Envoi de fichiers à l'aide de POST avec HttpURLConnection

Puisque les développeurs Android recommandent d'utiliser la HttpURLConnectionclasse, je me demandais si quelqu'un pouvait me donner un bon exemple sur la façon d'envoyer un "fichier" bitmap (en fait un flux en mémoire) via POST à ​​un serveur HTTP Apache. Je ne suis pas intéressé par les cookies ou l'authentification ou quoi que ce soit de compliqué, mais je veux juste avoir une implémentation fiable et logique. Tous les exemples que j'ai vus ici ressemblent plus à "essayons ceci et peut-être que ça marche".

En ce moment, j'ai ce code:

URL url;
HttpURLConnection urlConnection = null;
try {
    url = new URL("http://example.com/server.cgi");

    urlConnection = (HttpURLConnection) url.openConnection();

} catch (Exception e) {
    this.showDialog(getApplicationContext(), e.getMessage());
}
finally {
    if (urlConnection != null)
    {
        urlConnection.disconnect();
    }
}

où showDialog devrait simplement afficher un AlertDialog(en cas d'URL invalide?).

Maintenant, disons que je génère un bitmap comme ceci: à l' Bitmap image = this.getBitmap()intérieur d'un contrôle dérivé de Viewet je veux l'envoyer via POST. Quelle serait la procédure appropriée pour réaliser une telle chose? Quelles classes dois-je utiliser? Puis-je utiliser HttpPostcomme dans cet exemple ? Si oui, comment pourrais-je construire le InputStreamEntitypour mon bitmap? Je trouverais révoltant de devoir d'abord stocker le bitmap dans un fichier sur l'appareil.

Je dois également mentionner que j'ai vraiment besoin d'envoyer chaque pixel non modifié du bitmap d'origine au serveur, donc je ne peux pas le convertir en JPEG.

Je n'ai aucune idée de la raison pour laquelle la HttpURLConnectionclasse ne fournit aucun moyen d'envoyer des fichiers sans avoir à composer le wrapper de fichier manuellement. Voici ce que j'ai fini par faire, mais si quelqu'un connaît une meilleure solution, faites-le moi savoir.

Des données d'entrée:

Bitmap bitmap = myView.getBitmap();

Trucs statiques:

String attachmentName = "bitmap";
String attachmentFileName = "bitmap.bmp";
String crlf = "\r\n";
String twoHyphens = "--";
String boundary =  "*****";

Configurer la demande:

HttpURLConnection httpUrlConnection = null;
URL url = new URL("http://example.com/server.cgi");
httpUrlConnection = (HttpURLConnection) url.openConnection();
httpUrlConnection.setUseCaches(false);
httpUrlConnection.setDoOutput(true);

httpUrlConnection.setRequestMethod("POST");
httpUrlConnection.setRequestProperty("Connection", "Keep-Alive");
httpUrlConnection.setRequestProperty("Cache-Control", "no-cache");
httpUrlConnection.setRequestProperty(
    "Content-Type", "multipart/form-data;boundary=" + this.boundary);

Démarrer le wrapper de contenu:

DataOutputStream request = new DataOutputStream(
    httpUrlConnection.getOutputStream());

request.writeBytes(this.twoHyphens + this.boundary + this.crlf);
request.writeBytes("Content-Disposition: form-data; name=\"" +
    this.attachmentName + "\";filename=\"" + 
    this.attachmentFileName + "\"" + this.crlf);
request.writeBytes(this.crlf);

Convertir Bitmapen ByteBuffer:

//I want to send only 8 bit black & white bitmaps
byte[] pixels = new byte[bitmap.getWidth() * bitmap.getHeight()];
for (int i = 0; i < bitmap.getWidth(); ++i) {
    for (int j = 0; j < bitmap.getHeight(); ++j) {
        //we're interested only in the MSB of the first byte, 
        //since the other 3 bytes are identical for B&W images
        pixels[i + j] = (byte) ((bitmap.getPixel(i, j) & 0x80) >> 7);
    }
}

request.write(pixels);

Fin du wrapper de contenu:

request.writeBytes(this.crlf);
request.writeBytes(this.twoHyphens + this.boundary + 
    this.twoHyphens + this.crlf);

Vider le tampon de sortie:

request.flush();
request.close();

Avoir une réponse:

