使用Apache POI将文件嵌入到Excel中

Question

我正在使用Apache POI将数据导出到Excel文件中。在一个奇怪的需求中，我需要使用这个POI在Excel中嵌入一个文件。我有这个文件，可以将其作为流或字节数组。在谷歌搜索了很多时间后，我怀疑POI是否真的支持我的需求。我们能把文件嵌入Excel吗？-（

干杯，阿诺普

Answer 1

好吧，这花了很长时间才最终解决，因为有一些事情在开始时看起来不是很重要，但在没有正确设置时实际上损坏了文件--尤其是在Ole10Native包装器中，unknown2字段的一部分实际上包含了以下命令字符串的大小（以字节为单位）。

但首先要做的是：

当您希望将任意文件嵌入到office格式中时，最好使用OLE 1.0打包器。当您选择从文件中插入->Object时，通常会使用它。

• 嵌入对象的存储ID是随机分配的，还是有某种数字系统？
• 我搜索了关于Ole10Native包装器的更详细的描述，特别是ole 1.0打包器格式，但除了m$docu粗略地将其处理为一个大字节块之外，大多数源代码都进行了一些重组，看起来非常类似于poi Ole10Native类...当然，检查libre office源代码的想法也出现了，但我必须承认，我检查的那些只是让我困惑:(
• 哪个是嵌入对象的正确clsid？…也就是说，对于powerpoint有相当多的。因此，如果有疑问，显然需要通过以前从Office保存的文件查找clsid
• Excel 2010生成的Biff8文件中的嵌入对象不能被Libre Office打开！？！
• ole10Native对象包含一个命令行条目。如果有人可以用它启动嵌入对象以外的其他东西，那将会很有趣...
• BiffViewer崩溃时，我使用的预览图像大于某些块大小(~6KB)。因此，要么图像需要分块，要么BiffViewer实现错误...这也造成了一段时间的混乱...

测试了POI 3.9，Libre Office 4.0，Office 2010（我已经没有Office 2003了...）

import java.awt.Color;
import java.io.*;
import java.lang.reflect.*;
import java.net.URL;

import javax.swing.ImageIcon;
import javax.swing.filechooser.FileSystemView;

import org.apache.poi.ddf.*;
import org.apache.poi.hpsf.ClassID;
import org.apache.poi.hslf.HSLFSlideShow;
import org.apache.poi.hslf.model.*;
import org.apache.poi.hslf.model.ShapeTypes;
import org.apache.poi.hslf.usermodel.SlideShow;
import org.apache.poi.hssf.dev.BiffViewer;
import org.apache.poi.hssf.model.*;
import org.apache.poi.hssf.record.*;
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.poifs.filesystem.*;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.util.*;

@SuppressWarnings("unused")
public class PoiOlePptInXls {

    public static final OleType PACKAGE = new OleType("{0003000C-0000-0000-C000-000000000046}");
    public static final OleType PPT_SHOW = new OleType("{64818D10-4F9B-11CF-86EA-00AA00B929E8}");
    public static final OleType XLS_WORKBOOK = new OleType("{00020841-0000-0000-C000-000000000046}");
    public static final OleType TXT_ONLY = new OleType("{5e941d80-bf96-11cd-b579-08002b30bfeb}"); // ???

    static class OleType {
        final String classId;
        OleType(String classId) {
            this.classId = classId;
        }
        ClassID getClassID() {
            ClassID cls = new ClassID();
            byte clsBytes[] = cls.getBytes();
            String clsStr = classId.replaceAll("[{}-]", "");
            for (int i=0; i<clsStr.length(); i+=2) {
                clsBytes[i/2] = (byte)Integer.parseInt(clsStr.substring(i, i+2), 16);
            }
            return cls;
        }
    }   

    public static void main(String[] args) throws Exception {
        POIFSFileSystem poifs = new POIFSFileSystem(); 

