org.apache.commons.collections
Class BeanMap

java.lang.Object
  |
  +--java.util.AbstractMap
        |
        +--org.apache.commons.collections.BeanMap

public class BeanMap

extends AbstractMap

implements Cloneable

An implementation of Map for JavaBeans which uses introspection to get and put properties in the bean. If an exception occurs during attempts to get or set a property then the property is considered non existent in the Map

Since:

1.0

Author:

James Strachan

Inner Class Summary

protected static class

BeanMap.MyMapEntry Map entry used by BeanMap.

Field Summary

static HashMap	defaultTransformers Maps primitive Class types to transformers.
static Object[]	NULL_ARGUMENTS An empty array.

Constructor Summary

BeanMap()
Constructs a new empty BeanMap.

BeanMap(Object bean)
Constructs a new BeanMap that operates on the specified bean.

Method Summary

void	clear() This method reinitializes the bean map to have default values for the bean's properties.
Object	clone() Clone this bean map using the following process: If there is no underlying bean, return a cloned BeanMap without a bean.
boolean	containsKey(Object name) Returns true if the bean defines a property with the given name.
boolean	containsValue(Object value) Returns true if the bean defines a property whose current value is the given object.
protected Object	convertType(Class newType, Object value) Converts the given value to the given type.
protected Object[]	createWriteMethodArguments(Method method, Object value) Creates an array of parameters to pass to the given mutator method.
Iterator	entryIterator() Convenience method for getting an iterator over the entries.
Set	entrySet() Get the mappings for this BeanMap
protected void	firePropertyChange(Object key, Object oldValue, Object newValue) Called during a successful put(Object,Object) operation.
Object	get(Object name) Returns the value of the bean's property with the given name.
Object	getBean() Returns the bean currently being operated on.
protected Method	getReadMethod(Object name) Returns the accessor for the property with the given name.
Class	getType(String name) Returns the type of the property with the given name.
protected Transformer	getTypeTransformer(Class aType) Returns a transformer for the given primitive type.
protected Method	getWriteMethod(Object name) Returns the mutator for the property with the given name.
Iterator	keyIterator() Convenience method for getting an iterator over the keys.
Set	keySet() Get the keys for this BeanMap.
protected void	logInfo(Exception e) Logs the given exception to System.out.
protected void	logWarn(Exception e) Logs the given exception to System.err.
Object	put(Object name, Object value) Sets the bean property with the given name to the given value.
void	putAllWriteable(BeanMap map) Puts all of the writeable properties from the given BeanMap into this BeanMap.
protected void	reinitialise() Reinitializes this bean.
void	setBean(Object newBean) Sets the bean to be operated on by this map.
int	size() Returns the number of properties defined by the bean.
Iterator	valueIterator() Convenience method for getting an iterator over the values.
Collection	values() Returns the values for the BeanMap.

Methods inherited from class java.util.AbstractMap

equals, hashCode, isEmpty, putAll, remove, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

NULL_ARGUMENTS

public static final Object[] NULL_ARGUMENTS

An empty array. Used to invoke accessors via reflection.

defaultTransformers

public static HashMap defaultTransformers

Maps primitive Class types to transformers. The transformer transform strings into the appropriate primitive wrapper.

Constructor Detail

BeanMap

public BeanMap()

Constructs a new empty BeanMap.

BeanMap

public BeanMap(Object bean)

Constructs a new BeanMap that operates on the specified bean. If the given bean is null, then this map will be empty.

Parameters:

bean - the bean for this map to operate on

Method Detail

clone

public Object clone()
             throws CloneNotSupportedException

Clone this bean map using the following process:

• If there is no underlying bean, return a cloned BeanMap without a bean.
• Since there is an underlying bean, try to instantiate a new bean of the same type using Class.newInstance().
• If the instantiation fails, throw a CloneNotSupportedException
• Clone the bean map and set the newly instantiated bean as the underyling bean for the bean map.
• Copy each property that is both readable and writable from the existing object to a cloned bean map.
• If anything fails along the way, throw a CloneNotSupportedException.

  Overrides:

  clone in class Object

putAllWriteable

public void putAllWriteable(BeanMap map)

Puts all of the writeable properties from the given BeanMap into this BeanMap. Read-only properties will be ignored.

Parameters:

map - the BeanMap whose properties to put

clear

public void clear()

This method reinitializes the bean map to have default values for the bean's properties. This is accomplished by constructing a new instance of the bean which the map uses as its underlying data source. This behavior for clear() differs from the Map contract in that the mappings are not actually removed from the map (the mappings for a BeanMap are fixed).

Overrides:

clear in class AbstractMap

containsKey

public boolean containsKey(Object name)

Returns true if the bean defines a property with the given name. The given name must be a String; if not, this method returns false. This method will also return false if the bean does not define a property with that name.

Overrides:

containsKey in class AbstractMap

Parameters:

name - the name of the property to check

Returns:

false if the given name is null or is not a String; false if the bean does not define a property with that name; or true if the bean does define a property with that name

containsValue

public boolean containsValue(Object value)

Returns true if the bean defines a property whose current value is the given object.

Overrides:

containsValue in class AbstractMap

Parameters:

value - the value to check

Returns:

false true if the bean has at least one property whose current value is that object, false otherwise

get

public Object get(Object name)

Returns the value of the bean's property with the given name. The given name must be a String and must not be null; otherwise, this method returns null. If the bean defines a property with the given name, the value of that property is returned. Otherwise, null is returned.

