How to use

writeTo

method

in

org.apache.http.entity.mime.MultipartEntity

try
  entity.writeTo(bos);

 HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");

FileBody fileBody = new FileBody(new File(fileName));
MultipartEntity multipartEntity = new MultipartEntity(HttpMultipartMode.STRICT);
multipartEntity.addPart("file", fileBody);

connection.setRequestProperty("Content-Type", multipartEntity.getContentType().getValue());
OutputStream out = connection.getOutputStream();
try {
  multipartEntity.writeTo(out);
} finally {
  out.close();
}
int status = connection.getResponseCode();
...

@Override
public void writeTo(final OutputStream outstream) throws IOException {
  super.writeTo(new CountingOutputStream(outstream, this.listener));
}

@Override
public byte[] getBody() throws AuthFailureError
{
  ByteArrayOutputStream bos = new ByteArrayOutputStream();
  try
  {
    mEntity.writeTo(bos);
  }
  catch (IOException e)
  {
    VinciLog.e("IOException writing to ByteArrayOutputStream bos, building the multipart request.", e);
  }
  return bos.toByteArray();
}

 File  f = new File(path);
BufferedOutputStream out = new BufferedOutputStream( socket.getOutputStream() );
String filename=path.substring(path.lastIndexOf("/")+1);

// create a multipart message
MultipartEntity multipartContent = new MultipartEntity();

// send the file inputstream as data
InputStreamBody isb = new InputStreamBody(new FileInputStream(f), "image/jpeg", filename);

// add key value pair. The key "imageFile" is arbitrary
multipartContent.addPart("imageFile", isb);

multipartContent.writeTo(out);
out.flush();
out.close();

 File  f = new File(path);
BufferedOutputStream out = new BufferedOutputStream( socket.getOutputStream() );
String filename=path.substring(path.lastIndexOf("/")+1);

// create a multipart message
MultipartEntity multipartContent = new MultipartEntity();

// send the file inputstream as data
InputStreamBody isb = new InputStreamBody(new FileInputStream(f), "image/jpeg", filename);

// add key value pair. The key "imageFile" is arbitrary
multipartContent.addPart("imageFile", isb);

multipartContent.writeTo(out);
out.flush();
out.close();

 MultipartEntity reqEntity = new MultipartEntity();
// add your ContentBody fields as normal...

// Now, pull out the contents of everything you've added and set it as the payload
ByteArrayOutputStream bos = new ByteArrayOutputStream((int)reqEntity.getContentLength());
reqEntity.writeTo(bos);
oAuthReq.addPayload(bos.toByteArray());

// Finally, set the Content-type header (with the boundary marker):
Header contentType = reqEntity.getContentType();
oAuthReq.addHeader(contentType.getName(), contentType.getValue());

// Sign and send like normal:
service.signRequest(new Token(oAuthToken, oAuthSecret), oAuthReq);
Response oauthResp = oAuthReq.send();

  @Override
  public Entity build()
  {
    try
    {
      final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
      apacheMultipartEntity.writeTo(outputStream);
      final InputStream inputStream = new ByteArrayInputStream(outputStream.toByteArray());
      final Header header = apacheMultipartEntity.getContentType();
      final Map<String, String> headers = Maps.newHashMap();
      headers.put(header.getName(), header.getValue());
      return new MultiPartEntity(headers, inputStream);
    }
    catch (IOException e)
    {
      throw new RuntimeException(e);
    }
  }
}

 ServletResponse httpResponse = ctx.getResponse();    
ResponseFacade rf = (ResponseFacade) httpResponse;
httpResponse.setCharacterEncoding("UTF-8");
httpResponse.setContentType("multipart/mixed");
MultipartEntity entity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE, "SEPERATOR_STRING",Charset.forName("UTF-8"));
entity.addPart("json", new StringBody(CMD + "#" + content, "text/plain",  Charset.forName("UTF-8")));
entity.addPart("image", new ByteArrayBody(data, "image/jpeg", "file"));

httpResponse.setContentLength((int) entity.getContentLength());

entity.writeTo(httpResponse.getOutputStream());
ctx.complete();

