计算机系统是Windows XP，手机是Alcatel OT-806D。它们通过手机的USB线连接。我启动了一个命令行java J2SE程序（c:\>path_to_the_src\java net.Example）：
package net;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Vector;
public class Example implements net.Network_iface {
// set the speed of the serial port
public static int speed = 115200;
private static net.Network network;
private static boolean resend_active = false;
public static void main(String[] args) {
network = new net.Network(0, new net.Example(), 255);
// reading the speed if
if (args.length > 0) {
try {
speed = Integer.parseInt(args[0]);
} catch (NumberFormatException e) {
System.out.println("the speed must be an integer\n");
System.exit(1);
}
}
// initializing reader from command line
int i, inp_num = 0;
String input;
BufferedReader in_stream = new BufferedReader(new InputStreamReader(
System.in));
// getting a list of the available serial ports
Vector<String> ports = network.getPortList();
// choosing the port to connect to
System.out.println();
if (ports.size() > 0) {
System.out.println("the following serial ports have been detected:");
}
else {
System.out.println("sorry, no serial ports were found on your computer\n");
System.exit(0);
}
for (i = 0; i < ports.size(); ++i) {
System.out.println(" " + Integer.toString(i + 1) + ": " + ports.elementAt(i));
}
boolean valid_answer = false;
while (!valid_answer) {
System.out.println("enter the id (1,2,...) of the connection to connect to: ");
try {
input = in_stream.readLine();
inp_num = Integer.parseInt(input);
if ((inp_num < 1) || (inp_num >= ports.size() + 1))
System.out.println("your input is not valid");
else
valid_answer = true;
} catch (NumberFormatException ex) {
System.out.println("please enter a correct number");
} catch (IOException e) {
System.out.println("there was an input error\n");
System.exit(1);
}
}
// connecting to the selected port
if (network.connect(ports.elementAt(inp_num - 1), speed)) {
System.out.println();
} else {
System.out.println("sorry, there was an error connecting\n");
System.exit(1);
}
// asking whether user wants to mirror traffic
System.out.println("do you want this tool to send back all the received messages?");
valid_answer = false;
while (!valid_answer) {
System.out.println("'y' for yes or 'n' for no: ");
try {
input = in_stream.readLine();
if (input.equals("y")) {
resend_active = true;
valid_answer = true;
} else if (input.equals("n")) {
valid_answer = true;
} else if (input.equals("q")) {
System.out.println("example terminated\n");
System.exit(0);
}
} catch (IOException e) {
System.out.println("there was an input error\n");
System.exit(1);
}
}
// reading in numbers (bytes) to be sent over the serial port
System.out.println("type 'q' to end the example");
while (true) {
try {
Thread.sleep(1000);
} catch (InterruptedException e1) {
}
System.out.println("\nenter a number between 0 and 254 to be sent ('q' to exit): ");
try {
input = in_stream.readLine();
if (input.equals("q")) {
System.out.println("example terminated\n");
network.disconnect();
System.exit(0);
}
inp_num = Integer.parseInt(input);
if ((inp_num > 255) || (inp_num < 0)) {
System.out.println("the number you entered is not valid");
} else {
int temp[] = { inp_num };
network.writeSerial(1, temp); // ecriture dans le port série
System.out.println("sent " + inp_num + " over the serial port");
}
} catch (NumberFormatException ex) {
System.out.println("please enter a correct number");
} catch (IOException e) {
System.out.println("there was an input error");
}
}
}
public void networkDisconnected(int id) {
System.exit(0);
}
public void parseInput(int id, int numBytes, int[] message) {
if (resend_active) {
network.writeSerial(numBytes, message);
System.out.print("received and sent back the following message: ");
} else {
System.out.print("received the following message: ");
}
System.out.print(message[0]);
for (int i = 1; i < numBytes; ++i) {
System.out.print(", ");
System.out.print(message[i]);
}
System.out.println();
}
public void writeLog(int id, String text) {
System.out.println(" log: |" + text + "|");
}
}
package net;
import gnu.io.*;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Enumeration;
import java.util.Vector;
public class Network {
private InputStream inputStream;
private OutputStream outputStream;
/**
* The status of the connection.
*/
private boolean connected = false;
/**
* The Thread used to receive the data from the Serial interface.
