org.simpleframework.xml.Attribute Maven / Gradle / Ivy
/*
* Attribute.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;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Retention;
/**
* The Attribute annotation represents a serializable XML
* attribute within an XML element. An object annotated with this is
* typically a primitive or enumerated type. Conversion from the
* attribute to primitive type is done with a Transform
* object. If a suitable transform can be found then this will convert
* the attribute string value to an object instance, which can be
* assigned to the annotated field, or passed to the annotated method.
*
* @author Niall Gallagher
*
* @see org.simpleframework.xml.transform.Transformer
*/
@Retention(RetentionPolicy.RUNTIME)
public @interface Attribute {
/**
* This represents the name of the XML attribute. Annotated fields
* or methods can optionally provide the name of the XML attribute
* they represent. If a name is not provided then the field or
* method name is used in its place. A name can be specified if
* the field or method name is not suitable for the XML attribute.
*
* @return the name of the XML attribute this represents
*/
public String name() default "";
/**
* This is used to provide a default value for the attribute if
* the annotated field or method is null. This ensures the the
* serialization process writes the attribute with a value even
* if the value is null, and allows deserialization to determine
* whether the value within the object was null or not.
*
* @return this returns the default attribute value to use
*/
public String empty() default "";
/**
* Determines whether the attribute is required within an XML
* element. Any field marked as not required will not have its
* value set when the object is deserialized. If an object is to
* be serialized only a null attribute will not appear as XML.
*
* @return true if the attribute is required, false otherwise
*/
public boolean required() default true;
}