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Posted to dev@commons.apache.org by rd...@apache.org on 2004/05/12 00:46:13 UTC
cvs commit: jakarta-commons/beanutils/optional/bean-collections/src/java/org/apache/commons/beanutils BeanMap.java
rdonkin 2004/05/11 15:46:13
Added: beanutils/optional/bean-collections/src/java/org/apache/commons/beanutils
BeanMap.java
Log:
Added BeanMap from collections. (Thanks Stephen)
Revision Changes Path
1.1 jakarta-commons/beanutils/optional/bean-collections/src/java/org/apache/commons/beanutils/BeanMap.java
Index: BeanMap.java
===================================================================
/*
* Copyright 2001-2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.beanutils;
import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
import org.apache.commons.collections.list.UnmodifiableList;
import org.apache.commons.collections.keyvalue.AbstractMapEntry;
import org.apache.commons.collections.set.UnmodifiableSet;
import org.apache.commons.collections.Transformer;
/**
* An implementation of Map for JavaBeans which uses introspection to
* get and put properties in the bean.
* <p>
* If an exception occurs during attempts to get or set a property then the
* property is considered non existent in the Map
*
* @since Commons Collections 1.0
* @version $Revision: 1.1 $ $Date: 2004/05/11 22:46:13 $
*
* @author James Strachan
* @author Stephen Colebourne
*/
public class BeanMap extends AbstractMap implements Cloneable {
private transient Object bean;
private transient HashMap readMethods = new HashMap();
private transient HashMap writeMethods = new HashMap();
private transient HashMap types = new HashMap();
/**
* An empty array. Used to invoke accessors via reflection.
*/
public static final Object[] NULL_ARGUMENTS = {};
/**
* Maps primitive Class types to transformers. The transformer
* transform strings into the appropriate primitive wrapper.
*/
public static HashMap defaultTransformers = new HashMap();
static {
defaultTransformers.put(
Boolean.TYPE,
new Transformer() {
public Object transform( Object input ) {
return Boolean.valueOf( input.toString() );
}
}
);
defaultTransformers.put(
Character.TYPE,
new Transformer() {
public Object transform( Object input ) {
return new Character( input.toString().charAt( 0 ) );
}
}
);
defaultTransformers.put(
Byte.TYPE,
new Transformer() {
public Object transform( Object input ) {
return Byte.valueOf( input.toString() );
}
}
);
defaultTransformers.put(
Short.TYPE,
new Transformer() {
public Object transform( Object input ) {
return Short.valueOf( input.toString() );
}
}
);
defaultTransformers.put(
Integer.TYPE,
new Transformer() {
public Object transform( Object input ) {
return Integer.valueOf( input.toString() );
}
}
);
defaultTransformers.put(
Long.TYPE,
new Transformer() {
public Object transform( Object input ) {
return Long.valueOf( input.toString() );
}
}
);
defaultTransformers.put(
Float.TYPE,
new Transformer() {
public Object transform( Object input ) {
return Float.valueOf( input.toString() );
}
}
);
defaultTransformers.put(
Double.TYPE,
new Transformer() {
public Object transform( Object input ) {
return Double.valueOf( input.toString() );
}
}
);
}
// Constructors
//-------------------------------------------------------------------------
/**
* Constructs a new empty <code>BeanMap</code>.
*/
public BeanMap() {
}
/**
* Constructs a new <code>BeanMap</code> that operates on the
* specified bean. If the given bean is <code>null</code>, then
* this map will be empty.
*
* @param bean the bean for this map to operate on
*/
public BeanMap(Object bean) {
this.bean = bean;
initialise();
}
// Map interface
//-------------------------------------------------------------------------
public String toString() {
return "BeanMap<" + String.valueOf(bean) + ">";
}
/**
* Clone this bean map using the following process:
*
* <ul>
* <li>If there is no underlying bean, return a cloned BeanMap without a
* bean.
*
* <li>Since there is an underlying bean, try to instantiate a new bean of
* the same type using Class.newInstance().
*
* <li>If the instantiation fails, throw a CloneNotSupportedException
*
* <li>Clone the bean map and set the newly instantiated bean as the
* underlying bean for the bean map.
*
* <li>Copy each property that is both readable and writable from the
* existing object to a cloned bean map.
*
* <li>If anything fails along the way, throw a
* CloneNotSupportedException.
