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*
* http://www.apache.org/licenses/LICENSE-2.0
*
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package org.apache.commons.beanutils;
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.
See Also: Version: $Id$
/**
* <p>DynaClass which implements the <code>MutableDynaClass</code> interface.</p>
*
* <p>A <code>MutableDynaClass</code> is a specialized extension to <code>DynaClass</code>
* that allows properties to be added or removed dynamically.</p>
*
* <p>This implementation has one slightly unusual default behaviour - calling
* the <code>getDynaProperty(name)</code> method for a property which doesn't
* exist returns a <code>DynaProperty</code> rather than <code>null</code>. The
* reason for this is that <code>BeanUtils</code> calls this method to check if
* a property exists before trying to set the value. This would defeat the object
* of the <code>LazyDynaBean</code> which automatically adds missing properties
* when any of its <code>set()</code> methods are called. For this reason the
* <code>isDynaProperty(name)</code> method has been added to this implementation
* in order to determine if a property actually exists. If the more <i>normal</i>
* behaviour of returning <code>null</code> is required, then this can be achieved
* by calling the <code>setReturnNull(true)</code>.</p>
*
* <p>The <code>add(name, type, readable, writable)</code> method is not implemented
* and always throws an <code>UnsupportedOperationException</code>. I believe
* this attributes need to be added to the <code>DynaProperty</code> class
* in order to control read/write facilities.</p>
*
* @version $Id$
* @see LazyDynaBean
*/
public class LazyDynaClass extends BasicDynaClass implements MutableDynaClass {
Controls whether changes to this DynaClass's properties are allowed.
/**
* Controls whether changes to this DynaClass's properties are allowed.
*/
protected boolean restricted;
Controls whether the getDynaProperty()
method returns
null if a property doesn't exist - or creates a new one.
Default is false
.
/**
* <p>Controls whether the <code>getDynaProperty()</code> method returns
* null if a property doesn't exist - or creates a new one.</p>
*
* <p>Default is <code>false</code>.
*/
protected boolean returnNull = false;
Construct a new LazyDynaClass with default parameters.
/**
* Construct a new LazyDynaClass with default parameters.
*/
public LazyDynaClass() {
this(null, (DynaProperty[])null);
}
Construct a new LazyDynaClass with the specified name.
Params: - name – Name of this DynaBean class
/**
* Construct a new LazyDynaClass with the specified name.
*
* @param name Name of this DynaBean class
*/
public LazyDynaClass(final String name) {
this(name, (DynaProperty[])null);
}
Construct a new LazyDynaClass with the specified name and DynaBean class.
Params: - name – Name of this DynaBean class
- dynaBeanClass – The implementation class for new instances
/**
* Construct a new LazyDynaClass with the specified name and DynaBean class.
*
* @param name Name of this DynaBean class
* @param dynaBeanClass The implementation class for new instances
*/
public LazyDynaClass(final String name, final Class<?> dynaBeanClass) {
this(name, dynaBeanClass, null);
}
Construct a new LazyDynaClass with the specified name and properties.
Params: - name – Name of this DynaBean class
- properties – Property descriptors for the supported properties
/**
* Construct a new LazyDynaClass with the specified name and properties.
*
* @param name Name of this DynaBean class
* @param properties Property descriptors for the supported properties
*/
public LazyDynaClass(final String name, final DynaProperty[] properties) {
this(name, LazyDynaBean.class, properties);
}
Construct a new LazyDynaClass with the specified name, DynaBean class and properties.
Params: - name – Name of this DynaBean class
- dynaBeanClass – The implementation class for new instances
- properties – Property descriptors for the supported properties
/**
* Construct a new LazyDynaClass with the specified name, DynaBean class and properties.
*
* @param name Name of this DynaBean class
* @param dynaBeanClass The implementation class for new instances
* @param properties Property descriptors for the supported properties
*/
public LazyDynaClass(final String name, final Class<?> dynaBeanClass, final DynaProperty properties[]) {
super(name, dynaBeanClass, properties);
}
Is this DynaClass currently restricted.
If restricted, no changes to the existing registration of
property names, data types, readability, or writeability are allowed.
