java - 如何从套接字读取 JSON 数据而不是一行？

Question

我的应用程序通过 WiFi direct 连接到传感器。然后它连接到套接字并应该读取数据。数据是 JSON，看起来像 {"d":{temp_mC";33416,"h​​umidity_ppm"...更多数据...}}。传感器每 2 分钟发送一次数据。之前我只能读取服务器发送的行，但由于传感器不发送行，我需要重做我的 TCPClient 类。我认为我可以实现此代码。

ByteArrayOutputStream result = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int length;
while ((length = socket.getInputStream().read(buffer)) != -1) {
result.write(buffer, 0, length);
}
// StandardCharsets.UTF_8.name() > JDK 7
return result.toString("UTF-8");

要将 JSON 数据转换为字符串，然后我必须对其进行解析，但那是稍后的事。

我的旧代码看起来像这样，有人知道如何重新编写我的旧代码来实现上述方法或类似的方法，以便我可以读取 JSON 数据并将其转换为字符串以便稍后解析它吗？

TcpClient

public class TcpClient {

....

/**
 * Constructor of the class. OnMessagedReceived listens for the messages received from server
 */
public TcpClient(OnMessageReceived listener) {
    mMessageListener = listener;

}

/**
 * Sends the message entered by client to the server
 *
 * @param message text entered by client
 */

/**
 * Close the connection and release the members
 */
public void stopClient() {

    mRun = false;

    mMessageListener = null;
    mBufferIn = null;
    mServerMessage = null;
}

public void run() {

    mRun = true;

    try {
        //here you must put your computer's IP address.
        InetAddress serverAddr = InetAddress.getByName(SERVER_IP);

        Log.e("TCP Client", "C: Connecting...");

        //create a socket to make the connection with the server
        Socket socket = new Socket(serverAddr, SERVER_PORT);

        try {


            //receives the message which the server sends back
            mBufferIn = new BufferedReader(new InputStreamReader(socket.getInputStream()));


            //in this while the client listens for the messages sent by the server
            while (mRun) {

                mServerMessage = mBufferIn.readLine();

                if (mServerMessage != null && mMessageListener != null) {
                    //call the method messageReceived from MyActivity class
                    mMessageListener.messageReceived(mServerMessage);
                }

            }

            Log.e("RESPONSE FROM SERVER", "S: Received Message: '" + mServerMessage + "'");

        } catch (Exception e) {

            Log.e("TCP", "S: Error", e);

        } finally {
            //the socket must be closed. It is not possible to reconnect to this socket
            // after it is closed, which means a new socket instance has to be created.
            socket.close();
        }

    } catch (Exception e) {

        Log.e("TCP", "C: Error", e);

    }

}

//Declare the interface. The method messageReceived(String message) will must be implemented in the MyActivity
//class at on asynckTask doInBackground
public interface OnMessageReceived {
    public void messageReceived(String message);
}

}

我在其他 Activity 中的 AsyncClass

  public class ConnectTask extends AsyncTask<String, String, TcpClient> {

    @Override
    protected TcpClient doInBackground(String... message) {

        //we create a TCPClient object
        mTcpClient = new TcpClient(new TcpClient.OnMessageReceived() {
            @Override
            //here the messageReceived method is implemented
            public void messageReceived(String message) {
                //this method calls the onProgressUpdate
                publishProgress(message);
            }
        });
        mTcpClient.run();

        return null;
    }

    @Override
    protected void onProgressUpdate(String... values) {
        super.onProgressUpdate(values);
        CO2 = values[0];
        //response received from server
        Log.d("CO2", values[0]);
        //process server response here....

    }

}

Answer 1

处理这种情况的正确方法是一次发送整个数据。

可以通过首先发送数据大小，然后发送数据内容来实现，如下所示:

outputStream.writeInt(message.length); 
outputStream.write(message);

在读取消息时，解析长度，然后读取整个消息，如下所示:

int len = socketDataInputStream.readInt();                    
byte[] message = new byte[len];
socketDataInputStream.readFully(message, 0, message.length);

希望这有帮助，祝你好运。