*
* <ul>
*/
public Object clone() throws CloneNotSupportedException {
BeanMap newMap = (BeanMap)super.clone();
if(bean == null) {
// no bean, just an empty bean map at the moment. return a newly
// cloned and empty bean map.
return newMap;
}
Object newBean = null;
Class beanClass = null;
try {
beanClass = bean.getClass();
newBean = beanClass.newInstance();
} catch (Exception e) {
// unable to instantiate
throw new CloneNotSupportedException
("Unable to instantiate the underlying bean \"" +
beanClass.getName() + "\": " + e);
}
try {
newMap.setBean(newBean);
} catch (Exception exception) {
throw new CloneNotSupportedException
("Unable to set bean in the cloned bean map: " +
exception);
}
try {
// copy only properties that are readable and writable. If its
// not readable, we can't get the value from the old map. If
// its not writable, we can't write a value into the new map.
Iterator readableKeys = readMethods.keySet().iterator();
while(readableKeys.hasNext()) {
Object key = readableKeys.next();
if(getWriteMethod(key) != null) {
newMap.put(key, get(key));
}
}
} catch (Exception exception) {
throw new CloneNotSupportedException
("Unable to copy bean values to cloned bean map: " +
exception);
}
return newMap;
}
/**
* Puts all of the writable properties from the given BeanMap into this
* BeanMap. Read-only and Write-only properties will be ignored.
*
* @param map the BeanMap whose properties to put
*/
public void putAllWriteable(BeanMap map) {
Iterator readableKeys = map.readMethods.keySet().iterator();
while (readableKeys.hasNext()) {
Object key = readableKeys.next();
if (getWriteMethod(key) != null) {
this.put(key, map.get(key));
}
}
}
/**
* 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 <code>clear()</code> differs from the Map contract in that
* the mappings are not actually removed from the map (the mappings for a
* BeanMap are fixed).
*/
public void clear() {
if(bean == null) return;
Class beanClass = null;
try {
beanClass = bean.getClass();
bean = beanClass.newInstance();
}
catch (Exception e) {
throw new UnsupportedOperationException( "Could not create new instance of class: " + beanClass );
}
}
/**
* Returns true if the bean defines a property with the given name.
* <p>
* The given name must be a <code>String</code>; if not, this method
* returns false. This method will also return false if the bean
* does not define a property with that name.
* <p>
* Write-only properties will not be matched as the test operates against
* property read methods.
*
* @param name the name of the property to check
* @return false if the given name is null or is not a <code>String</code>;
* false if the bean does not define a property with that name; or
* true if the bean does define a property with that name
*/
public boolean containsKey(Object name) {
Method method = getReadMethod(name);
return method != null;
}
/**
* Returns true if the bean defines a property whose current value is
* the given object.
*
* @param value the value to check
* @return false true if the bean has at least one property whose
* current value is that object, false otherwise
*/
public boolean containsValue(Object value) {
// use default implementation
return super.containsValue(value);
}
/**
* Returns the value of the bean's property with the given name.
* <p>
* The given name must be a {@link String} and must not be
* null; otherwise, this method returns <code>null</code>.
* If the bean defines a property with the given name, the value of
* that property is returned. Otherwise, <code>null</code> is
* returned.
* <p>
* Write-only properties will not be matched as the test operates against
* property read methods.
*
* @param name the name of the property whose value to return
* @return the value of the property with that name
*/
public Object get(Object name) {
if ( bean != null ) {
Method method = getReadMethod( name );
if ( method != null ) {
try {
return method.invoke( bean, NULL_ARGUMENTS );
}
catch ( IllegalAccessException e ) {
logWarn( e );
}
catch ( IllegalArgumentException e ) {
logWarn( e );
}
catch ( InvocationTargetException e ) {
logWarn( e );
}
catch ( NullPointerException e ) {
logWarn( e );
}
}
}
return null;
}
/**
* Sets the bean property with the given name to the given value.
*
* @param name the name of the property to set
* @param value the value to set that property to
* @return the previous value of that property
* @throws IllegalArgumentException if the given name is null;
* if the given name is not a {@link String}; if the bean doesn't
* define a property with that name; or if the bean property with
* that name is read-only
*/
public Object put(Object name, Object value) throws IllegalArgumentException, ClassCastException {
if ( bean != null ) {
Object oldValue = get( name );
Method method = getWriteMethod( name );
if ( method == null ) {
throw new IllegalArgumentException( "The bean of type: "+ bean.getClass().getName() + " has no property called: " + name );
}
try {
Object[] arguments = createWriteMethodArguments( method, value );
method.invoke( bean, arguments );
Object newValue = get( name );
firePropertyChange( name, oldValue, newValue );
}
catch ( InvocationTargetException e ) {
logInfo( e );
throw new IllegalArgumentException( e.getMessage() );
}
catch ( IllegalAccessException e ) {
logInfo( e );
throw new IllegalArgumentException( e.getMessage() );
}
return oldValue;
}
return null;
}
/**
* Returns the number of properties defined by the bean.
*
* @return the number of properties defined by the bean
*/
public int size() {
return readMethods.size();
}
/**
* Get the keys for this BeanMap.
