PPMD Streaming String Compression

Demonstrates streaming string compression using PPMD. Data may be compressed in chunks by initially calling one of the BeginCompress* methods, followed by 0 or more calls to a MoreCompress* method, and terminating with a call to an EndCompress* method.

Likewise, data may be decompressed by calling a BeginDecompress* method, followed by 0 or more MoreDecompress* calls, and ending with an EndDecompress* method call.

This example demonstrates string-to-string compression and decompression in chunks.

The functionality in this example is available in pre-release only:

Download Chilkat Java Library (Pre-Release)

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[])
  {
    CkCompression compress = new CkCompression();

    //  Any string argument automatically begins a 30-day trial.
    boolean success;
    success = compress.UnlockComponent("30-day trial");
    if (success != true) {
        System.out.println("Compression component unlock failed");
        return;
    }

    compress.put_Algorithm("ppmd");
    compress.put_Charset("ansi");
    compress.put_EncodingMode("base64");

    String strData;
    int i;

    String strCompressed;

    //  Create a long string to compress.
    strData = "abcdefg1122334455667788";
    strData = strData + "\r\n";

    //  Note: BeginCompressStringENC may return a zero-length
    //  string.  This is normal if the input is buffered and no
    //  compressed data is yet available.
    //  However, a null reference indicates an error -- which is
    //  generally only possible if the component was never unlocked.
    strCompressed = compress.beginCompressStringENC(strData);

    //  Compress 100 more chunks of data.  Each call to
    //  MoreCompressStringENC may or may not produce additional
    //  compressed output.
    for (i = 0; i <= 99; i++) {
        strData = "abcdefg1122334455667788";
        strData = strData + "\r\n";

        strCompressed = strCompressed + compress.moreCompressStringENC(strData);
    }

    //  Finalize the compression with a single call to EndCompressStringENC:
    strCompressed = strCompressed + compress.endCompressStringENC();

    //  Display the compressed string.
    //  The result will be:
    //  ec8YZ5vk9za18d0plwuV7R65em9OZge9gJXht/QAAAAAAAAAABNOZQAAKw==

    System.out.println(strCompressed);

    //  Decompress back to the original in a single call.
    String strOriginal;
    strOriginal = compress.decompressStringENC(strCompressed);

    //  Display the uncompressed original:
    System.out.println("--- Original ---");
    System.out.println(strOriginal);

    //  Decompress in multiple calls.  It doesn't matter how the
    //  compressed data is split -- it could be fed to the decompressor
    //  one char at a time if desired.
    String chunk1;
    chunk1 = "ec8YZ5vk9za1";
    String chunk2;
    chunk2 = "8d0p";
    String chunk3;
    chunk3 = "lwuV7R65em9OZge9gJXht/QAAAA";
    String chunk4;
    chunk4 = "AAAAAABNOZQAAKw==";

    strOriginal = "";
    strOriginal = compress.beginDecompressStringENC(chunk1);
    strOriginal = strOriginal + compress.moreDecompressStringENC(chunk2);
    strOriginal = strOriginal + compress.moreDecompressStringENC(chunk3);
    strOriginal = strOriginal + compress.moreDecompressStringENC(chunk4);
    strOriginal = strOriginal + compress.endDecompressStringENC();

    //  Display the uncompressed original after decompressing in chunks:
    System.out.println("--- Original after Decompressing from Chunks ---");
    System.out.println(strOriginal);
  }
}