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Apache Commons BeanUtils provides an easy-to-use but flexible wrapper around reflection and introspection.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.io.Serializable;
import java.lang.reflect.InvocationTargetException;
/**
* Implementation of DynaBean that wraps a standard JavaBean
* instance, so that DynaBean APIs can be used to access its properties.
*
*
* The most common use cases for this class involve wrapping an existing java bean.
* (This makes it different from the typical use cases for other DynaBean's.)
* For example:
*
*
* Object aJavaBean = ...;
* ...
* DynaBean db = new WrapDynaBean(aJavaBean);
* ...
*
IMPLEMENTATION NOTE - This implementation does not
* support the contains() and remove() methods.
*
* @version $Id: WrapDynaBean.java 1547902 2013-12-04 20:35:01Z oheger $
*/
public class WrapDynaBean implements DynaBean, Serializable {
// ---------------------------------------------------------- Constructors
/**
* Construct a new DynaBean associated with the specified
* JavaBean instance.
*
* @param instance JavaBean instance to be wrapped
*/
public WrapDynaBean(Object instance) {
this(instance, null);
}
/**
* Creates a new instance of {@code WrapDynaBean}, associates it with the specified
* JavaBean instance, and initializes the bean's {@code DynaClass}. Using this
* constructor this {@code WrapDynaBean} instance can be assigned a class which has
* been configured externally. If no {@code WrapDynaClass} is provided, a new one is
* created using a standard mechanism.
*
* @param instance JavaBean instance to be wrapped
* @param cls the optional {@code WrapDynaClass} to be used for this bean
* @since 1.9
*/
public WrapDynaBean(Object instance, WrapDynaClass cls) {
this.instance = instance;
this.dynaClass = (cls != null) ? cls : (WrapDynaClass) getDynaClass();
}
// ---------------------------------------------------- Instance Variables
/**
* The DynaClass "base class" that this DynaBean
* is associated with.
*/
protected transient WrapDynaClass dynaClass = null;
/**
* The JavaBean instance wrapped by this WrapDynaBean.
*/
protected Object instance = null;
// ------------------------------------------------------ DynaBean Methods
/**
* Does the specified mapped property contain a value for the specified
* key value?
*
* @param name Name of the property to check
* @param key Name of the key to check
* @return true if the mapped property contains a value for
* the specified key, otherwise false
*
* @exception IllegalArgumentException if there is no property
* of the specified name
*/
public boolean contains(String name, String key) {
throw new UnsupportedOperationException
("WrapDynaBean does not support contains()");
}
/**
* Return the value of a simple property with the specified name.
*
* @param name Name of the property whose value is to be retrieved
* @return The property's value
*
* @exception IllegalArgumentException if there is no property
* of the specified name
*/
public Object get(String name) {
Object value = null;
try {
value = getPropertyUtils().getSimpleProperty(instance, name);
} catch (InvocationTargetException ite) {
Throwable cause = ite.getTargetException();
throw new IllegalArgumentException
("Error reading property '" + name +
"' nested exception - " + cause);
} catch (Throwable t) {
throw new IllegalArgumentException
("Error reading property '" + name +
"', exception - " + t);
}
return (value);
}
/**
* Return the value of an indexed property with the specified name.
*
* @param name Name of the property whose value is to be retrieved
* @param index Index of the value to be retrieved
* @return The indexed property's value
*
* @exception IllegalArgumentException if there is no property
* of the specified name
* @exception IllegalArgumentException if the specified property
* exists, but is not indexed
* @exception IndexOutOfBoundsException if the specified index
* is outside the range of the underlying property
* @exception NullPointerException if no array or List has been
* initialized for this property
*/
public Object get(String name, int index) {
Object value = null;
try {
value = getPropertyUtils().getIndexedProperty(instance, name, index);
} catch (IndexOutOfBoundsException e) {
throw e;
} catch (InvocationTargetException ite) {
Throwable cause = ite.getTargetException();
throw new IllegalArgumentException
("Error reading indexed property '" + name +
"' nested exception - " + cause);
} catch (Throwable t) {
throw new IllegalArgumentException
("Error reading indexed property '" + name +
"', exception - " + t);
}
return (value);
}
/**
* Return the value of a mapped property with the specified name,
* or null if there is no value for the specified key.
*
* @param name Name of the property whose value is to be retrieved
* @param key Key of the value to be retrieved
* @return The mapped property's value
*
* @exception IllegalArgumentException if there is no property
* of the specified name
* @exception IllegalArgumentException if the specified property
* exists, but is not mapped
*/
public Object get(String name, String key) {
Object value = null;
try {
value = getPropertyUtils().getMappedProperty(instance, name, key);
} catch (InvocationTargetException ite) {
Throwable cause = ite.getTargetException();
throw new IllegalArgumentException
("Error reading mapped property '" + name +
"' nested exception - " + cause);
} catch (Throwable t) {
throw new IllegalArgumentException
("Error reading mapped property '" + name +
"', exception - " + t);
}
return (value);
}
/**
* Return the DynaClass instance that describes the set of
* properties available for this DynaBean.