Returns: true
if this MutableDynaClass
cannot be changed otherwise false
/**
* <p>Is this DynaClass currently restricted.</p>
* <p>If restricted, no changes to the existing registration of
* property names, data types, readability, or writeability are allowed.</p>
* @return <code>true</code> if this {@link MutableDynaClass} cannot be changed
* otherwise <code>false</code>
*/
public boolean isRestricted() {
return 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.
Params: - restricted –
true
if this MutableDynaClass
cannot be changed otherwise false
/**
* <p>Set whether this DynaClass is currently restricted.</p>
* <p>If restricted, no changes to the existing registration of
* property names, data types, readability, or writeability are allowed.</p>
* @param restricted <code>true</code> if this {@link MutableDynaClass} cannot
* be changed otherwise <code>false</code>
*/
public void setRestricted(final boolean restricted) {
this.restricted = restricted;
}
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.
/**
* Should this DynaClass return a <code>null</code> from
* the <code>getDynaProperty(name)</code> method if the property
* doesn't exist.
*
* @return <code>true</code> if a <code>null</code> {@link DynaProperty}
* should be returned if the property doesn't exist, otherwise
* <code>false</code> if a new {@link DynaProperty} should be created.
*/
public boolean isReturnNull() {
return returnNull;
}
Set whether this DynaClass should return a null
from
the getDynaProperty(name)
method if the property
doesn't exist.
Params: - returnNull –
true
if a null
DynaProperty
should be returned if the property doesn't exist, otherwise false
if a new DynaProperty
should be created.
/**
* Set whether this DynaClass should return a <code>null</code> from
* the <code>getDynaProperty(name)</code> method if the property
* doesn't exist.
* @param returnNull <code>true</code> if a <code>null</code> {@link DynaProperty}
* should be returned if the property doesn't exist, otherwise
* <code>false</code> if a new {@link DynaProperty} should be created.
*/
public void setReturnNull(final boolean returnNull) {
this.returnNull = returnNull;
}
Add a new dynamic property with no restrictions on data type,
readability, or writeability.
Params: - 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 a new dynamic property with no restrictions on data type,
* readability, or writeability.
*
* @param name Name of the new dynamic property
*
* @throws IllegalArgumentException if name is null
* @throws IllegalStateException if this DynaClass is currently
* restricted, so no new properties can be added
*/
public void add(final String name) {
add(new DynaProperty(name));
}
Add a new dynamic property with the specified data type, but with
no restrictions on readability or writeability.
Params: - 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 a new dynamic property with the specified data type, but with
* no restrictions on readability or writeability.
*
* @param name Name of the new dynamic property
* @param type Data type of the new dynamic property (null for no
* restrictions)
*
* @throws IllegalArgumentException if name is null
* @throws IllegalStateException if this DynaClass is currently
* restricted, so no new properties can be added
*/
public void add(final String name, final Class<?> type) {
if (type == null) {
add(name);
} else {
add(new DynaProperty(name, type));
}
}
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.
Params: - 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
/**
* <p>Add a new dynamic property with the specified data type, readability,
* and writeability.</p>
*
* <p><strong>N.B.</strong>Support for readable/writeable properties has not been implemented
* and this method always throws a <code>UnsupportedOperationException</code>.</p>
*
* <p>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 <code>DynaProperty</code> class
* (which they are not) and is the reason this method has not been implemented.</p>
*
* @param name Name of the new dynamic property
* @param type Data type of the new dynamic property (null for no
* restrictions)
* @param readable Set to <code>true</code> if this property value
* should be readable
* @param writeable Set to <code>true</code> if this property value
* should be writeable
*
* @throws UnsupportedOperationException anytime this method is called
*/
public void add(final String name, final Class<?> type, final boolean readable, final boolean writeable) {
throw new java.lang.UnsupportedOperationException("readable/writable properties not supported");
}
Add a new dynamic property.
Params: - 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
/**
* Add a new dynamic property.
*
* @param property Property the new dynamic property to add.
