Java

Decompress Large Binary File in Blocks

See more Compression Examples

Decompresses a large binary file in blocks. Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    CkFileAccess facSrc = new CkFileAccess();
    CkFileAccess facDest = new CkFileAccess();

    //  Open a previously compressed file for decompressing.
    //  See Compress Large File in Blocks

    success = facSrc.OpenForRead("c:/temp/qa_output/compressedBmp.dat");
    if (success == false) {
        System.out.println(facSrc.lastErrorText());
        return;
        }

    //  If we compress in 32K chunks, find out how many blocks there will be.
    int blockSize = 32768;
    int numBlocks = facSrc.GetNumBlocks(blockSize);

    //  Open an output file for the decompressed data.
    success = facDest.OpenForWrite("c:/temp/qa_output/decompressed.bmp");
    if (success == false) {
        System.out.println(facDest.lastErrorText());
        return;
        }

    CkCompression compress = new CkCompression();
    compress.put_Algorithm("deflate");

    CkByteData decompressedBytes = new CkByteData();
    CkByteData compressedBytes = new CkByteData();

    //  Assuming numBlocks > 1
    compress.put_FirstChunk(true);
    compress.put_LastChunk(false);

    int i = 0;
    while (i < numBlocks) {
        success = facSrc.ReadBlock(i,blockSize,compressedBytes);

        success = compress.DecompressBytes(compressedBytes,decompressedBytes);
        facDest.FileWrite(decompressedBytes);

        i = i+1;

        compress.put_FirstChunk(false);
        if (i == (numBlocks - 1)) {
            compress.put_LastChunk(true);
            }

        }

    facSrc.FileClose();
    facDest.FileClose();

    System.out.println("Finished decompressing file.");
  }
}