(Java) REST Stream Multipart Body from File

Demonstrates how to send a multipart/form-data HTTP request, where one of the parts contains data streamed directly from a file. This is good for cases where the file to be uploaded is very large.

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

    CkRest rest = new CkRest();

    // Connect to the destination web server.
    boolean bTls = true;
    int port = 443;
    boolean bAutoReconnect = true;
    boolean success = rest.Connect("www.somewebserver.com",port,bTls,bAutoReconnect);

    // This example will send the following multipart/form-data request.
    // The Content-Length is automatically computed and added by Chilkat.

    // 	POST /some_path HTTP/1.1
    // 	Content-Type: multipart/form-data; boundary=---------------------------735323031399963166993862150
    // 	Content-Length: 834
    // 
    // 	-----------------------------735323031399963166993862150
    // 	Content-Disposition: form-data; name="text1"
    // 
    // 	text 123 abc
    // 	-----------------------------735323031399963166993862150
    // 	Content-Disposition: form-data; name="text2"
    // 
    // 	xyz
    // 	-----------------------------735323031399963166993862150
    // 	Content-Disposition: form-data; name="file1"; filename="a.txt"
    // 	Content-Type: text/plain
    // 
    // 	Content of a.txt.
    // 
    // 	-----------------------------735323031399963166993862150
    // 	Content-Disposition: form-data; name="file2"; filename="a.html"
    // 	Content-Type: text/html
    // 
    // 	<!DOCTYPE html><title>Content of a.html.</title>
    // 
    // 	-----------------------------735323031399963166993862150
    // 	Content-Disposition: form-data; name="file3"; filename="starfish.jpg"
    // 	Content-Type: image/jpeg
    // 
    // 	binary data goes here
    // 	-----------------------------735323031399963166993862150--

    // Set the Content-Type for the topmost MIME part.
    rest.AddHeader("Content-Type","multipart/form-data");

    // Specify each part of the request.
    rest.put_PartSelector("1");
    rest.AddHeader("Content-Disposition","form-data; name=\"text1\"");
    rest.SetMultipartBodyString("text 123 abc");

    rest.put_PartSelector("2");
    rest.AddHeader("Content-Disposition","form-data; name=\"text2\"");
    rest.SetMultipartBodyString("xyz");

    rest.put_PartSelector("3");
    rest.AddHeader("Content-Disposition","form-data; name=\"file1\"; filename=\"a.txt\"");
    rest.AddHeader("Content-Type","text/plain");
    rest.SetMultipartBodyString("Content of a.txt.");

    rest.put_PartSelector("4");
    rest.AddHeader("Content-Disposition","form-data; name=\"file2\"; filename=\"a.html\"");
    rest.AddHeader("Content-Type","text/html");
    CkStringBuilder sbHtml = new CkStringBuilder();
    sbHtml.LoadFile("qa_data/html/a.html","utf-8");
    rest.SetMultipartBodySb(sbHtml);

    rest.put_PartSelector("5");
    rest.AddHeader("Content-Disposition","form-data; name=\"file3\"; filename=\"starfish.jpg\"");
    rest.AddHeader("Content-Type","image/jpeg");

    // When the request is sent, stream this part directly from the file.
    // This avoids having to load the entire file into memory.
    CkStream fileStream = new CkStream();
    fileStream.put_SourceFile("qa_data/jpg/starfish.jpg");
    rest.SetMultipartBodyStream(fileStream);

    String responseBody = rest.fullRequestMultipart("POST","/some_path");
    if (rest.get_LastMethodSuccess() != true) {
        System.out.println(rest.lastErrorText());
        return;
        }

    // ...
    // ...

    // Clear the REST object for any subsequent requests..
    rest.ClearAllHeaders();
    rest.ClearAllParts();
    rest.put_PartSelector("");
  }
}