Java串口编程
Javax.comm是Sun公司提供的，用于开发平台独立的通讯应用程序的扩展API。（ps：这里javax的x很准确地表明了它是一个扩展包，而不是核心包（core package），但由于历史原因，javax下的并不都是扩展包，比如swing包已经是Java核心架构的一部分了，不过为了与Java1.1编码兼容，仍使用javax.swing。）javax.comm可以访问RS232接口（串口）及有限制地访问IEEE-1284（并口）。
下载
需要到其官方主页http://java.sun.com/products/javacomm/下载这个API，目前的最新版本是3.0。不过可惜的是，Sun目前没有推出此API在Windows平台下的3.0版本，主页上列出的三个版本，分别是运行在x86和Sparc结构下的Solaris系统，以及x86下的Linux系统。要下载Windows版本只能去寻找较老的版本了。我所找到的2个网址是http://llk.media.mit.edu/projects/cricket/software/javaSerial.zip（两个文件夹里面有所需的3个文件），http://mdubuc.freeshell.org/Jolt/javacomm20-win32.zip和（完整的2.0版本，还有examples）。
安装
这里的所谓安装就是把三个重要的文件放到指定的目录下。
将下载的文件解压缩后，在\javacomm20-win32\commapi目录下有必需的三个文件comm.jar，javax.comm. properties和win32comm.dll。将文件comm.jar拷贝到%JAVA_HOME%\jre\lib\ext;文件 javax.comm. properties拷贝到%JAVA_HOME%\jre\lib; 文件win32comm.dll拷贝到%JAVA_HOME%\bin。注意%JAVA_HOME%是jdk的路径，而非jre。
API
在javax.comm下有13个类和接口，分别是
4个接口
CommDriver 可负载设备（the loadable device）驱动程序接口的一部分
CommPortOwnershipListener 传递各种通讯端口的所有权事件
ParallelPortEventListener 传递并行端口事件
SerialPortEventListener 传递串行端口事件
6个类
CommPort 通讯端口
CommPortIdentifier通讯端口管理
ParallelPort 并行通讯端口
ParallelPortEvent 并行端口事件
SerialPort RS-232串行通讯端口
SerialPortEvent 串行端口事件
3个异常类
NoSuchPortException 当驱动程序不能找到指定端口时抛出
PortInUseException 当碰到指定端口正在使用中时抛出
UnsupportedCommOperationException 驱动程序不允许指定操作时抛出
实例
同API一起下载的还有一个examples文件，里面有6个程序。首先看最简单的读、写程序。
读串口的例程
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import java.io.*;
import java.util.*;
import javax.comm.*;
public class SimpleRead implements Runnable, SerialPortEventListener {
static CommPortIdentifier portId;
static Enumeration portList;//枚举类
InputStream inputStream;
SerialPort serialPort;
Thread readThread;
public static void main(String[] args) {
portList = CommPortIdentifier.getPortIdentifiers();
while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();
if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
// if (portId.getName().equals("COM1")) {
if (portId.getName().equals("/dev/term/a"))
{
SimpleRead reader = new SimpleRead();
}
}
}
}
public SimpleRead() {
try {
serialPort = (SerialPort) portId.open("SimpleReadApp", 2000);
} catch (PortInUseException e) {}
try {
inputStream = serialPort.getInputStream();
} catch (IOException e) {}
try {
serialPort.addEventListener(this);
} catch (TooManyListenersException e) {}
serialPort.notifyOnDataAvailable(true);
try {
serialPort.setSerialPortParams(9600,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
} catch (UnsupportedCommOperationException e) {}
readThread = new Thread(this);
readThread.start();
}
public void run() {
try {
Thread.sleep(20000);
} catch (InterruptedException e) {}
}
//串口事件
public void serialEvent(SerialPortEvent event) {
switch(event.getEventType()) {
case SerialPortEvent.BI:
case SerialPortEvent.OE:
case SerialPortEvent.FE:
case SerialPortEvent.PE:
case SerialPortEvent.CD:
case SerialPortEvent.CTS:
case SerialPortEvent.DSR:
case SerialPortEvent.RI:
case SerialPortEvent.OUTPUT_BUFFER_EMPTY:
break;
case SerialPortEvent.DATA_AVAILABLE:
byte[] readBuffer = new byte[20];
try {
while (inputStream.available() > 0) {
int numBytes = inputStream.read(readBuffer);
}
System.out.print(new String(readBuffer));
} catch (IOException e) {}
break;
}
}
}
import java.io.*;
import java.util.*;
import javax.comm.*;
public class SimpleRead implements Runnable, SerialPortEventListener {
static CommPortIdentifier portId;
static Enumeration portList;//枚举类
InputStream inputStream;
SerialPort serialPort;
Thread readThread;
public static void main(String[] args) {
portList = CommPortIdentifier.getPortIdentifiers();
while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();
if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
// if (portId.getName().equals("COM1")) {
if (portId.getName().equals("/dev/term/a"))
{
SimpleRead reader = new SimpleRead();
}
}
}
}
public SimpleRead() {
try {
serialPort = (SerialPort) portId.open("SimpleReadApp", 2000);
} catch (PortInUseException e) {}
try {
