xmpserializerrdf.java

flash xmp sdk,flash官方SDK

// =================================================================================================
// ADOBE SYSTEMS INCORPORATED
// Copyright 2006-2007 Adobe Systems Incorporated
// All Rights Reserved
//
// NOTICE:  Adobe permits you to use, modify, and distribute this file in accordance with the terms
// of the Adobe license agreement accompanying it.
// =================================================================================================

package com.adobe.xmp.impl;

import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import com.adobe.xmp.XMPConst;
import com.adobe.xmp.XMPError;
import com.adobe.xmp.XMPException;
import com.adobe.xmp.XMPMeta;
import com.adobe.xmp.XMPMetaFactory;
import com.adobe.xmp.options.SerializeOptions;


/**
 * Serializes the <code>XMPMeta</code>-object using the standard RDF serialization format. 
 * The output is written to an <code>OutputStream</code> 
 * according to the <code>SerializeOptions</code>. 
 * 
 * @since   11.07.2006
 */
public class XMPSerializerRDF
{
	/** default padding */
	private static final int DEFAULT_PAD = 2048;	
	/** */
	private static final String PACKET_HEADER  =
		"<?xpacket begin=\"\uFEFF\" id=\"W5M0MpCehiHzreSzNTczkc9d\"?>";
	/** The w/r is missing inbetween */
	private static final String PACKET_TRAILER = "<?xpacket end=\"";
	/** */
	private static final String PACKET_TRAILER2 = "\"?>"; 
	/** */
	private static final String RDF_XMPMETA_START = 
		"<x:xmpmeta xmlns:x=\"adobe:ns:meta/\" x:xmptk=\"";
	/** */
	private static final String RDF_XMPMETA_END   = "</x:xmpmeta>";
	/** */
	private static final String RDF_RDF_START = 
		"<rdf:RDF xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\">";
	/** */
	private static final String RDF_RDF_END       = "</rdf:RDF>";
	
	/** */
	private static final String RDF_SCHEMA_START  = "<rdf:Description rdf:about=";
	/** */
	private static final String RDF_SCHEMA_END    = "</rdf:Description>";
	/** */
	private static final String RDF_STRUCT_START  = "<rdf:Description";
	/** */
	private static final String RDF_STRUCT_END    = "</rdf:Description>";
	/** a set of all rdf attribute qualifier */
	static final Set RDF_ATTR_QUALIFIER = new HashSet(Arrays.asList(new String[] {
			XMPConst.XML_LANG, "rdf:resource", "rdf:ID", "rdf:bagID", "rdf:nodeID" }));
	
	/** the metadata object to be serialized. */ 
	private XMPMetaImpl xmp; 
	/** the output stream to serialize to */ 
	private CountOutputStream outputStream;
	/** this writer is used to do the actual serialisation */
	private OutputStreamWriter writer;
	/** the stored serialisation options */
	private SerializeOptions options;
	/** the size of one unicode char, for UTF-8 set to 1 
	 *  (Note: only valid for ASCII chars lower than 0x80),
	 *  set to 2 in case of UTF-16 */
	private int unicodeSize = 1; // UTF-8
	/** the padding in the XMP Packet, or the length of the complete packet in
	 *  case of option <em>exactPacketLength</em>. */ 
	private int padding;

	
	/**
	 * The actual serialisation.
	 * 
	 * @param xmp the metadata object to be serialized
	 * @param out outputStream the output stream to serialize to
	 * @param options the serialization options
	 * 
	 * @throws XMPException If case of wrong options or any other serialisaton error.
	 */
	public void serialize(XMPMeta xmp, OutputStream out, 
			SerializeOptions options) throws XMPException
	{
		try
		{
			outputStream = new CountOutputStream(out); 
			writer = new OutputStreamWriter(outputStream, options.getEncoding());
			
			this.xmp = (XMPMetaImpl) xmp;
			this.options = options;
			this.padding = options.getPadding();

			writer = new OutputStreamWriter(outputStream, options.getEncoding());
			
			checkOptionsConsistence();
			
			// serializes the whole packet, but don't write the tail yet 
			// and flush to make sure that the written bytes are calculated correctly
			String tailStr = serializeAsRDF();
			writer.flush();
			
			// adds padding
			addPadding(tailStr.length());

