| /* |
| * 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. |
| */ |
| |
| /* $Id$ */ |
| |
| package org.apache.fop.pdf; |
| |
| import java.io.IOException; |
| import java.io.OutputStream; |
| import java.io.Writer; |
| import java.lang.ref.Reference; |
| import java.lang.ref.SoftReference; |
| |
| /** |
| * Class representing a PDF object reference. The object holds a soft reference to the actual |
| * PDF object so the garbage collector can free the object if it's not referenced elsewhere. The |
| * important thing about the class is the reference information to the actual PDF object in the |
| * PDF file. |
| */ |
| public class PDFReference implements PDFWritable { |
| |
| private int objectNumber; |
| private int generation; |
| |
| private Reference objReference; |
| |
| /** |
| * Creates a new PDF reference. |
| * @param obj the object to be referenced |
| */ |
| public PDFReference(PDFObject obj) { |
| this.objectNumber = obj.getObjectNumber(); |
| this.generation = obj.getGeneration(); |
| this.objReference = new SoftReference(obj); |
| } |
| |
| /** |
| * Creates a new PDF reference, but without a reference to the original object. |
| * @param ref an object reference |
| */ |
| public PDFReference(String ref) { |
| if (ref == null) { |
| throw new NullPointerException("ref must not be null"); |
| } |
| String[] parts = ref.split(" "); |
| assert parts.length == 3; |
| this.objectNumber = Integer.parseInt(parts[0]); |
| this.generation = Integer.parseInt(parts[1]); |
| assert "R".equals(parts[2]); |
| } |
| |
| /** |
| * Returns the PDF object |
| * @return the PDF object, or null if it has been released |
| */ |
| public PDFObject getObject() { |
| if (this.objReference != null) { |
| PDFObject obj = (PDFObject)this.objReference.get(); |
| if (obj == null) { |
| this.objReference = null; |
| } |
| return obj; |
| } else { |
| return null; |
| } |
| } |
| |
| /** |
| * Returns the object number. |
| * @return the object number |
| */ |
| public int getObjectNumber() { |
| return this.objectNumber; |
| } |
| |
| /** |
| * Returns the generation. |
| * @return the generation |
| */ |
| public int getGeneration() { |
| return this.generation; |
| } |
| |
| /** {@inheritDoc} */ |
| public String toString() { |
| return getObjectNumber() + " " + getGeneration() + " R"; |
| } |
| |
| /** {@inheritDoc} */ |
| public void outputInline(OutputStream out, Writer writer) throws IOException { |
| writer.write(toString()); |
| } |
| |
| } |