если вы используете пакет org.apache.commons.httpclient.HttpClient, возможно, это вам поможет!
HttpConnectionManager httpConnectionManager = new MultiThreadedHttpConnectionManager();
//here should set HttpConnectionManagerParams but not important for you
HttpClient httpClient = new HttpClient(httpConnectionManager);
PostMethod postMethod = new PostMethod("http://localhost/media");
FilePart filePart = new FilePart("file", new File(filepath));
StringPart typePart = new StringPart("type", fileContent.getType(), "utf-8");
StringPart fileNamePart = new StringPart("fileName", fileContent.getFileName(), "utf-8");
StringPart timestampPart = new StringPart("timestamp", ""+fileContent.getTimestamp(),"utf-8");
Part[] parts = { typePart, fileNamePart, timestampPart, filePart };
MultipartRequestEntity multipartRequestEntity = new MultipartRequestEntity(parts, postMethod.getParams());
postMethod.setRequestEntity(multipartRequestEntity);
httpClient.executeMethod(postMethod);
String responseStr = postMethod.getResponseBodyAsString();