niagara框架中串口的打开方式

一直好奇niagara框架中串口是如何打开的，最近通过看源码，大致明白了，现记录如下

首先从BModbusAsyncNetwork这个类看起，在niagara help中查找没有源码，不过没关系，利用反编译看，重点代码如下

//BModbusAsyncNetwork是一个BIServicepublic void serviceStarted() throws Exception {//必须看父类的实现        super.serviceStarted();        getNameSubscriber().subscribe(getSerialPortConfig());        getSerialPortConfig().setSerialHelperParent(this);        ...    }

    public void startComm() throws Exception {        if (getSerialPortConfig().getPortName().equals("none")) {            configFail("No port selected for Modbus communication.");        } else {            try {//还是要看父类的实现                super.startComm();                configOk();            } catch (Exception e) {                configFail(new StringBuffer("Could not enable Modbus serial communication (").append(e).append(')').toString());                throw e;            }        }        ...    }

//对父类抽象方法的重写  protected Comm makeComm() {        return new ModbusAsyncSerialComm(this);    }

回溯父类，其中BBasicNetwork比较重要（有niagara源码）

/**   * Builds the communication handler (Comm).   */  public void serviceStarted()    throws Exception  {    buildComm();  }

 /**   * Initializes the basic network with a new communication handler (Comm)   * for both the transmit and receive drivers.  After creating   * a new Comm, this method calls initComm(Comm comm)   * with the new Comm to allow subclasses to perform any initialization   * (i.e. adding custom UnsolicitedMessageListeners for handling unsolicited received    * messages).     */  private void buildComm()    throws Exception  {    comm = makeComm();    initComm(comm);  }

 /**   * This method starts the Communication handler   * (Comm) if the network is not down/fault/out-of-service   * and the current Comm is not null.   */  public void startComm()    throws Exception  {    if((!isDisabled()) && (!isFatalFault()) && (comm != null))    {      if (getLog().isTraceOn()) getLog().trace(getName() + " *** Starting Communication Handler ***");      comm.start();      if (getLog().isTraceOn()) getLog().trace(getName() + " *** Started Communication Handler ***");    }  }

  /**   * Start the basic network.  This starts the Communication handler   * (Comm) if the network is not down/fault/out-of-service.   */  public void started()    throws Exception  {                     super.started();    try    {      startComm();    }    catch (Exception e)    {      getLog().error("Could not start communication handler", e);    }  }

接下来要看comm.start()，comm是Comm对象（有niagara源码）其start()里主要调用了started()，对于BModbusAsyncNetwork，comm是ModbusAsyncSerialComm ，

    protected boolean started() throws Exception {        try {            BISerialService bISerialService = (BISerialService) Sys.getService(BISerialService.TYPE);            this.serialPort = ((BModbusAsyncNetwork) getNetwork()).getSerialPortConfig().open(getNetwork().getName());            this.serialPort.enableReceiveTimeout(bISerialService.getMinTimeout());            this.in = this.serialPort.getInputStream();            this.out = this.serialPort.getOutputStream();            ...

getSerialPortConfig()返回的是BSerialHelper对象（有niagara源码），其open()方法为

  /**   * Opens the serial port and sets the port parameters.   * Returns the serial port as a BISerialPort.   *    * @param String owner - The name of the owner to set for the serial port.   */  public BISerialPort open(String owner)    throws Exception  {            BISerialService platSvc = (BISerialService) Sys.getService(BISerialService.TYPE);    ((BComponent)platSvc).lease();  // create a subscription to force the platform service to lazy-init    try    {      port = platSvc.openPort(getPortName(), owner);    }

可以看到是通过BISerialService来打开串口的，遇到接口就只能猜测一下了。。。还好，最终发现在我的电脑上是BSerialPortPlatformServiceWin64，它的父类BSerialPortPlatformService实现了该接口，openPort()的核心代码如下

  public BISerialPort openPort(String paramString1, String paramString2)    throws PortNotFoundException, PortDeniedException  {    ...    Object localObject = (BSerialPort)get(paramString1);    ...    try    {      ((BSerialPort)localObject).openPort();      return new BSerialPortHandle((BSerialPort)localObject);    }    ...  }

get(paramString1)这个看上去比较奇怪，其实它是BComplex的方法（获得slot），这些BSerialPort是如何添加的能，这就要看它的抽象方法loadPortIdentifiers()了，这里看BSerialPortPlatformServiceWin64的实现

  protected String[] loadPortIdentifiers()    throws Exception{       ...     Enumeration localEnumeration = CommPortIdentifier.getPortIdentifiers();    while (localEnumeration.hasMoreElements())    {      CommPortIdentifier localCommPortIdentifier1 = (CommPortIdentifier)localEnumeration.nextElement();      if (localCommPortIdentifier1.getPortType() == 1)      {        localVector.add(localCommPortIdentifier1);      }    }    ...        BSerialPortWin64 localBSerialPortWin64 = new BSerialPortWin64(arrayOfCommPortIdentifier[j], j);        add(SlotPath.escape(arrayOfString[j]), localBSerialPortWin64, 3);}

是不是很熟悉了，RxTx库哈哈，add()实现slot的动态添加