以前经常用C语言操作串口，实现一些发送接收之类的小功能，最近项目中也用到了串口通信，不过语言变成了Java，这个搞起来略蛋疼。

Java说起来就是各种库各种引用，所以得到某些需求先google搜一把~~比如之前搞半天的读取网页内容，自己边琢磨边写，又是charset，又是proxy，又是什么browsertype的，晕头转向，最后拿Jsoup一会儿就搞定了……不过使用之前要充分考虑可扩展性和API的丰富程度，不然后面程序体积变大集成起来很蛋疼。好了废话不说，讲讲串口的问题……

总述

Java常用的(我用到的)串口工具有俩：javacomm和RXTX，前者只支持win32，后者32和64位和其他版本都有。使用方法类似，所以就放到一起说：

下载到压缩包会看到readme之类的提示，然后把对应的dll文件和jar文件分别拷贝到/bin和/lib目录下，然后在出问题的时候继续查看readme。接着跑一下附带的例程。

具体使用过程就是：配置端口波特率、校验位等信息；打开串口；写数据；读输出；关闭。这一系列步骤在写程序的时候一定不要弄颠倒了。

串口配置

需要配置的有4项：

波特率(baudrate)— 一般9600、115200即可

(数据位)dataBits— 一般8 bits

DATABITS_5:5 bits

DATABITS_6:6 bits

DATABITS_7:7 bits

DATABITS_8:8 bits

(停止位)stopBits — 一般1 stop bit

STOPBITS_1:1 stop bit

STOPBITS_2:2 stop bits

STOPBITS_1_5:1.5 stop bits

(校验位)parity — 不需校验位的话，选择SerialPort.PARITY_NONE

PARITY_NONE:no parity

PARITY_ODD:odd parity

PARITY_EVEN:even parity

PARITY_MARK:mark parity

PARITY_SPACE:space parity

流量控制模式(FlowControlMode) — 一般FLOWCONTROL_NONE

FLOWCONTROL_NONE: no flow control

FLOWCONTROL_RTSCTS_IN: RTS/CTS (hardware) flow control for input

FLOWCONTROL_RTSCTS_OUT:RTS/CTS (hardware) flow control for output

FLOWCONTROL_XONXOFF_IN:XON/XOFF (software) flow control for input

FLOWCONTROL_XONXOFF_OUT:XON/XOFF (software) flow control for output

事件监听

addEventListener(SerialPortEventListener lsnr)

用于监听串口事件(SerialEvents)，可监听的事件有：

BI(Break interrupt)

CD(Carrier detect)

CTS(Clear to send)

DATA_AVAILABLE(Data available at the serial port)

DSR(Data set ready)

eventType(Deprecated. Replaced by getEventType method)

FE(Framing error)

OE(Overrun error)

OUTPUT_BUFFER_EMPTY(Output buffer is empty)

PE(Parity error)

RI(Ring indicator)

读数据

通过SerialPortEventListener来，读取到DATA_AVAILABLE，保存并处理串口内容。

写数据

使用getOutputStream来向串口发送数据，是发送数据的唯一方法。使用时，向OutPutStream中写入byte串即可，之后用SerialPortEventListener获取回馈结果。

RXTX例程(来自 这里 )：

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publicclassUSBCommimplementsSerialPortEventListener{

publicstaticfinalStringMESSAGE="MESSAGE TO BE SEND";

/**

* Stream for the storage of incoming data

*/

privateInputStreaminputStream;

/**

* Stream for the dispatching of data

*/

privateOutputStreamoutputStream;

/**

* Timeout of the USB port

*/

privatefinalintPORT_TIMEOUT=2000;

/**

* Representation of the serial port used for the communication

*/

publicSerialPortserialPort;

/**

* Buffer that stores the received bytes from the media

*/

protectedLinkedBlockingQueuereceivedBytes;

/**

* Builds a new manager for the communication via USB port.

* @exception IOException if an error occurred during the opening of the USB port

*/

publicUSBComm(Stringcomm)throwsIOException{

receivedBytes=newLinkedBlockingQueue(100000);

Stringport=comm;//place the right COM port here, OS dependent

//Check that the USB port exists and is recognized:

Enumeration>portList=CommPortIdentifier.getPortIdentifiers();

booleanportFound=false;

CommPortIdentifierportId=null;

while(portList.hasMoreElements()){

portId=(CommPortIdentifier)portList.nextElement();

if(portId.getPortType()==CommPortIdentifier.PORT_SERIAL){

if(portId.getName().equals(port)){

Log.logAndDisplay(LogLevel.INFO,"SerialConnection","Found port: "+port);

portFound=true;

break;

}

}

}

if(!portFound)

thrownewIOException("port "+port+" not found.");

try{

Log.logAndDisplay(LogLevel.INFO,"SerialConnection","USB port "+port+" opening...");

serialPort=(SerialPort)portId.open("USBCommunicator",PORT_TIMEOUT);

inputStream=serialPort.getInputStream();

outputStream=serialPort.getOutputStream();

serialPort.addEventListener(this);

serialPort.notifyOnDataAvailable(true);

Thread.sleep(1000);

serialPort.setSerialPortParams(serialPort.getBaudRate(),

serialPort.getDataBits(),

serialPort.getStopBits(),

serialPort.getParity());

serialPort.setFlowControlMode(serialPort.getFlowControlMode());

}catch(Exceptione){

System.err.println(e.getMessage());

thrownewIOException(e.getMessage());

}

}

publicvoidcloseUSB(){

//close the streams for serial port:

try{

inputStream.close();

outputStream.close();

}catch(IOExceptione){

System.err.println("Cannot close streams:"+e.getMessage());

}

}

/**

* Listener for USB events

*

* @param event new event occurred on the USB port

*/

publicvoidserialEvent(SerialPortEventevent){

switch(event.getEventType()){

caseSerialPortEvent.BI:

caseSerialPortEvent.OE:

caseSerialPortEvent.FE:

caseSerialPortEvent.PE:

caseSerialPortEvent.CD:

caseSerialPortEvent.CTS:

caseSerialPortEvent.DSR:

caseSerialPortEvent.RI:

caseSerialPortEvent.OUTPUT_BUFFER_EMPTY:

//nothing to do...

break;

caseSerialPortEvent.DATA_AVAILABLE:

bytereceived=-1;

do{

try{

received=(byte)inputStream.read();

}catch(IOExceptione){

System.err.println("Error reading USB:"+e.getMessage());

}

synchronized(receivedBytes){

try{

receivedBytes.add(received);

}catch(IllegalStateExceptionew){

System.err.println(ew.getMessage());

receivedBytes.poll();

receivedBytes.add(received);

}

}

}while(received!=-1);

break;

}

}

publicvoidwrite(byte[]buffer){

try{

outputStream.write(buffer);

//outputStream.flush();

}catch(IOExceptione){

System.err.println("Cannot write:"+e.getMessage());

}

}

publicstaticvoidmain(String[]args){

USBCommusb;

try{

usb=newUSBComm("COM73");// change to your port

byte[]b=MESSAGE.getBytes();

usb.write(b);

usb.serialPort.close();

usb.closeUSB();

}catch(IOExceptione){

System.err.println("IOException:"+e.getMessage());

}

}

}

后记嗯……好像也啥都没写的样子(我会告诉你这篇其实是测试帖代码效果的吗)……总之去看javacomm附带有例程 / RXTX的例程就可以了……