 URL url = new URL(baseURL+"/projects/"+projectId+"/CSVUpload?authenticity_token="+URLEncoder.encode(authToken, "UTF-8"));
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");

MultipartEntity entity = new MultipartEntity();
entity.addPart("utf8", new StringBody("\u2713", "text/plain", Charset.forName("UTF-8")));
entity.addPart("csv", new FileBody(csvToUpload, "text/csv"));

connection.setRequestProperty("Content-Type", entity.getContentType().getValue());
OutputStream out = connection.getOutputStream();
try {
  entity.writeTo(out);
} finally {
  out.close();
}
connection.getResponseCode();

private void addMultiparts(List<MultiPartEntity> multiParts, HttpURLConnection conn) throws IOException {
  MultipartEntity multipartEntity =
      new MultipartEntity(HttpMultipartMode.STRICT);
  for (MultiPartEntity part : multiParts) {
    multipartEntity.addPart(part.getPartName(), part.getEntity());
  }
  conn.setDoOutput(true);
  conn.setRequestProperty("Content-Type",
      multipartEntity.getContentType().getValue());
  //try to write to the output stream of the connection
  OutputStream outStream = conn.getOutputStream();
  multipartEntity.writeTo(outStream);
  outStream.close();
}

private void addMultiparts(List<MultiPartEntity> multiParts, HttpURLConnection conn) throws IOException {
  MultipartEntity multipartEntity =
      new MultipartEntity(HttpMultipartMode.STRICT);
  for (MultiPartEntity part : multiParts) {
    multipartEntity.addPart(part.getPartName(), part.getEntity());
  }
  conn.setDoOutput(true);
  conn.setRequestProperty("Content-Type",
      multipartEntity.getContentType().getValue());
  //try to write to the output stream of the connection
  OutputStream outStream = conn.getOutputStream();
  multipartEntity.writeTo(outStream);
  outStream.close();
}

entity.writeTo(httpcon.getOutputStream());
os.close();
httpcon.connect();

conn.addRequestProperty(reqEntity.getContentType().getName(), reqEntity.getContentType().getValue());
OutputStream os = conn.getOutputStream();
reqEntity.writeTo(os);
os.close();
conn.connect();

conn.addRequestProperty(reqEntity.getContentType().getName(), reqEntity.getContentType().getValue());
OutputStream os = conn.getOutputStream();
reqEntity.writeTo(os);
os.close();
conn.connect();

/* You will have done this bit earlier to authorize the user
 OAuthService service = new ServiceBuilder().provider(TwitterApi.SSL.class).apiKey("[YOUR API KEY]").apiSecret("[YOUR SECRET]").callback("twitter://callback").build();
 Token accessToken = Do you oauth authorization as normal 
 */  
 OAuthRequest request = new OAuthRequest(Verb.POST, "https://upload.twitter.com/1/statuses/update_with_media.json");
 MultipartEntity entity = new MultipartEntity();
 try {
   entity.addPart("status", new StringBody("insert vacuous statement here"));
   entity.addPart("media", new FileBody(new File("/path/of/your/image/file")));
   ByteArrayOutputStream out = new ByteArrayOutputStream();
   entity.writeTo(out);
   request.addPayload(out.toByteArray());
   request.addHeader(entity.getContentType().getName(), entity.getContentType().getValue());
   service.signRequest(accessToken, request);
   Response response = request.send();
   if (response.isSuccessful()) {
     // you're all good
   }
 } catch (UnsupportedEncodingException e) {
   e.printStackTrace();
 } catch (IOException e) {
   e.printStackTrace();
 }

entity.writeTo(out);

try
  entity.writeTo(bos);

try
  entity.writeTo(bos);

try
  entity.writeTo(bos);