Since Struts 1.1) [false]
rulesets - Comma-delimited list of fully qualified classnames of additional 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)
validating - Should we use a validating XML parser to process the configuration file (strongly recommended)? [true]

Version:: $Rev: 264684 $ $Date: 2005-08-30 04:08:01 +0100 (Tue, 30 Aug 2005) $

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 org.apache.struts.util.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

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.

org.apache.struts.util.MessageResources getInternal()
          Return the MessageResources instance containing our internal message strings.

protected org.apache.struts.config.ModuleConfig getModuleConfig(javax.servlet.http.HttpServletRequest request)
          Return the module configuration object for the currently selected module.

private RequestProcessor getProcessorForModule(org.apache.struts.config.ModuleConfig config)
          Returns the RequestProcessor for the given module or null if one does not exist.

protected RequestProcessor getRequestProcessor(org.apache.struts.config.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 org.apache.struts.config.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(org.apache.struts.config.ModuleConfig config)
          Initialize the data sources for the specified module.

protected void initModuleMessageResources(org.apache.struts.config.ModuleConfig config)
          Initialize the application MessageResources for the specified module.

protected void initModulePlugIns(org.apache.struts.config.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

doDelete, doHead, doOptions, doPut, doTrace, getLastModified, service, service

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, toString, wait, wait, wait

Field Detail

config

protected java.lang.String config

Comma-separated list of context-relative path(s) to our configuration resource(s) for the default module.

configDigester

protected org.apache.commons.digester.Digester configDigester

The Digester used to produce ModuleConfig objects from a Struts configuration file.

Since:: Struts 1.1

convertNull

protected boolean convertNull

The flag to request backwards-compatible conversions for form bean properties of the Java wrapper class types.

Since:: Struts 1.1

dataSources

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.

internal

protected org.apache.struts.util.MessageResources internal

The resources object for our internal resources.

internalName

protected java.lang.String internalName

The Java base name of our internal resources.

Since:: Struts 1.1

log

protected static org.apache.commons.logging.Log log

Commons Logging instance.

Since:: Struts 1.1

processor

protected RequestProcessor processor

The RequestProcessor instance we will use to process all incoming requests.

Since:: Struts 1.1

registrations

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!

servletMapping

protected java.lang.String servletMapping

The URL pattern to which we are mapped in our web application deployment descriptor.

servletName

protected java.lang.String servletName

The servlet name under which we are registered in our web application deployment descriptor.

Constructor Detail

ActionServlet

public ActionServlet()

Method Detail

destroy

public void destroy()

Gracefully shut down this controller servlet, releasing any resources that were allocated at initialization.

init

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.

initModulePrefixes

protected 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.

Since:: Struts 1.2

doGet

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.

doPost

public void doPost(javax.servlet.http.HttpServletRequest request,
                   javax.servlet.http.HttpServletResponse response)
            throws java.io.IOException,
                   javax.servlet.ServletException

Process an HTTP "POST" request.

addServletMapping

public 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.

getInternal

public org.apache.struts.util.MessageResources getInternal()

Return the MessageResources instance containing our internal message strings.

Since:: Struts 1.1

destroyModules

protected void destroyModules()

Gracefully terminate use of any modules associated with this application (if any).

Since:: Struts 1.1

destroyConfigDigester

protected void destroyConfigDigester()

Gracefully release any configDigester instance that we have created.

Since:: Struts 1.1

destroyInternal

protected void destroyInternal()

Gracefully terminate use of the internal MessageResources.

getModuleConfig

protected org.apache.struts.config.ModuleConfig getModuleConfig(javax.servlet.http.HttpServletRequest request)

Return the module configuration object for the currently selected module.

Since:: Struts 1.1

getRequestProcessor

protected RequestProcessor getRequestProcessor(org.apache.struts.config.ModuleConfig config)
                                        throws javax.servlet.ServletException

Look up and return the RequestProcessor responsible for the specified module, creating a new one if necessary.