* <p>
* Write-only properties are <b>not</b> included in the returned set of
* property names, although it is possible to set their value and to get
* their type.
*
* @return BeanMap keys. The Set returned by this method is not
* modifiable.
*/
public Set keySet() {
return UnmodifiableSet.decorate(readMethods.keySet());
}
/**
* Gets a Set of MapEntry objects that are the mappings for this BeanMap.
* <p>
* Each MapEntry can be set but not removed.
*
* @return the unmodifiable set of mappings
*/
public Set entrySet() {
return UnmodifiableSet.decorate(new AbstractSet() {
public Iterator iterator() {
return entryIterator();
}
public int size() {
return BeanMap.this.readMethods.size();
}
});
}
/**
* Returns the values for the BeanMap.
*
* @return values for the BeanMap. The returned collection is not
* modifiable.
*/
public Collection values() {
ArrayList answer = new ArrayList( readMethods.size() );
for ( Iterator iter = valueIterator(); iter.hasNext(); ) {
answer.add( iter.next() );
}
return UnmodifiableList.decorate(answer);
}
// Helper methods
//-------------------------------------------------------------------------
/**
* Returns the type of the property with the given name.
*
* @param name the name of the property
* @return the type of the property, or <code>null</code> if no such
* property exists
*/
public Class getType(String name) {
return (Class) types.get( name );
}
/**
* Convenience method for getting an iterator over the keys.
* <p>
* Write-only properties will not be returned in the iterator.
*
* @return an iterator over the keys
*/
public Iterator keyIterator() {
return readMethods.keySet().iterator();
}
/**
* Convenience method for getting an iterator over the values.
*
* @return an iterator over the values
*/
public Iterator valueIterator() {
final Iterator iter = keyIterator();
return new Iterator() {
public boolean hasNext() {
return iter.hasNext();
}
public Object next() {
Object key = iter.next();
return get(key);
}
public void remove() {
throw new UnsupportedOperationException( "remove() not supported for BeanMap" );
}
};
}
/**
* Convenience method for getting an iterator over the entries.
*
* @return an iterator over the entries
*/
public Iterator entryIterator() {
final Iterator iter = keyIterator();
return new Iterator() {
public boolean hasNext() {
return iter.hasNext();
}
public Object next() {
Object key = iter.next();
Object value = get(key);
return new MyMapEntry( BeanMap.this, key, value );
}
public void remove() {
throw new UnsupportedOperationException( "remove() not supported for BeanMap" );
}
};
}
// Properties
//-------------------------------------------------------------------------
/**
* Returns the bean currently being operated on. The return value may
* be null if this map is empty.
*
* @return the bean being operated on by this map
*/
public Object getBean() {
return bean;
}
/**
* Sets the bean to be operated on by this map. The given value may
* be null, in which case this map will be empty.
*
* @param newBean the new bean to operate on
*/
public void setBean( Object newBean ) {
bean = newBean;
reinitialise();
}
/**
* Returns the accessor for the property with the given name.
*
* @param name the name of the property
* @return the accessor method for the property, or null
*/
public Method getReadMethod(String name) {
return (Method) readMethods.get(name);
}
/**
* Returns the mutator for the property with the given name.
*
* @param name the name of the property
* @return the mutator method for the property, or null
*/
public Method getWriteMethod(String name) {
return (Method) writeMethods.get(name);
}
// Implementation methods
//-------------------------------------------------------------------------
/**
* Returns the accessor for the property with the given name.
*
* @param name the name of the property
* @return null if the name is null; null if the name is not a
* {@link String}; null if no such property exists; or the accessor
* method for that property
*/
protected Method getReadMethod( Object name ) {
return (Method) readMethods.get( name );
}
/**
* Returns the mutator for the property with the given name.
*
* @param name the name of the
* @return null if the name is null; null if the name is not a
* {@link String}; null if no such property exists; null if the
* property is read-only; or the mutator method for that property
*/
protected Method getWriteMethod( Object name ) {
return (Method) writeMethods.get( name );
}
/**
* Reinitializes this bean. Called during {@link #setBean(Object)}.
* Does introspection to find properties.
*/
protected void reinitialise() {
readMethods.clear();
writeMethods.clear();
types.clear();
initialise();
}
private void initialise() {
if(getBean() == null) return;
Class beanClass = getBean().getClass();
try {
//BeanInfo beanInfo = Introspector.getBeanInfo( bean, null );
BeanInfo beanInfo = Introspector.getBeanInfo( beanClass );
PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
if ( propertyDescriptors != null ) {
for ( int i = 0; i < propertyDescriptors.length; i++ ) {
PropertyDescriptor propertyDescriptor = propertyDescriptors[i];
if ( propertyDescriptor != null ) {
String name = propertyDescriptor.getName();
Method readMethod = propertyDescriptor.getReadMethod();
Method writeMethod = propertyDescriptor.getWriteMethod();
Class aType = propertyDescriptor.getPropertyType();
if ( readMethod != null ) {
readMethods.put( name, readMethod );
}
if ( writeMethods != null ) {
writeMethods.put( name, writeMethod );
}
types.put( name, aType );
}
}
}
}
catch ( IntrospectionException e ) {
logWarn( e );
}
}
/**
* Called during a successful {@link #put(Object,Object)} operation.
