bmpfile.java

Java案例开发集锦,里面提供了很好的学习例子

import java.awt.*;
import java.io.*;
import java.awt.image.*;

public class BMPFile extends Component {

  //--- 私有常量
  private final static int BITMAPFILEHEADER_SIZE = 14;
  private final static int BITMAPINFOHEADER_SIZE = 40;
  //--- 私有变量声明
  //--- 位图文件标头
  private byte bitmapFileHeader [] = new byte [14];
  private byte bfType [] = {'B', 'M'};
  private int bfSize = 0;
  private int bfReserved1 = 0;
  private int bfReserved2 = 0;
  private int bfOffBits = BITMAPFILEHEADER_SIZE + BITMAPINFOHEADER_SIZE;
  //--- 位图信息标头
  private byte bitmapInfoHeader [] = new byte [40];
  private int biSize = BITMAPINFOHEADER_SIZE;
  private int biWidth = 0;
  private int biHeight = 0;
  private int biPlanes = 1;
  private int biBitCount = 24;
  private int biCompression = 0;
  private int biSizeImage = 0x030000;
  private int biXPelsPerMeter = 0x0;
  private int biYPelsPerMeter = 0x0;
  private int biClrUsed = 0;
  private int biClrImportant = 0;
  //--- 位图原始数据
  private int bitmap [];
  //--- 文件部分
  private FileOutputStream fo;
  //--- 缺省构造函数
  public BMPFile() {
  }
public void saveBitmap (String parFilename, Image parImage, int
parWidth, int parHeight) {
     try {
        fo = new FileOutputStream (parFilename);
        save (parImage, parWidth, parHeight);
        fo.close (); 
     }
     catch (Exception saveEx) {
        saveEx.printStackTrace ();
     }
  }
  /*
   * saveMethod 是该进程的主方法。该方法
   * 将调用 convertImage 方法以将内存图像转换为
   * 字节数组；writeBitmapFileHeader 方法创建并写入
   * 位图文件标头；writeBitmapInfoHeader 创建 
   * 信息标头；writeBitmap 写入图像。
   *
   */
  private void save (Image parImage, int parWidth, int parHeight) {
     try {
        convertImage (parImage, parWidth, parHeight);
        writeBitmapFileHeader ();
        writeBitmapInfoHeader ();
        writeBitmap ();
     }
     catch (Exception saveEx) {
        saveEx.printStackTrace ();
     }
  }
  /*
   * convertImage 将内存图像转换为位图格式 (BRG)。
   * 它还计算位图信息标头所用的某些信息。
   */
  private boolean convertImage (Image parImage, int parWidth, int parHeight) {
     int pad;
     bitmap = new int [parWidth * parHeight];
     PixelGrabber pg = new PixelGrabber (parImage, 0, 0, parWidth, parHeight,
                                         bitmap, 0, parWidth);

     try {
        pg.grabPixels ();
     }
     catch (InterruptedException e) {
        e.printStackTrace ();
        return (false);
     }
     pad = (4 - ((parWidth * 3) % 4)) * parHeight;
     biSizeImage = ((parWidth * parHeight) * 3) + pad;
     bfSize = biSizeImage + BITMAPFILEHEADER_SIZE +
BITMAPINFOHEADER_SIZE;
     biWidth = parWidth;
     biHeight = parHeight;
     return (true);
  }
  /*
   * writeBitmap 将象素捕获器返回的图像转换为
   * 所需的格式。请记住：扫描行在位图文件中是
   * 反向存储的！
   *
   * 每个扫描行必须补足为 4 个字节。
   */
  private void writeBitmap () {
      int size;
      int value;
      int j;
      int i;
      int rowCount;
      int rowIndex;
      int lastRowIndex;
      int pad;
      int padCount;
      byte rgb [] = new byte [3];
      size = (biWidth * biHeight) - 1;
      pad = 4 - ((biWidth * 3) % 4);
      if (pad == 4) // <==== 错误修正
         pad = 0; // <==== 错误修正
      rowCount = 1;
      padCount = 0;
      rowIndex = size - biWidth;
      lastRowIndex = rowIndex;
      try {
         for (j = 0; j < size; j++) {
            value = bitmap [rowIndex];
            rgb [0] = (byte) (value & 0xFF);
            rgb [1] = (byte) ((value >> 8) & 0xFF);
            rgb [2] = (byte) ((value >> 16) & 0xFF);
            fo.write (rgb);
            if (rowCount == biWidth) {
               padCount += pad;
               for (i = 1; i <= pad; i++) {
                  fo.write (0x00);
               }
               rowCount = 1;
               rowIndex = lastRowIndex - biWidth;
               lastRowIndex = rowIndex;
            }
            else
               rowCount++;
            rowIndex++;
         }
         //--- 更新文件大小
         bfSize += padCount - pad;
         biSizeImage += padCount - pad;
      }
      catch (Exception wb) {
         wb.printStackTrace ();
      }
   } 
  /*
   * writeBitmapFileHeader 将位图文件标头写入文件中。
   *
   */
  private void writeBitmapFileHeader () {
     try {
        fo.write (bfType);
        fo.write (intToDWord (bfSize));
        fo.write (intToWord (bfReserved1));
        fo.write (intToWord (bfReserved2));
        fo.write (intToDWord (bfOffBits));
     }
     catch (Exception wbfh) {
        wbfh.printStackTrace ();
     }
  }
  /*
   *
   * writeBitmapInfoHeader 将位图信息标头
   * 写入文件中。
   *
   */
  private void writeBitmapInfoHeader () {
     try {
        fo.write (intToDWord (biSize));
        fo.write (intToDWord (biWidth));
        fo.write (intToDWord (biHeight));
        fo.write (intToWord (biPlanes));
        fo.write (intToWord (biBitCount));
        fo.write (intToDWord (biCompression));
        fo.write (intToDWord (biSizeImage));
        fo.write (intToDWord (biXPelsPerMeter));
        fo.write (intToDWord (biYPelsPerMeter));
        fo.write (intToDWord (biClrUsed));
        fo.write (intToDWord (biClrImportant));
     }
     catch (Exception wbih) {
        wbih.printStackTrace ();
     }
  }
  /*
   *
   * intToWord 将整数转换为单字，返回值
   * 存储在一个双字节数组中。
   *
   */
  private byte [] intToWord (int parValue) {
     byte retValue [] = new byte [2];
     retValue [0] = (byte) (parValue & 0x00FF);
     retValue [1] = (byte) ((parValue >> 8) & 0x00FF);
     return (retValue);
  }
  /*
   *
   * intToDWord 将整数转换为双字，返回值
   * 存储在一个 4 字节数组中。
   *
   */
  private byte [] intToDWord (int parValue) {
     byte retValue [] = new byte [4];
     retValue [0] = (byte) (parValue & 0x00FF);
     retValue [1] = (byte) ((parValue >> 8) & 0x000000FF);
     retValue [2] = (byte) ((parValue >> 16) & 0x000000FF);
     retValue [3] = (byte) ((parValue >> 24) & 0x000000FF);
     return (retValue);
  }
}