c# web service -Object reference not set to an instance of an object

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In this code I get bytes null where i used this to encode the string of image from android and i am decoding from here , i want to upload image in drive.

C#

[WebMethod]
   public string ImageConvert(string _FromString)
   {
       string MailFile = "";
       try
       {

           string s_bitImage = _FromString;
           <big></big>byte[] bytes = Convert.FromBase64String(s_bitImage);
           System.Drawing.Bitmap image;

           string fileName = "";
           string FolderLocation = System.Web.Configuration.WebConfigurationManager.AppSettings["G:/serverdata/"].ToString();


           using (MemoryStream ms = new MemoryStream(bytes, 0, bytes.Length))
           {
               fileName = Guid.NewGuid().ToString();
               image = (Bitmap)System.Drawing.Bitmap.FromStream(ms);

               MailFile = FolderLocation + fileName + ".png";
               image.Save(Server.MapPath(MailFile));
           }
       }
       catch (Exception ex)
       {
           MailFile = ex.Message;
       }


       return MailFile;

   }

Posted 14-Aug-12 2:05am

AndroidVivek

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Comments

[no name] 14-Aug-12 9:08am

Why are you not checking to see if _FromString is a valid string?

Sergey Alexandrovich Kryukov 14-Aug-12 12:08pm

It would throw an exception, that's why. Therefore, I'm not sure bytes is null; and I'm unsure where is the exception. And there is no a way to debug it without a sample of "_FromString".
--SA

AndroidVivek 16-Aug-12 4:38am

Input stream is not coming null i checked it out and you can also check from below code.

Sergey Alexandrovich Kryukov 16-Aug-12 12:52pm

Then I don't quite understand what's going on, probably I missed something...
--SA

3 solutions

Solution 2

hey still get error , would you can help any more..i need to upload photo in sever via android phone...

this is my android side code which is working encoding....

bm = BitmapFactory.decodeResource( getResources(),R.drawable.images);
bmImage.setImageBitmap(bm);

outStream = new FileOutputStream(file);
bm.compress(Bitmap.CompressFormat.PNG, 100, outStream);
outStream.flush();
outStream.close();

// Bitmap bm = BitmapFactory.decodeFile("/path/to/image.jpg");
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 100, baos);
byte[] b = baos.toByteArray();

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

// Toast.makeText(getApplicationContext(),"ENCODED" + encodedImage, 1).show();

SoapObject request = new SoapObject(NAMESPACE,METHOD_NAME);

//Toast.makeText(getApplicationContext(),"request " + request, 1).show();

request.addProperty("_FromString",encodedImage);

Toast.makeText(getApplicationContext(),"request2 " + request.addProperty("_FromString",encodedImage), 1).show();

SoapSerializationEnvelope envelop = new SoapSerializationEnvelope(SoapEnvelope.VER11);

//Toast.makeText(getApplicationContext(),"encode " + encodedImage, 1).show();

//Toast.makeText(getApplicationContext(),"Envelop " + envelop, 1).show();

envelop.dotNet=true;
envelop.setOutputSoapObject(request);

HttpTransportSE aht = new HttpTransportSE(URL);

//Toast.makeText(getApplicationContext(),"aht " + aht, 1).show();

aht.call(SOAP_ACTION, envelop);

SoapPrimitive result = (SoapPrimitive)envelop.getResponse();

String s = result.toString();

Toast.makeText(getApplicationContext(),"Response " +s, 1).show();

Posted 15-Aug-12 19:27pm

AndroidVivek

Solution 3

Are you sure bytes is null? AFAIK, it is initialized but not null only in the cases where input string is an empty string. In cases where input parameter is null or if it is not a valid base64 string, it will throw exception.

I would suggest checking the value you are providing to the method. I suspect it is empty string.

Also, please do not post replies to your own question. Update your question with additional information.

Posted 15-Aug-12 20:16pm

dan!sh

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Kuthuparakkal · Accepted Answer · 2012-08-14T19:36:00

Instead of making a memory stream you can write the image as:

C#

using (FileStream fsNew = new FileStream(Server.MapPath(MailFile), FileMode.Create, FileAccess.Write))
            {
                try
                {
                    fsNew.Write(bytes, 0, bytes.Length);
                }
                catch (Exception ex)
                {
                    throw ex;
                }
            }

Also if you are specific to MemoryStream, flush it before using it.

C#

using (MemoryStream ms = new MemoryStream(bytes, 0, bytes.Length))
           {
               fileName = Guid.NewGuid().ToString();

ms.Flush();

C#

    image = (Bitmap)System.Drawing.Bitmap.FromStream(ms);

    MailFile = FolderLocation + fileName + ".png";
    image.Save(Server.MapPath(MailFile));
}