javolution.xml.XMLObjectReader Maven / Gradle / Ivy
/*
* Javolution - Java(TM) Solution for Real-Time and Embedded Systems
* Copyright (C) 2012 - Javolution (http://javolution.org/)
* All rights reserved.
*
* Permission to use, copy, modify, and distribute this software is
* freely granted, provided that this notice is preserved.
*/
package javolution.xml;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import javolution.xml.internal.stream.XMLStreamReaderImpl;
import javolution.xml.stream.XMLStreamException;
import javolution.xml.stream.XMLStreamReader;
/**
* This class restores objects which have been serialized in XML
* format using an {@link XMLObjectWriter}.
*
* When the XML document is parsed, each elements are recursively
* processed and Java objects are created using the {@link XMLFormat}
* of the class as identified by the {@link XMLBinding}.
*
* Multiple objects can be read from the same XML input.
* For example:[code]
* XMLObjectReader reader = XMLObjectReader.newInstance(inputStream);
* while (reader.hasNext()) {
* Message message = reader.read("Message", Message.class);
* }
* reader.close(); // The underlying stream is closed.
* [/code]
*
* @author Jean-Marie Dautelle
* @version 4.0, September 4, 2006
*/
public class XMLObjectReader {
/**
* Hold the xml element used when parsing.
*/
private final XMLFormat.InputElement _xml = new XMLFormat.InputElement();
/**
* Holds reader if any.
*/
private Reader _reader;
/**
* Holds input stream if any.
*/
private InputStream _inputStream;
/**
* Returns a XML object reader having the specified
* input stream as input.
*
* @param in the input stream.
*/
public static XMLObjectReader newInstance(InputStream in)
throws XMLStreamException {
XMLObjectReader reader = new XMLObjectReader();
reader.setInput(in);
return reader;
}
/**
* Returns a XML object reader (potentially recycled) having the specified
* input stream/encoding as input.
*
* @param in the input stream.
* @param encoding the input stream encoding
*/
public static XMLObjectReader newInstance(InputStream in, String encoding)
throws XMLStreamException {
XMLObjectReader reader = new XMLObjectReader();
reader.setInput(in, encoding);
return reader;
}
/**
* Returns a XML object reader (potentially recycled) having the specified
* reader as input.
*
* @param in the reader source.
*/
public static XMLObjectReader newInstance(Reader in)
throws XMLStreamException {
XMLObjectReader reader = new XMLObjectReader();
reader.setInput(in);
return reader;
}
/**
* Default constructor.
*/
public XMLObjectReader() {}
/**
* Returns the stream reader being used by this reader (it can be
* used to set prefix, read prologs, etc).
*
* @return the stream reader.
*/
public XMLStreamReader getStreamReader() {
return _xml._reader;
}
/**
* Sets the input stream source for this XML object reader
* (encoding retrieved from XML prolog if any).
*
* @param in the source input stream.
* @return this
* @see XMLStreamReaderImpl#setInput(InputStream)
*/
public XMLObjectReader setInput(InputStream in) throws XMLStreamException {
if ((_inputStream != null) || (_reader != null))
throw new IllegalStateException("Reader not closed or reset");
_xml._reader.setInput(in);
_inputStream = in;
return this;
}
/**
* Sets the input stream source and encoding for this XML object reader.
*
* @param in the input source.
* @param encoding the associated encoding.
* @return this
* @see XMLStreamReaderImpl#setInput(InputStream, String)
*/
public XMLObjectReader setInput(InputStream in, String encoding)
throws XMLStreamException {
if ((_inputStream != null) || (_reader != null))
throw new IllegalStateException("Reader not closed or reset");
_xml._reader.setInput(in, encoding);
_inputStream = in;
return this;
}
/**
* Sets the reader input source for this XML stream reader.
*
* @param in the source reader.
* @return this
* @see XMLStreamReaderImpl#setInput(Reader)
*/
public XMLObjectReader setInput(Reader in) throws XMLStreamException {
if ((_inputStream != null) || (_reader != null))
throw new IllegalStateException("Reader not closed or reset");
_xml._reader.setInput(in);
_reader = in;
return this;
}
/**
* Sets the XML binding to use with this object reader.
*
* @param binding the XML binding to use.
* @return this
*/
public XMLObjectReader setBinding(XMLBinding binding) {
_xml.setBinding(binding);
return this;
}
/**
* Sets the XML reference resolver to use with this object reader
* (the same resolver can be used accross multiple readers).
*
* @param referenceResolver the XML reference resolver.
* @return this
*/
public XMLObjectReader setReferenceResolver(
XMLReferenceResolver referenceResolver) {
_xml.setReferenceResolver(referenceResolver);
return this;
}
/**
* Indicates if more elements can be read. This method
* positions the reader at the start of the
* next element to be read (if any).
*
* @return true if more element/data to be read;
* false otherwise.
* @see XMLFormat.InputElement#hasNext()
*/
public boolean hasNext() throws XMLStreamException {
return _xml.hasNext();
}
/**
* Returns the object corresponding to the next element/data.
*
* @return the next nested object (can be null)
* @throws XMLStreamException if hasNext() == false
* @see XMLFormat.InputElement#getNext()
*/
@SuppressWarnings("unchecked")
public T read() throws XMLStreamException {
return (T) _xml.getNext();
}
/**
* Returns the object corresponding to the next nested element only
* if it has the specified local name.
*
* @param name the local name of the next element.
* @return the next content object or null if the
* local name does not match.
* @see XMLFormat.InputElement#get(String)
*/
@SuppressWarnings("unchecked")
public T read(String name) throws XMLStreamException {
return (T) _xml.get(name);
}
/**
* Returns the object corresponding to the next nested element only
* if it has the specified local name and namespace URI.
*
* @param localName the local name.
* @param uri the namespace URI.
* @return the next content object or null if the
* name/uri does not match.
* @see XMLFormat.InputElement#get(String, String)
*/
@SuppressWarnings("unchecked")
public T read(String localName, String uri) throws XMLStreamException {
return (T) _xml.get(localName, uri);
}
/**
* Returns the object corresponding to the next nested element only
* if it has the specified local name; the actual object type is identified
* by the specified class parameter.
*
* @param name the name of the element to match.
* @param cls the non-abstract class identifying the object to return.
* @return read(name, null, cls)
*/
public T read(String name, Class cls) throws XMLStreamException {
return _xml.get(name, cls);
}
/**
* Returns the object corresponding to the next nested element only
* if it has the specified local name and namespace URI; the
* actual object type is identified by the specified class parameter.
*
* @param localName the local name.
* @param uri the namespace URI.
* @param cls the non-abstract class identifying the object to return.
* @return the next content object or null if no match.
*/
public T read(String localName, String uri, Class cls)
throws XMLStreamException {
return _xml.get(localName, uri, cls);
}
/**
* Closes this reader and its underlying input then {@link #reset reset}
* this reader for potential reuse.
*/
public void close() throws XMLStreamException {
try {
if (_inputStream != null) {
_inputStream.close();
reset();
} else if (_reader != null) {
_reader.close();
reset();
}
} catch (IOException e) {
throw new XMLStreamException(e);
}
}
/**
* Resets this object reader for reuse.
*/
public void reset() {
_xml.reset();
_reader = null;
_inputStream = null;
}
}