        HSSFWorkbook wb = new HSSFWorkbook();
        HSSFSheet sheet = wb.createSheet();
        HSSFPatriarch patriarch = sheet.createDrawingPatriarch();

        int previewIdxPpt = generatePreview(wb, "application/powerpoint");
        int storageIdPpt = packageOleData(poifs, getSamplePPT(), "Example.ppt", "Example.ppt", "Example.ppt");
        int previewIdxXls = generatePreview(wb, "application/excel");
        int storageIdXls = packageOleData(poifs, getSampleXLS(), "Example.xls", "Example.xls", "Example.xls");
        int previewIdxTxt = generatePreview(wb, "text/plain");
        int storageIdTxt = packageOleData(poifs, getSampleTXT(), "Example.txt", "Example.txt", "Example.txt");

        int rowoffset = 5;
        int coloffset = 5;

        CreationHelper ch = wb.getCreationHelper();
        HSSFClientAnchor anchor = (HSSFClientAnchor)ch.createClientAnchor();
        anchor.setAnchor((short)(2+coloffset), 1+rowoffset, 0, 0, (short)(3+coloffset), 5+rowoffset, 0, 0);
        anchor.setAnchorType(ClientAnchor.DONT_MOVE_AND_RESIZE);

        HSSFObjectData oleShape = createObjectData(poifs, storageIdPpt, 1, anchor, previewIdxPpt);
        addShape(patriarch, oleShape);

        anchor = (HSSFClientAnchor)ch.createClientAnchor();
        anchor.setAnchor((short)(5+coloffset), 1+rowoffset, 0, 0, (short)(6+coloffset), 5+rowoffset, 0, 0);
        anchor.setAnchorType(ClientAnchor.DONT_MOVE_AND_RESIZE);

        oleShape = createObjectData(poifs, storageIdXls, 2, anchor, previewIdxXls);
        addShape(patriarch, oleShape);

        anchor = (HSSFClientAnchor)ch.createClientAnchor();
        anchor.setAnchor((short)(3+coloffset), 10+rowoffset, 0, 0, (short)(5+coloffset), 11+rowoffset, 0, 0);
        anchor.setAnchorType(ClientAnchor.DONT_MOVE_AND_RESIZE);

        oleShape = createObjectData(poifs, storageIdTxt, 3, anchor, previewIdxTxt);
        addShape(patriarch, oleShape);

        anchor = (HSSFClientAnchor)ch.createClientAnchor();
        anchor.setAnchor((short)(1+coloffset), -2+rowoffset, 0, 0, (short)(7+coloffset), 14+rowoffset, 0, 0);
        anchor.setAnchorType(ClientAnchor.DONT_MOVE_AND_RESIZE);

        HSSFSimpleShape circle = patriarch.createSimpleShape(anchor);
        circle.setShapeType(HSSFSimpleShape.OBJECT_TYPE_OVAL);
        circle.setNoFill(true);

        poifs.getRoot().createDocument("Workbook", new ByteArrayInputStream(wb.getBytes()));

        FileOutputStream fos = new FileOutputStream("ole_ppt_in_xls.xls");
        poifs.writeFilesystem(fos);
        fos.close();
    }

    static void addShape(HSSFPatriarch patriarch, HSSFShape shape) throws Exception {
        patriarch.addShape(shape);
        Method m = HSSFPatriarch.class.getDeclaredMethod("onCreate", HSSFShape.class);
        m.setAccessible(true);
        m.invoke(patriarch, shape);
    }

    static HSSFObjectData createObjectData(POIFSFileSystem poifs, int storageId, int objectIdx, HSSFClientAnchor anchor, int previewIdx) {
        ObjRecord obj = new ObjRecord();
        CommonObjectDataSubRecord ftCmo = new CommonObjectDataSubRecord();
        ftCmo.setObjectType(CommonObjectDataSubRecord.OBJECT_TYPE_PICTURE);
        ftCmo.setObjectId(objectIdx);
        ftCmo.setLocked(true);
        ftCmo.setPrintable(true);
        ftCmo.setAutofill(true);
        ftCmo.setAutoline(true);
        ftCmo.setReserved1(0);
        ftCmo.setReserved2(0);
        ftCmo.setReserved3(0);
        obj.addSubRecord(ftCmo);

        obj.addSubRecord(SubRecord.createSubRecord(new LittleEndianByteArrayInputStream(new byte[]{7,0,2,0,2,0}), 0));
        obj.addSubRecord(SubRecord.createSubRecord(new LittleEndianByteArrayInputStream(new byte[]{8,0,2,0,1,0}), 0));

