使用 java.awt.image.BufferedImage 创建 BIFF8 BITMAP 记录需要很多时间 - 有没有更好的方法？

Question

所以我正在创建一个 HSSFSheet，它具有使用 apache poi 设置的背景位图和自己的低级代码。 https://www.openoffice.org/sc/excelfileformat.pdf 为 Record BITMAP, BIFF8 声明：

Pixel data (array of height lines of the bitmap, from bottom line to top line, see below)

...

In each line all pixels are written from left to right. Each pixel is stored as 3-byte array: the red, green, and blue component of the colour of the pixel, in this order. The size of each line is aligned to multiples of 4 by inserting zero bytes after the last pixel.

完整声明见PDF图片：

为了实现这一点，我的方法是使用类型为 BufferedImage.TYPE_3BYTE_BGR 的 java.awt.image.BufferedImage。然后以正确的顺序（从底线到顶线）从 BufferedImage 的光栅中获取所有字节 R G B，并在宽度（x 方向）上填充到 4 的倍数。

见代码：

import java.io.FileOutputStream;
import java.io.FileInputStream;

import org.apache.poi.hssf.usermodel.*;

import org.apache.poi.hssf.record.RecordBase;
import org.apache.poi.hssf.record.StandardRecord;
import org.apache.poi.hssf.model.InternalSheet;
import org.apache.poi.util.LittleEndianOutput;

import java.lang.reflect.Field;

import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;

import java.awt.image.BufferedImage;
import java.awt.Graphics2D;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

import javax.imageio.ImageIO;

public class CreateExcelHSSFSheetBackgroundBitmap {

 static List<Byte> getBackgroundBitmapData(String filePath) throws Exception {

  //see https://www.openoffice.org/sc/excelfileformat.pdf - BITMAP

  List<Byte> data = new ArrayList<Byte>();

  // get file byte data in type BufferedImage.TYPE_3BYTE_BGR
  BufferedImage in = ImageIO.read(new FileInputStream(filePath));
  BufferedImage image = new BufferedImage(in.getWidth(), in.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
  Graphics2D graphics = image.createGraphics();
  graphics.drawImage(in, null, 0, 0);
  graphics.dispose();

  short width = (short)image.getWidth();
  short height = (short)image.getHeight();

  // each pixel has 3 bytes but the width bytes must be filled up to multiple of 4
  int widthBytesMultOf4 = (int)((width * 3 + 3) / 4 * 4);

// --- this part takes much time but I have not found any better possibility

  // put the bytes R G B into the data; lines of the bitmap must be from bottom line to top line
  int bytes = 0;
  for (short y = (short)(height - 1); y >= 0; y--) {
   for (short x = 0; x < width; x++) {
    int r = image.getData().getSample(x, y, 2);
    data.add(Byte.valueOf((byte)r));
    bytes++;
    int g = image.getData().getSample(x, y, 1);
    data.add(Byte.valueOf((byte)g));
    bytes++;
    int b = image.getData().getSample(x, y, 0);
    data.add(Byte.valueOf((byte)b));
    bytes++;
   } 
   // fill up x with 0 bytes up to multiple of 4
   for (int x = width * 3; x < widthBytesMultOf4; x++) {
    data.add(Byte.valueOf((byte)0));
    bytes++;
   }
  }

// ---

  // size  12 bytes (additional headers, see below) + picture bytes
  int size = 12 + bytes;

  // get size int as LITTLE_ENDIAN bytes
  ByteBuffer bSize = ByteBuffer.allocate(4);
  bSize.order(ByteOrder.LITTLE_ENDIAN);
  bSize.putInt(size);

  // get width short as LITTLE_ENDIAN bytes
  ByteBuffer bWidth = ByteBuffer.allocate(2);
  bWidth.order(ByteOrder.LITTLE_ENDIAN);
  bWidth.putShort(width);

  // get height short as LITTLE_ENDIAN bytes
  ByteBuffer bHeight = ByteBuffer.allocate(2);
  bHeight.order(ByteOrder.LITTLE_ENDIAN);
  bHeight.putShort(height);

  // put the record headers into the data
  Byte[] dataPart = new Byte[] { 0x09, 0x00, 0x01, 0x00, 
     bSize.array()[0], bSize.array()[1], bSize.array()[2], bSize.array()[3], // size
     //now 12 bytes follow
     0x0C, 0x00, 0x00, 0x00, 
     bWidth.array()[0], bWidth.array()[1], // width
     bHeight.array()[0], bHeight.array()[1], // height
     0x01, 0x00, 0x18, 0x00
   }; 

  data.addAll(0, Arrays.asList(dataPart));

  return data;
 }

 public static void main(String[] args) throws Exception {

  HSSFWorkbook workbook = new HSSFWorkbook();
  HSSFSheet sheet = workbook.createSheet("Sheet1");
  sheet = workbook.createSheet("Sheet2"); // this sheet gets the background image set

  // we need the binary records of the sheet
  // get InternalSheet
  Field _sheet = HSSFSheet.class.getDeclaredField("_sheet");
  _sheet.setAccessible(true); 
  InternalSheet internalsheet = (InternalSheet)_sheet.get(sheet); 

  // get List of RecordBase
  Field _records = InternalSheet.class.getDeclaredField("_records");
  _records.setAccessible(true);
  @SuppressWarnings("unchecked") 
  List<RecordBase> records = (List<RecordBase>)_records.get(internalsheet);

  // get bytes of the image file
  List<Byte> data = getBackgroundBitmapData("dummyText.png"); //PNG must not have transparency

  // do creating BitmapRecord and ContinueRecords from the data in parts of 8220 bytes
  BitmapRecord bitmapRecord = null;
  List<ContinueRecord> continueRecords = new ArrayList<ContinueRecord>();
  int bytes = 0;
  if (data.size() > 8220) {
   bitmapRecord = new BitmapRecord(data.subList(0, 8220));
   bytes = 8220;
   while (bytes < data.size()) {
    if ((bytes + 8220) < data.size()) {
     continueRecords.add(new ContinueRecord(data.subList(bytes, bytes + 8220)));
     bytes += 8220;
    } else {
     continueRecords.add(new ContinueRecord(data.subList(bytes, data.size())));
     break;
    }
   }
  } else {
   bitmapRecord = new BitmapRecord(data);
  }

  // add the records after PageSettingsBlock
  int i = 0;
  for (RecordBase r : records) {
   if (r instanceof org.apache.poi.hssf.record.aggregates.PageSettingsBlock) {
    break;
   }
   i++;
  }
  records.add(++i, bitmapRecord);
  for (ContinueRecord continueRecord : continueRecords) {
   records.add(++i, continueRecord);  
  }

  // debug output
  for (RecordBase r : internalsheet.getRecords()) {
   System.out.println(r);
  }

  // write out workbook
  workbook.write(new FileOutputStream("CreateExcelHSSFSheetBackgroundBitmap.xls"));
  workbook.close();

 }

 static class BitmapRecord extends StandardRecord {

  //see https://www.openoffice.org/sc/excelfileformat.pdf - BITMAP

  List<Byte> data = new ArrayList<Byte>();

  BitmapRecord(List<Byte> data) {
   this.data = data;
  }

  public int getDataSize() { 
   return data.size(); 
  }

  public short getSid() {
   return (short)0x00E9;
  }

  public void serialize(LittleEndianOutput out) {
   for (Byte b : data) {
    out.writeByte(b);
   }
  }
 }

 static class ContinueRecord extends StandardRecord {

  //see https://www.openoffice.org/sc/excelfileformat.pdf - CONTINUE

  List<Byte> data = new ArrayList<Byte>();

  ContinueRecord(List<Byte> data) {
   this.data = data;
  }

  public int getDataSize() { 
   return data.size(); 
  }

  public short getSid() {
   return (short)0x003C;
  }

  public void serialize(LittleEndianOutput out) {
   for (Byte b : data) {
    out.writeByte(b);
   }
  }
 }

}

代码有效，但

之间的部分

// --- this part takes much time but I have not found any better possibility

和

// ---

需要花费很多时间，因为根据上述奇怪的格式需要为每个像素获取 3 个字节的 R G B。

有人知道更好的方法吗？也许上面的奇怪格式并没有我想的那么奇怪，它已经有其他用法了？

Answer 1

通常这只是程序员自己的愚蠢 ;-)。在德语中有一句话："Can't see the forest because of the trees.".

