| /* gnu.java.beans.PersistenceParser |
| Copyright (C) 2004, 2005 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath 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 |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| package gnu.java.beans.decoder; |
| |
| import java.beans.ExceptionListener; |
| import java.beans.XMLDecoder; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.LinkedList; |
| import java.util.List; |
| |
| import javax.xml.parsers.ParserConfigurationException; |
| import javax.xml.parsers.SAXParser; |
| import javax.xml.parsers.SAXParserFactory; |
| |
| import org.xml.sax.Attributes; |
| import org.xml.sax.SAXException; |
| import org.xml.sax.helpers.DefaultHandler; |
| |
| /** The PersistenceParser parses an XML data stream and delegates actions to ElementHandler |
| * instances. The parser catches and recovers from all exception which reside from wrong usage |
| * of attributes and tags. |
| * |
| * @author Robert Schuster |
| */ |
| public class PersistenceParser extends DefaultHandler implements Context |
| { |
| /** The ExceptionListener instance which is informed of non-critical parsing exceptions. |
| */ |
| private ExceptionListener exceptionListener; |
| |
| /** When an element was not usable all elements inside it should be skipped. |
| * This is done by skipping startElement() and endElement() invocations whenever |
| * this value is above 0. |
| */ |
| private int skipElement; |
| |
| /** Stores the Creator instances which can instantiate the appropriate handler implementation |
| * for a given element. |
| */ |
| private HashMap handlerCreators = new HashMap(); |
| |
| /** Denotes the current ElementHandler. To avoid checking for null-values it is pre-assigned |
| * with a DummyHandler instance which must not be used but acts as a root element. |
| */ |
| private ElementHandler currentHandler; |
| |
| /** The real root element that stores all objects created during parsing. |
| * Package-private to avoid an accessor method. |
| */ |
| JavaHandler javaHandler; |
| |
| /** Stores the decoded objects. */ |
| private List objects = new LinkedList(); |
| |
| /** The XMLDecoder instance that started this PersistenceParser */ |
| private XMLDecoder decoder; |
| |
| /** Creates a PersistenceParser which reads XML data from the given InputStream, reports |
| * exceptions to ExceptionListener instance, stores resulting object in the DecoderContext |
| * and uses the given ClassLoader to resolve classes. |
| * |
| * @param inputStream |
| * @param exceptionListener |
| * @param decoderContext |
| * @param cl |
| */ |
| public PersistenceParser( |
| InputStream inputStream, |
| ExceptionListener exceptionListener, |
| ClassLoader cl, |
| XMLDecoder decoder) |
| { |
| |
| this.exceptionListener = exceptionListener; |
| this.decoder = decoder; |
| |
| DummyHandler dummyHandler = new DummyHandler(); |
| currentHandler = dummyHandler; |
| javaHandler = new JavaHandler(dummyHandler, this, cl); |
| |
| SAXParserFactory factory = SAXParserFactory.newInstance(); |
| |
| SAXParser parser; |
| try |
| { |
| parser = factory.newSAXParser(); |
| } |
| catch (ParserConfigurationException pce) |
| { |
| // should not happen when a parser is available because we did |
| // not request any requirements on the XML parser |
| throw (InternalError) new InternalError( |
| "No SAX Parser available.").initCause( |
| pce); |
| } |
| catch (SAXException saxe) |
| { |
| // should not happen when a parser is available because we did |
| // not request any requirements on the XML parser |
| throw (InternalError) new InternalError( |
| "No SAX Parser available.").initCause( |
| saxe); |
| } |
| |
| // prepares a map of Creator instances which can instantiate a handler which is |
| // appropriate for the tag that is used as a key for the Creator |
| handlerCreators.put("java", new JavaHandlerCreator()); |
| |
| // calls methods (properties), constructors, access fields |
| handlerCreators.put("object", new ObjectHandlerCreator()); |
| handlerCreators.put("void", new VoidHandlerCreator()); |
| |
| handlerCreators.put("array", new ArrayHandlerCreator()); |
| |
| // these handler directly create an Object (or null) |
| handlerCreators.put("class", new ClassHandlerCreator()); |
| handlerCreators.put("null", new NullHandlerCreator()); |
| |
| handlerCreators.put("char", new CharHandlerCreator()); |
| handlerCreators.put("string", new StringHandlerCreator()); |
| handlerCreators.put("boolean", new BooleanHandlerCreator()); |
| handlerCreators.put("byte", new ByteHandlerCreator()); |
| handlerCreators.put("short", new ShortHandlerCreator()); |
| handlerCreators.put("int", new IntHandlerCreator()); |
| handlerCreators.put("long", new LongHandlerCreator()); |
| handlerCreators.put("float", new FloatHandlerCreator()); |
| handlerCreators.put("double", new DoubleHandlerCreator()); |
| |
| // parses the data and sends all exceptions to the ExceptionListener |
| try |
| { |
| parser.parse(inputStream, this); |
| } |
| catch (SAXException saxe) |
| { |
| exceptionListener.exceptionThrown( |
| new IllegalArgumentException("XML data not well-formed.")); |
| } |
| catch (IOException ioe) |
| { |
| exceptionListener.exceptionThrown(ioe); |
| } |
| } |
| |
| public void startElement( |
| String uri, |
| String localName, |
| String qName, |
| Attributes attributes) |
| throws SAXException |
| { |
| /* The element is skipped if |
| * a) the current handler has already failed or a previous error occured |
| * which makes all children obsolete |
| */ |
| if (currentHandler.hasFailed() || skipElement > 0) |
| { |
| exceptionListener.exceptionThrown( |
| new IllegalArgumentException( |
| "Element unusable due to previous error: " + qName)); |
| |
| skipElement++; |
| |
| return; |
| } |
| |
| /* b) Subelements are not allowed within the current ElementHandler. |
| */ |
| if (!currentHandler.isSubelementAllowed(qName)) |
| { |
| exceptionListener.exceptionThrown( |
| new IllegalArgumentException( |
