Java

REST Read Response with Stream API

See more REST Examples

Demonstrates how to make a REST call that returns a binary body, and to receive the body through a stream API. 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.

    CkRest rest = new CkRest();

    //  Connect to the Amazon AWS REST server.
    boolean bTls = true;
    int port = 443;
    boolean bAutoReconnect = true;
    success = rest.Connect("s3.amazonaws.com",port,bTls,bAutoReconnect);

    //  ----------------------------------------------------------------------------
    //  Important: For buckets created in regions outside us-east-1,
    //  there are three important changes that need to be made.
    //  See Working with S3 Buckets in Non-us-east-1 Regions for the details.
    //  ----------------------------------------------------------------------------

    //  Provide AWS credentials for the REST call.
    CkAuthAws authAws = new CkAuthAws();
    authAws.put_AccessKey("AWS_ACCESS_KEY");
    authAws.put_SecretKey("AWS_SECRET_KEY");
    authAws.put_ServiceName("s3");
    success = rest.SetAuthAws(authAws);

    //  Set the bucket name via the HOST header.
    //  In this case, the bucket name is "chilkat100".
    rest.put_Host("chilkat100.s3.amazonaws.com");

    //  Send the request to download the JPG.
    success = rest.SendReqNoBody("GET","/starfish.jpg");
    if (success != true) {
        System.out.println(rest.lastErrorText());
        return;
        }

    //  Read the response header.
    int responseStatusCode = rest.ReadResponseHeader();
    if (responseStatusCode < 0) {
        System.out.println(rest.lastErrorText());
        return;
        }

    System.out.println("Response status code = " + responseStatusCode);

    //  We expect a 200 response status if the JPG data is coming.
    //  Otherwise, we'll get a string response body with an error message(or no response body).
    if (responseStatusCode != 200) {
        String errResponse = rest.readRespBodyString();
        if (rest.get_LastMethodSuccess() != true) {
            System.out.println(rest.lastErrorText());
            }
        else {
            System.out.println(errResponse);
            }

        return;
        }

    CkStream bodyStream = new CkStream();
    //  Set a 10 second read timeout for the stream. 
    //  (Give up if no data arrives within 10 seconds after calling a read method.)
    bodyStream.put_ReadTimeoutMs(10000);

    //  Create a background thread task to read the response body (which feeds
    //  it to the bodyStream object.)
    CkTask readResponseBodyTask = rest.ReadRespBodyStreamAsync(bodyStream,true);

    //  Start the task. 
    success = readResponseBodyTask.Run();

    //  The application can now read the bodyStream...
    CkByteData nextChunk = new CkByteData();
    while ((bodyStream.get_EndOfStream() != true)) {

        //  Read the next chunk of bytes (whatever is immediately available,
        //  or wait for more data (up to 10 seconds because we set the stream's ReadTimeoutMs property)
        success = bodyStream.ReadBytes(nextChunk);
        if (success != true) {
            System.out.println("Failed to receive more response data.");
            //  Make sure the background task is aborted/cancelled.
            success = readResponseBodyTask.Cancel();

            return;
            }

        //  OK.. the app has the next chunk of the body, and may do whatever it wishes with it...
        //  See the CkByteData online reference documentation for 
        //  information about accessing and manipulating the byte data.

        }

    System.out.println("Successfully received the entire response body.");
  }
}