* @return The associated DynaClass
*/
public DynaClass getDynaClass() {
if (dynaClass == null) {
dynaClass = WrapDynaClass.createDynaClass(instance.getClass());
}
return (this.dynaClass);
}
/**
* Remove any existing value for the specified key on the
* specified mapped property.
*
* @param name Name of the property for which a value is to
* be removed
* @param key Key of the value to be removed
*
* @exception IllegalArgumentException if there is no property
* of the specified name
*/
public void remove(String name, String key) {
throw new UnsupportedOperationException
("WrapDynaBean does not support remove()");
}
/**
* Set the value of a simple property with the specified name.
*
* @param name Name of the property whose value is to be set
* @param value Value to which this property is to be set
*
* @exception ConversionException if the specified value cannot be
* converted to the type required for this property
* @exception IllegalArgumentException if there is no property
* of the specified name
* @exception NullPointerException if an attempt is made to set a
* primitive property to null
*/
public void set(String name, Object value) {
try {
getPropertyUtils().setSimpleProperty(instance, name, value);
} catch (InvocationTargetException ite) {
Throwable cause = ite.getTargetException();
throw new IllegalArgumentException
("Error setting property '" + name +
"' nested exception -" + cause);
} catch (Throwable t) {
throw new IllegalArgumentException
("Error setting property '" + name +
"', exception - " + t);
}
}
/**
* Set the value of an indexed property with the specified name.
*
* @param name Name of the property whose value is to be set
* @param index Index of the property to be set
* @param value Value to which this property is to be set
*
* @exception ConversionException if the specified value cannot be
* converted to the type required for this property
* @exception IllegalArgumentException if there is no property
* of the specified name
* @exception IllegalArgumentException if the specified property
* exists, but is not indexed
* @exception IndexOutOfBoundsException if the specified index
* is outside the range of the underlying property
*/
public void set(String name, int index, Object value) {
try {
getPropertyUtils().setIndexedProperty(instance, name, index, value);
} catch (IndexOutOfBoundsException e) {
throw e;
} catch (InvocationTargetException ite) {
Throwable cause = ite.getTargetException();
throw new IllegalArgumentException
("Error setting indexed property '" + name +
"' nested exception - " + cause);
} catch (Throwable t) {
throw new IllegalArgumentException
("Error setting indexed property '" + name +
"', exception - " + t);
}
}
/**
* Set the value of a mapped property with the specified name.
*
* @param name Name of the property whose value is to be set
* @param key Key of the property to be set
* @param value Value to which this property is to be set
*
* @exception ConversionException if the specified value cannot be
* converted to the type required for this property
* @exception IllegalArgumentException if there is no property
* of the specified name
* @exception IllegalArgumentException if the specified property
* exists, but is not mapped
*/
public void set(String name, String key, Object value) {
try {
getPropertyUtils().setMappedProperty(instance, name, key, value);
} catch (InvocationTargetException ite) {
Throwable cause = ite.getTargetException();
throw new IllegalArgumentException
("Error setting mapped property '" + name +
"' nested exception - " + cause);
} catch (Throwable t) {
throw new IllegalArgumentException
("Error setting mapped property '" + name +
"', exception - " + t);
}
}
/**
* Gets the bean instance wrapped by this DynaBean.
* For most common use cases,
* this object should already be known
* and this method safely be ignored.
* But some creators of frameworks using DynaBean's may
* find this useful.
*
* @return the java bean Object wrapped by this DynaBean
*/
public Object getInstance() {
return instance;
}
// ------------------------------------------------------ Protected Methods
/**
* Return the property descriptor for the specified property name.
*
* @param name Name of the property for which to retrieve the descriptor
* @return The descriptor for the specified property
*
* @exception IllegalArgumentException if this is not a valid property
* name for our DynaClass
*/
protected DynaProperty getDynaProperty(String name) {
DynaProperty descriptor = getDynaClass().getDynaProperty(name);
if (descriptor == null) {
throw new IllegalArgumentException
("Invalid property name '" + name + "'");
}
return (descriptor);
}
/**
* Returns the {@code PropertyUtilsBean} instance to be used for accessing properties.
* If available, this object is obtained from the associated {@code WrapDynaClass}.
*
* @return the associated {@code PropertyUtilsBean}
*/
private PropertyUtilsBean getPropertyUtils() {
PropertyUtilsBean propUtils = null;
if (dynaClass != null) {
propUtils = dynaClass.getPropertyUtilsBean();
}
return (propUtils != null) ? propUtils : PropertyUtilsBean.getInstance();
}
}