inputStream = serialPort.getInputStream();
} catch (IOException e) {}
try {
serialPort.addEventListener(this);
} catch (TooManyListenersException e) {}
serialPort.notifyOnDataAvailable(true);
try {
serialPort.setSerialPortParams(9600,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
} catch (UnsupportedCommOperationException e) {}
readThread = new Thread(this);
readThread.start();
}
public void run() {
try {
Thread.sleep(20000);
} catch (InterruptedException e) {}
}
//串口事件
public void serialEvent(SerialPortEvent event) {
switch(event.getEventType()) {
case SerialPortEvent.BI:
case SerialPortEvent.OE:
case SerialPortEvent.FE:
case SerialPortEvent.PE:
case SerialPortEvent.CD:
case SerialPortEvent.CTS:
case SerialPortEvent.DSR:
case SerialPortEvent.RI:
case SerialPortEvent.OUTPUT_BUFFER_EMPTY:
break;
case SerialPortEvent.DATA_AVAILABLE:
byte[] readBuffer = new byte[20];
try {
while (inputStream.available() > 0) {
int numBytes = inputStream.read(readBuffer);
}
System.out.print(new String(readBuffer));
} catch (IOException e) {}
break;
}
}
}
(PS:不推荐Thread的这种用法，详见《Core Java VolumeII》)
写串口的例程
把字符串"Hello, world!\n"写到系统的第一个串口
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import java.io.*;
import java.util.*;
import javax.comm.*;
public class SimpleWrite {
static Enumeration portList;
static CommPortIdentifier portId;
static String messageString = "Hello, world!\n";
static SerialPort serialPort;
static OutputStream outputStream;
public static void main(String[] args) {
portList = CommPortIdentifier.getPortIdentifiers();
while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();
if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
// if (portId.getName().equals("COM1")) {
if (portId.getName().equals("/dev/term/a")) {
try {
serialPort = (SerialPort)
portId.open("SimpleWriteApp", 2000);
} catch (PortInUseException e) {}
try {
outputStream = serialPort.getOutputStream();
} catch (IOException e) {}
try {
serialPort.setSerialPortParams(9600,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
} catch (UnsupportedCommOperationException e) {}
try {
outputStream.write(messageString.getBytes());
} catch (IOException e) {}
}
}
}
}
}
import java.io.*;
import java.util.*;
import javax.comm.*;
public class SimpleWrite {
static Enumeration portList;
static CommPortIdentifier portId;
static String messageString = "Hello, world!\n";
static SerialPort serialPort;
static OutputStream outputStream;
public static void main(String[] args) {
portList = CommPortIdentifier.getPortIdentifiers();
while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();
if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
// if (portId.getName().equals("COM1")) {
if (portId.getName().equals("/dev/term/a")) {
try {
serialPort = (SerialPort)
portId.open("SimpleWriteApp", 2000);
} catch (PortInUseException e) {}
try {
outputStream = serialPort.getOutputStream();
} catch (IOException e) {}
try {
serialPort.setSerialPortParams(9600,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
} catch (UnsupportedCommOperationException e) {}
try {
outputStream.write(messageString.getBytes());
} catch (IOException e) {}
}
}
}
}
}
上面两个例程都经过了简化，在打开端口，并且传输结束后没有关闭数据流和串口。在例程中我们看
到CommPortIdentifier提供了打开通讯端口的方法open，但却没有相应关闭端口的方法，关闭端口需要调
用javax.comm.CommPort类的close()。CommPort是这个包中的一个高级抽象，它定义了端口可作的各种事
情：获取I/O数据流对象，控制缓冲区大小，调整输入的处理。
============================================================
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public SerialReader(HashMap params) {
serialParams = params;
init();
}
private void init() {
try {
// 参数初始化
int timeout = Integer.parseInt(serialParams.get(PARAMS_TIMEOUT).toString());
int rate = Integer.parseInt(serialParams.get(PARAMS_RATE).toString());
int dataBits = Integer.parseInt(serialParams.get(PARAMS_DATABITS).toString());
int stopBits = Integer.parseInt(serialParams.get(PARAMS_STOPBITS).toString());
int parity = Integer.parseInt(serialParams.get(PARAMS_PARITY).toString());