        EmbeddedObjectRefSubRecord ftPictFmla;
        try {
            Constructor<EmbeddedObjectRefSubRecord> con = EmbeddedObjectRefSubRecord.class.getDeclaredConstructor();
            con.setAccessible(true);
            ftPictFmla = con.newInstance();
        } catch (Exception e) {
            throw new RuntimeException("oops", e);
        }

        setField(ftPictFmla, "field_2_unknownFormulaData", new byte[]{2, 0, 0, 0, 0});
        setField(ftPictFmla, "field_4_ole_classname", "Paket");
        setField(ftPictFmla, "field_5_stream_id", (Integer)storageId);

        obj.addSubRecord(ftPictFmla);
        obj.addSubRecord(new EndSubRecord());

        // create temporary picture, but don't attach it.
        // It's neccessary to create the sp-container, which need to be minimal modified
        // for oleshapes

        HSSFPicture shape = new HSSFPicture(null, anchor);
        EscherContainerRecord spContainer;

        try {
            Method m = HSSFPicture.class.getDeclaredMethod("createSpContainer");
            m.setAccessible(true);
            spContainer = (EscherContainerRecord)m.invoke(shape);
        } catch (Exception e) {
            throw new RuntimeException("oops", e);
        }

        EscherSpRecord spRecord = spContainer.getChildById(EscherSpRecord.RECORD_ID);
        spRecord.setFlags(spRecord.getFlags() |  EscherSpRecord.FLAG_OLESHAPE);
        spRecord.setShapeType((byte)0x4B);
        EscherOptRecord optRecord = spContainer.getChildById(EscherOptRecord.RECORD_ID);

        EscherProperty ep = new EscherSimpleProperty(EscherProperties.BLIP__PICTUREID, false, false, 1);
        optRecord.addEscherProperty(ep);

        DirectoryEntry oleRoot;
        try {
            oleRoot = (DirectoryEntry)poifs.getRoot().getEntry(formatStorageId(storageId));
        } catch (FileNotFoundException e) {
            throw new RuntimeException("oops", e);
        }
        HSSFObjectData oleShape = new HSSFObjectData(spContainer, obj, oleRoot); 
        oleShape.setPictureIndex(previewIdx);
        return oleShape;
    }

    static void setField(Object clazz, String fieldname, Object value) {
        try {
            Field f = clazz.getClass().getDeclaredField(fieldname);
            f.setAccessible(true);
            f.set(clazz, value);
        } catch (Exception e) {
            throw new RuntimeException("oops", e);
        }
    }

    static void addOleStreamEntry(DirectoryEntry dir) throws IOException {
        final String OLESTREAM_NAME = "\u0001Ole";
        if (!dir.hasEntry(OLESTREAM_NAME)) {
            // the following data was taken from an example libre office document
            // beside this "\u0001Ole" record there were several other records, e.g. CompObj,
            // OlePresXXX, but it seems, that they aren't neccessary
            byte oleBytes[] = { 1, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
            dir.createDocument(OLESTREAM_NAME, new ByteArrayInputStream(oleBytes));
        }       
    }

    static String formatStorageId(int storageId) {
        return String.format("MBD%1$08X", storageId);
    }

    static int packageOleData(POIFSFileSystem poifs, byte oleData[], String label, String fileName, String command) throws IOException {
        DirectoryNode root = poifs.getRoot();
        // get free MBD-Node
        int storageId = 0;
        DirectoryEntry oleDir = null;
        do {
            String storageStr = formatStorageId(++storageId);
            if (!root.hasEntry(storageStr)) {
                oleDir = root.createDirectory(storageStr);
                oleDir.setStorageClsid(PACKAGE.getClassID());
            }
        } while (oleDir == null);

        addOleStreamEntry(oleDir);