InputStream responseStream = new 
    BufferedInputStream(httpUrlConnection.getInputStream());

BufferedReader responseStreamReader = 
    new BufferedReader(new InputStreamReader(responseStream));

String line = "";
StringBuilder stringBuilder = new StringBuilder();

while ((line = responseStreamReader.readLine()) != null) {
    stringBuilder.append(line).append("\n");
}
responseStreamReader.close();

String response = stringBuilder.toString();

Fermer le flux de réponse:

responseStream.close();

Fermez la connexion:

httpUrlConnection.disconnect();

PS: Bien sûr, j'ai dû encapsuler la requête private class AsyncUploadBitmaps extends AsyncTask<Bitmap, Void, String>, afin de rendre la plate-forme Android heureuse, car elle n'aime pas avoir des requêtes réseau sur le fil principal.

En fait, j'ai trouvé un meilleur moyen d'envoyer des fichiers en utilisant HttpURLConnection en utilisant MultipartEntity

private static String multipost(String urlString, MultipartEntity reqEntity) {
    try {
        URL url = new URL(urlString);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setReadTimeout(10000);
        conn.setConnectTimeout(15000);
        conn.setRequestMethod("POST");
        conn.setUseCaches(false);
        conn.setDoInput(true);
        conn.setDoOutput(true);

        conn.setRequestProperty("Connection", "Keep-Alive");
        conn.addRequestProperty("Content-length", reqEntity.getContentLength()+"");
        conn.addRequestProperty(reqEntity.getContentType().getName(), reqEntity.getContentType().getValue());

        OutputStream os = conn.getOutputStream();
        reqEntity.writeTo(conn.getOutputStream());
        os.close();
        conn.connect();

        if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
            return readStream(conn.getInputStream());
        }

    } catch (Exception e) {
        Log.e(TAG, "multipart post error " + e + "(" + urlString + ")");
    }
    return null;        
}

private static String readStream(InputStream in) {
    BufferedReader reader = null;
    StringBuilder builder = new StringBuilder();
    try {
        reader = new BufferedReader(new InputStreamReader(in));
        String line = "";
        while ((line = reader.readLine()) != null) {
            builder.append(line);
        }
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (reader != null) {
            try {
                reader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    return builder.toString();
} 

En supposant que vous téléchargez une image avec des données bitmap:

    Bitmap bitmap = ...;
    String filename = "filename.png";
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.PNG, 100, bos);
    ContentBody contentPart = new ByteArrayBody(bos.toByteArray(), filename);

    MultipartEntity reqEntity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE);
    reqEntity.addPart("picture", contentPart);
    String response = multipost("http://server.com", reqEntity);

Et voila! Vos données de publication contiendront un champ d'image avec le nom de fichier et le chemin sur votre serveur.

Pour télécharger le fichier sur le serveur avec un paramètre en utilisant MultipartUtilityde manière simple.

MultipartUtility.java

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);
        Log.e("URL", "URL : " + requestURL.toString());
        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 String finish() throws IOException {
        StringBuffer response = new StringBuffer();

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

        return response.toString();
    }
}

À uploadvous fileavec les paramètres.

REMARQUE: mettez ce code ci-dessous dans non-ui-thread pour obtenir une réponse.

String charset = "UTF-8";
String requestURL = "YOUR_URL";

MultipartUtility multipart = new MultipartUtility(requestURL, charset);
multipart.addFormField("param_name_1", "param_value");
multipart.addFormField("param_name_2", "param_value");
multipart.addFormField("param_name_3", "param_value");
multipart.addFilePart("file_param_1", new File(file_path));
String response = multipart.finish(); // response from server.

La solution de Jaydipsinh Zala n'a pas fonctionné pour moi, je ne sais pas pourquoi mais elle semble proche de la solution.