在循环外简单地获取 BufferedImage 的 Raster 而不是一遍又一遍地在循环内获取它可以极大地提高速度：

...
  // put the bytes R G B into the data; lines of the bitmap must be from bottom line to top line
  int bytes = 0;
  Raster raster = image.getData();
  for (short y = (short)(height - 1); y >= 0; y--) {
   for (short x = 0; x < width; x++) {
    int r = raster.getSample(x, y, 2);
    data.add(Byte.valueOf((byte)r));
    bytes++;
    int g = raster.getSample(x, y, 1);
    data.add(Byte.valueOf((byte)g));
    bytes++;
    int b = raster.getSample(x, y, 0);
    data.add(Byte.valueOf((byte)b));
    bytes++;
   } 
   // fill up x with 0 bytes up to multiple of 4
   for (int x = width * 3; x < widthBytesMultOf4; x++) {
    data.add(Byte.valueOf((byte)0));
    bytes++;
   }
  }
...

但是@Gagravarr 在他的评论中的提示看起来也很有趣。

2.4.19 BkHim

The BkHim record specifies image data for a sheet (1) background

cf (2 bytes): A signed integer that specifies the image format. MUST be a value from the following:

Value: 0x0009

Meaning: Bitmap format. The image data is stored in a bitmap format as described in [MSDN-BMP]

Value: 0x000E

Meaning: Native format. The image data is stored in the native format of another application and cannot be directly processed.

这听起来好像是 0x000E 第一个字节而不是 0x0009 然后可以直接存储原始图片字节（PNG、JPG、BMP 等）。明天试试这个。

好吧，微软的 "documentations" 往往徒劳无功。 https://interoperability.blob.core.windows.net/files/MS-XLS/[MS-XLS].pdf 似乎正确但不完整，至少在第 211 页：2.4.19 Bk他。所以使用 0x000E 而不是 0x0009 将不会简单地允许存储原生 imageBlob。

还有0x0009的描述：

Bitmap format. The image data is stored in a bitmap format as described in [MSDN-BMP]

仅链接到对此处必须使用哪种位图的不完整描述。与开头的 header 结构和从底线到顶线的像素字节无关。而且也不需要通过在最后一个像素后插入零字节来将每行的大小对齐为 4 的倍数。但是不知道这一切，即使使用位图 0x0009 也行不通。

当我使用 Excel 的 GUI 将任何类型的背景图像放入 *.xls 文件的工作表中，然后使用十六进制转储查看该文件时，这看起来总是喜欢：

0xe900SSSS09000100SSSSSSSS0c000000WWWWHHHH01001800PPP...

其中 S 表示大小，W 表示宽度，H 表示高度，P 表示像素字节。

这与我是否将 BMP、JPG 或 PNG 作为背景图像放入工作表无关。总是使用这种特殊类型的 BMP 数据。

所以 OpenOffice 在 https://www.openoffice.org/sc/excelfileformat.pdf 中使用逆向工程所认识到的比 Microsoft 的 "documentation" 更有用。

因此，以下用于将背景图像放入 HSSFSheet 的代码对我来说适用于多种不同类型的图像文件（BMP、PNG、JPG）。

也使用 List<Byte> data 更改为 byte[] data。所以org.apache.poi.hssf.record.ContinueRecord可以直接使用，千万不要重新创建。

import java.io.FileOutputStream;
import java.io.FileInputStream;
import java.io.ByteArrayOutputStream;

import org.apache.poi.hssf.usermodel.*;

import org.apache.poi.hssf.record.RecordBase;
import org.apache.poi.hssf.record.StandardRecord;
import org.apache.poi.hssf.record.ContinueRecord;
import org.apache.poi.hssf.model.InternalSheet;

import org.apache.poi.util.LittleEndianOutput;

import java.lang.reflect.Field;

import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;

import java.awt.image.BufferedImage;
import java.awt.image.Raster;
import java.awt.Graphics2D;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

import javax.imageio.ImageIO;

public class CreateExcelHSSFSheetBackgroundBMP {

 static byte[] getBackgroundBitmapData(String filePath) throws Exception {

  // see https://www.openoffice.org/sc/excelfileformat.pdf - 5.6 BITMAP
  // and https://interoperability.blob.core.windows.net/files/MS-XLS/[MS-XLS].pdf - 2.4.19 BkHim

