/*
* XMLIOManager.java
*
* Created on October 16, 2001, 8:03 AM
*/
package org.freehep.xml.io;
import java.util.*;
import org.jdom.*;
/**
* The XMLIOManager is in charge of saving and restoring any object
* configuration through XML. It internally assigns objects and unique
* identification string used for cross-reference among xml nodes.
*
* @author turri
* @version 1.0
*
*/
public class XMLIOManager {
private Hashtable objIdHash = new Hashtable();
private Hashtable idHash = new Hashtable();
private Hashtable nodeHash = new Hashtable();
private Hashtable classHash = new Hashtable();
private Hashtable refTable = new Hashtable();
private XMLIORegistry xmlioRegistry;
private XMLIOStreamManager xmlioStreamManager;
private boolean useId = true;
/**
* The basic constructor.
* @param xmlioRegistry The XMLIORegistry from which the XMLIOManager
* gets the XMLIOFactories and the XMLIOProxies to
* save and restore objects.
* @param xmlioStreamManager The xmlioStreamManager that deals with the input/output file.
*
*/
/* MD: never used
private XMLIOManager() {
this( new DefaultXMLIORegistry(), new XMLIOFileManager("defaultXMLIOFile.xml"), true);
}
*/
public XMLIOManager(String fileName) {
this( new DefaultXMLIORegistry(), new XMLIOFileManager(fileName), true);
}
/* MD: never used
private XMLIOManager( boolean useId ) {
this( new DefaultXMLIORegistry(), new XMLIOFileManager("defaultXMLIOFile.xml"), useId);
}
*/
/* MD: never used
private XMLIOManager( XMLIORegistry xmlioRegistry, XMLIOStreamManager xmlioFileManager ) {
this( xmlioRegistry, xmlioFileManager, true);
}
*/
private XMLIOManager( XMLIORegistry xmlioRegistry, XMLIOStreamManager xmlioFileManager, boolean useId ) {
setXMLIORegistry( xmlioRegistry );
setXMLIOStreamManager( xmlioFileManager );
this.useId = useId;
}
protected void setXMLIORegistry( XMLIORegistry xmlioRegistry ) {
this.xmlioRegistry = xmlioRegistry;
}
/**
* Get the XMLIORegistry.
* @return the XMLIORegistry
*
*/
public XMLIORegistry getXMLIORegistry() {
return xmlioRegistry;
}
public void setXMLIOStreamManager( XMLIOStreamManager xmlioStreamManager ) {
this.xmlioStreamManager = xmlioStreamManager;
}
public XMLIOStreamManager getXMLIOStreamManager() {
return xmlioStreamManager;
}
/**
* Restore an object from an xml node.
* @param nodeEl The node containing the object's information.
* This method should be used by the user to restore
* nested objects within the restore method of an object
* implementing the XMLIO interface.
* @return The restored object. The object is first created by
* invoking the create method on the corresponding XMLIOFactory.
* Once created the restore method is invoked either on the object
* itself (if it implements the XMLIO interface) or on the appropriate
* XMLIOProxy.
*
*/
public Object restore( Object obj, Element nodeEl ) {
String objIdRef = (String) nodeEl.getAttributeValue( "objIdRef" );
if ( objIdRef != null )
if ( useId )
if ( isObjIdRegistered( objIdRef ) )
return getObj( objIdRef );
else
return restore(obj, (Element) refTable.get(objIdRef) );
String objId = (String) nodeEl.getAttributeValue( "objId" );
if ( useId && isObjIdRegistered( objId ) ) return getObj( objId );
Class objClass;
if ( classHash.containsKey( nodeEl.getName() ) )
objClass = (Class) classHash.get( nodeEl.getName() );
else
objClass = xmlioRegistry.getIdClass(nodeEl.getName());
if ( obj == null )
obj = getXMLIOFactory( objClass ).createObject( objClass );
if ( useId ) registerObj( obj, objId );
if ( obj instanceof XMLIO ) ((XMLIO)obj).restore( this, nodeEl );
else getXMLIOProxy( objClass ).restore( obj, this, nodeEl);
return obj;
}
public Object restore( Element nodeEl ) {
return restore(null, nodeEl);
}
/**
* Save an object to an XML node.
* @param obj The object to be saved.
* @return The jdom Element containing the object's unique
* identification string (in the attribute "objId") and
* whose name is the object's identifier. The user will have
* to append to this node all the attributes and other
* jdom elemets required to save the object's configuration.
*
*/
public Element saveAs( Object obj, Class clazz ) {
String nodeName;
if ( nodeHash.containsKey( clazz ) ) nodeName = (String) nodeHash.get(clazz);
else nodeName = (String) xmlioRegistry.getClassId( clazz );
Element el = new Element( nodeName );
if ( isObjRegistered( obj ) ) el.setAttribute( "objIdRef", getObjId( obj ) );
else {
if ( useId ) el.setAttribute( "objId", registerObj( obj ) );
if ( obj instanceof XMLIO ) ((XMLIO)obj).save( this, el );
else getXMLIOProxy( clazz ).save( obj, this, el );
}
return el;
}
public Element save( Object obj ) {
return saveAs( obj, obj.getClass() );
}
/**
* The main method to save an array of objects to XML.
