Is it possible to post at the same time a string and an image to a webserver?

Question

There is a string variable and an image photo taken from the camera intent. The directory location of the photo is known. I want to make a HTTP post of the string variable and the image photo to a webserver at the same time. Is that possible ? If so , how to do it ?

Answer 1

From what I understand, you need to send an image and a string to your webserver within a single POST request. Here's how you'd proceed.

You first need to Base64 encode your image.

Start by converting your image into a byte array:

InputStream image = new FileInputStream(<path_to_image>);
byte[] buff = new byte[8192];
int readBytes;
ByteArrayOutputStream byteArrOS = new ByteArrayOutputStream(); 
try {
    while ( (readBytes = inputStream.read(buff) ) != -1) {
    byteArrOS.write(buff, 0, readBytes);
}
} catch (IOException e) {
    e.printStackTrace();
}
byte[] b = byteArrOS.toByteArray();

Then convert it to Base64:

String bsfEncodedImage = Base64.encodeToString(b, Base64.DEFAULT);

Then build a query with the the string and the resulting Base64 both encoded with URLEncoder and "utf-8":

strImgQuery = "str="+URLEncoder.encode(<string_data>, "utf-8")+"&image="+URLEncoder.encode(bsfEncodedImage, "utf-8");

Declare a new URL:

URL postUrl = new URL("http://<IP>/postreq");

Open the connection:

HttpURLConnection conn = (HttpURLConnection)postUrl.openConnection();

Set output to "true" (needed for a POST request but not for GET):

conn.setDoOutput(true);

Set the request method to POST:

conn.setRequestMethod("POST");

The timeout:

conn.setReadTimeout(1e4);

Buffer the output to the output stream and flush/run:

Writer buffWriter = new OutputStreamWriter(conn.getOutputStream());
buffWrite.write(strImgQuery);
buffWriter.flush();
buffWriter.close();

At server side you'll get the str and image POST params which is dependent on your server implementation.

Note that your url must follow the URL Specification, otherwise you'll get a MalformedURLException. If that's the case, be sure to check what exactly the issue is. For example if you use a non-existing ttp "protocol" instead of http your exception will look something like this:

java.net.MalformedURLException: unknown protocol: ttp
    at java.net.URL.<init>(URL.java:592)
    at java.net.URL.<init>(URL.java:482)
    at java.net.URL.<init>(URL.java:431)
    at com.pheromix.core.lang.NumberFormatExceptionExample.MalformedURLExceptionExample.sendGetRequest(MalformedURLExceptionExample.java:28)
    at com.pheromix.core.lang.NumberFormatExceptionExample.MalformedURLExceptionExample.main(MalformedURLExceptionExample.java:17)

Also, this is a synchronous operation and is ran on the UI thread. It might be costly or it might not depending on other operations you're already running and the size of the POST data. If the problem arises, run the job on another thread.

Answer 2

You can use URLEncoder

String strUrl = "http://192.168.1.9/impots/" +URLEncoder.encode("outil.php?action=OutilImporterDonneesMobile", "utf-8");
URL url = new URL(strUrl);