Object2XML


1   // You can redistribute this software and/or modify it under the terms of
2   // the Ozone Core License version 1 published by ozone-db.org.
3   //
4   // The original code and portions created by SMB are
5   // Copyright (C) 1997-@year@ by SMB GmbH. All rights reserved.
6   //
7   // $Id: Object2XML.java,v 1.3 2002/09/18 06:54:17 per_nyfelt Exp $
8   
9   package org.ozoneDB.core.xml;
10  
11  import org.ozoneDB.OzoneInterface;
12  import org.ozoneDB.OzoneProxy;
13  import org.ozoneDB.core.ObjectContainer;
14  import org.xml.sax.*;
15  import org.xml.sax.helpers.AttributesImpl  ;
16  
17  import java.lang.reflect.*;
18  import java.util.Hashtable  ;
19  
20  
21  /**
22   * This class transform an Object into XML.
23   *
24   * @version $Revision: 1.3 $
25   * @author <a HREF="http://www.softwarebuero.de">SMB</a>
26   */
27  
28  
29  public class Object2XML implements Consts {
30  
31      //
32      // member
33      //
34  
35      /**
36       * ObjCache saves the references of the processed objects.
37       */
38      private Hashtable   objCache = new Hashtable  ();
39  
40      /**
41       * This flag decides if transient member will be serialized or not.
42       */
43      private boolean serializeTransientFlag = false;
44  
45      /**
46       * The SAX handler for the XML content.
47       */
48      private ContentHandler ch;
49  
50      /**
51       * Factory for the attributes of the first obj-Tag.
52       */
53      private ObjAttsFactory oaf;
54  
55  
56      //
57      // construcor
58      //
59  
60  
61      /**
62       * @param contHandler
63       */
64      public Object2XML( ContentHandler contHandler ) {
65          ch = contHandler;
66          oaf = new OzoneObjAttsFactory();
67      }
68  
69  
70      /**
71       * @param contHandler
72       * @param serializeTransientFlag
73       */
74      public Object2XML( ContentHandler contHandler, boolean serializeTransientFlag ) {
75          this( contHandler );
76          this.serializeTransientFlag = serializeTransientFlag;
77      }
78  
79      //
80      // methods
81      //
82  
83  
84      /**
85       * ToXML(obj) gets an object and serialize this object into XML.
86       *
87       * @param obj (the Object)
88       */
89      public void toXML( Object   obj ) throws SAXException {
90         // ch.startDocument();
91          writeObjStartTag( obj.getClass().getName(), getID( obj ), oaf.additionallyAtts( obj ) );
92          objCache.put( getID( obj ), getID( obj ) );
93  
94          getMember( obj, obj.getClass() );
95  
96          writeObjEndTag();
97         // ch.endDocument();
98      }
99  
100 
101     /**
102      * GetMember gets the informations (name/type/value)
103      * of all members (private and protected too) !!
104      *
105      * @param obj (the Object)
106      * @param objClass (the Class of the Object)
107      */
108     protected void getMember( Object   obj, Class   objClass ) throws SAXException {
109        // System.out.println( "getMember(): " + objClass.getName() );
110 
111         Field[] fds = objClass.getDeclaredFields();
112 
113         AccessibleObject.setAccessible( fds, true );
114         for (int i = 0; i < fds.length; i++) {
115             Field fd = fds[i];
116 
117             // avoid converting the container of a database object
118             if (ObjectContainer.class.isAssignableFrom( fd.getType() )) {
119                 continue;
120             }
121             if (OzoneInterface.class.isAssignableFrom( fd.getType() )) {
122                 continue;
123             }
124             if (Modifier.isStatic( fd.getModifiers() )) {
125                 continue;
126             }
127             if (!serializeTransientFlag && Modifier.isTransient( fd.getModifiers() )) {
128                 continue;
129             }
130 
131             String   memberName = fd.getName();
132 
133             try {
134 
135                 Object   value = fd.get( obj );
136                 if (value instanceof org.ozoneDB.OzoneProxy)
137                     handleOzoneProxyMember( memberName, (OzoneProxy)value);
138                 else {
139                     writeMemberStartTag( memberName );
140                     getValue( value , fd.getType() );
141                 }
142 
143                 writeMemberEndTag();
144 
145             } catch (IllegalAccessException   iae) {
146                 System.err.println( "(getMember) EXCEPTION: " + iae );
147             }
148         }
149 
150         superClass( obj, objClass );
151     }
152 
153 
154     /**
155      * SuperClass gets the informations about the Superclass of the Object.