			// writes the tail
			write(tailStr);
			writer.flush();
			
			outputStream.close();
		}
		catch (IOException e)
		{
			throw new XMPException("Error writing to the OutputStream", XMPError.UNKNOWN);
		}
	}


	/**
	 * Calulates the padding according to the options and write it to the stream.
	 * @param tailLength the length of the tail string 
	 * @throws XMPException thrown if packet size is to small to fit the padding
	 * @throws IOException forwards writer errors
	 */
	private void addPadding(int tailLength) throws XMPException, IOException
	{
		if (options.getExactPacketLength())
		{
			// the string length is equal to the length of the UTF-8 encoding
			int minSize = outputStream.getBytesWritten() + tailLength * unicodeSize;
			if (minSize > padding)
			{
				throw new XMPException("Can't fit into specified packet size",
					XMPError.BADSERIALIZE);
			}
			padding -= minSize;	// Now the actual amount of padding to add.
		}

		// fix rest of the padding according to Unicode unit size.
		padding /= unicodeSize;
		
		int newlineLen = options.getNewline().length();
		if (padding >= newlineLen)
		{
			padding -= newlineLen;	// Write this newline last.
			while (padding >= (100 + newlineLen))
			{
				writeChars(100, ' ');
				writeNewline();
				padding -= (100 + newlineLen);
			}
			writeChars(padding, ' ');
			writeNewline();
		}
		else
		{
			writeChars(padding, ' ');				
		}
	}


	/**
	 * Checks if the supplied options are consistent.
	 * @throws XMPException Thrown if options are conflicting
	 */
	protected void checkOptionsConsistence() throws XMPException
	{
		if (options.getEncodeUTF16BE() | options.getEncodeUTF16LE())
		{
			unicodeSize = 2;
		}

		if (options.getExactPacketLength())
		{
			if (options.getOmitPacketWrapper() | options.getIncludeThumbnailPad())
			{
				throw new XMPException("Inconsistent options for exact size serialize",
						XMPError.BADOPTIONS);
			}
			if ((options.getPadding() & (unicodeSize - 1)) != 0)
			{
				throw new XMPException("Exact size must be a multiple of the Unicode element",
						XMPError.BADOPTIONS);
			}
		}
		else if (options.getReadOnlyPacket())
		{
			if (options.getOmitPacketWrapper() | options.getIncludeThumbnailPad())
			{
				throw new XMPException("Inconsistent options for read-only packet",
						XMPError.BADOPTIONS);
			}
			padding = 0;
		}
		else if (options.getOmitPacketWrapper())
		{
			if (options.getIncludeThumbnailPad())
			{
				throw new XMPException("Inconsistent options for non-packet serialize",
						XMPError.BADOPTIONS);
			}
			padding = 0;
		}
		else
		{
			if (padding == 0)
			{
				padding = DEFAULT_PAD * unicodeSize;
			}
			
			if (options.getIncludeThumbnailPad())
			{
				if (!xmp.doesPropertyExist(XMPConst.NS_XMP, "Thumbnails"))
				{
					padding += 10000 * unicodeSize;
				}
			}
		}
	}
	
	
	/**
	 * Writes the (optional) packet header and the outer rdf-tags. 
	 * @return Returns the packet end processing instraction to be written after the padding. 
	 * @throws IOException Forwarded writer exceptions.
	 * @throws XMPException 
	 */
	private String serializeAsRDF() throws IOException, XMPException
	{
		// Write the packet header PI.
		if (!options.getOmitPacketWrapper())
		{
			writeIndent(0);
			write(PACKET_HEADER);
			writeNewline();
		}
	
		// Write the xmpmeta element's start tag.
		writeIndent(0);
		write(RDF_XMPMETA_START);
		// Note: this flag can only be set by unit tests
		if (!options.getOmitVersionAttribute())
		{	
			write(XMPMetaFactory.getVersionInfo().getMessage());
		}	
		write("\">");
		writeNewline();
	
		// Write the rdf:RDF start tag.
		writeIndent(1);
		write(RDF_RDF_START);
		writeNewline();
		
		// Write all of the properties.
		if (options.getUseCompactFormat())
		{
			serializeCompactRDFSchemas();
		} 
		else
		{
			serializePrettyRDFSchemas();
		}
	
