Android™

Decompress Large Binary File in Blocks

See more Compression Examples

Decompresses a large binary file in blocks. Android™

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    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) {
        Log.i(TAG, 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) {
        Log.i(TAG, 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();

    Log.i(TAG, "Finished decompressing file.");

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}