delayRead = Integer.parseInt(serialParams.get(PARAMS_DELAY).toString());
String port = serialParams.get(PARAMS_PORT).toString();
// 打开端口
portId = CommPortIdentifier.getPortIdentifier(port);
serialPort = (SerialPort) portId.open("SerialReader", timeout);
inputStream = serialPort.getInputStream();
serialPort.addEventListener(this);
serialPort.notifyOnDataAvailable(true);
serialPort.setSerialPortParams(rate, dataBits, stopBits, parity);
} catch (PortInUseException e) {
System.out.println("端口已经被占用!");
e.printStackTrace();
} catch (TooManyListenersException e) {
System.out.println("端口监听者过多!");
e.printStackTrace();
} catch (UnsupportedCommOperationException e) {
System.out.println("端口操作命令不支持!");
e.printStackTrace();
} catch (NoSuchPortException e) {
System.out.println("端口不存在!");
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
Thread readThread = new Thread(this);
readThread.start();
}
public void run() {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
}
}
public void serialEvent(SerialPortEvent event) {
try {
// 等待1秒钟让串口把数据全部接收后在处理
Thread.sleep(delayRead);
System.out.print("serialEvent[" + event.getEventType() + "] ");
} catch (InterruptedException e) {
e.printStackTrace();
}
switch (event.getEventType()) {
case SerialPortEvent.BI: // 10
case SerialPortEvent.OE: // 7
case SerialPortEvent.FE: // 9
case SerialPortEvent.PE: // 8
case SerialPortEvent.CD: // 6
case SerialPortEvent.CTS: // 3
case SerialPortEvent.DSR: // 4
case SerialPortEvent.RI: // 5
case SerialPortEvent.OUTPUT_BUFFER_EMPTY: // 2
break;
case SerialPortEvent.DATA_AVAILABLE: // 1
try {
// 多次读取,将所有数据读入
// while (inputStream.available() > 0) {
// numBytes = inputStream.read(readBuffer);
// }
numBytes = inputStream.read(readBuffer);
changeMessage(readBuffer, numBytes);
} catch (IOException e) {
e.printStackTrace();
}
break;
}
}
// 通过observer pattern将收到的数据发送给observer
// 将buffer中的空字节删除后再发送更新消息,通知观察者
public void changeMessage(byte[] message, int length) {
setChanged();
byte[] temp = new byte[length];
System.arraycopy(message, 0, temp, 0, length);
// System.out.println("msg[" + numBytes + "]: [" + new String(temp) + "]");
notifyObservers(temp);
}
static void listPorts() {
Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();
while (portEnum.hasMoreElements()) {
CommPortIdentifier portIdentifier = (CommPortIdentifier) portEnum.nextElement();
System.out.println(portIdentifier.getName() + " - "
+ getPortTypeName(portIdentifier.getPortType()));
}
}
static String getPortTypeName(int portType) {
switch (portType) {
case CommPortIdentifier.PORT_I2C:
return "I2C";
case CommPortIdentifier.PORT_PARALLEL:
return "Parallel";
case CommPortIdentifier.PORT_RAW:
return "Raw";
case CommPortIdentifier.PORT_RS485:
return "RS485";
case CommPortIdentifier.PORT_SERIAL:
return "Serial";
default:
return "unknown type";
}
}
public static HashSet<CommPortIdentifier> getAvailableSerialPorts() {
HashSet<CommPortIdentifier> h = new HashSet<CommPortIdentifier>();
Enumeration thePorts = CommPortIdentifier.getPortIdentifiers();
while (thePorts.hasMoreElements()) {
CommPortIdentifier com = (CommPortIdentifier) thePorts.nextElement();
switch (com.getPortType()) {
case CommPortIdentifier.PORT_SERIAL:
try {
CommPort thePort = com.open("CommUtil", 50);
thePort.close();
h.add(com);
} catch (PortInUseException e) {
System.out.println("Port, " + com.getName() + ", is in use.");
} catch (Exception e) {
System.out.println("Failed to open port " + com.getName() + e);
}
}
}
return h;
}
public SerialReader(HashMap params) {
serialParams = params;
init();
}
private void init() {
try {
// 参数初始化
int timeout = Integer.parseInt(serialParams.get(PARAMS_TIMEOUT).toString());
int rate = Integer.parseInt(serialParams.get(PARAMS_RATE).toString());
int dataBits = Integer.parseInt(serialParams.get(PARAMS_DATABITS).toString());
int stopBits = Integer.parseInt(serialParams.get(PARAMS_STOPBITS).toString());
int parity = Integer.parseInt(serialParams.get(PARAMS_PARITY).toString());
