Implement serial service: Add SerialConnector

Author: J0B10

src/main/scala/org/codeoverflow/chatoverflow/requirement/service/serial/SerialConnector.scala

@@ -0,0 +1,97 @@
+package org.codeoverflow.chatoverflow.requirement.service.serial
+
+import java.io.PrintStream
+
+import com.fazecast.jSerialComm.{SerialPort, SerialPortInvalidPortException}
+import org.codeoverflow.chatoverflow.WithLogger
+import org.codeoverflow.chatoverflow.connector.Connector
+
+/**
+  * The serial connector allows to communicate with a device connected to the pcs serial port (like an Arduino)
+  *
+  * @param sourceIdentifier the port descriptor of the serial port to which the device is connected
+  */
+class SerialConnector(override val sourceIdentifier: String) extends Connector(sourceIdentifier) with WithLogger {
+
+  override protected var requiredCredentialKeys: List[String] = List()
+
+  private var serialPort: Option[SerialPort] = None
+  private var out: Option[PrintStream] = None
+  private val serialPortInputListener = new SerialPortInputListener
+
+  /**
+    * Sets the baud rate of the com port to a new value
+    *
+    * @param baudRate the new baud rate
+    * @throws java.lang.IllegalStateException if the serial port is not available yet
+    */
+  @throws(classOf[IllegalStateException])
+  def setBaudRate(baudRate: Int): Unit = {
+    if (serialPort.isEmpty) throw new IllegalStateException("Serial port is not available yet")
+    serialPort.get.setBaudRate(baudRate)
+  }
+
+  /**
+    *
+    * @throws java.lang.IllegalStateException if the serial port is not available yet
+    * @return the baud rate of the com port
+    */
+  @throws(classOf[IllegalStateException])
+  def getBaudRate: Int = {
+    if (serialPort.isEmpty) throw new IllegalStateException("Serial port is not available yet")
+    serialPort.get.getBaudRate
+  }
+
+  /**
+    *
+    * @throws java.lang.IllegalStateException if the serial port is not available yet
+    * @return print stream that outputs to the port
+    */
+  @throws(classOf[IllegalStateException])
+  def getPrintStream: PrintStream = {
+    if (serialPort.isEmpty)  throw new IllegalStateException("Serial port is not available yet")
+    out.get
+  }
+
+  /**
+    * Adds a new input listener that receives all data
+    * @param listener a listener that handles incoming data in a byte array
+    */
+  def addInputListener(listener: Array[Byte] => Unit): Unit = {
+    serialPortInputListener.addDataAvailableListener(_ => {
+      val buffer = new Array[Byte](serialPort.get.bytesAvailable())
+      serialPort.get.readBytes(buffer, buffer.length) //FIXME DOES IT CRASH?
+      listener(buffer)
+    })
+  }
+
+  /**
+    * Opens a connection with the serial port
+    */
+  override def start(): Boolean = {
+    try {
+      serialPort = Some(SerialPort.getCommPort(sourceIdentifier))
+      if (serialPort.get.openPort(1000)) {
+        serialPort.get.setComPortTimeouts(SerialPort.TIMEOUT_READ_SEMI_BLOCKING, 0, 0)
+        out = Some(new PrintStream(serialPort.get.getOutputStream))
+        serialPort.get.addDataListener(serialPortInputListener)
+        true
+      } else {
+        logger error s"Could not open serial port $sourceIdentifier"
+        false
+      }
+    } catch {
+      case e: SerialPortInvalidPortException =>
+        logger error s"Source identifier $sourceIdentifier is invalid: ${e.getMessage}"
+        false
+    }
+  }
+
+  /**
+    * Closes the connection with the port
+    */
+  override def stop(): Boolean = {
+    serialPort.foreach(_.closePort())
+    true
+  }
+}

src/main/scala/org/codeoverflow/chatoverflow/requirement/service/serial/SerialPortInputListener.scala

@@ -0,0 +1,20 @@
+package org.codeoverflow.chatoverflow.requirement.service.serial
+
+import com.fazecast.jSerialComm.{SerialPort, SerialPortDataListener, SerialPortEvent}
+
+import scala.collection.mutable.ListBuffer
+
+class SerialPortInputListener extends SerialPortDataListener {
+
+  private val listeners = ListBuffer[SerialPortEvent => Unit]()
+
+  override def getListeningEvents: Int = SerialPort.LISTENING_EVENT_DATA_AVAILABLE
+
+  override def serialEvent(event: SerialPortEvent): Unit = {
+    if (event.getEventType == SerialPort.LISTENING_EVENT_DATA_AVAILABLE) {
+      listeners.foreach(listener => listener(event))
+    }
+  }
+
+  def addDataAvailableListener(listener: SerialPortEvent => Unit): Unit = listeners += listener
+}