* @param objs The array of objects to be saved.
*
*/
public void saveToXML( Object[] objs, Element nodeEl ) {
resetObjId();
for ( int i = 0; i < objs.length; i++ ) {
nodeEl.addContent( save( objs[i] ) );
}
try {
xmlioStreamManager.saveRootElement( nodeEl );
} catch ( java.io.IOException ioe ) {
System.out.println(" Problem with file "+ioe.getMessage());
}
}
/**
* The main method to restore from xml.
* @return The array of the restored objects.
*
*/
public Object[] restoreFromXML() {
resetObjId();
Object[] objs = null;
try {
Element restoreElement = xmlioStreamManager.getRootElement();
//Create the list of references here.
List children = restoreElement.getChildren();
for (Iterator it = children.iterator(); it.hasNext(); )
loadRefTable( (Element) it.next() );
objs = new Object[ children.size() ];
int child = 0;
for (Iterator it = children.iterator(); it.hasNext(); )
objs[ child++ ] = restore( (Element) it.next() );
} catch ( JDOMException je ) {
System.out.println(" Problem with restoring "+je.getMessage());
} catch ( java.io.IOException ioe ) {
System.out.println(" Problem with file "+ioe.getMessage());
}
return objs;
}
/**
* Assign to a Class a string identifier.
* @param clName The Class.
* @param id The new identifier for the class.
*
*/
public void setClassId(Class clName, String id) {
nodeHash.put(clName, id);
classHash.put(id, clName);
}
protected void loadRefTable(Element el) {
String objId = el.getAttributeValue("objId");
if ( objId != null )
refTable.put( objId, el );
List children = el.getChildren();
for (Iterator it = children.iterator(); it.hasNext(); )
loadRefTable( (Element) it.next() );
}
/**
* Down here are only private and protected methods.
*
*/
/**
* Create the object's unique Id for cross-reference among xml nodes
* @param obj the object.
* @return the object's unique Id.
*/
private String makeObjId( Object obj ) {
String clName = obj.getClass().getName();
String pkgName = obj.getClass().getPackage().getName();
String idName = clName.substring( pkgName.length()+1, clName.length() ).trim();
while ( idName.indexOf('$') != -1 )
idName = idName.substring( idName.indexOf('$')+1, idName.length() ).trim();
int i = 1;
if ( idHash.containsKey( idName ) ) i = ( (Integer)( idHash.get( idName ) ) ).intValue() + 1;
idHash.put( idName, new Integer( i ) );
String objId = idName+i;
return objId;
}
/**
* Register object assigning an unique Id for cross-reference among xml nodes
* @param obj the object to be registered.
* @return the object's unique Id.
*/
private String registerObj( Object obj ) {
if ( objIdHash.contains( obj ) ) return getObjId( obj );
String objId = makeObjId( obj );
objIdHash.put( objId, obj );
return objId;
}
/**
* Register object with a pre-assigned Id for cross-reference among xml nodes
* @param obj the object to be registered
* @param objId the object's Id
*/
private void registerObj( Object obj, String objId ) {
if ( objIdHash.containsKey( objId ) ) return;
objIdHash.put( objId, obj);
}
/**
* Get the object's unique Id for cross-reference among xml nodes
* @param obj the object whose unique id we are looking for
* @return the unique String Id of object <code>obj</code>
* if no string is found the object itself is returned
*/
private String getObjId( Object obj ) {
for ( Enumeration keys = objIdHash.keys(); keys.hasMoreElements(); ) {
String key = (String) ( keys.nextElement() );
if ( objIdHash.get( key ).equals( obj ) ) return key;
}
return (String)obj;
}
/**
* Get the object corresponding to unique Id for cross-reference among xml nodes
* @param objId the object's unique String Id
* @return the object corrisponding to unique Id <code>objId</code>
* if the object is registered or the string <code>objId</code>
* if the object is not registered
*
*/
private Object getObj( String objId ) {
if ( objIdHash.containsKey( objId ) )
return objIdHash.get( objId );
return objId;
}
/**
* Check if an object is registered
* @param obj the object to be checked
* @return <code>true</code> if the object is registered
* <code>false</code> otherwise
*
*/
private boolean isObjRegistered( Object obj ) {
if ( objIdHash.contains( obj ) ) return true;
return false;
}
/**
* Check if an unique Id is registered
* @param objId the unique Id to be checked
* @return <code>true</code> if the unique Id is registered
* <code>false</code> otherwise
*
*/
private boolean isObjIdRegistered( String objId ) {
if ( objIdHash.containsKey( objId ) ) return true;
return false;
}
/**
* Reset the stored ids
*/
public void resetObjId() {
objIdHash.clear();
idHash.clear();
refTable.clear();
}
/**
* Get the XMLIOFactory to restore the xml node
* param nodeEl the node to be restored
* @return the XMLIOFactory
*
*/
protected XMLIOFactory getXMLIOFactory( Class objClass ) {
return xmlioRegistry.getXMLIOFactory( objClass );
}
protected XMLIOProxy getXMLIOProxy( Class objClass ) {
return xmlioRegistry.getXMLIOProxy( objClass );
}
}