org.simpleframework.xml.load.Label Maven / Gradle / Ivy
/*
* Label.java July 2006
*
* Copyright (C) 2006, Niall Gallagher
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA
*/
package org.simpleframework.xml.load;
/**
* The Label interface is used to describe an reference to
* a field annotated with an XML schema annotation. Because each field
* and annotation is different, there are different ways in which the
* annotation can be accessed. This provides a uniform means for
* accessing the field annotation details and the field properties.
*
* This also exposes a Converter object, which is used to
* convert an XML node into a property that can be assigned to the
* annotated field. Each converter returned is specific to the label
* and knows, based on the annotation, how to serialize the field.
*
* @author Niall Gallagher
*/
interface Label {
/**
* This is used to provide a configured empty value used when the
* annotated value is null. This ensures that XML can be created
* with required details regardless of whether values are null or
* not. It also provides a means for sensible default values.
*
* @param root this is the source object for the serialization
*
* @return this returns the string to use for default values
*/
public Object getEmpty(Source root) throws Exception;
/**
* This method returns a Converter which can be used to
* convert an XML node into an object value and vice versa. The
* converter requires only the source object in order to perform
* serialization or deserialization of the provided XML node.
*
* @param root this is the source object for the serialization
*
* @return this returns an object that is used for conversion
*/
public Converter getConverter(Source root) throws Exception;
/**
* This is used to acquire the name of the element or attribute
* that is used by the class schema. The name is determined by
* checking for an override within the annotation. If it contains
* a name then that is used, if however the annotation does not
* specify a name the the field or method name is used instead.
*
* @param source this is the source used to style the name
*
* @return returns the name that is used for the XML property
*/
public String getName(Source source) throws Exception;
/**
* This is used to acquire the name of the element or attribute
* that is used by the class schema. The name is determined by
* checking for an override within the annotation. If it contains
* a name then that is used, if however the annotation does not
* specify a name the the field or method name is used instead.
*
* @return returns the name that is used for the XML property
*/
public String getName() throws Exception;
/**
* This returns the dependant type for the annotation. This type
* is the type other than the annotated field or method type that
* the label depends on. For the ElementList and
* the ElementArray this is the component type that
* is deserialized individually and inserted into the container.
*
* @return this is the type that the annotation depends on
*/
public Class getDependant() throws Exception;
/**
* This is used to either provide the entry value provided within
* the annotation or compute a entry value. If the entry string
* is not provided the the entry value is calculated as the type
* of primitive the object is as a simplified class name.
*
* @return this returns the name of the XML entry element used
*/
public String getEntry() throws Exception;
/**
* This is used to acquire the contact object for this label. The
* contact retrieved can be used to set any object or primitive that
* has been deserialized, and can also be used to acquire values to
* be serialized in the case of object persistance. All contacts
* that are retrieved from this method will be accessible.
*
* @return returns the field that this label is representing
*/
public Contact getContact();
/**
* This acts as a convinience method used to determine the type of
* the field this represents. This is used when an object is written
* to XML. It determines whether a class attribute
* is required within the serialized XML element, that is, if the
* class returned by this is different from the actual value of the
* object to be serialized then that type needs to be remembered.
*
* @return this returns the type of the field class
*/
public Class getType();
/**
* This is used to acquire the name of the element or attribute
* as taken from the annotation. If the element or attribute
* explicitly specifies a name then that name is used for the
* XML element or attribute used. If however no overriding name
* is provided then the method or field is used for the name.
*
* @return returns the name of the annotation for the contact
*/
public String getOverride();
/**
* This is used to determine whether the annotation requires it
* and its children to be written as a CDATA block. This is done
* when a primitive or other such element requires a text value
* and that value needs to be encapsulated within a CDATA block.
*
* @return this returns true if the element requires CDATA
*/
public boolean isData();
/**
* Determines whether the XML attribute or element is required.
* This ensures that if an XML element is missing from a document
* that deserialization can continue. Also, in the process of
* serialization, if a value is null it does not need to be
* written to the resulting XML document.
*
* @return true if the label represents a some required data
*/
public boolean isRequired();
/**
* This is used to determine whether the label represents an
* inline XML entity. The ElementList annotation
* and the Text annotation represent inline
* items. This means that they contain no containing element
* and so can not specify overrides or special attributes.
*
* @return this returns true if the annotation is inline
*/
public boolean isInline();
/**
* This is used to describe the annotation and method or field
* that this label represents. This is used to provide error
* messages that can be used to debug issues that occur when
* processing a method. This should provide enough information
* such that the problem can be isolated correctly.
*
* @return this returns a string representation of the label
*/
public String toString();
}