156      *
157      * @param obj (the Object)
158      * @param objClass (the Class of the Object)
159      */
160     private void superClass( Object   obj, Class   objClass ) throws SAXException {
161 
162         Class   superClass = objClass.getSuperclass();
163         if (superClass == null) {
164             return;
165         }
166 
167         writeSuperClStartTag( superClass.getName() );
168 
169         getMember( obj, superClass );
170         writeSuperClEndTag();
171     }
172 
173     /**
174      * GetValue gets the value of the certain member.
175      *
176      * @param value (value of the member)
177      * @param valueType (the Class of the certain member)
178      */
179     protected void getValue( Object   value, Class   valueType ) throws SAXException {
180         if (value == null) {
181             return;
182         }
183 
184         if (objCache.containsKey( getID( value ) )) {
185             writeObjRefElement( getID( value ) );
186             return;
187         }
188 
189         objCache.put( getID( value ), getID( value ) );
190 
191         if (valueType.isPrimitive()) {
192             writeValueStartTag( valueType.getName(), getID( value ) );
193             writeValue( value.toString() );
194             writeValueEndTag();
195             return;
196         }
197 
198         if (   value instanceof Boolean   || value instanceof Byte    || value instanceof Character  
199             || value instanceof Double    || value instanceof Float   || value instanceof Long  
200             || value instanceof Integer   || value instanceof Short   || value instanceof String  ) {
201 
202             writeValueStartTag( value.getClass().getName(), getID( value ) );
203             writeValue( value.toString() );
204             writeValueEndTag();
205             return;
206         }
207 
208 
209         if (valueType.isArray()) {
210             int length = Array.getLength( value );
211             Class   subType = value.getClass().getComponentType();
212             writeArrayStartTag( valueType.getName(), getID( value ) );
213             for (int l = 0; l < length; l++) {
214 
215                 Object   subValue = Array.get( value, l );
216                 if(subValue == null)
217                     continue;
218 
219                 if (subType.isPrimitive()) {
220                     getValue( subValue , subType );
221                 } else {
222                     getValue( subValue , subValue.getClass());
223                 }
224             }
225             writeArrayEndTag();
226 
227         } else {
228             writeValueObjStartTag( value.getClass().getName(), getID( value ) );
229 
230             getMember( value, value.getClass() );
231             writeValueObjEndTag();
232         }
233     }
234 
235     /**
236      * This methode handles an OzoneProxy member.
237      *
238      * @param memberName (name of the member)
239      * @param proxy (the OzoneProxy object)
240      */
241     protected void handleOzoneProxyMember( String   memberName, OzoneProxy proxy) throws SAXException {
242         String   proxyType = proxy.getClass().getName();
243         String   objectID;
244 
245         try {
246 
247             Field remoteID = proxy.getClass().getField( REMOTE_ID );
248             Object   valueID = remoteID.get( proxy );
249             objectID = valueID.toString();
250 
251             writeMemberTagForOzoneProxy( memberName, proxyType, objectID );
252 
253         } catch (NoSuchFieldException   nsfe) {
254             System.err.println( "(handleOzoneProxyMember) EXCEPTION: " + nsfe );
255         } catch (IllegalAccessException   iae) {
256             System.err.println( "(handleOzoneProxyMember) EXCEPTION: " + iae );
257         }
258     }
259 
260     /**
261      * GetId gets the reference/address of the Object.
262      *
263      * @param obj (the Object)
264      * @return id
265      */
266     protected Integer   getID( Object   obj ) {
267         Integer   id = new Integer  ( System.identityHashCode( obj ) );
268         return id;
269     }
270 
271 
272     //
273     // writeMethods
274     // The writeMethods helps to write XML/SAX.