        Ole10Native2 oleNative = new Ole10Native2();
        oleNative.setLabel(label);
        oleNative.setFileName(fileName);
        oleNative.setCommand(command);
        oleNative.setDataBuffer(oleData);

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        oleNative.writeOut(bos);
        byte buf1[] = bos.toByteArray();

        oleDir.createDocument(Ole10Native2.OLE10_NATIVE, new ByteArrayInputStream(buf1));

        return storageId;
    }

    static byte[] getSamplePPT() {
        HSLFSlideShow ss = HSLFSlideShow.create();
        SlideShow ppt = new SlideShow(ss);
        Slide slide = ppt.createSlide();

        AutoShape sh1 = new AutoShape(ShapeTypes.Star32);
        sh1.setAnchor(new java.awt.Rectangle(50, 50, 100, 200));
        sh1.setFillColor(Color.red);
        slide.addShape(sh1);

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            ppt.write(bos);

            POIFSFileSystem poifs = new POIFSFileSystem(new ByteArrayInputStream(bos.toByteArray())); 
            poifs.getRoot().setStorageClsid(PPT_SHOW.getClassID());

            bos.reset();
            poifs.writeFilesystem(bos);

            return bos.toByteArray();
        } catch (IOException e) {
            throw new RuntimeException("bla", e);
        }
    }

    static byte[] getSampleXLS() {
        HSSFWorkbook wb = new HSSFWorkbook();
        HSSFSheet sheet = wb.createSheet();
        sheet.createRow(5).createCell(2).setCellValue("yo dawg i herd you like embeddet objekts, so we put a ole in your ole so you can save a file while you save a file");

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            wb.write(bos);

            POIFSFileSystem poifs = new POIFSFileSystem(new ByteArrayInputStream(bos.toByteArray())); 
            poifs.getRoot().setStorageClsid(XLS_WORKBOOK.getClassID());

            bos.reset();
            poifs.writeFilesystem(bos);

            return bos.toByteArray();
        } catch (IOException e) {
            throw new RuntimeException("bla", e);
        }
    }

    static byte[] getSampleTXT() {
        return "All your base are belong to us".getBytes();
    }

    /**
     * to be defined, how to create a preview image for a start, I've taken just
     * a dummy image, which will be replaced, when the user activates the ole
     * object
     * 
     * not really an alternativ:
     * http://stackoverflow.com/questions/16704624/how-
     * to-print-a-workbook-file-made-using-apache-poi-and-java
     * 
     * @return image index of the preview image
     */
    static int generatePreview(HSSFWorkbook workbook, String mimetype) {
        try {
            String url = "";
            if ("application/powerpoint".equals(mimetype)) {
                url = "http://upload.wikimedia.org/wikipedia/commons/thumb/a/a2/LibreOffice_Impress_icon_3.3.1_48_px.svg/40px-LibreOffice_Impress_icon_3.3.1_48_px.svg.png";
            } else if ("application/excel".equals(mimetype)) {
                url = "http://upload.wikimedia.org/wikipedia/commons/thumb/2/2d/LibreOffice_Calc_icon_3.3.1_48_px.svg/40px-LibreOffice_Calc_icon_3.3.1_48_px.svg.png";
            } else if ("text/plain".equals(mimetype)) {
                url = "http://upload.wikimedia.org/wikipedia/commons/thumb/a/a9/LibreOffice_Writer_icon_3.3.1_48_px.svg/40px-LibreOffice_Writer_icon_3.3.1_48_px.svg.png";
            }

