org.simpleframework.xml.core.CompositeValue Maven / Gradle / Ivy
/*
* CompositeValue.java July 2007
*
* Copyright (C) 2007, 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.core;
import org.simpleframework.xml.stream.InputNode;
import org.simpleframework.xml.stream.OutputNode;
import org.simpleframework.xml.stream.Style;
/**
* The CompositeValue object is used to convert an object
* to an from an XML element. This accepts only composite objects and
* will maintain all references within the object using the cycle
* strategy if required. This also ensures that should the value to
* be written to the XML element be null that nothing is written.
*
* @author Niall Gallagher
*
* @see org.simpleframework.xml.ElementMap
*/
class CompositeValue implements Converter {
/**
* This is the context used to support the serialization process.
*/
private final Context context;
/**
* This is the traverser used to read and write the value with.
*/
private final Traverser root;
/**
* This is the style used to style the names used for the XML.
*/
private final Style style;
/**
* This is the entry object used to provide configuration details.
*/
private final Entry entry;
/**
* This represents the type of object the value is written as.
*/
private final Class type;
/**
* Constructor for the CompositeValue object. This
* will create an object capable of reading an writing composite
* values from an XML element. This also allows a parent element
* to be created to wrap the key object if desired.
*
* @param context this is the root context for the serialization
* @param entry this is the entry object used for configuration
* @param type this is the type of object the value represents
*/
public CompositeValue(Context context, Entry entry, Class type) throws Exception {
this.root = new Traverser(context);
this.style = context.getStyle();
this.context = context;
this.entry = entry;
this.type = type;
}
/**
* This method is used to read the value object from the node. The
* value read from the node is resolved using the template filter.
* If the value data can not be found according to the annotation
* attributes then null is assumed and returned.
*
* @param node this is the node to read the value object from
*
* @return this returns the value deserialized from the node
*/
public Object read(InputNode node) throws Exception {
InputNode next = node.getNext();
if(next == null) {
return null;
}
if(next.isEmpty()) {
return null;
}
return root.read(next, type);
}
/**
* This method is used to read the value object from the node. The
* value read from the node is resolved using the template filter.
* If the value data can not be found according to the annotation
* attributes then null is assumed and returned.
*
* @param node this is the node to read the value object from
* @param value this is the value to deserialize in to
*
* @return this returns the value deserialized from the node
*
* @throws Exception if value is not null an exception is thrown
*/
public Object read(InputNode node, Object value) throws Exception {
if(value != null) {
throw new PersistenceException("Can not read value of %s", type);
}
return read(node);
}
/**
* This method is used to read the value object from the node. The
* value read from the node is resolved using the template filter.
* If the value data can not be found according to the annotation
* attributes then null is assumed and the node is valid.
*
* @param node this is the node to read the value object from
*
* @return this returns true if this represents a valid value
*/
public boolean validate(InputNode node) throws Exception {
String name = entry.getValue();
if(name == null) {
name = context.getName(type);
}
return validate(node, name);
}
/**
* This method is used to read the value object from the node. The
* value read from the node is resolved using the template filter.
* If the value data can not be found according to the annotation
* attributes then null is assumed and the node is valid.
*
* @param node this is the node to read the value object from
* @param key this is the name of the value element
*
* @return this returns true if this represents a valid value
*/
private boolean validate(InputNode node, String key) throws Exception {
String name = style.getElement(key);
InputNode next = node.getNext(name);
if(next == null) {
return true;
}
if(next.isEmpty()) {
return true;
}
return root.validate(next, type);
}
/**
* This method is used to write the value to the specified node.
* The value written to the node must be a composite object and if
* the object provided to this is null then nothing is written.
*
* @param node this is the node that the value is written to
* @param item this is the item that is to be written
*/
public void write(OutputNode node, Object item) throws Exception {
String key = entry.getValue();
if(key == null) {
key = context.getName(type);
}
String name = style.getElement(key);
root.write(node, item, type, name);
}
}