(MFC) Unzip One File to a Stream

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

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkZip.h>
#include <CkZipEntry.h>
#include <CkStream.h>
#include <CkTask.h>
#include <CkStringBuilder.h>

void ChilkatSample(void)
    {
    CkString strOut;

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

    CkZip zip;

    // First open a .zip.
    bool success = zip.OpenZip("qa_data/hamlet.zip");
    if (success != true) {
        strOut.append(zip.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Find the entry to be unzipped to a stream..
    CkZipEntry *entry = zip.FirstMatchingEntry("*hamlet.xml");
    if (zip.get_LastMethodSuccess() != true) {
        strOut.append(zip.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        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;
    streamA.put_SinkFile("qa_output/hamletA.xml");

    success = entry->UnzipToStream(streamA);
    if (success != true) {
        strOut.append(entry->lastErrorText());
        strOut.append("\r\n");
        delete entry;
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

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

    // ----------------------------------------------------------------
    // Case 2a: Uzip to a stream asynchronously. 
    CkStream streamB;

    CkTask *unzipTask = entry->UnzipToStreamAsync(streamB);
    if (entry->get_LastMethodSuccess() != true) {
        strOut.append(entry->lastErrorText());
        strOut.append("\r\n");
        delete entry;
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

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

    // Read the stream.  (this is reading the unzipped file data)
    CkStringBuilder sb;
    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);

    delete unzipTask;
    strOut.append("Success.");
    strOut.append("\r\n");

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

    unzipTask = entry->UnzipToStreamAsync(streamC);
    if (entry->get_LastMethodSuccess() != true) {
        strOut.append(entry->lastErrorText());
        strOut.append("\r\n");
        delete entry;
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    unzipTask->Run();

    while (streamC.get_EndOfStream() != true) {
        const char *s = streamC.readString();
        strOut.append(s);
        strOut.append("\r\n");
    }

    delete entry;
    delete unzipTask;
    strOut.append("Success.");
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }