Question

我无法找到类似于我的应用程序的内容，所以我想我会问一个新问题。我是开发android（和一般的java）的新手，但在C和Visual Basic中有一些先前的编程经验。我正在使用JPEG TTL相机（Link Sprite LS Y201）并拍照从TCP服务器发送到Android客户端设备。在客户端，我使用Async任务来连续从套接字获取数据。到目前为止，我已经能够获得一些字节并将它们存储在一个数组中。这是我的问题： 1.来自套接字的数据量未知。如何解释？ 2.如何检查是否已读取所有数据？ JPEG图像数据从十六进制值0xFFD8开始，结束值为0xFFD9。 3.如何将此数据更新为imageview？

感谢您抽出宝贵时间仔细研究这个问题。我真的很感激我能得到的任何帮助！

我目前的代码如下：

  // ----------------------- 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

在服务器端，在发送每张图片之前，您可以发送一个整数，其中包含您要转移的图像的大小。
可以使用available()函数。 inFromServer.available() == 0将告诉您是否已读取所有数据。

以下代码将执行此操作：

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

希望你觉得这很有用！祝你好运！

读取未知大小的图像字节数组以在Imageview中显示

1 个答案: