Java

Unzip One File to a Stream

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Demonstrates how to unzip a particular file contained within a .zip archive to a Chilkat stream. 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.

    CkZip zip = new CkZip();

    // First open a .zip.
    success = zip.OpenZip("qa_data/hamlet.zip");
    if (success == false) {
        System.out.println(zip.lastErrorText());
        return;
        }

    // Find the entry to be unzipped to a stream..
    CkZipEntry entry = new CkZipEntry();
    success = zip.EntryMatching("*hamlet.xml",entry);
    if (success == false) {
        System.out.println(zip.lastErrorText());
        return;
        }

    // There are three ways we can unzip (inflate) to a stream.
    // 
    // 1) Set a sink file on the stream object and call UnzipToStream synchronously.
    //    This unzips to the stream's sink (which is to simply unzip to a file in the filesystem).
    // 
    // 2) Create a stream object and call UnzipToStreamAsync.  This starts the unzip in a background
    //    thread (after Task.Run is called).  Your application can then read the unzipped (inflated) file
    //    directly from the stream.
    // 
    // 3) (not shown in this example) Unzip to a stream object that is the source of something else.
    //    

    // ----------------------------------------------------------------
    // Case 1: Unzip to a file by setting the sink of streamA to a file.
    CkStream streamA = new CkStream();
    streamA.put_SinkFile("qa_output/hamletA.xml");

    success = entry.UnzipToStream(streamA);
    if (success != true) {
        System.out.println(entry.lastErrorText());
        return;
        }

    // Close the stream to close the output file.
    success = streamA.WriteClose();

    // ----------------------------------------------------------------
    // Case 2a: Uzip to a stream asynchronously. 
    CkStream streamB = new CkStream();

    CkTask unzipTask = entry.UnzipToStreamAsync(streamB);
    if (entry.get_LastMethodSuccess() != true) {
        System.out.println(entry.lastErrorText());
        return;
        }

    // Start the background unzip thread.
    unzipTask.Run();

    // Read the stream.  (this is reading the unzipped file data)
    CkStringBuilder sb = new CkStringBuilder();
    while (streamB.get_EndOfStream() != true) {
        // Each call to ReadSb appends to the contents of sb.
        streamB.ReadSb(sb);
        }

    sb.WriteFile("qa_output/hamletB.xml","utf-8",false);

    System.out.println("Success.");

    // ----------------------------------------------------------------
    // Case 2b: Uzip to a stream asynchronously and emit output while reading. 
    CkStream streamC = new CkStream();

    unzipTask = entry.UnzipToStreamAsync(streamC);
    if (entry.get_LastMethodSuccess() != true) {
        System.out.println(entry.lastErrorText());
        return;
        }

    unzipTask.Run();

    while (streamC.get_EndOfStream() != true) {
        String s = streamC.readString();
        System.out.println(s);
        }

    System.out.println("Success.");
  }
}