hirondelle.web4j.request
Class RequestParserImpl

Object
  hirondelle.web4j.request.RequestParser
      hirondelle.web4j.request.RequestParserImpl

public class RequestParserImpl
extends RequestParser

Maps each HTTP request to a concrete Action.

Default implementation of RequestParser.

This implementation extracts the URI Mapping String from the underlying request, and maps it to a specific Action class, and calls its constructor by passing a RequestParser. (Here, each Action must have a public constructor which takes a RequestParser as its single parameter.)

There are two kinds of mapping available :

• implicit mapping - simple, and recommended
• explicit mapping - requires an extra step, and overrides the implicit mapping

URI Mapping String

The 'URI Mapping String' is extracted from the underlying request. It is simply the concatention of HttpServletRequest.getServletPath() and HttpServletRequest.getPathInfo() (minus the extension - .do, for example).

(The servlet path is the part of the URI which has been mapped to a servlet by the servlet-mapping entries in the web.xml.)

Implicit Mapping

If no explicit mapping exists in an Action, then it will implicitly map to the URI Mapping String that corresponds to a modified version of its package-qualified name :

• take the package-qualified class name
• change '.' characters to '/'
• remove the base package prefix, configured in web.xml as ImplicitMappingRemoveBasePackage

Example of an implicit mapping :

Class Name:	hirondelle.fish.main.member.MemberEdit
ImplicitMappingRemoveBasePackage (web.xml):	hirondelle.fish
Implicit Mapping calculated as:	/main/member/MemberEdit

Which maps to the following requests:

Request 1:	http://www.blah.com/fish/main/member/MemberEdit.list
Request 2:	http://www.blah.com/fish/main/member/MemberEdit.do?Operation=List
URI Mapping String calculated as:	/main/member/MemberEdit

Explicit Mapping

An Action may declare an explicit mapping to a URI Mapping String simply by declaring a field of the form (for example) :

  public static final String EXPLICIT_URI_MAPPING = "/translate/basetext/BaseTextEdit";
 

Explicit mappings override implicit mappings.

Fine-Grained Security

Fine-grained security allows <security-constraint> items to be specifed for various extensions, where the extensions represent various action verbs, such as .list, .change, and so on. In that case, the conventional .do is replaced with several different extensions. See the User Guide for more information on fine-grained security.

Looking Up Action, Given URI

It's a common requirement to look up an action class, given a URI. Various sources can be used to perform that task:

• the application's javadoc listing of Constant Field Values can be quickly searched for an explicit EXPLICIT_URI_MAPPING
• all mappings are logged upon startup at CONFIG level
• the source code itself can be searched, if necessary

Constructor Summary

RequestParserImpl(HttpServletRequest aRequest, HttpServletResponse aResponse)
Constructor.

Method Summary

static String	getImplicitMappingRemoveBasePackage() Return the String configured in web.xml as being the base or root package that is to be ignored by the default Action mapping mechanism.
Action	getWebAction() Map an HTTP request to a concrete implementation of Action.
static void	initWebActionMappings() Scan for Action mappings.

Methods inherited from class hirondelle.web4j.request.RequestParser

getInstance, getRawParamValue, getRawParamValues, getRequest, getResponse, isFileUploadRequest, toId, toIds, toSafeText, toSafeTexts, toSupportedObject, toSupportedObjects

Methods inherited from class Object

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

Constructor Detail

RequestParserImpl

public RequestParserImpl(HttpServletRequest aRequest,
                         HttpServletResponse aResponse)

Constructor.

Parameters:

aRequest - passed to the super class.

aResponse - passed to the super class.

Method Detail

initWebActionMappings

public static void initWebActionMappings()

Scan for Action mappings. Called by the framework upon startup. Scans for all classes that implement Action. Stores either an implicit or an explicit mapping. Implicit mappings are the recommended style.

If a problem with mapping is detected, then a RuntimeException is thrown, and the application will not load. This protects the application, by forcing some important errors to occur during startup, instead of during normal operation. Possible errors include :

• the EXPLICIT_URI_MAPPING field is not a public static final String
• the same mapping is used for more than one Action

getWebAction

public final Action getWebAction()

Map an HTTP request to a concrete implementation of Action.

Extract the URI Mapping String from the underlying request, and map it to an Action.

Specified by:

getWebAction in class RequestParser

getImplicitMappingRemoveBasePackage

public static final String getImplicitMappingRemoveBasePackage()

Return the String configured in web.xml as being the base or root package that is to be ignored by the default Action mapping mechanism. See web.xml for more information.