读取大小未知的图像字节数组以显示在Imageview中

Question

I was unable to find something similar to my application so I thought I would ask a new question. I am new to developing android (and java in general) but have some prior programming experience in C and Visual Basic. I am using a JPEG TTL Camera (Link Sprite LS Y201) and taking a picture to send from a TCP server to an android client device. On the client side, I am using an Async task to continuously get the data from the socket. So far, I have been able to get some bytes and store them in an array. Here are my questions: 1. The amount of data coming in from the socket is unknown. How to account for that? 2. How to check if all the data was read? The JPEG image data starts at hex value 0xFFD8 and ending value is 0xFFD9. 3. How to update this data to an imageview?

Thank you as well for taking the time to look this over. I really appreciate any help I can get!

The code I currently have is below:

  // ----------------------- THE NETWORK TASK - begin ----------------------------
public class NetworkTask extends AsyncTask<Void, byte[], Boolean> {
    Socket nsocket; //Network Socket
    InputStream nis; //Network Input Stream
    OutputStream nos; //Network Output Stream
    BufferedReader inFromServer;//Buffered reader to store the incoming bytes

    @Override
    protected void onPreExecute() {
        //change the connection status to "connected" when the task is started
        changeConnectionStatus(true);
    }

    @Override
    protected Boolean doInBackground(Void... params) { //This runs on a different thread
        boolean result = false;
        try {
            //create a new socket instance
            SocketAddress sockaddr = new InetSocketAddress("192.168.1.115",5050);
            nsocket = new Socket();
            nsocket.connect(sockaddr, 5000);//connect and set a 10 second connection timeout
            if (nsocket.isConnected()) {//when connected
                nis = nsocket.getInputStream();//get input
                nos = nsocket.getOutputStream();//and output stream from the socket
                BufferedInputStream inFromServer = new BufferedInputStream(nis);//"attach the inputstreamreader"
                while(true){//while connected
                    ByteArrayBuffer baf = new ByteArrayBuffer(256);
                    int msgFromServer = 0;
                    while((msgFromServer = inFromServer.read()) != -1){;//read the lines coming from the socket
                        baf.append((byte) msgFromServer);
                        byte[] ImageArray = baf.toByteArray();
                        publishProgress(ImageArray);//update the publishProgress
                    }

                }
            }
        //catch exceptions
        } catch (IOException e) {
            e.printStackTrace();
            result = true;
        } catch (Exception e) {
            e.printStackTrace();
            result = true;
        } finally {
            closeSocket();
        }
        return result;
    }

    //Method closes the socket
    public void closeSocket(){
        try {
            nis.close();
            nos.close();
            nsocket.close();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //Method tries to send Strings over the socket connection
    public void SendDataToNetwork(String cmd) { //You run this from the main thread.
        try {
            if (nsocket.isConnected()) {
                nos.write(cmd.getBytes());
                nos.flush();
            } else {
                outputText("SendDataToNetwork: Cannot send message. Socket is closed");
            }
        } catch (Exception e) {
            outputText("SendDataToNetwork: Message send failed. Caught an exception");
        }
    }

    //Methods is called every time a new byte is received from the socket connection
    @Override
    protected void onProgressUpdate(byte[]... values) {
        if (values.length > 0) {//if the received data is at least one byte
            if(values[85]== 255 ){//Start of image is at the 85th byte



                ///This is where I get lost. How to start updating imageview with JPEG bytes?




            }
        }

    }

    //Method is called when task is cancelled
    @Override
    protected void onCancelled() {
        changeConnectionStatus(false);//change the connection to "disconnected"
    }

    //Method is called after taskexecution
    @Override
    protected void onPostExecute(Boolean result) {
        if (result) {
            outputText("onPostExecute: Completed with an Error.");
        } else {
            outputText("onPostExecute: Completed.");
        }
        changeConnectionStatus(false);//change connectionstaus to disconnected
    }
}
// ----------------------- THE NETWORK TASK - end ----------------------------

Answer 1

1. On the server side, before sending each image, you could send an integer with the size of the image you're abut to transfer.
2. The available() function can be used for that. inFromServer.available() == 0 will tell you whether all data was read.

3. The following code will do it:

    byte[] ImageArray = baf.toByteArray(); Bitmap bitmap = BitmapFactory.decodeByteArray(ImageArray, 0, ImageArray.length); imageView.setImageBitmap(bitmap); 

Hope you find this useful! Good luck!