		// Write the rdf:RDF end tag.
		writeIndent(1);
		write(RDF_RDF_END);
		writeNewline();
	
		// Write the xmpmeta end tag.
		writeIndent(0);		
		write(RDF_XMPMETA_END);
		writeNewline();
		
		// Write the packet trailer PI into the tail string as UTF-8.
		String tailStr = "";
		if (!options.getOmitPacketWrapper())
		{
			for (int level = options.getBaseIndent(); level > 0; level--)
			{
				tailStr += options.getIndent();
			}

			tailStr += PACKET_TRAILER;
			tailStr += options.getReadOnlyPacket() ? 'r' : 'w';
			tailStr += PACKET_TRAILER2;
		}
		
		return tailStr;
	}

	
	/**
	 * Serializes the metadata in pretty-printed manner.
	 * @throws IOException Forwarded writer exceptions
	 * @throws XMPException 
	 */
	private void serializePrettyRDFSchemas() throws IOException, XMPException
	{
		if (xmp.getRoot().getChildrenLength() > 0)
		{
			for (Iterator it = xmp.getRoot().iterateChildren(); it.hasNext(); )
			{
				XMPNode currSchema = (XMPNode) it.next();
				serializePrettyRDFSchema(currSchema);
			}
		}
		else
		{
			writeIndent(2);
			write(RDF_SCHEMA_START); // Special case an empty XMP object.
			writeTreeName();
			write("/>");
			writeNewline();
		}		
	}


	/**
	 * @throws IOException
	 */
	private void writeTreeName() throws IOException
	{
		write('"');
		String name = xmp.getRoot().getName();
		if (name != null)
		{	
			appendNodeValue(name, true);
		}	
		write('"');
	}
	
	
	/**
	 * Serializes the metadata in compact manner.
	 * @throws IOException Forwarded writer exceptions
	 * @throws XMPException 
	 */
	private void serializeCompactRDFSchemas() throws IOException, XMPException
	{
		// Begin the rdf:Description start tag.
		writeIndent(2);
		write(RDF_SCHEMA_START);
		writeTreeName();
		
		// Write all necessary xmlns attributes.
		Set usedPrefixes = new HashSet();
		usedPrefixes.add("xml");
		usedPrefixes.add("rdf");

		for (Iterator it = xmp.getRoot().iterateChildren(); it.hasNext();)
		{
			XMPNode schema = (XMPNode) it.next();
			declareUsedNamespaces(schema, usedPrefixes, 4);
		}
	
		// Write the top level "attrProps" and close the rdf:Description start tag.
		boolean allAreAttrs = true;
		for (Iterator it = xmp.getRoot().iterateChildren(); it.hasNext();)
		{
			XMPNode schema = (XMPNode) it.next();
			allAreAttrs &= serializeCompactRDFAttrProps (schema, 3);
		}

		if (!allAreAttrs)
		{
			write('>');
			writeNewline();
		}
		else
		{
			write("/>");
			writeNewline();
			return;	// ! Done if all properties in all schema are written as attributes.
		}
	
		// Write the remaining properties for each schema.
		for (Iterator it = xmp.getRoot().iterateChildren(); it.hasNext();)
		{
			XMPNode schema = (XMPNode) it.next();
			serializeCompactRDFElementProps (schema, 3);
		}

		// Write the rdf:Description end tag.
		writeIndent(2);
		write(RDF_SCHEMA_END);
		writeNewline();
	}


	
	/**
	 * Write each of the parent's simple unqualified properties as an attribute. Returns true if all
	 * of the properties are written as attributes.
	 * 
	 * @param parentNode the parent property node
	 * @param indent the current indent level
	 * @return Returns true if all properties can be rendered as RDF attribute.
	 * @throws IOException
	 */
	private boolean serializeCompactRDFAttrProps(XMPNode parentNode, int indent) throws IOException
	{
		boolean allAreAttrs = true;
	
		for (Iterator it = parentNode.iterateChildren(); it.hasNext();)
		{
			XMPNode prop = (XMPNode) it.next();
		
			if (canBeRDFAttrProp(prop))
			{
				writeNewline();
				writeIndent(indent);
				write(prop.getName());
				write("=\"");
				appendNodeValue(prop.getValue(), true);
				write('"');
			}
			else
			{
				allAreAttrs = false;