delayRead = Integer.parseInt(serialParams.get(PARAMS_DELAY).toString());
String port = serialParams.get(PARAMS_PORT).toString();
// 打开端口
portId = CommPortIdentifier.getPortIdentifier(port);
serialPort = (SerialPort) portId.open("SerialReader", timeout);
inputStream = serialPort.getInputStream();
serialPort.addEventListener(this);
serialPort.notifyOnDataAvailable(true);
serialPort.setSerialPortParams(rate, dataBits, stopBits, parity);
} catch (PortInUseException e) {
System.out.println("端口已经被占用!");
e.printStackTrace();
} catch (TooManyListenersException e) {
System.out.println("端口监听者过多!");
e.printStackTrace();
} catch (UnsupportedCommOperationException e) {
System.out.println("端口操作命令不支持!");
e.printStackTrace();
} catch (NoSuchPortException e) {
System.out.println("端口不存在!");
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
Thread readThread = new Thread(this);
readThread.start();
}
public void run() {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
}
}
public void serialEvent(SerialPortEvent event) {
try {
// 等待1秒钟让串口把数据全部接收后在处理
Thread.sleep(delayRead);
System.out.print("serialEvent[" + event.getEventType() + "] ");
} catch (InterruptedException e) {
e.printStackTrace();
}
switch (event.getEventType()) {
case SerialPortEvent.BI: // 10
case SerialPortEvent.OE: // 7
case SerialPortEvent.FE: // 9
case SerialPortEvent.PE: // 8
case SerialPortEvent.CD: // 6
case SerialPortEvent.CTS: // 3
case SerialPortEvent.DSR: // 4
case SerialPortEvent.RI: // 5
case SerialPortEvent.OUTPUT_BUFFER_EMPTY: // 2
break;
case SerialPortEvent.DATA_AVAILABLE: // 1
try {
// 多次读取,将所有数据读入
// while (inputStream.available() > 0) {
// numBytes = inputStream.read(readBuffer);
// }
numBytes = inputStream.read(readBuffer);
changeMessage(readBuffer, numBytes);
} catch (IOException e) {
e.printStackTrace();
}
break;
}
}
// 通过observer pattern将收到的数据发送给observer
// 将buffer中的空字节删除后再发送更新消息,通知观察者
public void changeMessage(byte[] message, int length) {
setChanged();
byte[] temp = new byte[length];
System.arraycopy(message, 0, temp, 0, length);
// System.out.println("msg[" + numBytes + "]: [" + new String(temp) + "]");
notifyObservers(temp);
}
static void listPorts() {
Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();
while (portEnum.hasMoreElements()) {
CommPortIdentifier portIdentifier = (CommPortIdentifier) portEnum.nextElement();
System.out.println(portIdentifier.getName() + " - "
+ getPortTypeName(portIdentifier.getPortType()));
}
}
static String getPortTypeName(int portType) {
switch (portType) {
case CommPortIdentifier.PORT_I2C:
return "I2C";
case CommPortIdentifier.PORT_PARALLEL:
return "Parallel";
case CommPortIdentifier.PORT_RAW:
return "Raw";
case CommPortIdentifier.PORT_RS485:
return "RS485";
case CommPortIdentifier.PORT_SERIAL:
return "Serial";
default:
return "unknown type";
}
}
public static HashSet<CommPortIdentifier> getAvailableSerialPorts() {
HashSet<CommPortIdentifier> h = new HashSet<CommPortIdentifier>();
Enumeration thePorts = CommPortIdentifier.getPortIdentifiers();
while (thePorts.hasMoreElements()) {
CommPortIdentifier com = (CommPortIdentifier) thePorts.nextElement();
switch (com.getPortType()) {
case CommPortIdentifier.PORT_SERIAL:
try {
CommPort thePort = com.open("CommUtil", 50);
thePort.close();
h.add(com);
} catch (PortInUseException e) {
System.out.println("Port, " + com.getName() + ", is in use.");
} catch (Exception e) {
System.out.println("Failed to open port " + com.getName() + e);
}
}
}
return h;
}
}
---------- 3 -----------------
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package serial;
import java.util.Observable;
import java.util.Observer;
class CommDataObserver implements Observer {
String name;
public CommDataObserver(String name) {
this.name = name;
}
public void update(Observable o, Object arg) {
System.out.println("[" + name + "] GetMessage:\n [" + new String((byte[]) arg) + "]");
}
}
本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/wind520/archive/2009/01/19/3837036.aspx