| "Element is not allowed here: " + qName)); |
| |
| skipElement++; |
| |
| return; |
| } |
| |
| /* c) The tag name is not a key in the map of Creator instances. This means that |
| * either the XML data is of a newer version or simply contains a miss-spelled element. |
| */ |
| if (!handlerCreators.containsKey(qName)) |
| { |
| exceptionListener.exceptionThrown( |
| new IllegalArgumentException( |
| "Element unusable because tag is unknown: " + qName)); |
| |
| skipElement++; |
| |
| return; |
| } |
| |
| // creates a new handler for the new element |
| AbstractElementHandler handler = |
| ((Creator) handlerCreators.get(qName)).createHandler( |
| currentHandler); |
| |
| // makes it the current handler to receive character data |
| currentHandler = handler; |
| |
| // starts the handler |
| currentHandler.start(attributes, exceptionListener); |
| } |
| |
| public void endElement(String uri, String localName, String qName) |
| throws SAXException |
| { |
| // skips processing the current handler if we are parsing an element |
| // which was marked invalid (in startElement() ) |
| if (skipElement > 0) |
| { |
| skipElement--; |
| return; |
| } |
| |
| // invokes the handler's finishing method |
| currentHandler.end(exceptionListener); |
| |
| // removes the current handler and reactivates its parent |
| currentHandler = currentHandler.getParent(); |
| } |
| |
| /** Transfers character data to the current handler |
| */ |
| public void characters(char[] ch, int start, int length) |
| throws SAXException |
| { |
| // prevents sending character data of invalid elements |
| if (skipElement > 0) |
| return; |
| |
| currentHandler.characters(ch, start, length); |
| } |
| |
| /** Creator interface provided a mechanism to instantiate ElementHandler instances |
| * for the appropriate tag. |
| * |
| * @author Robert Schuster |
| */ |
| interface Creator |
| { |
| /** Creates an ElementHandler instance using the given ElementHandler as its parent. |
| * |
| * @param parent The parent ElementHandler of the result. |
| * @return A new ElementHandler instance. |
| */ |
| AbstractElementHandler createHandler(ElementHandler parent); |
| } |
| |
| class BooleanHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new BooleanHandler(parent); |
| } |
| } |
| |
| class ByteHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new ByteHandler(parent); |
| } |
| } |
| |
| class ShortHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new ShortHandler(parent); |
| } |
| } |
| |
| class IntHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new IntHandler(parent); |
| } |
| } |
| |
| class LongHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new LongHandler(parent); |
| } |
| } |
| |
| class FloatHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new FloatHandler(parent); |
| } |
| } |
| |
| class DoubleHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new DoubleHandler(parent); |
| } |
| } |
| |
| class CharHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new CharHandler(parent); |
| } |
| } |
| |
| class StringHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new StringHandler(parent); |
| } |
| } |
| |
| class JavaHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return javaHandler; |
| } |
| } |
| |
| class ObjectHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new ObjectHandler(parent); |
| } |
| } |
| |
| class VoidHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new VoidHandler(parent); |
| } |
| } |
| |
| class ClassHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new ClassHandler(parent); |
| } |
| } |
| |
| class NullHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new NullHandler(parent); |
| } |
| } |
| |
| class ArrayHandlerCreator implements Creator |
| { |
| public AbstractElementHandler createHandler(ElementHandler parent) |
| { |
| return new ArrayHandler(parent); |
| } |
| } |
| |
| /** Adds a decoded object to the Context. */ |
| public void addParameterObject(Object o) throws AssemblyException |
| { |
| objects.add(o); |
| } |
| |
| public void notifyStatement(Context outerContext) throws AssemblyException |
| { |
| // can be ignored because theis Context does not react to statement and expressions |
| // differently |
| } |
| |
| public Object endContext(Context outerContext) throws AssemblyException |
| { |
| return null; |
| } |
| |
| public boolean subContextFailed() |
| { |
| // failing of subcontexts is no problem for the mother of all contexts |
| return false; |
| } |
| |
| public void set(int index, Object o) throws AssemblyException |
| { |
| // not supported |
| throw new AssemblyException( |
| new IllegalArgumentException("Set method is not allowed in decoder context.")); |
| } |
| |
| public Object get(int index) throws AssemblyException |
| { |
| // not supported |
| throw new AssemblyException( |
| new IllegalArgumentException("Get method is not allowed in decoder context.")); |
| } |
| |
| public Object getResult() |
| { |
| // returns the XMLDecoder instance which is requested by child contexts this way. |
| // That is needed to invoke methods on the decoder. |
| return decoder; |
| } |
| |
| public void setId(String id) |
| { |
| exceptionListener.exceptionThrown(new IllegalArgumentException("id attribute is not allowed for <java> tag.")); |
| } |
| |
| public String getId() |
| { |
| // appears to have no id |
| return null; |
| } |
| |
| public boolean isStatement() |
| { |
| // this context is a statement by definition because it never returns anything to a parent because |
| // there is no such parent (DummyContext does not count!) |
| return true; |
| } |
| |
| public void setStatement(boolean b) |
| { |
| // ignores that because this Context is always a statement |
| } |
| |
| /** Returns an Iterator instance which returns the decoded objects. |
| * |
| * This method is used by the XMLDecoder directly. |
| */ |
| public Iterator iterator() |
| { |
| return objects.iterator(); |
| } |
| |
| } |