  // get file byte data in type BufferedImage.TYPE_3BYTE_BGR
  BufferedImage in = ImageIO.read(new FileInputStream(filePath));
  BufferedImage image = new BufferedImage(in.getWidth(), in.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
  Graphics2D graphics = image.createGraphics();
  graphics.drawImage(in, null, 0, 0);
  graphics.dispose();

  short width = (short)image.getWidth();
  short height = (short)image.getHeight();

  // each pixel has 3 bytes but the width bytes must be filled up to multiple of 4
  int widthBytesMultOf4 = (int)((width * 3 + 3) / 4 * 4);

  // size 12 bytes (additional headers, see below) + picture bytes
  int size = 12 + height * widthBytesMultOf4;

  // create the header section
  ByteBuffer headers = ByteBuffer.allocate(20);
  headers.order(ByteOrder.LITTLE_ENDIAN);
  headers.putShort((short)0x09); // 0x0009 = signed integer that specifies the image format BMP
  headers.putShort((short)0x01); // reserved (2 bytes): MUST be 0x0001
  headers.putInt(size); // signed integer that specifies the size of imageBlob in bytes
  // BMP header section:
  headers.putInt(0x0C); // length 0x0C = 12 bytes
  headers.putShort(width); // pixels width
  headers.putShort(height); // pixels heigth
  headers.putShort((short)0x01); // number of planes: always 1
  headers.putShort((short)0x18); // color depth 0x018 = 24 bit

  //create data ByteArrayOutputStream
  ByteArrayOutputStream data = new ByteArrayOutputStream();

  // write headers section
  data.write(headers.array());

  // put the bytes R G B into the data; lines of the bitmap must be from bottom line to top line
  Raster raster = image.getData();
  for (short y = (short)(height - 1); y >= 0; y--) {
   for (short x = 0; x < width; x++) {
    int r = raster.getSample(x, y, 2);
    data.write((byte)r);
    int g = raster.getSample(x, y, 1);
    data.write((byte)g);
    int b = raster.getSample(x, y, 0);
    data.write((byte)b);
   } 
   // fill up x with 0 bytes up to multiple of 4
   for (int x = width * 3; x < widthBytesMultOf4; x++) {
    data.write((byte)0);
   }
  }

  return data.toByteArray();
 }

 public static void main(String[] args) throws Exception {

  HSSFWorkbook workbook = new HSSFWorkbook();
  HSSFSheet sheet = workbook.createSheet("Sheet1");
  sheet = workbook.createSheet("Sheet2"); // this sheet gets the background image set

  // we need the binary records of the sheet
  // get InternalSheet
  Field _sheet = HSSFSheet.class.getDeclaredField("_sheet");
  _sheet.setAccessible(true); 
  InternalSheet internalsheet = (InternalSheet)_sheet.get(sheet); 

  // get List of RecordBase
  Field _records = InternalSheet.class.getDeclaredField("_records");
  _records.setAccessible(true);
  @SuppressWarnings("unchecked") 
  List<RecordBase> records = (List<RecordBase>)_records.get(internalsheet);

  // get bytes of the image file
  byte[] data = getBackgroundBitmapData("dummyText.png"); //PNG must not have transparency

  // do creating BitmapRecord and ContinueRecords from the data in parts of 8220 bytes
  BitmapRecord bitmapRecord = null;
  List<ContinueRecord> continueRecords = new ArrayList<ContinueRecord>();
  int bytes = 0;
  if (data.length > 8220) {
   bitmapRecord = new BitmapRecord(Arrays.copyOfRange(data, 0, 8220));
   bytes = 8220;
   while (bytes < data.length) {
    if ((bytes + 8220) < data.length) {
     continueRecords.add(new ContinueRecord(Arrays.copyOfRange(data, bytes, bytes + 8220)));
     bytes += 8220;
    } else {
     continueRecords.add(new ContinueRecord(Arrays.copyOfRange(data, bytes, data.length)));
     break;
    }
   }
  } else {
   bitmapRecord = new BitmapRecord(data);
  }