            InputStream is = new URL(url).openStream();
            byte previewImg[] = IOUtils.toByteArray(is);
            is.close();
            int pictIdx = workbook.addPicture(previewImg, HSSFWorkbook.PICTURE_TYPE_PNG);
            return pictIdx;
        } catch (IOException e) {
            throw new RuntimeException("not really?", e);
        }
    }

    /*
     * Helper - determine length of zero terminated string (ASCIIZ).
     */
    private static int getStringLength(byte[] data, int ofs) {
        int len = 0;
        while (len + ofs < data.length && data[ofs + len] != 0) {
            len++;
        }
        len++;
        return len;
    }

}

具有写支持的POI的Ole10Native类：

import java.io.*;
import org.apache.poi.poifs.filesystem.*;
import org.apache.poi.util.*;

/**
 * Represents an Ole10Native record which is wrapped around certain binary files
 * being embedded in OLE2 documents.
 * 
 * @author Rainer Schwarze
 */
public class Ole10Native2 {
    public static final String OLE10_NATIVE = "\u0001Ole10Native";
    protected static final String ISO1 = "ISO-8859-1";

    // (the fields as they appear in the raw record:)
    protected int totalSize; // 4 bytes, total size of record not including this
                                // field
    protected short flags1 = 2; // 2 bytes, unknown, mostly [02 00]
    protected String label; // ASCIIZ, stored in this field without the
                            // terminating zero
    protected String fileName; // ASCIIZ, stored in this field without the
                                // terminating zero
    protected short flags2 = 0; // 2 bytes, unknown, mostly [00 00]
    protected short unknown1 = 3; 
    protected String command; // ASCIIZ, stored in this field without the
                                // terminating zero
    protected byte[] dataBuffer; // varying size, the actual native data
    protected short flags3 = 0; // some final flags? or zero terminators?,
                                // sometimes not there


    /**
     * Creates an instance of this class from an embedded OLE Object. The OLE
     * Object is expected to include a stream "{01}Ole10Native" which
     * contains the actual data relevant for this class.
     * 
     * @param poifs
     *            POI Filesystem object
     * @return Returns an instance of this class
     * @throws IOException
     *             on IO error
     * @throws Ole10NativeException
     *             on invalid or unexcepted data format
     */
    public static Ole10Native2 createFromEmbeddedOleObject(POIFSFileSystem poifs) throws IOException, Ole10NativeException {
        return createFromEmbeddedOleObject(poifs.getRoot());
    }

    /**
     * Creates an instance of this class from an embedded OLE Object. The OLE
     * Object is expected to include a stream "{01}Ole10Native" which
     * contains the actual data relevant for this class.
     * 
     * @param directory
     *            POI Filesystem object
     * @return Returns an instance of this class
     * @throws IOException
     *             on IO error
     * @throws Ole10NativeException
     *             on invalid or unexcepted data format
     */
    public static Ole10Native2 createFromEmbeddedOleObject(DirectoryNode directory) throws IOException, Ole10NativeException {
        boolean plain = false;

        try {
            directory.getEntry("\u0001Ole10ItemName");
            plain = true;
        } catch (FileNotFoundException ex) {
            plain = false;
        }

        DocumentEntry nativeEntry = (DocumentEntry) directory.getEntry(OLE10_NATIVE);
        byte[] data = new byte[nativeEntry.getSize()];
        directory.createDocumentInputStream(nativeEntry).read(data);

        return new Ole10Native2(data, 0, plain);
    }

    /**
     * Creates an instance and fills the fields based on the data in the given
     * buffer.
     * 
     * @param data
     *            The buffer containing the Ole10Native record
     * @param offset
     *            The start offset of the record in the buffer
     * @throws Ole10NativeException
     *             on invalid or unexcepted data format
     */
    public Ole10Native2(byte[] data, int offset) throws Ole10NativeException {
        this(data, offset, false);
    }

