org.apache.commons.beanutils

Class LazyDynaClass

java.lang.Object

org.apache.commons.beanutils.BasicDynaClass

org.apache.commons.beanutils.LazyDynaClass

All Implemented Interfaces:

Serializable, DynaClass, MutableDynaClass

public class LazyDynaClass
extends BasicDynaClass
implements MutableDynaClass

DynaClass which implements the MutableDynaClass interface.

A MutableDynaClass is a specialized extension to DynaClass that allows properties to be added or removed dynamically.

This implementation has one slightly unusual default behaviour - calling the getDynaProperty(name) method for a property which doesn't exist returns a DynaProperty rather than null. The reason for this is that BeanUtils calls this method to check if a property exists before trying to set the value. This would defeat the object of the LazyDynaBean which automatically adds missing properties when any of its set() methods are called. For this reason the isDynaProperty(name) method has been added to this implementation in order to determine if a property actually exists. If the more normal behaviour of returning null is required, then this can be achieved by calling the setReturnNull(true).

The add(name, type, readable, writable) method is not implemented and always throws an UnsupportedOperationException. I believe this attributes need to be added to the DynaProperty class in order to control read/write facilities.

Version:

$Id$

See Also:

LazyDynaBean, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	restricted Controls whether changes to this DynaClass's properties are allowed.
protected boolean	returnNull Controls whether the getDynaProperty() method returns null if a property doesn't exist - or creates a new one.

Fields inherited from class org.apache.commons.beanutils.BasicDynaClass

constructor, constructorTypes, constructorValues, dynaBeanClass, name, properties, propertiesMap

Constructor Summary

Constructors

Constructor and Description
LazyDynaClass() Construct a new LazyDynaClass with default parameters.
LazyDynaClass(String name) Construct a new LazyDynaClass with the specified name.
LazyDynaClass(String name, Class<?> dynaBeanClass) Construct a new LazyDynaClass with the specified name and DynaBean class.
LazyDynaClass(String name, Class<?> dynaBeanClass, DynaProperty[] properties) Construct a new LazyDynaClass with the specified name, DynaBean class and properties.
LazyDynaClass(String name, DynaProperty[] properties) Construct a new LazyDynaClass with the specified name and properties.

Method Summary

Modifier and Type	Method and Description
protected void	add(DynaProperty property) Add a new dynamic property.
void	add(String name) Add a new dynamic property with no restrictions on data type, readability, or writeability.
void	add(String name, Class<?> type) Add a new dynamic property with the specified data type, but with no restrictions on readability or writeability.
void	add(String name, Class<?> type, boolean readable, boolean writeable) Add a new dynamic property with the specified data type, readability, and writeability.
DynaProperty	getDynaProperty(String name) Return a property descriptor for the specified property.
boolean	isDynaProperty(String name) Indicate whether a property actually exists.
boolean	isRestricted() Is this DynaClass currently restricted.
boolean	isReturnNull() Should this DynaClass return a null from the getDynaProperty(name) method if the property doesn't exist.
void	remove(String name) Remove the specified dynamic property, and any associated data type, readability, and writeability, from this dynamic class.
void	setRestricted(boolean restricted) Set whether this DynaClass is currently restricted.
void	setReturnNull(boolean returnNull) Set whether this DynaClass should return a null from the getDynaProperty(name) method if the property doesn't exist.

Methods inherited from class org.apache.commons.beanutils.BasicDynaClass

getDynaBeanClass, getDynaProperties, getName, newInstance, setDynaBeanClass, setProperties

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.commons.beanutils.DynaClass

getDynaProperties, getName, newInstance

Field Detail

restricted

protected boolean restricted

Controls whether changes to this DynaClass's properties are allowed.

returnNull

protected boolean returnNull

Controls whether the getDynaProperty() method returns null if a property doesn't exist - or creates a new one.

Default is false.

Constructor Detail

LazyDynaClass

public LazyDynaClass()

Construct a new LazyDynaClass with default parameters.

LazyDynaClass

public LazyDynaClass(String name)

Construct a new LazyDynaClass with the specified name.

Parameters:

name - Name of this DynaBean class

LazyDynaClass

public LazyDynaClass(String name,
                     Class<?> dynaBeanClass)

Construct a new LazyDynaClass with the specified name and DynaBean class.

Parameters:

name - Name of this DynaBean class

dynaBeanClass - The implementation class for new instances

LazyDynaClass

public LazyDynaClass(String name,
                     DynaProperty[] properties)

Construct a new LazyDynaClass with the specified name and properties.

Parameters:

name - Name of this DynaBean class

properties - Property descriptors for the supported properties

LazyDynaClass

public LazyDynaClass(String name,
                     Class<?> dynaBeanClass,
                     DynaProperty[] properties)

Construct a new LazyDynaClass with the specified name, DynaBean class and properties.

