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- /*
- * 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 String indirectReference;
-
- private Reference objReference;
-
- /**
- * Creates a new PDF reference.
- * @param obj the object to be referenced
- */
- public PDFReference(PDFObject obj) {
- this.indirectReference = obj.referencePDF();
- 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");
- }
- this.indirectReference = ref;
- }
-
- /**
- * 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;
- }
- }
-
- /** {@inheritDoc} */
- public String toString() {
- return this.indirectReference;
- }
-
- /** {@inheritDoc} */
- public void outputInline(OutputStream out, Writer writer) throws IOException {
- writer.write(toString());
- }
-
- }
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