(Android™) Streaming Compression

Compress and decompress using a stream.

Chilkat Android™ Downloads Android™ Java Libraries Android C/C++ Libraries

// 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);

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

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

    CkStream streamC = new CkStream();

    // This example sets the source and sink of the stream to files.
    // A stream can have use other streams as a source or sink,
    // or the application can itself be the source/sink by directly
    // reading or writing a stream.  (See below for an example of this..)
    streamC.put_SourceFile("qa_data/hamlet.xml");
    streamC.put_SinkFile("qa_output/hamlet_compressed.dat");

    // Compress from source to sink.
    boolean success = compress.CompressStream(streamC);
    if (success != true) {
        Log.i(TAG, compress.lastErrorText());
        return;
        }

    Log.i(TAG, "File-to-file deflate compression successful.");
    // Note: The FileSize method returns a signed 32-bit integer.  If the file is potentially larger than 2GB, call FileSizeStr instead to return
    // the size of the file as a string, then convert to an integer value.
    Log.i(TAG, "Original size = " + String.valueOf(fac.FileSize(streamC.sourceFile())));
    Log.i(TAG, "Compressed size = " + String.valueOf(fac.FileSize(streamC.sinkFile())));

    // Now do file-to-file decompression
    CkStream streamD = new CkStream();
    streamD.put_SourceFile("qa_output/hamlet_compressed.dat");
    streamD.put_SinkFile("qa_output/hamlet_restored.xml");

    // Decompress from source to sink.
    success = compress.DecompressStream(streamD);
    if (success != true) {
        Log.i(TAG, compress.lastErrorText());
        return;
        }

    Log.i(TAG, "File-to-file deflate decompression successful.");

    // Let's double-check to see that the files are equal in size and content:

    boolean bFilesEqual = fac.FileContentsEqual(streamC.sourceFile(),streamD.sinkFile());
    if (bFilesEqual != true) {
        Log.i(TAG, "The output file is not equal to the input file!");
        }
    else {
        Log.i(TAG, "The file was successfully compressed and decompressed.");
        }

    // ---------------------------------------------------------------------
    // Now let's decompress again, but this time w/ the application reading
    // the decompressed data directly from a stream.
    CkStream streamA = new CkStream();

    streamA.put_SourceFile("qa_output/hamlet_compressed.dat");

    // Start decompressing in a background thread.
    CkTask task = compress.DecompressStreamAsync(streamA);
    success = task.Run();

    // Read decompressed data from streamA:
    String decompressedText;
    while ((streamA.get_EndOfStream() != true)) {
        if (streamA.get_DataAvailable() == true) {
            decompressedText = streamA.readString();
            Log.i(TAG, decompressedText);
            }

        }

    // Let's make sure the background task finished and that the decompress was successful.
    // It should already be the case that the task is finished.
    while ((task.get_Finished() != true)) {
        task.SleepMs(20);
        }

    // The decompressor may have finished, but it is possible that data
    // remains to be flushed.  
    if (streamA.get_DataAvailable() == true) {
        decompressedText = streamA.readString();
        Log.i(TAG, decompressedText);
        }

    // Did streamA succeed in reading the entire file?
    if (task.get_TaskSuccess() != true) {
        Log.i(TAG, "async decompress failed:");
        Log.i(TAG, task.resultErrorText());
        success = false;
        }

    Log.i(TAG, "The async decompress was successful.");

  }

  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."
  }
}