    /**
     * Creates an instance and fills the fields based on the data in the given
     * buffer.
     * 
     * @param data
     *            The buffer containing the Ole10Native record
     * @param offset
     *            The start offset of the record in the buffer
     * @param plain
     *            Specified 'plain' format without filename
     * @throws Ole10NativeException
     *             on invalid or unexcepted data format
     */
    public Ole10Native2(byte[] data, int offset, boolean plain) throws Ole10NativeException {
        int ofs = offset; // current offset, initialized to start

        if (data.length < offset + 2) {
            throw new Ole10NativeException("data is too small");
        }

        totalSize = LittleEndian.getInt(data, ofs);
        ofs += LittleEndianConsts.INT_SIZE;

        if (plain) {
            dataBuffer = new byte[totalSize - 4];
            System.arraycopy(data, 4, dataBuffer, 0, dataBuffer.length);
            int dataSize = totalSize - 4;

            byte[] oleLabel = new byte[8];
            System.arraycopy(dataBuffer, 0, oleLabel, 0, Math.min(dataBuffer.length, 8));
            label = "ole-" + HexDump.toHex(oleLabel);
            fileName = label;
            command = label;
        } else {
            flags1 = LittleEndian.getShort(data, ofs);
            ofs += LittleEndianConsts.SHORT_SIZE;

            int len = getStringLength(data, ofs);
            label = StringUtil.getFromCompressedUnicode(data, ofs, len - 1);
            ofs += len;

            len = getStringLength(data, ofs);
            fileName = StringUtil.getFromCompressedUnicode(data, ofs, len - 1);
            ofs += len;

            flags2 = LittleEndian.getShort(data, ofs);
            ofs += LittleEndianConsts.SHORT_SIZE;

            unknown1 = LittleEndian.getShort(data, ofs);
            ofs += LittleEndianConsts.SHORT_SIZE;

            len = LittleEndian.getInt(data, ofs);
            ofs += LittleEndianConsts.INT_SIZE;

            command = StringUtil.getFromCompressedUnicode(data, ofs, len - 1);
            ofs += len;

            if (totalSize < ofs) {
                throw new Ole10NativeException("Invalid Ole10Native");
            }

            int dataSize = LittleEndian.getInt(data, ofs);
            ofs += LittleEndianConsts.INT_SIZE;

            if (dataSize < 0 || totalSize - (ofs - LittleEndianConsts.INT_SIZE) < dataSize) {
                throw new Ole10NativeException("Invalid Ole10Native");
            }

            dataBuffer = new byte[dataSize];
            System.arraycopy(data, ofs, dataBuffer, 0, dataSize);
            ofs += dataSize;

//          if (unknown1.length > 0) {
//              flags3 = LittleEndian.getShort(data, ofs);
//              ofs += LittleEndianConsts.SHORT_SIZE;
//          } else {
//              flags3 = 0;
//          }
        }
    }

    public Ole10Native2() {}

    /*
     * Helper - determine length of zero terminated string (ASCIIZ).
     */
    private static int getStringLength(byte[] data, int ofs) {
        int len = 0;
        while (len + ofs < data.length && data[ofs + len] != 0) {
            len++;
        }
        len++;
        return len;
    }

    /**
     * Returns the value of the totalSize field - the total length of the
     * structure is totalSize + 4 (value of this field + size of this field).
     * 
     * @return the totalSize
     */
    public int getTotalSize() {
        return totalSize;
    }

    /**
     * Returns flags1 - currently unknown - usually 0x0002.
     * 
     * @return the flags1
     */
    public short getFlags1() {
        return flags1;
    }

    /**
     * Returns the label field - usually the name of the file (without
     * directory) but probably may be any name specified during
     * packaging/embedding the data.
     * 
     * @return the label
     */
    public String getLabel() {
        return label;
    }

    /**
     * Returns the fileName field - usually the name of the file being embedded
     * including the full path.
     * 
     * @return the fileName
     */
    public String getFileName() {
        return fileName;
    }

    /**
     * Returns flags2 - currently unknown - mostly 0x0000.
     * 
     * @return the flags2
     */
    public short getFlags2() {
        return flags2;
    }

