Uploading Multiple files at once with Post and Header parameter in Android

MultiPartUtility.java

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
 
/**
 * This utility class provides an abstraction layer for sending multipart HTTP
 * POST requests to a web server.
 * @author www.codejava.net
 *
 */

public class MultipartUtility {
    private final String boundary;
    private static final String LINE_FEED = "\r\n";
    private HttpURLConnection httpConn;
    private String charset;
    private OutputStream outputStream;
    private PrintWriter writer;
 
    /**
     * This constructor initializes a new HTTP POST request with content type
     * is set to multipart/form-data
     * @param requestURL
     * @param charset
     * @throws IOException
     */
    public MultipartUtility(String requestURL, String charset)
            throws IOException {
        this.charset = charset;
         
        // creates a unique boundary based on time stamp
        boundary = "===" + System.currentTimeMillis() + "===";
         
        URL url = new URL(requestURL);
        httpConn = (HttpURLConnection) url.openConnection();
        httpConn.setUseCaches(false);
        httpConn.setDoOutput(true); // indicates POST method
        httpConn.setDoInput(true);
        httpConn.setRequestProperty("Content-Type",
                "multipart/form-data; boundary=" + boundary);
        httpConn.setRequestProperty("User-Agent", "CodeJava Agent");
        httpConn.setRequestProperty("Test", "Bonjour");
        outputStream = httpConn.getOutputStream();
        writer = new PrintWriter(new OutputStreamWriter(outputStream, charset),
                true);
    }
 
    /**
     * Adds a form field to the request
     * @param name field name
     * @param value field value
     */
    public void addFormField(String name, String value) {
        writer.append("--" + boundary).append(LINE_FEED);
        writer.append("Content-Disposition: form-data; name=\"" + name + "\"")
                .append(LINE_FEED);
        writer.append("Content-Type: text/plain; charset=" + charset).append(
                LINE_FEED);
        writer.append(LINE_FEED);
        writer.append(value).append(LINE_FEED);
        writer.flush();
    }
 
    /**
     * Adds a upload file section to the request
     * @param fieldName name attribute in <input type="file" name="..." />
     * @param uploadFile a File to be uploaded
     * @throws IOException
     */
    public void addFilePart(String fieldName, File uploadFile)
            throws IOException {
        String fileName = uploadFile.getName();
        writer.append("--" + boundary).append(LINE_FEED);
        writer.append(
                "Content-Disposition: form-data; name=\"" + fieldName
                        + "\"; filename=\"" + fileName + "\"")
                .append(LINE_FEED);
        writer.append(
                "Content-Type: "
                        + URLConnection.guessContentTypeFromName(fileName))
                .append(LINE_FEED);
        writer.append("Content-Transfer-Encoding: binary").append(LINE_FEED);
        writer.append(LINE_FEED);
        writer.flush();
 
        FileInputStream inputStream = new FileInputStream(uploadFile);
        byte[] buffer = new byte[4096];
        int bytesRead = -1;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }
        outputStream.flush();
        inputStream.close();
         
        writer.append(LINE_FEED);
        writer.flush();    
    }
 
    /**
     * Adds a header field to the request.
     * @param name - name of the header field
     * @param value - value of the header field
     */
    public void addHeaderField(String name, String value) {
        writer.append(name + ": " + value).append(LINE_FEED);
        writer.flush();
    }
     
    /**
     * Completes the request and receives response from the server.
     * @return a list of Strings as response in case the server returned
     * status OK, otherwise an exception is thrown.
     * @throws IOException
     */
    /*
    public List<String> finish() throws IOException {
        List<String> response = new ArrayList<String>();
 
        writer.append(LINE_FEED).flush();
        writer.append("--" + boundary + "--").append(LINE_FEED);
        writer.close();
 