Donc, en fusionnant celui-ci avec la grande solution et l'explication de Mihai Todor , le résultat est cette classe qui fonctionne actuellement pour moi. Si cela aide quelqu'un:

MultipartUtility2V.java

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.file.Files;

public class MultipartUtilityV2 {
    private HttpURLConnection httpConn;
    private DataOutputStream request;
    private final String boundary =  "*****";
    private final String crlf = "\r\n";
    private final String twoHyphens = "--";

    /**
     * This constructor initializes a new HTTP POST request with content type
     * is set to multipart/form-data
     *
     * @param requestURL
     * @throws IOException
     */
    public MultipartUtilityV2(String requestURL)
            throws IOException {

        // creates a unique boundary based on time stamp
        URL url = new URL(requestURL);
        httpConn = (HttpURLConnection) url.openConnection();
        httpConn.setUseCaches(false);
        httpConn.setDoOutput(true); // indicates POST method
        httpConn.setDoInput(true);

        httpConn.setRequestMethod("POST");
        httpConn.setRequestProperty("Connection", "Keep-Alive");
        httpConn.setRequestProperty("Cache-Control", "no-cache");
        httpConn.setRequestProperty(
                "Content-Type", "multipart/form-data;boundary=" + this.boundary);

        request =  new DataOutputStream(httpConn.getOutputStream());
    }

    /**
     * Adds a form field to the request
     *
     * @param name  field name
     * @param value field value
     */
    public void addFormField(String name, String value)throws IOException  {
        request.writeBytes(this.twoHyphens + this.boundary + this.crlf);
        request.writeBytes("Content-Disposition: form-data; name=\"" + name + "\""+ this.crlf);
        request.writeBytes("Content-Type: text/plain; charset=UTF-8" + this.crlf);
        request.writeBytes(this.crlf);
        request.writeBytes(value+ this.crlf);
        request.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();
        request.writeBytes(this.twoHyphens + this.boundary + this.crlf);
        request.writeBytes("Content-Disposition: form-data; name=\"" +
                fieldName + "\";filename=\"" +
                fileName + "\"" + this.crlf);
        request.writeBytes(this.crlf);

        byte[] bytes = Files.readAllBytes(uploadFile.toPath());
        request.write(bytes);
    }

    /**
     * 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 ="";

        request.writeBytes(this.crlf);
        request.writeBytes(this.twoHyphens + this.boundary +
                this.twoHyphens + this.crlf);

        request.flush();
        request.close();

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

            BufferedReader responseStreamReader =
                    new BufferedReader(new InputStreamReader(responseStream));

            String line = "";
            StringBuilder stringBuilder = new StringBuilder();

            while ((line = responseStreamReader.readLine()) != null) {
                stringBuilder.append(line).append("\n");
            }
            responseStreamReader.close();

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

        return response;
    }
}

Cette réponse https://stackoverflow.com/a/33149413/6481542 m'a permis de télécharger à 90% des fichiers volumineux sur un serveur de développement Django, mais j'ai dû utiliser setFixedLengthStreamingMode pour que cela fonctionne. Cela nécessite de définir Content-Length avant d'écrire le contenu, ce qui nécessite une réécriture assez importante de la réponse ci-dessus. Voici mon résultat final

public class MultipartLargeUtility {
    private final String boundary;
    private static final String LINE_FEED = "\r\n";
    private HttpURLConnection httpConn;
    private String charset;
    private OutputStream outputStream;
    private PrintWriter writer;
    private final int maxBufferSize = 4096;
    private long contentLength = 0;
    private URL url;

    private List<FormField> fields;
    private List<FilePart> files;

    private class FormField {
        public String name;
        public String value;

        public FormField(String name, String value) {
            this.name = name;
            this.value = value;
        }
    }

    private class FilePart {
        public String fieldName;
        public File uploadFile;

        public FilePart(String fieldName, File uploadFile) {
            this.fieldName = fieldName;
            this.uploadFile = uploadFile;
        }
    }

    /**
     * This constructor initializes a new HTTP POST request with content type
     * is set to multipart/form-data
     *
     * @param requestURL
     * @param charset
     * @throws IOException
     */
    public MultipartLargeUtility(String requestURL, String charset, boolean requireCSRF)
            throws IOException {
        this.charset = charset;

        // creates a unique boundary based on time stamp
        boundary = "===" + System.currentTimeMillis() + "===";
        url = new URL(requestURL);
        fields = new ArrayList<>();
        files = new ArrayList<>();

        if (requireCSRF) {
            getCSRF();
        }
    }

    /**
     * Adds a form field to the request
     *
     * @param name  field name
     * @param value field value
     */
    public void addFormField(String name, String value)
            throws UnsupportedEncodingException {
        String fieldContent = "--" + boundary + LINE_FEED;
        fieldContent += "Content-Disposition: form-data; name=\"" + name + "\"" + LINE_FEED;
        fieldContent += "Content-Type: text/plain; charset=" + charset + LINE_FEED;
        fieldContent += LINE_FEED;
        fieldContent += value + LINE_FEED;
        contentLength += fieldContent.getBytes(charset).length;
        fields.add(new FormField(name, value));
    }

