com.opensymphony.xwork2.conversion.impl
Class InstantiatingNullHandler

java.lang.Object
  extended by com.opensymphony.xwork2.conversion.impl.InstantiatingNullHandler
All Implemented Interfaces:
NullHandler

public class InstantiatingNullHandler
extends Object
implements NullHandler

Provided that the key ReflectionContextState.CREATE_NULL_OBJECTS is in the action context with a value of true (this key is set only during the execution of the ParametersInterceptor), OGNL expressions that have caused a NullPointerException will be temporarily stopped for evaluation while the system automatically tries to solve the null references by automatically creating the object.

The following rules are used when handling null references:

For example, if a form element has a text field named person.name and the expression person evaluates to null, then this class will be invoked. Because the person expression evaluates to a Person class, a new Person is created and assigned to the null reference. Finally, the name is set on that object and the overall effect is that the system automatically created a Person object for you, set it by calling setUsers() and then finally called getUsers().setName() as you would typically expect.
Field Summary
static String CREATE_NULL_OBJECTS
          Deprecated. Use ReflectionContextState.CREATE_NULL_OBJECTS instead
private static Logger LOG
           
private  ObjectFactory objectFactory
           
private  ObjectTypeDeterminer objectTypeDeterminer
           
private  ReflectionProvider reflectionProvider
           
 
Constructor Summary
InstantiatingNullHandler()
           
 
Method Summary
private  Object createObject(Class clazz, Object target, String property, Map<String,Object> context)
           
 Object nullMethodResult(Map<String,Object> context, Object target, String methodName, Object[] args)
          Method called on target returned null.
 Object nullPropertyValue(Map<String,Object> context, Object target, Object property)
          Property in target evaluated to null.
 void setObjectFactory(ObjectFactory fac)
           
 void setObjectTypeDeterminer(ObjectTypeDeterminer det)
           
 void setReflectionProvider(ReflectionProvider prov)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

CREATE_NULL_OBJECTS

@Deprecated
public static final String CREATE_NULL_OBJECTS
Deprecated. Use ReflectionContextState.CREATE_NULL_OBJECTS instead
See Also:
Constant Field Values

LOG

private static final Logger LOG

reflectionProvider

private ReflectionProvider reflectionProvider

objectFactory

private ObjectFactory objectFactory

objectTypeDeterminer

private ObjectTypeDeterminer objectTypeDeterminer
Constructor Detail

InstantiatingNullHandler

public InstantiatingNullHandler()
Method Detail

setObjectTypeDeterminer

public void setObjectTypeDeterminer(ObjectTypeDeterminer det)

setReflectionProvider

public void setReflectionProvider(ReflectionProvider prov)

setObjectFactory

public void setObjectFactory(ObjectFactory fac)

nullMethodResult

public Object nullMethodResult(Map<String,Object> context,
                               Object target,
                               String methodName,
                               Object[] args)
Description copied from interface: NullHandler
Method called on target returned null.

Specified by:
nullMethodResult in interface NullHandler

nullPropertyValue

public Object nullPropertyValue(Map<String,Object> context,
                                Object target,
                                Object property)
Description copied from interface: NullHandler
Property in target evaluated to null. Property can be a constant String property name or a DynamicSubscript.

Specified by:
nullPropertyValue in interface NullHandler

createObject

private Object createObject(Class clazz,
                            Object target,
                            String property,
                            Map<String,Object> context)
                     throws Exception
Throws:
Exception


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