Since:: Struts 1.1

getProcessorForModule

private RequestProcessor getProcessorForModule(org.apache.struts.config.ModuleConfig config)

Returns the RequestProcessor for the given module or null if one does not exist. This method will not create a RequestProcessor.

initModuleConfigFactory

protected void initModuleConfigFactory()

Initialize the factory used to create the module configuration.

Since:: Struts 1.2

initModuleConfig

protected org.apache.struts.config.ModuleConfig initModuleConfig(java.lang.String prefix,
                                                                 java.lang.String paths)
                                                          throws javax.servlet.ServletException

Initialize the module configuration information for the specified module.

Since:: Struts 1.1

parseModuleConfigFile

protected void parseModuleConfigFile(org.apache.commons.digester.Digester digester,
                                     java.lang.String path)
                              throws javax.servlet.UnavailableException

Parses one module config file.

Since:: Struts 1.2

handleConfigException

private void handleConfigException(java.lang.String path,
                                   java.lang.Exception e)
                            throws javax.servlet.UnavailableException

Simplifies exception handling in the parseModuleConfigFile method.

initModuleDataSources

protected void initModuleDataSources(org.apache.struts.config.ModuleConfig config)
                              throws javax.servlet.ServletException

Initialize the data sources for the specified module.

Since:: Struts 1.1

initModulePlugIns

protected void initModulePlugIns(org.apache.struts.config.ModuleConfig config)
                          throws javax.servlet.ServletException

Initialize the plug ins for the specified module.

Since:: Struts 1.1

initModuleMessageResources

protected void initModuleMessageResources(org.apache.struts.config.ModuleConfig config)
                                   throws javax.servlet.ServletException

Initialize the application MessageResources for the specified module.

Since:: Struts 1.1

initConfigDigester

protected 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).

Since:: Struts 1.1

addRuleSets

private void addRuleSets()
                  throws javax.servlet.ServletException

Add any custom RuleSet instances to configDigester that have been specified in the rulesets init parameter.

isValidating

private boolean isValidating()

Check the status of the validating initialization parameter.

initInternal

protected void initInternal()
                     throws javax.servlet.ServletException

Initialize our internal MessageResources bundle.

initOther

protected void initOther()
                  throws javax.servlet.ServletException

Initialize other global characteristics of the controller servlet.

initServlet

protected 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.

process

protected 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.

Overview

Package

Class

Use

Deprecated

Index

Home >> All >> org >> apache >> struts >> [ action overview ]

PREV CLASS NEXT CLASS

SUMMARY:

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DETAIL: FIELD | CONSTR | METHOD

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 org.apache.struts.util.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.

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.
`org.apache.struts.util.MessageResources`	`getInternal()` Return the `MessageResources` instance containing our internal message strings.
`protected org.apache.struts.config.ModuleConfig`	`getModuleConfig(javax.servlet.http.HttpServletRequest request)` Return the module configuration object for the currently selected module.
`private RequestProcessor`	`getProcessorForModule(org.apache.struts.config.ModuleConfig config)` Returns the RequestProcessor for the given module or null if one does not exist.
`protected RequestProcessor`	`getRequestProcessor(org.apache.struts.config.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 org.apache.struts.config.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(org.apache.struts.config.ModuleConfig config)` Initialize the data sources for the specified module.
`protected void`	`initModuleMessageResources(org.apache.struts.config.ModuleConfig config)` Initialize the application `MessageResources` for the specified module.
`protected void`	`initModulePlugIns(org.apache.struts.config.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.

org.apache.struts.action Class ActionServlet

config

configDigester

convertNull

dataSources

internal

internalName

log

processor

registrations

servletMapping

servletName

ActionServlet

destroy

init

initModulePrefixes

doGet

doPost

addServletMapping

getInternal

destroyModules

destroyConfigDigester

destroyInternal

getModuleConfig

getRequestProcessor

getProcessorForModule

initModuleConfigFactory

initModuleConfig

parseModuleConfigFile

handleConfigException

initModuleDataSources

initModulePlugIns

initModuleMessageResources

initConfigDigester

addRuleSets

isValidating

initInternal

initOther

initServlet

process

org.apache.struts.action
Class ActionServlet