Class ParametersInterceptor

  extended by com.opensymphony.xwork2.interceptor.AbstractInterceptor
      extended by com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
          extended by com.opensymphony.xwork2.interceptor.ParametersInterceptor
All Implemented Interfaces:

public class ParametersInterceptor
extends MethodFilterInterceptor

This interceptor sets all parameters on the value stack.

This interceptor gets all parameters from ActionContext.getParameters() and sets them on the value stack by calling ValueStack.setValue(String, Object), typically resulting in the values submitted in a form request being applied to an action in the value stack. Note that the parameter map must contain a String key and often containers a String[] for the value.

The interceptor takes one parameter named 'ordered'. When set to true action properties are guaranteed to be set top-down which means that top action's properties are set first. Then it's subcomponents properties are set. The reason for this order is to enable a 'factory' pattern. For example, let's assume that one has an action that contains a property named 'modelClass' that allows to choose what is the underlying implementation of model. By assuring that modelClass property is set before any model properties are set, it's possible to choose model implementation during action.setModelClass() call. Similiarily it's possible to use action.setPrimaryKey() property set call to actually load the model class from persistent storage. Without any assumption on parameter order you have to use patterns like 'Preparable'.

Because parameter names are effectively OGNL statements, it is important that security be taken in to account. This interceptor will not apply any values in the parameters map if the expression contains an assignment (=), multiple expressions (,), or references any objects in the context (#). This is all done in the acceptableName(String) method. In addition to this method, if the action being invoked implements the ParameterNameAware interface, the action will be consulted to determine if the parameter should be set.

In addition to these restrictions, a flag (ReflectionContextState.DENY_METHOD_EXECUTION) is set such that no methods are allowed to be invoked. That means that any expression such as person.doSomething() or person.getName() will be explicitely forbidden. This is needed to make sure that your application is not exposed to attacks by malicious users.

While this interceptor is being invoked, a flag (ReflectionContextState.CREATE_NULL_OBJECTS) is turned on to ensure that any null reference is automatically created - if possible. See the type conversion documentation and the InstantiatingNullHandler javadocs for more information.

Finally, a third flag (XWorkConverter.REPORT_CONVERSION_ERRORS) is set that indicates any errors when converting the the values to their final data type (String[] -> int) an unrecoverable error occured. With this flag set, the type conversion errors will be reported in the action context. See the type conversion documentation and the XWorkConverter javadocs for more information.

If you are looking for detailed logging information about your parameters, turn on DEBUG level logging for this interceptor. A detailed log of all the parameter keys and values will be reported.

Note: Since XWork 2.0.2, this interceptor extends MethodFilterInterceptor, therefore being able to deal with excludeMethods / includeMethods parameters. See [Workflow Interceptor] (class DefaultWorkflowInterceptor) for documentation and examples on how to use this feature.

Interceptor parameters:

Extending the interceptor:

The best way to add behavior to this interceptor is to utilize the ParameterNameAware interface in your actions. However, if you wish to apply a global rule that isn't implemented in your action, then you could extend this interceptor and override the acceptableName(String) method.

Example code:

 <action name="someAction" class="com.examples.SomeAction">
     <interceptor-ref name="params"/>
     <result name="success">good_result.ftl</result>

Patrick Lightbody
See Also:
Serialized Form

Field Summary
Fields inherited from class com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
excludeMethods, includeMethods, log
Constructor Summary
Method Summary
protected  boolean acceptableName(java.lang.String name)
protected  void addParametersToContext(ActionContext ac, java.util.Map<java.lang.String,java.lang.Object> newParams)
          Adds the parameters into context's ParameterMap
 java.lang.String doIntercept(ActionInvocation invocation)
          Subclasses must override to implement the interceptor logic.
protected  java.util.Set getExcludeParamsSet()
          Gets a set of regular expressions of parameters to remove from the parameter map
protected  java.util.Comparator<java.lang.String> getOrderedComparator()
          Gets an instance of the comparator to use for the ordered sorting.
protected  boolean isAccepted(java.lang.String paramName)
protected  boolean isExcluded(java.lang.String paramName)
 boolean isOrdered()
          Whether to order the parameters or not
protected  java.util.Map<java.lang.String,java.lang.Object> retrieveParameters(ActionContext ac)
          Gets the parameter map to apply from wherever appropriate
 void setAcceptParamNames(java.lang.String commaDelim)
static void setDevMode(java.lang.String mode)
 void setExcludeParams(java.lang.String commaDelim)
          Sets a comma-delimited list of regular expressions to match parameters that should be removed from the parameter map.
 void setOrdered(boolean ordered)
          Set whether to order the parameters by object depth or not
protected  void setParameters(java.lang.Object action, ValueStack stack, java.util.Map<java.lang.String,java.lang.Object> parameters)
 void setValueStackFactory(ValueStackFactory valueStackFactory)
Methods inherited from class com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
applyInterceptor, getExcludeMethodsSet, getIncludeMethodsSet, intercept, setExcludeMethods, setIncludeMethods
Methods inherited from class com.opensymphony.xwork2.interceptor.AbstractInterceptor
destroy, init
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public ParametersInterceptor()
Method Detail


public void setValueStackFactory(ValueStackFactory valueStackFactory)


public static void setDevMode(java.lang.String mode)


public void setAcceptParamNames(java.lang.String commaDelim)


public java.lang.String doIntercept(ActionInvocation invocation)
                             throws java.lang.Exception
Description copied from class: MethodFilterInterceptor
Subclasses must override to implement the interceptor logic.

Specified by:
doIntercept in class MethodFilterInterceptor
invocation - the action invocation
the result of invocation


protected java.util.Map<java.lang.String,java.lang.Object> retrieveParameters(ActionContext ac)
Gets the parameter map to apply from wherever appropriate

ac - The action context
The parameter map to apply


protected void addParametersToContext(ActionContext ac,
                                      java.util.Map<java.lang.String,java.lang.Object> newParams)
Adds the parameters into context's ParameterMap

ac - The action context
newParams - The parameter map to apply

In this class this is a no-op, since the parameters were fetched from the same location. In subclasses both retrieveParameters() and addParametersToContext() should be overridden.


protected void setParameters(java.lang.Object action,
                             ValueStack stack,
                             java.util.Map<java.lang.String,java.lang.Object> parameters)


protected java.util.Comparator<java.lang.String> getOrderedComparator()
Gets an instance of the comparator to use for the ordered sorting. Override this method to customize the ordering of the parameters as they are set to the action.

A comparator to sort the parameters


protected boolean acceptableName(java.lang.String name)


protected boolean isAccepted(java.lang.String paramName)


protected boolean isExcluded(java.lang.String paramName)


public boolean isOrdered()
Whether to order the parameters or not

True to order


public void setOrdered(boolean ordered)
Set whether to order the parameters by object depth or not

ordered - True to order them


protected java.util.Set getExcludeParamsSet()
Gets a set of regular expressions of parameters to remove from the parameter map

A set of compiled regular expression patterns


public void setExcludeParams(java.lang.String commaDelim)
Sets a comma-delimited list of regular expressions to match parameters that should be removed from the parameter map.

commaDelim - A comma-delimited list of regular expressions

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