Upload files from Java client to a HTTP server

You'd normally use java.net.URLConnection to fire HTTP requests. You'd also normally use multipart/form-data encoding for mixed POST content (binary and character data). Click the link, it contains information and an example how to compose a multipart/form-data request body. The specification is in more detail described in RFC2388.

Here's a kickoff example:

String url = "http://example.com/upload";String charset = "UTF-8";String param = "value";File textFile = new File("/path/to/file.txt");File binaryFile = new File("/path/to/file.bin");String boundary = Long.toHexString(System.currentTimeMillis()); // Just generate some unique random value.String CRLF = "\r\n"; // Line separator required by multipart/form-data.URLConnection connection = new URL(url).openConnection();connection.setDoOutput(true);connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);try (    OutputStream output = connection.getOutputStream();    PrintWriter writer = new PrintWriter(new OutputStreamWriter(output, charset), true);) {    // Send normal param.    writer.append("--" + boundary).append(CRLF);    writer.append("Content-Disposition: form-data; name=\"param\"").append(CRLF);    writer.append("Content-Type: text/plain; charset=" + charset).append(CRLF);    writer.append(CRLF).append(param).append(CRLF).flush();    // Send text file.    writer.append("--" + boundary).append(CRLF);    writer.append("Content-Disposition: form-data; name=\"textFile\"; filename=\"" + textFile.getName() + "\"").append(CRLF);    writer.append("Content-Type: text/plain; charset=" + charset).append(CRLF); // Text file itself must be saved in this charset!    writer.append(CRLF).flush();    Files.copy(textFile.toPath(), output);    output.flush(); // Important before continuing with writer!    writer.append(CRLF).flush(); // CRLF is important! It indicates end of boundary.    // Send binary file.    writer.append("--" + boundary).append(CRLF);    writer.append("Content-Disposition: form-data; name=\"binaryFile\"; filename=\"" + binaryFile.getName() + "\"").append(CRLF);    writer.append("Content-Type: " + URLConnection.guessContentTypeFromName(binaryFile.getName())).append(CRLF);    writer.append("Content-Transfer-Encoding: binary").append(CRLF);    writer.append(CRLF).flush();    Files.copy(binaryFile.toPath(), output);    output.flush(); // Important before continuing with writer!    writer.append(CRLF).flush(); // CRLF is important! It indicates end of boundary.    // End of multipart/form-data.    writer.append("--" + boundary + "--").append(CRLF).flush();}// Request is lazily fired whenever you need to obtain information about response.int responseCode = ((HttpURLConnection) connection).getResponseCode();System.out.println(responseCode); // Should be 200

This code is less verbose when you use a 3rd party library like Apache Commons HttpComponents Client.

The Apache Commons FileUpload as some incorrectly suggest here is only of interest in the server side. You can't use and don't need it at the client side.

See also

• Using java.net.URLConnection to fire and handle HTTP requests

Here is how you would do it with Apache HttpClient (this solution is for those who don't mind using a 3rd party library):

    HttpEntity entity = MultipartEntityBuilder.create()                       .addPart("file", new FileBody(file))                       .build();    HttpPost request = new HttpPost(url);    request.setEntity(entity);    HttpClient client = HttpClientBuilder.create().build();    HttpResponse response = client.execute(request);

click link get example file upload clint java with apache HttpComponents

http://hc.apache.org/httpcomponents-client-ga/httpmime/examples/org/apache/http/examples/entity/mime/ClientMultipartFormPost.java

and library downalod link

https://hc.apache.org/downloads.cgi

use 4.5.3.zip it's working fine in my code

and my working code..

import java.io.File;import org.apache.http.HttpEntity;import org.apache.http.client.methods.CloseableHttpResponse;import org.apache.http.client.methods.HttpPost;import org.apache.http.entity.ContentType;import org.apache.http.entity.mime.MultipartEntityBuilder;import org.apache.http.entity.mime.content.FileBody;import org.apache.http.entity.mime.content.StringBody;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.util.EntityUtils;public class ClientMultipartFormPost {     public static void main(String[] args) throws Exception {          CloseableHttpClient httpclient = HttpClients.createDefault();          try {             HttpPost httppost = new HttpPost("http://localhost:8080/MyWebSite1/UploadDownloadFileServlet");             FileBody bin = new FileBody(new File("E:\\meter.jpg"));             StringBody comment = new StringBody("A binary file of some kind", ContentType.TEXT_PLAIN);             HttpEntity reqEntity = MultipartEntityBuilder.create()                .addPart("bin", bin)                .addPart("comment", comment)                .build();             httppost.setEntity(reqEntity);             System.out.println("executing request " + httppost.getRequestLine());             CloseableHttpResponse response = httpclient.execute(httppost);           try {                System.out.println("----------------------------------------");                System.out.println(response.getStatusLine());                HttpEntity resEntity = response.getEntity();                if (resEntity != null) {                     System.out.println("Response content length: " +    resEntity.getContentLength());                }              EntityUtils.consume(resEntity);             } finally {                 response.close();            }       } finally {          httpclient.close();      }   }}