/*
* This file is part of the DiffX library.
*
* For licensing information please see the file license.txt included in the release.
* A copy of this licence can also be found at
* http://www.opensource.org/licenses/artistic-license-2.0.php
*/
package com.topologi.diffx.xml;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Collection;
import java.util.Date;
import java.util.Enumeration;
import java.util.Hashtable;
/**
* This class provides methods to serialize objects to XML.
*
* <p>There is no mechanism to prevent infinite loops if some objects (lists,...) reference
* themselves.
*
* <p>The underlying XML document is generated using an XML string buffer.
*
* @version 7 March 2005
* @author Christophe Lauret
*/
public final class XMLSerializer {
// TODO: make an interface out of this class.
// TODO: make the dateformat a class attribute.
/**
* Date formatter.
*/
private static final DateFormat DF = new SimpleDateFormat("dd/MM/yyyy");
/**
* Used to store the xml document of this class.
*
* <p>Classes extending this class should use their constructors to set the size of the
* <code>XMLStringBuffer</code>.
*/
private final XMLWriter xml;
/**
* Creates a new XML serializer using the specified XML writer.
*
* @param xml The XML string buffer to be used
*/
public XMLSerializer(XMLWriter xml) {
this.xml = xml;
}
/**
* Returns the underlying XML document.
*
* @return the xml stringbuffer
*/
public XMLWriter getXML() {
return this.xml;
}
/**
* Serialises the given object using the given name as element name.
*
* <p>This implementation is recursive. It calls itself for fields which are not of
* primitive type.
*
* @param o Object to be serialised as xml
* @param name Name of object
*
* @throws IOException Should an I/O error occur.
*/
public void serialize(Object o, String name) throws IOException {
if (o != null) {
// get rid of some nasty symbols from qualified names and inner classes
if (name.lastIndexOf('.') != -1) {
name = name.substring(name.lastIndexOf('.')+1);
}
if (name.lastIndexOf('$') != -1) {
name = name.substring(name.lastIndexOf('$')+1);
}
name = name.toLowerCase();
// numbers
if (o instanceof Number) {
this.xml.openElement(name, false);
this.xml.writeText(o.toString());
this.xml.closeElement();
// strings
} else if (o instanceof String) {
this.xml.openElement(name, false);
this.xml.writeText(o.toString());
this.xml.closeElement();
// characters
} else if (o instanceof Character) {
this.xml.openElement(name, false);
this.xml.writeText(((Character)o).charValue());
this.xml.closeElement();
// boolean
} else if (o instanceof Boolean) {
this.xml.openElement(name, false);
this.xml.writeText(o.toString());
this.xml.closeElement();
// dates
} else if (o instanceof Date) {
this.xml.openElement(name, false);
this.xml.writeText(DF.format((Date)o));
this.xml.closeElement();
// collection
} else if (o instanceof Collection<?>) {
this.xml.openElement(name, ((Collection<?>)o).size() != 0);
serializeCollection((Collection<?>)o);
this.xml.closeElement();
// hashtable
} else if (o instanceof Hashtable<?,?>) {
this.xml.openElement(name, ((Hashtable<?,?>)o).size() != 0);
serializeHashtable((Hashtable<?,?>)o);
this.xml.closeElement();
// other objects
} else {
this.xml.openElement(name, true);
serializeObject(o);
this.xml.closeElement();
}
}
}
/**
* Serialises the given Collection to xml.
*
* <p>Iterates over every object and call the {@link #serialize} method.
*
* @param c The Collection to be serialised to XML
*
* @throws IOException Should an I/O error occur.
*/
public void serializeCollection(Collection<?> c) throws IOException {
for (Object o : c) {
serialize(o, o.getClass().getName());
}
}
/**
* Serialise the given <code>Hashtable</code> to xml.
*
* <p>This methods only works if the {@link Hashtable} contains <code>String</code>
* objects.
*
* @param h The hashtable to be serialized to XML
*
* @throws IOException Should an I/O error occur.
*/
public void serializeHashtable(Hashtable<?, ?> h) throws IOException {
this.xml.openElement("map", !h.isEmpty());
for (Enumeration<?> e = h.keys(); e.hasMoreElements();) {
Object key = e.nextElement();
Object value = h.get(key);
this.xml.openElement("element");
this.xml.openElement("key");
serialize(key, "key");
this.xml.closeElement();
this.xml.openElement("value");
serialize(value, "value");
this.xml.closeElement();
this.xml.closeElement();
}
this.xml.closeElement();
}
/**
* Serialises the given object to xml by using the public methods <code>getXXX()</code>.
*
* <p>This method calls every <code>getXXX()</code> method from the object to get the
* returned object and then calls the {@link #serialize(Object, String)} method with
* the returned object and the name <i>xxx</i> in lower case.
*
* @param o The object to be serialised as XML
*
* @throws IOException Should an I/O error occur.
*/
public void serializeObject(Object o) throws IOException {
if (o instanceof XMLSerializable) {
try {
Object[] args = new Object[0]; // required by the invoke method
Class<?> cls = o.getClass();
Method[] meth = cls.getMethods();
for (Method element : meth) {
String methodName = element.getName();
if (methodName.startsWith("get") && !"getClass".equals(methodName)) {
Object retObj = element.invoke(o, args);
String attribute = methodName.substring(3).toLowerCase();
serialize(retObj, attribute);
}
}
} catch (IllegalAccessException ex) {
ex.printStackTrace();
} catch (InvocationTargetException ex) {
ex.getTargetException().printStackTrace();
}
} else if (o instanceof XMLWritable) {
((XMLWritable)o).toXML(this.xml);
}
}
}