Sending files using POST with HttpURLConnection

Question

Since the Android developers recommend to use the HttpURLConnection class  I was wondering if anyone can provide me with a good example on how to send a bitmap  file   actually an in-memory stream  via POST to an Apache HTTP server  I m not interested in cookies or authentication or anything complicated  but I just want to have a reliable and logic implementation  All the examples that I ve seen around here look more like  let s try this and maybe it works    Right now  I have this 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              where showDialog should just display an AlertDialog  in case of an invalid URL     Now  let s say that I generate a bitmap like so  Bitmap image   this getBitmap   inside a control derived from View and I want to send it via POST  What would be the proper procedure to achieve such a thing  What classes do I need to use  Can I use HttpPost like in this example  If so  how would I construct the InputStreamEntity for my bitmap  I would find it revolting to be required to first store the bitmap in a file on the device     I should also mention that I really need to send every unaltered pixel of the original bitmap to the server  so I can t convert it to JPEG

User · Answer

I actually found a better way to send files using HttpURLConnection using 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();
}

Assuming you are uploading an image with bitmap data:

    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);

And Voila! Your post data will contain picture field along with the filename and path on your server.

User · Answer

I haven t tested this  but you might try using PipedInputStream and PipedOutputStream   It might look something like   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

User · Answer

This answer https   stackoverflow com a 33149413 6481542 got me 90  of the way with uploading large files to a development Django server  but I had to use setFixedLengthStreamingMode to make it worked   That requires setting the Content-Length before writing the content  thus requiring a fairly significant rewrite of the above answer   Here s my end result  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 lt FormField gt  fields      private List lt FilePart gt  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 lt  gt             files   new ArrayList lt  gt              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  lt input type  file  name         gt          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 lt String gt  finish   throws IOException           List lt String gt  response   new ArrayList lt String gt             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 lt HttpCookie gt  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              Usage is largely the same as in the above answer  but I ve included CSRF support that Django uses by default with forms  boolean useCSRF   true  MultipartLargeUtility multipart   new MultipartLargeUtility url   UTF-8  useCSRF   multipart addFormField  param1   value    multipart addFilePart  filefield  new File   path to file     List lt String gt  response   multipart finish    Log w TAG  SERVER REPLIED     for String line   response        Log w TAG   Upload Files Response       line

User · Answer

based on Mihai s solution  if anyone has the problem of saving images on the server like what happened on my server  change the Bitmap to bytebuffer part to     ByteArrayOutputStream bos   new ByteArrayOutputStream            bitmap compress Bitmap CompressFormat JPEG 100 bos           byte   pixels   bos toByteArray

User · Answer

To upload file on server with some parameter using MultipartUtility in simple way   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  lt input type  file  name         gt          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              To upload you file along with parameters   NOTE   put this code below in non-ui-thread to get response   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

User · Answer

The solution of Jaydipsinh Zala didn t work for me  I don t know why but it seems to be close to the solution    So merging this one with the great solution and explanation of Mihai Todor  the result is this class that currently works for me  If it helps someone   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  lt input type  file  name         gt          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

User · Answer

Here is what i did for uploading photo using post request   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               NOTE  This code requires libraries so Follow the instructions here in order to get the libraries

User · Answer

I found using okHttp a lot easier as I could not get any of these solutions to work  https   stackoverflow com a 37942387 447549

User · Answer

I tried the solutions above and none worked for me out of the box   However http   www baeldung com httpclient-post-http-request  Line 6 POST Multipart Request worked within seconds  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

User · Answer

I have no idea why the HttpURLConnection class does not provide any means to send files without having to compose the file wrapper manually  Here s what I ended up doing  but if someone knows a better solution  please let me know   Input data   Bitmap bitmap   myView getBitmap      Static stuff   String attachmentName    bitmap   String attachmentFileName    bitmap bmp   String crlf     r n   String twoHyphens    --   String boundary               Setup the request   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     Start content wrapper   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     Convert Bitmap to ByteBuffer     I want to send only 8 bit black  amp  white bitmaps byte   pixels   new byte bitmap getWidth     bitmap getHeight     for  int i   0  i  lt  bitmap getWidth      i        for  int j   0  j  lt  bitmap getHeight      j              we re interested only in the MSB of the first byte             since the other 3 bytes are identical for B amp W images         pixels i   j     byte    bitmap getPixel i  j   amp  0x80   gt  gt  7            request write pixels     End content wrapper   request writeBytes this crlf   request writeBytes this twoHyphens   this boundary        this twoHyphens   this crlf     Flush output buffer   request flush    request close      Get response   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      Close response stream   responseStream close      Close the connection   httpUrlConnection disconnect      PS  Of course I had to wrap the request in private class AsyncUploadBitmaps extends AsyncTask lt Bitmap  Void  String gt   in order to make the Android platform happy  because it doesn t like to have network requests on the main thread

[android] Sending files using POST with HttpURLConnection

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