Overrides:

get in class AbstractMap

Parameters:

name - the name of the property whose value to return

Returns:

the value of the property with that name

put

public Object put(Object name,
                  Object value)
           throws IllegalArgumentException,
                  ClassCastException

Sets the bean property with the given name to the given value.

Overrides:

put in class AbstractMap

Parameters:

name - the name of the property to set

value - the value to set that property to

Returns:

the previous value of that property

Throws:

IllegalArgumentException - if the given name is null; if the given name is not a String; if the bean doesn't define a property with that name; or if the bean property with that name is read-only

size

public int size()

Returns the number of properties defined by the bean.

Overrides:

size in class AbstractMap

Returns:

the number of properties defined by the bean

keySet

public Set keySet()

Get the keys for this BeanMap.

Overrides:

keySet in class AbstractMap

Returns:

BeanMap keys. The Set returned by this method is not modifiable.

entrySet

public Set entrySet()

Get the mappings for this BeanMap

Overrides:

entrySet in class AbstractMap

Returns:

BeanMap mappings. The Set returned by this method is not modifiable.

values

public Collection values()

Returns the values for the BeanMap.

Overrides:

values in class AbstractMap

Returns:

values for the BeanMap. The returned collection is not modifiable.

getType

public Class getType(String name)

Returns the type of the property with the given name.

Parameters:

name - the name of the property

Returns:

the type of the property, or null if no such property exists

keyIterator

public Iterator keyIterator()

Convenience method for getting an iterator over the keys.

Returns:

an iterator over the keys

valueIterator

public Iterator valueIterator()

Convenience method for getting an iterator over the values.

Returns:

an iterator over the values

entryIterator

public Iterator entryIterator()

Convenience method for getting an iterator over the entries.

Returns:

an iterator over the entries

getBean

public Object getBean()

Returns the bean currently being operated on. The return value may be null if this map is empty.

Returns:

the bean being operated on by this map

setBean

public void setBean(Object newBean)

Sets the bean to be operated on by this map. The given value may be null, in which case this map will be empty.

Parameters:

newBean - the new bean to operate on

getReadMethod

protected Method getReadMethod(Object name)

Returns the accessor for the property with the given name.

Parameters:

name - the name of the property

Returns:

null if the name is null; null if the name is not a String; null if no such property exists; or the accessor method for that property

getWriteMethod

protected Method getWriteMethod(Object name)

Returns the mutator for the property with the given name.

Parameters:

name - the name of the

Returns:

null if the name is null; null if the name is not a String; null if no such property exists; null if the property is read-only; or the mutator method for that property

reinitialise

protected void reinitialise()

Reinitializes this bean. Called during setBean(Object). Does introspection to find properties.

firePropertyChange

protected void firePropertyChange(Object key,
                                  Object oldValue,
                                  Object newValue)

Called during a successful put(Object,Object) operation. Default implementation does nothing. Override to be notified of property changes in the bean caused by this map.

Parameters:

key - the name of the property that changed

oldValue - the old value for that property

newValue - the new value for that property

createWriteMethodArguments

protected Object[] createWriteMethodArguments(Method method,
                                              Object value)
                                       throws IllegalAccessException,
                                              ClassCastException

Creates an array of parameters to pass to the given mutator method. If the given object is not the right type to pass to the method directly, it will be converted using convertType(Class,Object).

Parameters:

method - the mutator method

value - the value to pass to the mutator method

Returns:

an array containing one object that is either the given value or a transformed value

Throws:

IllegalAccessException - if convertType(Class,Object) raises it

IllegalArgumentException - if any other exception is raised by convertType(Class,Object)

convertType

protected Object convertType(Class newType,
                             Object value)
                      throws InstantiationException,
                             IllegalAccessException,
                             IllegalArgumentException,
                             InvocationTargetException

Converts the given value to the given type. First, reflection is is used to find a public constructor declared by the given class that takes one argument, which must be the precise type of the given value. If such a constructor is found, a new object is created by passing the given value to that constructor, and the newly constructed object is returned.

If no such constructor exists, and the given type is a primitive type, then the given value is converted to a string using its toString() method, and that string is parsed into the correct primitve type using, for instance, Integer.valueOf(String) to convert the string into an int.

If no special constructor exists and the given type is not a primitive type, this method returns the original value.

Parameters:

newType - the type to convert the value to

value - the value to conert

Returns:

the converted value

Throws:

NumberFormatException - if newType is a primitive type, and the string representation of the given value cannot be converted to that type

InstantiationException - if the constructor found with reflection raises it

InvocationTargetExcetpion - if the constructor found with reflection raises it

IllegalAccessException - never

IllegalArgumentException - never

getTypeTransformer

protected Transformer getTypeTransformer(Class aType)

Returns a transformer for the given primitive type.

Parameters:

aType - the primitive type whose transformer to return

Returns:

a transformer that will convert strings into that type, or null if the given type is not a primitive type

logInfo

protected void logInfo(Exception e)

Logs the given exception to System.out. Used to display warnings while accessing/mutating the bean.

Parameters:

e - the exception to log

logWarn

protected void logWarn(Exception e)

Logs the given exception to System.err. Used to display errors while accessing/mutating the bean.

Parameters:

e - the exception to log