    /**
     * 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();

        String fieldContent = "--" + boundary + LINE_FEED;
        fieldContent += "Content-Disposition: form-data; name=\"" + fieldName
                + "\"; filename=\"" + fileName + "\"" + LINE_FEED;
        fieldContent += "Content-Type: "
                + URLConnection.guessContentTypeFromName(fileName) + LINE_FEED;
        fieldContent += "Content-Transfer-Encoding: binary" + LINE_FEED;
        fieldContent += LINE_FEED;
        // file content would go here
        fieldContent += LINE_FEED;
        contentLength += fieldContent.getBytes(charset).length;
        contentLength += uploadFile.length();
        files.add(new FilePart(fieldName, uploadFile));
    }

    /**
     * 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>();
        String content = "--" + boundary + "--" + LINE_FEED;
        contentLength += content.getBytes(charset).length;

        if (!openConnection()) {
            return response;
        }

        writeContent();

        // 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;
    }

    private boolean getCSRF()
            throws IOException {
        /// First, need to get CSRF token from server
        /// Use GET request to get the token
        CookieManager cookieManager = new CookieManager();
        CookieHandler.setDefault(cookieManager);
        HttpURLConnection conn = null;

        conn = (HttpURLConnection) url.openConnection();

        conn.setUseCaches(false); // Don't use a Cached Copy
        conn.setRequestMethod("GET");
        conn.setRequestProperty("Connection", "Keep-Alive");
        conn.getContent();
        conn.disconnect();

        /// parse the returned object for the CSRF token
        CookieStore cookieJar = cookieManager.getCookieStore();
        List<HttpCookie> cookies = cookieJar.getCookies();
        String csrf = null;
        for (HttpCookie cookie : cookies) {
            Log.d("cookie", "" + cookie);
            if (cookie.getName().equals("csrftoken")) {
                csrf = cookie.getValue();
                break;
            }
        }
        if (csrf == null) {
            Log.d(TAG, "Unable to get CSRF");
            return false;
        }
        Log.d(TAG, "Received cookie: " + csrf);

        addFormField("csrfmiddlewaretoken", csrf);
        return true;
    }

    private boolean openConnection()
            throws IOException {
        httpConn = (HttpURLConnection) url.openConnection();
        httpConn.setUseCaches(false);
        httpConn.setDoOutput(true);    // indicates POST method
        httpConn.setDoInput(true);
        //httpConn.setRequestProperty("Accept-Encoding", "identity");
        httpConn.setFixedLengthStreamingMode(contentLength);
        httpConn.setRequestProperty("Connection", "Keep-Alive");
        httpConn.setRequestProperty("Content-Type",
                "multipart/form-data; boundary=" + boundary);
        outputStream = new BufferedOutputStream(httpConn.getOutputStream());
        writer = new PrintWriter(new OutputStreamWriter(outputStream, charset),
                true);
        return true;
    }

    private void writeContent()
            throws IOException {

        for (FormField field : fields) {
            writer.append("--" + boundary).append(LINE_FEED);
            writer.append("Content-Disposition: form-data; name=\"" + field.name + "\"")
                    .append(LINE_FEED);
            writer.append("Content-Type: text/plain; charset=" + charset).append(
                    LINE_FEED);
            writer.append(LINE_FEED);
            writer.append(field.value).append(LINE_FEED);
            writer.flush();
        }

        for (FilePart filePart : files) {
            String fileName = filePart.uploadFile.getName();
            writer.append("--" + boundary).append(LINE_FEED);
            writer.append(
                    "Content-Disposition: form-data; name=\"" + filePart.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(filePart.uploadFile);
            int bufferSize = Math.min(inputStream.available(), maxBufferSize);
            byte[] buffer = new byte[bufferSize];
            int bytesRead = -1;
            while ((bytesRead = inputStream.read(buffer, 0, bufferSize)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }
            outputStream.flush();
            inputStream.close();
            writer.append(LINE_FEED);
            writer.flush();
        }