* Default implementation does nothing. Override to be notified of
* property changes in the bean caused by this map.
*
* @param key the name of the property that changed
* @param oldValue the old value for that property
* @param newValue the new value for that property
*/
protected void firePropertyChange( Object key, Object oldValue, Object newValue ) {
}
// Implementation classes
//-------------------------------------------------------------------------
/**
* Map entry used by {@link BeanMap}.
*/
protected static class MyMapEntry extends AbstractMapEntry {
private BeanMap owner;
/**
* Constructs a new <code>MyMapEntry</code>.
*
* @param owner the BeanMap this entry belongs to
* @param key the key for this entry
* @param value the value for this entry
*/
protected MyMapEntry( BeanMap owner, Object key, Object value ) {
super( key, value );
this.owner = owner;
}
/**
* Sets the value.
*
* @param value the new value for the entry
* @return the old value for the entry
*/
public Object setValue(Object value) {
Object key = getKey();
Object oldValue = owner.get( key );
owner.put( key, value );
Object newValue = owner.get( key );
super.setValue( newValue );
return oldValue;
}
}
/**
* 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 {@link #convertType(Class,Object)}.
*
* @param method the mutator method
* @param value the value to pass to the mutator method
* @return an array containing one object that is either the given value
* or a transformed value
* @throws IllegalAccessException if {@link #convertType(Class,Object)}
* raises it
* @throws IllegalArgumentException if any other exception is raised
* by {@link #convertType(Class,Object)}
*/
protected Object[] createWriteMethodArguments( Method method, Object value ) throws IllegalAccessException, ClassCastException {
try {
if ( value != null ) {
Class[] types = method.getParameterTypes();
if ( types != null && types.length > 0 ) {
Class paramType = types[0];
if ( ! paramType.isAssignableFrom( value.getClass() ) ) {
value = convertType( paramType, value );
}
}
}
Object[] answer = { value };
return answer;
}
catch ( InvocationTargetException e ) {
logInfo( e );
throw new IllegalArgumentException( e.getMessage() );
}
catch ( InstantiationException e ) {
logInfo( e );
throw new IllegalArgumentException( e.getMessage() );
}
}
/**
* 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.<P>
*
* If no such constructor exists, and the given type is a primitive
* type, then the given value is converted to a string using its
* {@link Object#toString() toString()} method, and that string is
* parsed into the correct primitive type using, for instance,
* {@link Integer#valueOf(String)} to convert the string into an
* <code>int</code>.<P>
*
* If no special constructor exists and the given type is not a
* primitive type, this method returns the original value.
*
* @param newType the type to convert the value to
* @param value the value to convert
* @return 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
* @throws InstantiationException if the constructor found with
* reflection raises it
* @throws InvocationTargetException if the constructor found with
* reflection raises it
* @throws IllegalAccessException never
* @throws IllegalArgumentException never
*/
protected Object convertType( Class newType, Object value )
throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
// try call constructor
Class[] types = { value.getClass() };
try {
Constructor constructor = newType.getConstructor( types );
Object[] arguments = { value };
return constructor.newInstance( arguments );
}
catch ( NoSuchMethodException e ) {
// try using the transformers
Transformer transformer = getTypeTransformer( newType );
if ( transformer != null ) {
return transformer.transform( value );
}
return value;
}
}
/**
* Returns a transformer for the given primitive type.
*
* @param aType the primitive type whose transformer to return
* @return a transformer that will convert strings into that type,
* or null if the given type is not a primitive type
*/
protected Transformer getTypeTransformer( Class aType ) {
return (Transformer) defaultTransformers.get( aType );
}
/**
* Logs the given exception to <code>System.out</code>. Used to display
* warnings while accessing/mutating the bean.
*
* @param ex the exception to log
*/
protected void logInfo(Exception ex) {
// Deliberately do not use LOG4J or Commons Logging to avoid dependencies
System.out.println( "INFO: Exception: " + ex );
}
/**
* Logs the given exception to <code>System.err</code>. Used to display
* errors while accessing/mutating the bean.
*
* @param ex the exception to log
*/
protected void logWarn(Exception ex) {
// Deliberately do not use LOG4J or Commons Logging to avoid dependencies
System.out.println( "WARN: Exception: " + ex );
ex.printStackTrace();
}
}
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