  // add the records after PageSettingsBlock
  int i = 0;
  for (RecordBase r : records) {
   if (r instanceof org.apache.poi.hssf.record.aggregates.PageSettingsBlock) {
    break;
   }
   i++;
  }
  records.add(++i, bitmapRecord);
  for (ContinueRecord continueRecord : continueRecords) {
   records.add(++i, continueRecord);  
  }

  // debug output
  for (RecordBase r : internalsheet.getRecords()) {
   System.out.println(r.getClass());
  }

  // write out workbook
  FileOutputStream out = new FileOutputStream("CreateExcelHSSFSheetBackgroundBMP.xls");
  workbook.write(out);
  workbook.close();
  out.close();

 }

 static class BitmapRecord extends StandardRecord {

  // see https://www.openoffice.org/sc/excelfileformat.pdf - 5.6 BITMAP
  // and https://interoperability.blob.core.windows.net/files/MS-XLS/[MS-XLS].pdf - 2.4.19 BkHim

  byte[] data;

  BitmapRecord(byte[] data) {
   this.data = data;
  }

  public int getDataSize() { 
   return data.length; 
  }

  public short getSid() {
   return (short)0x00E9;
  }

  public void serialize(LittleEndianOutput out) {
   out.write(data);
  }
 }

}

Answer 2

这是您的代码的修改版本，对我有用，而且速度非常快。

我一直在使用 byte[]（和 ByteArrayOutputStream），不再使用 List<Byte>。
由于我们已经有了 TYPE_3BYTE_BGR 的 BufferedImage，我们几乎可以直接将其用作 BMP 输出。我们只需要 a) 在前面添加一个有效的 BMP header 和 b) 写入 bottom-up，c) 将每个扫描线（行）填充到 32 位边界和 d) 切换 BGR -> RGB 顺序。
我正在使用 Raster 将数据行复制（填充）到输出中，因为复制较大的块比复制单个字节更快。

如评论中所述，该结构是具有 BITMAPCOREHEADER 的标准 BMP（没有文件 header）。不幸的是，ImageIO BMPImageWriter 总是写入文件 header 并使用 40 字节的 BITMAPINFOHEADER。您可能可以绕过这些问题，并使用标准编写器，通过稍微修改数据（提示：文件 header 包含偏移量 10 处的像素数据偏移量），但由于核心 BMP 格式是微不足道的要实现，它可能就像下面一样容易。

虽然文档肯定暗示可以直接使用其他格式，如 PNG 和 JPEG，但我没能正确地做到这一点。

如果您愿意，可能还有改进的余地，以避免一些字节数组复制（即使用 offset/length 并将整个数据数组传递给 Bitmap/ContinueRecord 而不是 Arrays.copyOfRange()).

代码：

import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.awt.image.Raster;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.lang.reflect.Field;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import javax.imageio.ImageIO;

import org.apache.poi.hssf.model.InternalSheet;
import org.apache.poi.hssf.record.RecordBase;
import org.apache.poi.hssf.record.StandardRecord;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.util.LittleEndianOutput;

public class CreateExcelHSSFSheetBackgroundBitmap {

    static byte[] getBackgroundBitmapData(String filePath) throws Exception {

        //see https://www.openoffice.org/sc/excelfileformat.pdf - BITMAP

        // get file byte data in type BufferedImage.TYPE_3BYTE_BGR
        BufferedImage in = ImageIO.read(new FileInputStream(filePath));
        BufferedImage image = new BufferedImage(in.getWidth(), in.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
        Graphics2D graphics = image.createGraphics();
        graphics.drawImage(in, null, 0, 0);
        graphics.dispose();

        // calculate row size (c)
        int rowSize = ((24 * image.getWidth() + 31) / 32) * 4;

        ByteArrayOutputStream output = new ByteArrayOutputStream(image.getHeight() * rowSize * 3 + 1024);

        // put the record headers into the data
        ByteBuffer header = ByteBuffer.allocate(8 + 12);
        header.order(ByteOrder.LITTLE_ENDIAN);

        // Undocumented XLS stuff
        header.putShort((short) 0x09);
        header.putShort((short) 0x01);
        header.putInt(image.getHeight() * rowSize + 12); // Size of image stream