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

L'utilisation est en grande partie la même que dans la réponse ci-dessus, mais j'ai inclus le support CSRF que Django utilise par défaut avec les formulaires

boolean useCSRF = true;
MultipartLargeUtility multipart = new MultipartLargeUtility(url, "UTF-8",useCSRF);
multipart.addFormField("param1","value");
multipart.addFilePart("filefield",new File("/path/to/file"));
List<String> response = multipart.finish();
Log.w(TAG,"SERVER REPLIED:");
for(String line : response) {
    Log.w(TAG, "Upload Files Response:::" + line);
}

basé sur la solution de Mihai, si quelqu'un a le problème de sauvegarder des images sur le serveur comme ce qui s'est passé sur mon serveur. changez la partie Bitmap en bytebuffer en:

ByteArrayOutputStream bos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.JPEG,100,bos);
        byte[] pixels = bos.toByteArray();

Je n'ai pas testé cela, mais vous pouvez essayer d'utiliser PipedInputStream et PipedOutputStream. Cela pourrait ressembler à quelque chose comme:

final Bitmap bmp = … // your bitmap

// Set up Piped streams
final PipedOutputStream pos = new PipedOutputStream(new ByteArrayOutputStream());
final PipedInputStream pis = new PipedInputStream(pos);

// Send bitmap data to the PipedOutputStream in a separate thread
new Thread() {
    public void run() {
        bmp.compress(Bitmap.CompressFormat.PNG, 100, pos);
    }
}.start();

// Send POST request
try {
    // Construct InputStreamEntity that feeds off of the PipedInputStream
    InputStreamEntity reqEntity = new InputStreamEntity(pis, -1);

    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost = new HttpPost(url);
    reqEntity.setContentType("binary/octet-stream");
    reqEntity.setChunked(true);
    httppost.setEntity(reqEntity);
    HttpResponse response = httpclient.execute(httppost);
} catch (Exception e) {
    e.printStackTrace()
}

Voici ce que j'ai fait pour télécharger une photo à l'aide de la demande de publication.

public void uploadFile(int directoryID, String filePath) {
    Bitmap bitmapOrg = BitmapFactory.decodeFile(filePath);
    ByteArrayOutputStream bao = new ByteArrayOutputStream();

    String upload_url = BASE_URL + UPLOAD_FILE;
    bitmapOrg.compress(Bitmap.CompressFormat.JPEG, 90, bao);

    byte[] data = bao.toByteArray();

    HttpClient httpClient = new DefaultHttpClient();
    HttpPost postRequest = new HttpPost(upload_url);
    MultipartEntity entity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE);

    try {
        // Set Data and Content-type header for the image
        FileBody fb = new FileBody(new File(filePath), "image/jpeg");
        StringBody contentString = new StringBody(directoryID + "");

        entity.addPart("file", fb);
        entity.addPart("directory_id", contentString);
        postRequest.setEntity(entity);

        HttpResponse response = httpClient.execute(postRequest);
        // Read the response
        String jsonString = EntityUtils.toString(response.getEntity());
        Log.e("response after uploading file ", jsonString);

    } catch (Exception e) {
        Log.e("Error in uploadFile", e.getMessage());
    }
}

REMARQUE: ce code nécessite des bibliothèques. Suivez les instructions ici pour obtenir les bibliothèques.

J'ai trouvé l'utilisation d'okHttp beaucoup plus facile car je ne pouvais faire fonctionner aucune de ces solutions: https://stackoverflow.com/a/37942387/447549

J'ai essayé les solutions ci-dessus et aucune n'a fonctionné pour moi hors de la boîte.

Cependant http://www.baeldung.com/httpclient-post-http-request . La demande en plusieurs parties POST ligne 6 a fonctionné en quelques secondes

public void whenSendMultipartRequestUsingHttpClient_thenCorrect() 
  throws ClientProtocolException, IOException {
    CloseableHttpClient client = HttpClients.createDefault();
    HttpPost httpPost = new HttpPost("http://www.example.com");

    MultipartEntityBuilder builder = MultipartEntityBuilder.create();
    builder.addTextBody("username", "John");
    builder.addTextBody("password", "pass");
    builder.addBinaryBody("file", new File("test.txt"),
      ContentType.APPLICATION_OCTET_STREAM, "file.ext");

    HttpEntity multipart = builder.build();
    httpPost.setEntity(multipart);

    CloseableHttpResponse response = client.execute(httpPost);
    client.close();
}