Parameters:

name - Name of this DynaBean class

dynaBeanClass - The implementation class for new instances

properties - Property descriptors for the supported properties

Method Detail

isRestricted

public boolean isRestricted()

Is this DynaClass currently restricted.

If restricted, no changes to the existing registration of property names, data types, readability, or writeability are allowed.

Specified by:

isRestricted in interface MutableDynaClass

Returns:

true if this MutableDynaClass cannot be changed otherwise false

setRestricted

public void setRestricted(boolean restricted)

Set whether this DynaClass is currently restricted.

If restricted, no changes to the existing registration of property names, data types, readability, or writeability are allowed.

Specified by:

setRestricted in interface MutableDynaClass

Parameters:

restricted - true if this MutableDynaClass cannot be changed otherwise false

isReturnNull

public boolean isReturnNull()

Should this DynaClass return a null from the getDynaProperty(name) method if the property doesn't exist.

Returns:

true if a null DynaProperty should be returned if the property doesn't exist, otherwise false if a new DynaProperty should be created.

setReturnNull

public void setReturnNull(boolean returnNull)

Set whether this DynaClass should return a null from the getDynaProperty(name) method if the property doesn't exist.

Parameters:

returnNull - true if a null DynaProperty should be returned if the property doesn't exist, otherwise false if a new DynaProperty should be created.

add

public void add(String name)

Add a new dynamic property with no restrictions on data type, readability, or writeability.

Specified by:

add in interface MutableDynaClass

Parameters:

name - Name of the new dynamic property

Throws:

IllegalArgumentException - if name is null

IllegalStateException - if this DynaClass is currently restricted, so no new properties can be added

add

public void add(String name,
                Class<?> type)

Add a new dynamic property with the specified data type, but with no restrictions on readability or writeability.

Specified by:

add in interface MutableDynaClass

Parameters:

name - Name of the new dynamic property

type - Data type of the new dynamic property (null for no restrictions)

Throws:

IllegalArgumentException - if name is null

IllegalStateException - if this DynaClass is currently restricted, so no new properties can be added

add

public void add(String name,
                Class<?> type,
                boolean readable,
                boolean writeable)

Add a new dynamic property with the specified data type, readability, and writeability.

N.B.Support for readable/writeable properties has not been implemented and this method always throws a UnsupportedOperationException.

I'm not sure the intention of the original authors for this method, but it seems to me that readable/writable should be attributes of the DynaProperty class (which they are not) and is the reason this method has not been implemented.

Specified by:

add in interface MutableDynaClass

Parameters:

name - Name of the new dynamic property

type - Data type of the new dynamic property (null for no restrictions)

readable - Set to true if this property value should be readable

writeable - Set to true if this property value should be writeable

Throws:

UnsupportedOperationException - anytime this method is called

add

protected void add(DynaProperty property)

Add a new dynamic property.

Parameters:

property - Property the new dynamic property to add.

Throws:

IllegalArgumentException - if name is null

IllegalStateException - if this DynaClass is currently restricted, so no new properties can be added

remove

public void remove(String name)

Remove the specified dynamic property, and any associated data type, readability, and writeability, from this dynamic class. NOTE - This does NOT cause any corresponding property values to be removed from DynaBean instances associated with this DynaClass.

Specified by:

remove in interface MutableDynaClass

Parameters:

name - Name of the dynamic property to remove

Throws:

IllegalArgumentException - if name is null

IllegalStateException - if this DynaClass is currently restricted, so no properties can be removed

getDynaProperty

public DynaProperty getDynaProperty(String name)

Return a property descriptor for the specified property.

If the property is not found and the returnNull indicator is true, this method always returns null.

If the property is not found and the returnNull indicator is false a new property descriptor is created and returned (although its not actually added to the DynaClass's properties). This is the default beahviour.

The reason for not returning a null property descriptor is that BeanUtils uses this method to check if a property exists before trying to set it - since these Lazy implementations automatically add any new properties when they are set, returning null from this method would defeat their purpose.

Specified by:

getDynaProperty in interface DynaClass

Overrides:

getDynaProperty in class BasicDynaClass

Parameters:

name - Name of the dynamic property for which a descriptor is requested

Returns:

The dyna property for the specified name

Throws:

IllegalArgumentException - if no property name is specified

isDynaProperty

public boolean isDynaProperty(String name)

Indicate whether a property actually exists.

N.B. Using getDynaProperty(name) == null doesn't work in this implementation because that method might return a DynaProperty if it doesn't exist (depending on the returnNull indicator).

Parameters:

name - The name of the property to check

Returns:

true if there is a property of the specified name, otherwise false

Throws:

IllegalArgumentException - if no property name is specified