Refactor ObjectStream Parsing. RES-713

Author: michaeldemey

src/main/java/com/itextpdf/rups/view/itext/ObjectStreamParser.java

@@ -0,0 +1,56 @@
+package com.itextpdf.rups.view.itext;
+
+import com.itextpdf.io.source.PdfTokenizer;
+import com.itextpdf.io.source.RandomAccessFileOrArray;
+import com.itextpdf.io.source.RandomAccessSourceFactory;
+import com.itextpdf.kernel.pdf.PdfName;
+import com.itextpdf.kernel.pdf.PdfStream;
+import com.itextpdf.rups.model.LoggerHelper;
+import com.itextpdf.rups.view.Console;
+
+import java.io.IOException;
+import java.util.Arrays;
+
+/**
+ * Utility class to parse ObjectStreams to extract the offset of a given object id within the stream.
+ */
+public class ObjectStreamParser {
+
+    /**
+     * Parses an ObjectStream to find the offset to the passed parameter, compressedObjectNumber. This offset is
+     * relative to the ObjectStream and not to the complete file, as described in the specification.
+     *
+     * If an Object ID isn't found inside the ObjectStream, this will return -1.
+     *
+     * @param objStm The ObjectStream to parse
+     * @param compressedObjectNumber the ID of the object of which you want the offset
+     * @return the offset of the object or -1 if the object is not found
+     */
+    public int parseObjectStream(PdfStream objStm, int compressedObjectNumber) {
+        byte[] objStmBytes = objStm.getBytes(true);
+        int byteOffsetOfFirst = objStm.getAsInt(PdfName.First);
+
+        PdfTokenizer pdfTokenizer = new PdfTokenizer(
+                new RandomAccessFileOrArray(
+                        new RandomAccessSourceFactory()
+                                .createSource(
+                                        Arrays.copyOfRange(objStmBytes, 0, byteOffsetOfFirst))));
+
+        try {
+            while (pdfTokenizer.nextToken()) {
+                if ( pdfTokenizer.getTokenType().equals(PdfTokenizer.TokenType.Number )) {
+                    int objNumber = pdfTokenizer.getIntValue();
+                    pdfTokenizer.nextToken();
+                    if ( objNumber == compressedObjectNumber ) {
+                        return pdfTokenizer.getIntValue();
+                    }
+                }
+            }
+        } catch (IOException e) {
+            LoggerHelper.error(e.getMessage(), e, ObjectStreamParser.class);
+            return -1;
+        }
+
+        return -1;
+    }
+}

src/main/java/com/itextpdf/rups/view/itext/XRefTable.java

@@ -188,38 +188,10 @@ private String getByteOffSetByRow(int rowIndex) {
                 int objStreamNumber = indirectReference.getObjStreamNumber();
                 PdfObject refersTo = indirectReference.getRefersTo();
                 int compressedObjectNumber = refersTo.getIndirectReference().getObjNumber();
-                int internalCompressedObjectOffset = -1;
                 PdfObject objectByIndex = objects.loadObjectByReference(objStreamNumber);
 
                 PdfStream objStm = (PdfStream) objectByIndex;
-                byte[] objStmBytes = objStm.getBytes(true);
-                int byteOffsetOfFirst = objStm.getAsInt(PdfName.First);
-
-                PdfTokenizer pdfTokenizer = new PdfTokenizer(
-                        new RandomAccessFileOrArray( new RandomAccessSourceFactory().createSource(Arrays.copyOfRange(objStmBytes, 0, byteOffsetOfFirst)))
-                );
-
-                try {
-                    while (pdfTokenizer.nextToken()) {
-                        if ( pdfTokenizer.getTokenType().equals(PdfTokenizer.TokenType.Number )) {
-                            int objNumber = pdfTokenizer.getIntValue();
-                            pdfTokenizer.nextToken();
-                            int internalByteOffset = pdfTokenizer.getIntValue();
-                            if ( objNumber == compressedObjectNumber ) {
-                                internalCompressedObjectOffset = internalByteOffset;
-                                break;
-                            }
-                        }
-                    }
-                } catch (IOException e) {
-                    throw new RuntimeException(e);
-                }
-
-
-
-
-                PdfIndirectReference streamIndRef = objectByIndex.getIndirectReference();
-                long streamOffset = streamIndRef.getOffset();
+                int internalCompressedObjectOffset = new ObjectStreamParser().parseObjectStream(objStm, compressedObjectNumber);
 
                 return String.format(
                         Language.XREF_BYTE_OFFSET_OBJECT_STREAM.getString(),