*
* @throws IllegalArgumentException if name is null
* @throws IllegalStateException if this DynaClass is currently
* restricted, so no new properties can be added
*/
protected void add(final DynaProperty property) {
if (property.getName() == null) {
throw new IllegalArgumentException("Property name is missing.");
}
if (isRestricted()) {
throw new IllegalStateException("DynaClass is currently restricted. No new properties can be added.");
}
// Check if property already exists
if (propertiesMap.get(property.getName()) != null) {
return;
}
// Create a new property array with the specified property
final DynaProperty[] oldProperties = getDynaProperties();
final DynaProperty[] newProperties = new DynaProperty[oldProperties.length+1];
System.arraycopy(oldProperties, 0, newProperties, 0, oldProperties.length);
newProperties[oldProperties.length] = property;
// Update the properties
setProperties(newProperties);
}
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.
Params: - 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
/**
* Remove the specified dynamic property, and any associated data type,
* readability, and writeability, from this dynamic class.
* <strong>NOTE</strong> - This does <strong>NOT</strong> cause any
* corresponding property values to be removed from DynaBean instances
* associated with this DynaClass.
*
* @param name Name of the dynamic property to remove
*
* @throws IllegalArgumentException if name is null
* @throws IllegalStateException if this DynaClass is currently
* restricted, so no properties can be removed
*/
public void remove(final String name) {
if (name == null) {
throw new IllegalArgumentException("Property name is missing.");
}
if (isRestricted()) {
throw new IllegalStateException("DynaClass is currently restricted. No properties can be removed.");
}
// Ignore if property doesn't exist
if (propertiesMap.get(name) == null) {
return;
}
// Create a new property array of without the specified property
final DynaProperty[] oldProperties = getDynaProperties();
final DynaProperty[] newProperties = new DynaProperty[oldProperties.length-1];
int j = 0;
for (int i = 0; i < oldProperties.length; i++) {
if (!(name.equals(oldProperties[i].getName()))) {
newProperties[j] = oldProperties[i];
j++;
}
}
// Update the properties
setProperties(newProperties);
}
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.
Params: - name – Name of the dynamic property for which a descriptor
is requested
Throws: - IllegalArgumentException – if no property name is specified
Returns: The dyna property for the specified name
/**
* <p>Return a property descriptor for the specified property.</p>
*
* <p>If the property is not found and the <code>returnNull</code> indicator is
* <code>true</code>, this method always returns <code>null</code>.</p>
*
* <p>If the property is not found and the <code>returnNull</code> indicator is
* <code>false</code> a new property descriptor is created and returned (although
* its not actually added to the DynaClass's properties). This is the default
* beahviour.</p>
*
* <p>The reason for not returning a <code>null</code> property descriptor is that
* <code>BeanUtils</code> uses this method to check if a property exists
* before trying to set it - since these <i>Lazy</i> implementations automatically
* add any new properties when they are set, returning <code>null</code> from
* this method would defeat their purpose.</p>
*
* @param name Name of the dynamic property for which a descriptor
* is requested
* @return The dyna property for the specified name
*
* @throws IllegalArgumentException if no property name is specified
*/
@Override
public DynaProperty getDynaProperty(final String name) {
if (name == null) {
throw new IllegalArgumentException("Property name is missing.");
}
DynaProperty dynaProperty = propertiesMap.get(name);
// If it doesn't exist and returnNull is false
// create a new DynaProperty
if (dynaProperty == null && !isReturnNull() && !isRestricted()) {
dynaProperty = new DynaProperty(name);
}
return dynaProperty;
}
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).
Params: - name – The name of the property to check
Throws: - IllegalArgumentException – if no property name is specified
Returns: true
if there is a property of the
specified name, otherwise false
/**
* <p>Indicate whether a property actually exists.</p>
*
* <p><strong>N.B.</strong> Using <code>getDynaProperty(name) == null</code>
* doesn't work in this implementation because that method might
* return a DynaProperty if it doesn't exist (depending on the
* <code>returnNull</code> indicator).</p>
*
* @param name The name of the property to check
* @return <code>true</code> if there is a property of the
* specified name, otherwise <code>false</code>
* @throws IllegalArgumentException if no property name is specified
*/
public boolean isDynaProperty(final String name) {
if (name == null) {
throw new IllegalArgumentException("Property name is missing.");
}
return propertiesMap.get(name) == null ? false : true;
}
}