Java tutorial
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See the License for the specific language governing permissions and limitations under the License. ==================================================================== */ package org.apache.poi.hssf.record; import java.io.IOException; import java.util.ArrayList; import java.util.List; import org.apache.poi.util.HexDump; import org.apache.poi.util.LittleEndian; import org.apache.poi.util.LittleEndianByteArrayInputStream; import org.apache.poi.util.LittleEndianByteArrayOutputStream; import org.apache.poi.util.RecordFormatException; /** * OBJRECORD (0x005D)<p> * * The obj record is used to hold various graphic objects and controls. */ public final class ObjRecord extends Record implements Cloneable { public final static short sid = 0x005D; private static final int NORMAL_PAD_ALIGNMENT = 2; private static int MAX_PAD_ALIGNMENT = 4; private List<SubRecord> subrecords; /** used when POI has no idea what is going on */ private final byte[] _uninterpretedData; /** * Excel seems to tolerate padding to quad or double byte length */ private boolean _isPaddedToQuadByteMultiple; //00000000 15 00 12 00 01 00 01 00 11 60 00 00 00 00 00 0D .........`...... //00000010 26 01 00 00 00 00 00 00 00 00 &......... public ObjRecord() { subrecords = new ArrayList<>(2); // TODO - ensure 2 sub-records (ftCmo 15h, and ftEnd 00h) are always created _uninterpretedData = null; } public ObjRecord(RecordInputStream in) { // TODO - problems with OBJ sub-records stream // MS spec says first sub-record is always CommonObjectDataSubRecord, // and last is always EndSubRecord. OOO spec does not mention ObjRecord(0x005D). // Existing POI test data seems to violate that rule. Some test data // seems to contain garbage, and a crash is only averted by stopping at // what looks like the 'EndSubRecord' // Check if this can be continued, if so then the // following wont work properly byte[] subRecordData = in.readRemainder(); if (LittleEndian.getUShort(subRecordData, 0) != CommonObjectDataSubRecord.sid) { // seems to occur in just one junit on "OddStyleRecord.xls" (file created by CrystalReports) // Excel tolerates the funny ObjRecord, and replaces it with a corrected version // The exact logic/reasoning is not yet understood _uninterpretedData = subRecordData; subrecords = null; return; } //YK: files produced by OO violate the condition below /* if (subRecordData.length % 2 != 0) { String msg = "Unexpected length of subRecordData : " + HexDump.toHex(subRecordData); throw new RecordFormatException(msg); } */ subrecords = new ArrayList<>(); LittleEndianByteArrayInputStream subRecStream = new LittleEndianByteArrayInputStream(subRecordData); CommonObjectDataSubRecord cmo = (CommonObjectDataSubRecord) SubRecord.createSubRecord(subRecStream, 0); subrecords.add(cmo); while (true) { SubRecord subRecord = SubRecord.createSubRecord(subRecStream, cmo.getObjectType()); subrecords.add(subRecord); if (subRecord.isTerminating()) { break; } } final int nRemainingBytes = subRecordData.length - subRecStream.getReadIndex(); if (nRemainingBytes > 0) { // At present (Oct-2008), most unit test samples have (subRecordData.length % 2 == 0) _isPaddedToQuadByteMultiple = subRecordData.length % MAX_PAD_ALIGNMENT == 0; if (nRemainingBytes >= (_isPaddedToQuadByteMultiple ? MAX_PAD_ALIGNMENT : NORMAL_PAD_ALIGNMENT)) { if (!canPaddingBeDiscarded(subRecordData, nRemainingBytes)) { String msg = "Leftover " + nRemainingBytes + " bytes in subrecord data " + HexDump.toHex(subRecordData); throw new RecordFormatException(msg); } _isPaddedToQuadByteMultiple = false; } } else { _isPaddedToQuadByteMultiple = false; } _uninterpretedData = null; } /** * Some XLS files have ObjRecords with nearly 8Kb of excessive padding. These were probably * written by a version of POI (around 3.1) which incorrectly interpreted the second short of * the ftLbs subrecord (0x1FEE) as a length, and read that many bytes as padding (other bugs * helped allow this to occur). * * Excel reads files with this excessive padding OK, truncating the over-sized ObjRecord back * to the its proper size. POI does the same. */ private static boolean canPaddingBeDiscarded(byte[] data, int nRemainingBytes) { // make sure none of the padding looks important for (int i = data.length - nRemainingBytes; i < data.length; i++) { if (data[i] != 0x00) { return false; } } return true; } @Override public String toString() { StringBuffer sb = new StringBuffer(); sb.append("[OBJ]\n"); if (subrecords != null) { // there are special cases where this can be, see comments in constructor above for (final SubRecord record : subrecords) { sb.append("SUBRECORD: ").append(record); } } sb.append("[/OBJ]\n"); return sb.toString(); } @Override public int getRecordSize() { if (_uninterpretedData != null) { return _uninterpretedData.length + 4; } int size = 0; for (SubRecord record : subrecords) { size += record.getDataSize() + 4; } if (_isPaddedToQuadByteMultiple) { while (size % MAX_PAD_ALIGNMENT != 0) { size++; } } else { while (size % NORMAL_PAD_ALIGNMENT != 0) { size++; } } return size + 4; } @Override public int serialize(int offset, byte[] data) { int recSize = getRecordSize(); int dataSize = recSize - 4; try (LittleEndianByteArrayOutputStream out = new LittleEndianByteArrayOutputStream(data, offset, recSize)) { // NOSONAR out.writeShort(sid); out.writeShort(dataSize); if (_uninterpretedData == null) { for (int i = 0; i < subrecords.size(); i++) { SubRecord record = subrecords.get(i); record.serialize(out); } int expectedEndIx = offset + dataSize; // padding while (out.getWriteIndex() < expectedEndIx) { out.writeByte(0); } } else { out.write(_uninterpretedData); } } catch (IOException ioe) { // should never happen in practice throw new IllegalStateException(ioe); } return recSize; } @Override public short getSid() { return sid; } // FIXME: return Collections.unmodifiableList? public List<SubRecord> getSubRecords() { return subrecords; } public void clearSubRecords() { subrecords.clear(); } public void addSubRecord(int index, SubRecord element) { subrecords.add(index, element); } public boolean addSubRecord(SubRecord o) { return subrecords.add(o); } @Override public ObjRecord clone() { ObjRecord rec = new ObjRecord(); for (SubRecord record : subrecords) { rec.addSubRecord(record.clone()); } return rec; } }