        // BITMAPCOREHEADER (a)
        header.putInt(12);

        header.putShort((short) image.getWidth());
        header.putShort((short) image.getHeight()); // Use -height if writing top-down

        header.putShort((short) 1); // planes, always 1
        header.putShort((short) 24); // bitcount

        output.write(header.array());

        // Output rows bottom-up (b)
        Raster raster = image.getRaster()
                             .createChild(0, 0, image.getWidth(), image.getHeight(), 0, 0, new int[]{2, 1, 0}); // Reverse BGR -> RGB (d)
        byte[] row = new byte[rowSize]; // padded (c)

        for (int i = image.getHeight() - 1; i >= 0; i--) {
            row = (byte[]) raster.getDataElements(0, i, image.getWidth(), 1, row);
            output.write(row);
        }

        return output.toByteArray();
    }

    public static void main(String[] args) throws Exception {
        HSSFWorkbook workbook = new HSSFWorkbook();
        HSSFSheet sheet = workbook.createSheet("Sheet2"); // this sheet gets the background image set

        // we need the binary records of the sheet
        // get InternalSheet
        Field _sheet = HSSFSheet.class.getDeclaredField("_sheet");
        _sheet.setAccessible(true);
        InternalSheet internalsheet = (InternalSheet)_sheet.get(sheet);

        // get List of RecordBase
        Field _records = InternalSheet.class.getDeclaredField("_records");
        _records.setAccessible(true);
        @SuppressWarnings("unchecked")
        List<RecordBase> records = (List<RecordBase>)_records.get(internalsheet);

        // get bytes of the image file
        byte[] data = getBackgroundBitmapData("dummy.png"); //PNG must not have transparency

        // do creating BitmapRecord and ContinueRecords from the data in parts of 8220 bytes
        BitmapRecord bitmapRecord;
        List<ContinueRecord> continueRecords = new ArrayList<>();
        int bytes;

        if (data.length > 8220) {
            bitmapRecord = new BitmapRecord(Arrays.copyOfRange(data, 0, 8220));
            bytes = 8220;
            while (bytes < data.length) {
                if ((bytes + 8220) < data.length) {
                    continueRecords.add(new ContinueRecord(Arrays.copyOfRange(data, bytes, bytes + 8220)));
                    bytes += 8220;
                } else {
                    continueRecords.add(new ContinueRecord(Arrays.copyOfRange(data, bytes, data.length)));
                    break;
                }
            }
        } else {
            bitmapRecord = new BitmapRecord(data);
        }

        // add the records after PageSettingsBlock
        int i = 0;
        for (RecordBase r : records) {
            if (r instanceof org.apache.poi.hssf.record.aggregates.PageSettingsBlock) {
                break;
            }
            i++;
        }
        records.add(++i, bitmapRecord);
        for (ContinueRecord continueRecord : continueRecords) {
            records.add(++i, continueRecord);
        }

        // debug output
        for (RecordBase r : internalsheet.getRecords()) {
            System.out.println(r);
        }

        // write out workbook
        workbook.write(new FileOutputStream("backgroundImage.xls"));
        workbook.close();

    }

    static class BitmapRecord extends StandardRecord {

        //see https://www.openoffice.org/sc/excelfileformat.pdf - BITMAP

        byte[] data;

        BitmapRecord(byte[] data) {
            this.data = data;
        }

        public int getDataSize() {
            return data.length;
        }

        public short getSid() {
            return (short)0x00E9;
        }

        public void serialize(LittleEndianOutput out) {
            out.write(data);
        }
    }

    static class ContinueRecord extends StandardRecord {

        //see https://www.openoffice.org/sc/excelfileformat.pdf - CONTINUE

        byte[] data;

        ContinueRecord(byte[] data) {
            this.data = data;
        }

        public int getDataSize() {
            return data.length;
        }

        public short getSid() {
            return (short)0x003C;
        }

        public void serialize(LittleEndianOutput out) {
            out.write(data);
        }
    }
}

使用 java.awt.image.BufferedImage 创建 BIFF8 BITMAP 记录需要很多时间 - 有没有更好的方法？

Using java.awt.image.BufferedImage for creating BIFF8 BITMAP record takes much time - Is there any better approach?

java

bufferedimage

awt

apache-poi