(Java) Lower-Level REST API Methods (Google Cloud Storage)

The FullRequest* methods, such as FullRequestBinary, FullRequestMultipart, FullRequestNoBody, FullRequestStream, FullRequestString, etc. are high-level REST API methods that both send the request and receive the response. It is often the case that an application needs make a REST call, but with a finer level of control. The Chilkat REST API provides this feature. An application can break a REST call into the following parts:

1. Send the HTTP request. (via the SendReq* methods)
2. Receive the HTTP response header. (ReadResponseHeader)
3. Receive the HTTP response body. (via the ReadRespBody* methods)

This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.

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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[])
  {
    // This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.
    // It will create a bucket in Google Cloud Storage.
    boolean success;

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

    CkAuthGoogle gAuth = new CkAuthGoogle();
    // Obtain an access token as shown in one of the following examples:
    // See Get Access Token using a Service Account JSON Key
    // See Get Access Token using a P12 File

    CkRest rest = new CkRest();

    // Connect using TLS.
    boolean bAutoReconnect = true;
    success = rest.Connect("www.googleapis.com",443,true,bAutoReconnect);

    // Provide the authentication credentials (i.e. the access key)
    success = rest.SetAuthGoogle(gAuth);

    // Build the JSON request body for creating a bucket.
    // The only required property is the "name", but we'll add more
    // to make a better example..
    CkJsonObject jsonReqBody = new CkJsonObject();
    success = jsonReqBody.AddStringAt(-1,"name","chilkat-bucket-c");
    success = jsonReqBody.AddStringAt(-1,"kind","storage#bucket");
    success = jsonReqBody.AddStringAt(-1,"location","US");
    success = jsonReqBody.AddObjectAt(-1,"versioning");

    CkJsonObject pObjVersioning = jsonReqBody.ObjectOf("versioning");
    success = pObjVersioning.AddBoolAt(-1,"enabled",true);

    // Show the HTTP request body we'll be sending.
    System.out.println(jsonReqBody.emit());

    // Add the required query parameter.
    // See https://cloud.google.com/storage/docs/json_api/v1/buckets/insert
    success = rest.AddQueryParam("project","chilkattest-1050");

    // Add the Content-Type HTTP request header.
    success = rest.AddHeader("Content-Type","application/json; charset=UTF-8");

    // Send the REST HTTP request.
    success = rest.SendReqStringBody("POST","/storage/v1/b",jsonReqBody.emit());
    if (success != true) {
        System.out.println(rest.lastErrorText());
        return;
        }

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

    if (responseStatusCode != 200) {
        // The response was not successful.  We'll still need to receive 
        // the response body, which may contain an error message from the server.
        // If the response has no body, then the method for reading the
        // response body can still be called.  It will simply return with an empty
        // response body.

        // We can examine the response header and status text:
        System.out.println("Response status text: " + rest.responseStatusText());
        System.out.println("Response header: " + rest.responseHeader());
        }

    // Read the response body.  In this case we're expecting it to be JSON..
    String responseBodyStr = rest.readRespBodyString();
    if (rest.get_LastMethodSuccess() != true) {
        // We were unable to receive the response body.
        // Note: If the response did not include a body (such as for cases where
        // the Content-Length header is 0, or if the response status code implicitly
        // indicates no body, then ReadRespBodyString returns cktrue, and the
        // responseBodyString will be an empty string.
        System.out.println(rest.lastErrorText());
        return;
        }

    // Show the JSON response.
    System.out.println("Json Response: " + responseBodyStr);
  }
}