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

这是你的代码的一个修改版本,对我来说很有效,而且速度很快。

1. 我在用 byte[] ByteArrayOutputStream )到处都是,再也没有了 List<Byte> .
2. 因为我们已经有了 BufferedImage 属于 TYPE_3BYTE_BGR ,我们几乎可以直接将其用作BMP输出。我们只需要a)预先准备一个有效的BMP头,b)自下而上写入,c)将每个扫描线(行)填充到32位边界,d)切换BGR->RGB顺序。
3. Raster 将(填充的)数据行复制到输出中,因为复制较大的数据块比复制单个字节快。

正如在评论中已经指出的,该结构是一个标准的BMP,带有 BITMAPCOREHEADER (没有文件头)。不幸的是 ImageIO BMPImageWriter 始终写入文件头并使用 BITMAPINFOHEADER 也就是40字节。您可能可以绕过这些问题,使用标准的writer,只需稍微处理一下数据(提示:文件头包含偏移量为10的像素数据的偏移量),但由于核心BMP格式的实现非常简单,所以可能也很容易做到以下几点。

Bitmap/ContinueRecord 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);
        }
    }
}

通常这只是程序员自己的愚蠢;—)。在德语中有一句谚语:“看不见森林是因为有树。”。

Raster 的 BufferedImage 一次又一次地跳出环路而不是进入环路,会极大地提高速度:

...
  // 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++;
   }
  }
...

这个 BkHim公司 记录指定纸张(1)背景的图像数据

cf(2字节) :指定图像格式的有符号整数。必须是以下值:

值:0x0009

意思:位图格式。图像数据以位图格式存储,如[MSDN-BMP]所述

值:0x000E

意思:本机格式。图像数据以另一个应用程序的本机格式存储,不能直接处理。

0x000E 第一个字节而不是 0x0009 然后可以直接存储本地图片字节(PNG、JPG、BMP……)。明天试试这个。

嗯,微软的“文档”往往只是徒劳的努力。这个 https://interoperability.blob.core.windows.net/files/MS-XLS/[MS-XLS].pdf 打他。所以使用 0x000E 而不是 0x0009 不会简单地允许存储本机 imageBlob

0x0009

位图格式。图像数据以位图格式存储,如中所述 [MSDN-BMP]

只有链接到什么样的位图必须在这里使用不完整的描述。没有关于头结构的开始和像素字节从底线到顶行。而且也不需要在最后一个像素后插入零字节,将每行的大小调整为4的倍数。但即使使用位图也不知道这些 0x0009 不起作用。

当我把任何一种背景图像放进工作表中 *.xls Excel 的GUI,然后使用十六进制转储查看该文件,则始终如下所示:

e900型 09000100 SSSSSSSS 0亿 wwwhhh 01001800 购买力平价。。。

https://www.openoffice.org/sc/excelfileformat.pdf 比微软的“文档”更有用。

所以下面的代码将背景图像放入 HSSFSheet 适用于我测试多种不同类型的图像文件(BMP、PNG、JPG)。

也改变了使用 List<Byte> data 到 byte[] data . 所以呢 org.apache.poi.hssf.record.ContinueRecord

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);
  }
 }

}