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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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