    /**
     * Returns unknown1 field - currently unknown.
     * 
     * @return the unknown1
     */
    public short getUnknown1() {
        return unknown1;
    }

    /**
     * Returns the unknown2 field - currently being a byte[3] - mostly {0, 0,
     * 0}.
     * 
     * @return the unknown2
     */
//  public short getUnknown2() {
//      return unknown2;
//  }

    /**
     * Returns the command field - usually the name of the file being embedded
     * including the full path, may be a command specified during embedding the
     * file.
     * 
     * @return the command
     */
    public String getCommand() {
        return command;
    }

    /**
     * Returns the size of the embedded file. If the size is 0 (zero), no data
     * has been embedded. To be sure, that no data has been embedded, check
     * whether {@link #getDataBuffer()} returns <code>null</code>.
     * 
     * @return the dataSize
     */
    public int getDataSize() {
        return dataBuffer.length;
    }

    /**
     * Returns the buffer containing the embedded file's data, or
     * <code>null</code> if no data was embedded. Note that an embedding may
     * provide information about the data, but the actual data is not included.
     * (So label, filename etc. are available, but this method returns
     * <code>null</code>.)
     * 
     * @return the dataBuffer
     */
    public byte[] getDataBuffer() {
        return dataBuffer;
    }

    /**
     * Returns the flags3 - currently unknown.
     * 
     * @return the flags3
     */
    public short getFlags3() {
        return flags3;
    }

    /**
     * Have the contents printer out into an OutputStream, used when writing a
     * file back out to disk (Normally, atom classes will keep their bytes
     * around, but non atom classes will just request the bytes from their
     * children, then chuck on their header and return)
     */
    public void writeOut(OutputStream out) throws IOException {
        byte intbuf[] = new byte[LittleEndianConsts.INT_SIZE];
        byte shortbuf[] = new byte[LittleEndianConsts.SHORT_SIZE];
        byte bytebuf[] = new byte[LittleEndianConsts.BYTE_SIZE];
        // LittleEndian.putInt(_header, 4, _data.length);

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        bos.write(intbuf); // total size, will be determined later ..

        LittleEndian.putShort(shortbuf, 0, getFlags1());
        bos.write(shortbuf);

        bos.write(getLabel().getBytes(ISO1));
        bos.write(0);

        bos.write(getFileName().getBytes(ISO1));
        bos.write(0);

        LittleEndian.putShort(shortbuf, 0, getFlags2());
        bos.write(shortbuf);

        LittleEndian.putShort(shortbuf, 0, getUnknown1());
        bos.write(shortbuf);

        LittleEndian.putInt(intbuf, 0, getCommand().length()+1);
        bos.write(intbuf);

        bos.write(getCommand().getBytes(ISO1));
        bos.write(0);

        LittleEndian.putInt(intbuf, 0, getDataBuffer().length);
        bos.write(intbuf);

        bos.write(getDataBuffer());

        LittleEndian.putShort(shortbuf, 0, getFlags3());
        bos.write(shortbuf);

        // update total size - length of length-field (4 bytes)
        byte data[] = bos.toByteArray();
        totalSize = data.length - LittleEndianConsts.INT_SIZE;
        LittleEndian.putInt(data, 0, totalSize);

        out.write(data);
    }

    public void setFlags1(short flags1) {
        this.flags1 = flags1;
    }

    public void setFlags2(short flags2) {
        this.flags2 = flags2;
    }

    public void setFlags3(short flags3) {
        this.flags3 = flags3;
    }

    public void setLabel(String label) {
        this.label = label;
    }

    public void setFileName(String fileName) {
        this.fileName = fileName;
    }

    public void setCommand(String command) {
        this.command = command;
    }

    public void setUnknown1(short unknown1) {
        this.unknown1 = unknown1;
    }

//  public void setUnknown2(short unknown2) {
//      this.unknown2 = unknown2;
//  }

    public void setDataBuffer(byte dataBuffer[]) {
        this.dataBuffer = dataBuffer;
    }
}