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Description
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{snippet:id=javadoc|javadoc=true|url=org.apache.struts2.dispatcher.mapper.ActionMapper} |
DefaultActionMapper
By default, the DefaultActionMapper is used:
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{snippet:id=javadoc|javadoc=true|url=org.apache.struts2.dispatcher.mapper.DefaultActionMapper} |
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In Struts 2.1.6 and earlier the Redirect Action prefix is "redirect-action", it was changed to "redirectAction" after the release of Struts 2.1.6 |
Method prefix
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{snippet:id=method|javadoc=true|url=org.apache.struts2.dispatcher.mapper.DefaultActionMapper} |
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{snippet:id=method-example|lang=xml|javadoc=true|url=org.apache.struts2.dispatcher.mapper.DefaultActionMapper} |
Action prefix
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{snippet:id=action|javadoc=true|url=org.apache.struts2.dispatcher.mapper.DefaultActionMapper} |
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{snippet:id=action-example|lang=xml|javadoc=true|url=org.apache.struts2.dispatcher.mapper.DefaultActionMapper} |
Redirect prefix
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{snippet:id=redirect|javadoc=true|url=org.apache.struts2.dispatcher.mapper.DefaultActionMapper} |
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{snippet:id=redirect-example|lang=xml|javadoc=true|url=org.apache.struts2.dispatcher.mapper.DefaultActionMapper} |
Redirect-action prefix
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{snippet:id=redirect-action|javadoc=true|url=org.apache.struts2.dispatcher.mapper.DefaultActionMapper} |
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{snippet:id=redirect-action-example|lang=xml|javadoc=true|url=org.apache.struts2.dispatcher.mapper.DefaultActionMapper} |
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The ActionMapper interface provides a mapping between HTTP requests and action invocation requests and vice-versa.
When given an HttpServletRequest, the ActionMapper may return null if no action invocation request matches or it may return an {{ActionMapping}} that describes an action invocation for the framework to try.
The ActionMapper is not required to guarantee that the {{ActionMapping}} returned be a real action or otherwise ensure a valid request. Accordingly, most ActionMappers do not need to consult the Struts configuration just to determine if a request should be mapped.
Just as requests can be mapped from HTTP to an action invocation, the opposite is true as well. However, because HTTP requests (when shown in HTTP responses) must be in String form, a String is returned rather than an actual request object.
DefaultActionMapper
Default action mapper implementation, using the standard *.[ext]
(where ext usually action) pattern. The extension is looked up from the Struts configuration key {<b>{struts.action.extension}}.
To help with dealing with buttons and other related requirements, this mapper (and other {{ActionMapper}}s, we hope) has the ability to name a button with some predefined prefix and have that button name alter the execution behaviour. The four prefixes are:
- Method prefix -
method:default
- Action prefix -
action:dashboard
In addition to these four prefixes, this mapper also understands the action naming pattern of foo!bar
in either the extension form (eg: foo!bar.action
) or in the prefix form (eg: action:foo!bar
). This syntax tells this mapper to map to the action named foo
and the method bar
.
Method prefix
With method-prefix, instead of calling baz action's execute()
method (by default if it isn't overridden in struts.xml
to be something else), the baz action's anotherMethod()
will be called. A very elegant way determine which button is clicked. Alternatively, one would have submit button set a particular value on the action when clicked, and the execute()
method decides on what to do with the setted value depending on which button is clicked.
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Action prefix
With action-prefix, instead of executing baz action's execute()
method (by default if it isn't overridden in struts.xml to be something else), the anotherAction action's execute()
method (assuming again if it isn't overridden with something else in struts.xml
) will be executed.
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Allowed action name RegEx
By default the mapper will check if extracted action name matches provided RegEx, i.e. [a-zA-Z0-9._!/\-]*
. You redefine this RegEx by defining a constant in struts.xml
named struts.allowed.action.names
. If action name doesn't match the RegEx a default action name will be returned which is defined as index
. You can also redefine this by specifying constant struts.default.action.name
in struts.xml
Allowed method name RegEx
The same logic as above is used for extracted methods, the default RegEx (
[a-zA-Z_]*[0-9]*)
is used to check if method is allowed, you can change this by setting constant struts.allowed.method.names
in struts.xml
. If method doesn't match the RegEx a default method is returned, i.e. execute
. This can be changed by defining constant struts.default.method.name
in struts.xml
.
Please note that this funcionallity only works when Dynamic Method Invocation is enabled.
Custom ActionMapper
You can define your own ActionMapper by implementing org.apache.struts2.dispatcher.mapper.ActionMapper
then configuring Struts 2 to use the new class in struts.xml
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Possible uses of the ActionMapper include defining your own, cleaner namespaces, such as URLs like /person/1, which would be similar to a request to /getPerson.action?personID=1 using the DefaultActionMapper.
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It is configured through struts.xml. For example, with the following entries in struts.xml
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xml
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When CompositeActionMapper#getMapping(HttpServletRequest, ConfigurationManager)
or CompositeActionMapper#getUriFromActionMapping(ActionMapping)
is invoked, CompositeActionMapper
would go through these ActionMappers in sequence starting from ActionMapper identified by struts.mapper.composite.1
, followed by struts.mapper.composite.2
and finally struts.mapper.composite.3
(in this case) until either one of the ActionMapper return a valid result (not null) or it runs out of ActionMapper in which case it will just return null for both CompositeActionMapper#getMapping(HttpServletRequest, ConfigurationManager)
and CompositeActionMapper#getUriFromActionMapping(ActionMapping)
methods.
For example with the following in struts.xml:
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CompositeActionMapper
will be configured with 2 ActionMapper, namely "struts" which is org.apache.struts2.dispatcher.mapper.DefaultActionMapper
and "restful" which is org.apache.struts2.dispatcher.mapper.RestfulActionMapperRestfulActionMapper
. CompositeActionMapper
would consult each of them in order described above.
PrefixBasedActionMapper
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PrefixBasedActionProxyFactory
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ActionMapper and ActionMapping objects
The ActionMapper fetches the ActionMapping object corresponding to a given request. Essentially, the ActionMapping is a data transfer object that collects together details such as the Action class and method to execute. The mapping is utilized by the Dispatcher and various user interface components. It is customizable through struts.mapper.class
entry in struts.properties
or struts.xml
. Note that the value of this constant is the name of the bean of the new mapper.
Customize
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Custom ActionMapper must implement ActionMapper interface and have a default constructor.
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See also: RestfulActionMapper