Getting BLOB from mysql database to android

Question

I have a mysql database with the following schema

(int id, int sys_id, BLOB data)

There can be multiple data for the same sys_id, i.e. (1,1, blobdata1), (2,1, blobdata2) etc. are valid entries. the blob data is a compressed audio. When all the rows for a particular sys_id are combined a valid compressed audio data is produced.

I want to send this blob data to my android device. I have tried the following php code to send the data but it is not received as expected at the client side.

$conn = mysql_connect("localhost","root","");
mysql_select_db("mydb", $conn);

global $blobId;
$blobId = $_GET['id'];
$result = mysql_query("SELECT data FROM table WHERE sys_id=$blobId");
if( mysql_num_rows($result) == 0 )
die("No rows returned");

while($row = mysql_fetch_array($result) ) {
     // is this correct way of concatenating binary data
     $temp .= $row['data'];
}

// PROBLEM: what should be sent
echo $temp;

I don't mind if all the rows can be received at the client end and can be concatenated or operated upon locally there.

At the client side, I do the following:

// connect to the server
public void connect(URL url)
{

HttpURLConnection urlConnection = null;
    try {           
        urlConnection = (HttpURLConnection)url.openConnection();
        InputStream in = new BufferedInputStream(urlConnection.getInputStream());
        result = readStream(in);
            //problem, how should I now parse the resultant string
            decompress(result.getBytes()); // result.getBytes() returns null currently

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

// for reading the incoming stream
public static String readStream(InputStream in) throws IOException {
    StringBuilder sb = new StringBuilder();
    BufferedReader r = new BufferedReader(new InputStreamReader(in),1000);
    for (String line = r.readLine(); line != null; line =r.readLine()){
        sb.append(line);
    }
    in.close();
    return sb.toString();
} 

// definition for decompression utility
 public short[] decompress(byte[] codBytes);

You can send the audio as binary data as a string. And you can covert this binary data to an audio file from your android device. — fargath
– fargath, Commented Jun 5, 2012 at 6:40
@fargath The data is in compressed form. I am decompressing it at the client end. I tried echoing the generated value($temp) and then tried result.getBytes() at the client end (see the code above). But it doesn't help. — krammer
– krammer, Commented Jun 5, 2012 at 6:43

Melbourne Lopes · Accepted Answer · 2013-11-12 04:29:32Z

2

you can encode the data you want to send in JSON format as

 echo json_encode($response);

and send it as Json to your device and parse accordingly. for parsing refer Here

answered Nov 12, 2013 at 4:29

Melbourne Lopes

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