275     //
276     protected void writeObjStartTag( String   classname, Integer   id, Attributes additionallyAtts ) throws SAXException {
277 
278         AttributesImpl   atts;
279         if (additionallyAtts != null) {
280             atts = new AttributesImpl  ( additionallyAtts );
281         } else {
282             atts = new AttributesImpl  ();
283         }
284 
285         atts.addAttribute( "", ATTR_TYPE, ATTR_TYPE, "String", classname );
286         atts.addAttribute( "", ATTR_ID, ATTR_ID, "Integer", id + "" );
287 
288         ch.startElement( "", TAG_OBJ, TAG_OBJ, atts );
289     }
290 
291 
292     protected void writeObjEndTag() throws SAXException {
293         ch.endElement( "", TAG_OBJ, TAG_OBJ );
294     }
295 
296 
297     protected void writeSuperClStartTag( String   classname ) throws SAXException {
298         AttributesImpl   atts = new AttributesImpl  ();
299         atts.addAttribute( "", ATTR_TYPE, ATTR_TYPE, "String", classname );
300 
301         ch.startElement( "", TAG_SUPERCLASS, TAG_SUPERCLASS, atts );
302     }
303 
304 
305     protected void writeSuperClEndTag() throws SAXException {
306         ch.endElement( "", TAG_SUPERCLASS, TAG_SUPERCLASS );
307     }
308 
309 
310     protected void writeMemberStartTag( String   name ) throws SAXException {
311         AttributesImpl   atts = new AttributesImpl  ();
312         atts.addAttribute( "", ATTR_NAME, ATTR_NAME, "String", name );
313 
314         ch.startElement( "", TAG_MEMBER, TAG_MEMBER, atts );
315     }
316 
317     protected void writeMemberEndTag() throws SAXException {
318         ch.endElement( "", TAG_MEMBER, TAG_MEMBER );
319     }
320 
321     protected void writeMemberTagForOzoneProxy( String   name, String   proxyType, String   objectID ) throws SAXException {
322         AttributesImpl   atts = new AttributesImpl  ();
323         atts.addAttribute( "", ATTR_NAME, ATTR_NAME, "String", name );
324         atts.addAttribute( "", ATTR_PROXY_TYPE, ATTR_PROXY_TYPE, "java.lang.Class", proxyType );
325         atts.addAttribute( ATTR_XLINK_NAMESPACE, ATTR_XLINK_TYPE_LOCAL, ATTR_XLINK_TYPE_RAW,
326                            "String", ATTR_XLINK_TYPE_VALUE );
327         atts.addAttribute( ATTR_XLINK_NAMESPACE, ATTR_XLINK_HREF_LOCAL, ATTR_XLINK_HREF_RAW,
328                            "long", objectID );
329 
330         ch.startElement( "", TAG_MEMBER, TAG_MEMBER, atts );
331     }
332 
333     protected void writeValue( String   value ) throws SAXException {
334         ch.characters( value.toCharArray(), 0, value.length() );
335     }
336 
337 
338     protected void writeValueStartTag( String   type, Integer   id ) throws SAXException {
339         AttributesImpl   atts = new AttributesImpl  ();
340         atts.addAttribute( "", ATTR_TYPE, ATTR_TYPE, "String", type );
341         atts.addAttribute( "", ATTR_ID, ATTR_ID, "Integer", id + "" );
342 
343         ch.startElement( "", TAG_VALUE, TAG_VALUE, atts );
344     }
345 
346 
347     protected void writeValueEndTag() throws SAXException {
348         ch.endElement( "", TAG_VALUE, TAG_VALUE );
349     }
350 
351 
352     protected void writeValueObjStartTag( String   type, Integer   id ) throws SAXException {
353         AttributesImpl   atts = new AttributesImpl  ();
354         atts.addAttribute( "", ATTR_TYPE, ATTR_TYPE, "String", type );
355         atts.addAttribute( "", ATTR_ID, ATTR_ID, "Integer", id + "" );
356 
357         ch.startElement( "", TAG_VALUEOBJ, TAG_VALUEOBJ, atts );
358     }
359 
360 
361     protected void writeValueObjEndTag() throws SAXException {
362         ch.endElement( "", TAG_VALUEOBJ, TAG_VALUEOBJ );
363     }
364 
365 
366     protected void writeArrayStartTag( String   type, Integer   id ) throws SAXException {
367         AttributesImpl   atts = new AttributesImpl  ();
368         atts.addAttribute( "", ATTR_TYPE, ATTR_TYPE, "String", type );
369         atts.addAttribute( "", ATTR_ID, ATTR_ID, "Integer", id + "" );
370 
371         ch.startElement( "", TAG_VALUEARRAY, TAG_VALUEARRAY, atts );
372     }
373 
374 
375     protected void writeArrayEndTag() throws SAXException {
376         ch.endElement( "", TAG_VALUEARRAY, TAG_VALUEARRAY );
377     }
378 
379 
380     protected void writeObjRefElement( Integer   sourceId ) throws SAXException {
381         AttributesImpl   atts = new AttributesImpl  ();
382         atts.addAttribute( "", ATTR_REF, ATTR_REF, "Integer", sourceId + "" );
383 
384         ch.startElement( "", TAG_VALUE, TAG_VALUE, atts );
385         ch.endElement( "", TAG_VALUE, TAG_VALUE );
386     }
387 }
388
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags