java 串口通讯实例.doc

java 串口通讯实例（转）2010-01-28 12:33java串口通讯最近在搞C的串口通讯，C里面没有线程的概念，所以C对串口的读写只能在一个进程里面，这样如果串口的缓存有问题，就会导致报告丢失（正好是我们遇到的），我们来看看支持线程的java是如何来解决这个问题的。本文介绍了一个简单的通过串口实现全双工通讯的Java类库，该类库大大的简化了对串口进行操作的过程。 本 类库主要包括：SerialBean.java (与其他应用程序的接口), SerialBuffer.java (用来保存从串口所接收数据的缓冲区), ReadSerial.java (从串口读取数据的程序)。另外本类库还提供了一个例程SerialExample.java 作为示范。在下面的内容中将逐一对这几个部分进行详细介绍。SerialBeanSerialBean是本类库与其他应用程序的接口。该类库中定义了SerialBean的构造方法以及初始化串口，从串口读取数据，往串口写入数据以及关闭串口的函数。具体介绍如下：public SerialBean(int PortID) 本函数构造一个指向特定串口的SerialBean，该串口由参数PortID所指定。PortID = 1 表示COM1，PortID = 2 表示COM2，由此类推。 public int Initialize() 本函数初始化所指定的串口并返回初始化结果。如果初始化成功返回1，否则返回-1。初始化的结果是该串口被SerialBean独占性使用，其参数被设置为9600, N, 8, 1。如果串口被成功初始化，则打开一个进程读取从串口传入的数据并将其保存在缓冲区中。 public String ReadPort(int Length) 本函数从串口(缓冲区)中读取指定长度的一个字符串。参数Length指定所返回字符串的长度。 public void WritePort(String Msg) 本函数向串口发送一个字符串。参数Msg是需要发送的字符串。 public void ClosePort() 本函数停止串口检测进程并关闭串口。SerialBean的源代码如下： package serial; import java.io.*; import java.util.*; import m.*; /* * * This bean provides some basic functions to implement full dulplex * information exchange through the srial port. * */ public class SerialBean static String PortName; CommPortIdentifier portId; SerialPort serialPort; static OutputStream out; static InputStream in; SerialBuffer SB; ReadSerial RT; /* * * Constructor * * param PortID the ID of the serial to be used. 1 for COM1, * 2 for COM2, etc. * */ public SerialBean(int PortID) PortName = COM + PortID; /* * * This function initialize the serial port for communication. It startss a * thread which consistently monitors the serial port. Any signal capturred * from the serial port is stored into a buffer area. * */ public int Initialize() int InitSuccess = 1; int InitFail = -1; try portId = CommPortIdentifier.getPortIdentifier(PortName); try serialPort = (SerialPort) portId.open(Serial_Communication, 2000); catch (PortInUseException e) return InitFail; /Use InputStream in to read from the serial port, and OutputStream /out to write to the serial port. try in = serialPort.getInputStream(); out = serialPort.getOutputStream(); catch (IOException e) return InitFail; /Initialize the communication parameters to 9600, 8, 1, none. try serialPort.setSerialPortParams(9600, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE); catch (UnsupportedCommOperationException e) return InitFail; catch (NoSuchPortException e) return InitFail; / when successfully open the serial port, create a new serial buffer, / then create a thread that consistently accepts incoming signals from / the serial port. Incoming signals are stored in the serial buffer. SB = new SerialBuffer(); RT = new ReadSerial(SB, in); RT.start(); / return success information return InitSuccess; /* * * This function returns a string with a certain length from the incomin * messages. * * param Length The length of the string to be returned. * */ public String ReadPort(int Length) String Msg; Msg = SB.GetMsg(Length); return Msg; /* * * This function sends a message through the serial port. * * param Msg The string to be sent. * */ public void WritePort(String Msg) int c; try for (int i = 0; i Content.length() available = false; while (available = false) try wait(); catch (InterruptedException e) CurrentMsg = Content.substring(0, LengthNeeded); TempContent = Content.substring(LengthNeeded); Content = TempContent; LengthNeeded = 1; notifyAll(); return CurrentMsg; /* * * This function stores a character captured from the serial port to the * buffer area. * * param t The char value of the character to be stored. * */ public synchronized void PutChar(int c) Character d = new Character(char) c); Content = Content.concat(d.toString(); if (LengthNeeded Content.length() available = true; notifyAll(); =ReadSerialReadSerial是一个进程，它不断的从指定的串口读取数据并将其存放到缓冲区中。public ReadSerial(SerialBuffer SB, InputStreamPort) 本函数构造一个ReadSerial进程，参数SB指定存放传入数据的缓冲区，参数Port指定从串口所接收的数据流。 public void run() ReadSerial进程的主函数，它不断的从指定的串口读取数据并将其存放到缓冲区中。ReadSerial的源代码如下：=package serial; import java.io.*; /* * * This class reads message from the specific serial port and save * the message to the serial buffer. * */ public class ReadSerial extends Thread private SerialBuffer ComBuffer; private InputStream ComPort; /* * * Constructor * * param SB The buffer to save the incoming messages. * param Port The InputStream from the specific serial port. * */ public ReadSerial(SerialBuffer SB, InputStream Port) ComBuffer = SB; ComPort = Port; public void run() int c; try while (true) c = ComPort.read(); ComBuffer.PutChar(c); catch (IOException e) =SerialExampleSerialExample是本类库所提供的一个例程。它所实现的功能是打开串口COM1，对其进行初始化，从串口读取信息对其进行处理后将处理结果发送到串口。 =import serial.*; import java.io.*; /* * * This is an example of how to use the SerialBean. It opens COM1 and reads * six messages with different length form the serial port. * */ class SerialExample public static void main(String args) /TO DO: Add your JAVA codes here SerialBean SB = new SerialBean(1); String Msg; SB.Initialize(); for (int i = 5; i = 10; i+) Msg = SB.ReadPort(i); SB.WritePort(Reply: + Msg); SB.ClosePort(); =编译与调试本 类库中使用了Java Communication API (m)。这是一个Java扩展类库，并不包括在标准的Java SDK当中。如果你尚未安装这个扩展类库的话，你应该从Sun公司的Java站点下载这个类库并将其安装在你的系统上。在所下载的包里面包括一个安装说 明，如果你没有正确安装这个类库及其运行环境的话，运行这