        // checks server's status code first
        int status = httpConn.getResponseCode();
        if (status == HttpURLConnection.HTTP_OK) {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    httpConn.getInputStream()));
            String line = null;
            while ((line = reader.readLine()) != null) {
                response.add(line);
            }
            reader.close();
            httpConn.disconnect();
        } else {
            throw new IOException("Server returned non-OK status: " + status);
        }
 
        return response;
    }
    */




    /**
     * Completes the request and receives response from the server.
     * @return a list of Strings as response in case the server returned
     * status OK, otherwise an exception is thrown.
     * @throws IOException
     */
    public String finish() throws IOException {
        String response = "";

        writer.append(LINE_FEED).flush();
        writer.append("--" + boundary + "--").append(LINE_FEED);
        writer.close();

        // checks server's status code first
        int status = httpConn.getResponseCode();
        if (status == HttpURLConnection.HTTP_OK) {

            BufferedInputStream in = new BufferedInputStream(httpConn.getInputStream());
            response = inputStreamToString(in);

            httpConn.disconnect();
        } else {
            throw new IOException("Server returned non-OK status: " + status);
        }

        return response;
    }


    private static String inputStreamToString(InputStream in) {
        String result = "";
        if (in == null) {
            return result;
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(in,"UTF-8"));
            StringBuilder out = new StringBuilder();
            String line;
            while ((line = reader.readLine()) != null) {
                out.append(line);
            }
            result = out.toString();
            reader.close();

            return result;
        } catch (Exception e) {
            // TODO: handle exception
            Logcat.e("InputStream", "Error : " + e.toString());
            return result;
        }

    }
}

Upload.php

<?php
  
    $file_path = "uploads/";
    $username = $_POST['Username'];
     
     /*
     Single upload
    $file_path = $file_path . basename( $_FILES['uploaded_file']['name']);
    if(move_uploaded_file($_FILES['uploaded_file']['tmp_name'], $file_path)) {
        echo "success user ".$username;
    } else{
        echo "fail user ".$username;
    }
    */
    
    	//Loop through each file
    	
    	 $success = array();
	 $failure = array();
	    
	for($i=0; $i<count($_FILES['uploaded_file']['name']); $i++) {
	  //Get the temp file path
	  $tmpFilePath = $_FILES['uploaded_file']['tmp_name'][$i];
	
	  //Make sure we have a filepath
	  if ($tmpFilePath != ""){
	    //Setup our new file path
	    $newFilePath = "uploads/" . $_FILES['uploaded_file']['name'][$i];
	
	
	   
	    //Upload the file into the temp dir
	    if(move_uploaded_file($tmpFilePath, $newFilePath)) {
		$success[] = $newFilePath;
	    }else{
	    	$failure[] = $newFilePath;
	    }
	    
	    
	  }
	}
	
	
	$result = array("Username" => $username, "Success"=>$success,"Failure"=>$failure);
	
	echo json_encode($result);
	

 ?>

Usage.java

public static void main(String[] args) {
 String charset = "UTF-8";
 File uploadFile1 = new File("e:/Test/PIC1.JPG");
 File uploadFile2 = new File("e:/Test/PIC2.JPG");
 String requestURL = "http://localhost:8080/FileUploadSpringMVC/uploadFile.do";

 try {
 MultipartUtility multipart = new MultipartUtility(requestURL, charset);

 multipart.addHeaderField("User-Agent", "CodeJava");
 multipart.addHeaderField("Test-Header", "Header-Value");

 multipart.addFormField("Username", "TestUser");
 
  multipart.addFilePart("uploaded_file[]", uploadFile1);
 multipart.addFilePart("fileUpload[]", uploadFile2);

 String response = multipart.finish();

 } catch (IOException ex) {
 System.err.println(ex);
 }
 }

Do you have any examples on how the request can be accepted and processed by a NodeJS application?

I think there's a bug on setting the charset. it needs to be:
writer.append("Content-Type: text/plain; charset="" + charset+""").append(LINE_FEED);

another thing,
on your php code it only retrieves the file $_FILES['uploaded_file'] (or uploadFile1) and not also the $_FILES[fileUpload'] (or uploadFile2)