apache-poi/src/ooxml/java/org/apache/poi/POIXMLDocument.java

/* ====================================================================
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
==================================================================== */
package org.apache.poi;

import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;

import org.apache.poi.poifs.common.POIFSConstants;
import org.apache.poi.util.IOUtils;
import org.openxml4j.exceptions.InvalidFormatException;
import org.openxml4j.exceptions.OpenXML4JException;
import org.openxml4j.opc.Package;
import org.openxml4j.opc.PackagePart;
import org.openxml4j.opc.PackagePartName;
import org.openxml4j.opc.PackageRelationship;
import org.openxml4j.opc.PackageRelationshipTypes;
import org.openxml4j.opc.PackagingURIHelper;


public abstract class POIXMLDocument {

    public static final String CORE_PROPERTIES_REL_TYPE = "http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-properties";
    
    public static final String EXTENDED_PROPERTIES_REL_TYPE = "http://schemas.openxmlformats.org/officeDocument/2006/relationships/extended-properties";
    
    /** The OPC Package */
    private Package pkg;

    /** The OPC core Package Part */
    private PackagePart corePart;
    
    protected POIXMLDocument() {}
    
    protected POIXMLDocument(Package pkg) throws IOException {
    	try {
	    	this.pkg = pkg;
	    	
	        PackageRelationship coreDocRelationship = this.pkg.getRelationshipsByType(
	                PackageRelationshipTypes.CORE_DOCUMENT).getRelationship(0);
	    
	        // Get core part
	        this.corePart = this.pkg.getPart(coreDocRelationship);
        } catch (OpenXML4JException e) {
            throw new IOException(e.toString());
    	}
    }
    protected POIXMLDocument(String path) throws IOException {
   		this(openPackage(path));
    }
    
    /**
     * Wrapper to open a package, returning an IOException
     *  in the event of a problem.
     * Works around shortcomings in java's this() constructor calls
     */
    protected static Package openPackage(String path) throws IOException {
        try {
            return Package.open(path);
        } catch (InvalidFormatException e) {
            throw new IOException(e.toString());
        }
    }
    
    protected Package getPackage() {
        return this.pkg;
    }
    
    protected PackagePart getCorePart() {
        return this.corePart;
    }

    /**
     * Get the PackagePart that is the target of a relationship.
     * 
     * @param rel The relationship
     * @return The target part
     * @throws InvalidFormatException
     */
    protected PackagePart getTargetPart(PackageRelationship rel) throws InvalidFormatException {
        PackagePartName relName = PackagingURIHelper.createPartName(rel.getTargetURI());
        PackagePart part = getPackage().getPart(relName);
        if (part == null) {
            throw new IllegalArgumentException("No part found for relationship " + rel);
        }
        return part;
    }
    
    /**
     * Checks that the supplied InputStream (which MUST
     *  support mark and reset, or be a PushbackInputStream) 
     *  has a OOXML (zip) header at the start of it.
     * If your InputStream does not support mark / reset,
     *  then wrap it in a PushBackInputStream, then be
     *  sure to always use that, and not the original!
     * @param inp An InputStream which supports either mark/reset, or is a PushbackInputStream 
     */
    public static boolean hasOOXMLHeader(InputStream inp) throws IOException {
    	// We want to peek at the first 4 bytes 
    	inp.mark(4);

    	byte[] header = new byte[4];
    	IOUtils.readFully(inp, header);

        // Wind back those 4 bytes
        if(inp instanceof PushbackInputStream) {
        	PushbackInputStream pin = (PushbackInputStream)inp;
        	pin.unread(header);
        } else {
        	inp.reset();
        }
    	
    	// Did it match the ooxml zip signature?
        return (
        	header[0] == POIFSConstants.OOXML_FILE_HEADER[0] && 
        	header[1] == POIFSConstants.OOXML_FILE_HEADER[1] && 
        	header[2] == POIFSConstants.OOXML_FILE_HEADER[2] && 
        	header[3] == POIFSConstants.OOXML_FILE_HEADER[3]
        );        	                                            
    }
}