*/
private Thread reader;
private SerialPort serialPort;
private boolean end = false;
private Network_iface contact;
private int divider;
private int id;
private int[] tempBytes;
int numTempBytes = 0, numTotBytes = 0;
public Network(int id, Network_iface contact, int divider) {
this.contact = contact;
this.divider = divider;
if (this.divider > 255)
this.divider = 255;
if (this.divider < 0)
this.divider = 0;
this.id = id;
tempBytes = new int[1024];
}
public Network(int id, Network_iface contact) {
this(id, contact, 255);
}
public Network(Network_iface contact) {
this(0, contact);
}
@SuppressWarnings("unchecked")
public Vector<String> getPortList() {
Enumeration<CommPortIdentifier> portList;
Vector<String> portVect = new Vector<String>();
portList = CommPortIdentifier.getPortIdentifiers();
CommPortIdentifier portId;
while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();
if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
portVect.add(portId.getName());
}
}
contact.writeLog(id, "found the following ports:");
for (int i = 0; i < portVect.size(); i++) {
contact.writeLog(id, (" " + (String) portVect.elementAt(i)));
}
return portVect;
}
public boolean connect(String portName) {
return connect(portName, 115200);
}
public boolean connect(String portName, int speed) {
CommPortIdentifier portIdentifier;
boolean conn = false;
try {
portIdentifier = CommPortIdentifier.getPortIdentifier(portName);
if (portIdentifier.isCurrentlyOwned()) {
contact.writeLog(id, "Error: Port is currently in use");
} else {
serialPort = (SerialPort) portIdentifier.open("RTBug_network",
2000);
serialPort.setSerialPortParams(speed, SerialPort.DATABITS_8,
SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
inputStream = serialPort.getInputStream();
outputStream = serialPort.getOutputStream();
reader = (new Thread(new SerialReader(inputStream)));
end = false;
reader.start();
connected = true;
contact.writeLog(id, "connection on " + portName
+ " established");
conn = true;
}
} catch (NoSuchPortException e) {
contact.writeLog(id, "the connection could not be made");
e.printStackTrace();
} catch (PortInUseException e) {
contact.writeLog(id, "the connection could not be made");
e.printStackTrace();
} catch (UnsupportedCommOperationException e) {
contact.writeLog(id, "the connection could not be made");
e.printStackTrace();
} catch (IOException e) {
contact.writeLog(id, "the connection could not be made");
e.printStackTrace();
}
return conn;
}
private class SerialReader implements Runnable {
InputStream in;
public SerialReader(InputStream in) {
this.in = in;
}
public void run() {
byte[] buffer = new byte[1024];
int len = -1, i, temp;
try {
while (!end) {
if ((in.available()) > 0) {
if ((len = this.in.read(buffer)) > -1) {
for (i = 0; i < len; i++) {
temp = buffer[i];
// adjust from C-Byte to Java-Byte
if (temp < 0)
temp += 256;
if (temp == divider) {
if (numTempBytes > 0) {
contact.parseInput(id, numTempBytes,
tempBytes);
}
numTempBytes = 0;
} else {
tempBytes[numTempBytes] = temp;
++numTempBytes;
}
}
}
}
}
} catch (IOException e) {
end = true;
try {
outputStream.close();
inputStream.close();
} catch (IOException e1) {
e1.printStackTrace();
}
serialPort.close();
connected = false;
contact.networkDisconnected(id);
contact.writeLog(id, "connection has been interrupted");
}
}
}
public boolean disconnect() {
boolean disconn = true;
end = true;
try {
reader.join();
} catch (InterruptedException e1) {
e1.printStackTrace();
disconn = false;
}
try {
outputStream.close();
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
disconn = false;
}
serialPort.close();
connected = false;
contact.networkDisconnected(id);
contact.writeLog(id, "connection disconnected");
return disconn;
}
public boolean isConnected() {
return connected;
}
public boolean writeSerial(String message) {
boolean success = false;
if (isConnected()) {
try {
outputStream.write(message.getBytes());
success = true;
} catch (IOException e) {
disconnect();
}
} else {
contact.writeLog(id, "No port is connected.");
}
return success;
}
public boolean writeSerial(int numBytes, int message[]) {
boolean success = true;
int i;
for (i = 0; i < numBytes; ++i) {
if (message[i] == divider) {
success = false;
break;
}
}
if (success && isConnected()) {
try {
for (i = 0; i < numBytes; ++i) {
outputStream.write(changeToByte(message[i]));
}
outputStream.write(changeToByte(divider));
} catch (IOException e) {
success = false;
disconnect();
}
} else if (!success) {
// message contains the divider
contact.writeLog(id, "The message contains the divider.");
} else {
contact.writeLog(id, "No port is connected.");
}
return success;
}
private byte changeToByte(int num) {
byte number;
int temp;
temp = num;
if (temp > 255)
temp = 255;
if (temp < 0)
temp = 0;
number = (byte) temp;
return number;
}
}
package net;
public interface Network_iface {
public void writeLog(int id, String text);
public void parseInput(int id, int numBytes, int[] message);
public void networkDisconnected(int id);
}
然后我启动了一个J2ME MIDlet：
public class lecturePortSerieMidlet extends MIDlet implements CommandListener, Runnable {
private Command exit=new Command("exit", Command.OK, 1);
private Form frm = new Form("test lecture serial port");
private TextField txt=new TextField(null, null, 10000, TextField.ANY), stat=new TextField("Status", null, 10000, TextField.ANY);;
private Thread lire;
private CommConnection com;
private InputStream is;
private InputStreamReader reader;
public lecturePortSerieMidlet()
{
frm.addCommand(exit);
frm.setCommandListener(this);
frm.append(new TextField("Ports :", System.getProperty("microedition.commports"), 10000, TextField.ANY));
frm.append(txt);
frm.append(stat);
lire = new Thread(this);
}
public void startApp() {
Display.getDisplay(this).setCurrent(frm);
lire.start();
stat.setString("lecture port série démarrée ...");
}
public void pauseApp() {
}
public void destroyApp(boolean unconditional) {
notifyDestroyed();
}
public void commandAction(Command c, Displayable d) {
if (c == exit)
destroyApp(true);
}
public void run() {
String str = null;
char[] buffer = new char[32];
StringBuffer sb = new StringBuffer( );
int count;
try {
com = (CommConnection) Connector.open("comm:0", Connector.READ);
is = com.openInputStream();
reader = new InputStreamReader(is);
while ((count = reader.read(buffer, 0, buffer.length)) > -1)
{
sb.append(buffer, 0, count);
}
str = sb.toString();
stat.setString("data = "+str);
is.close();
} catch (IOException ex) {
stat.setString(ex.getMessage());
}
}
}
所以场景是：我先执行命令行java程序，然后运行MIDlet。当我执行命令行java程序然后我选择程序识别的COM4端口，然后我输入程序要求的数字值。然后我发射了midlet。
问题是midlet显示0为System.getProperty("microedition.commports")的值，但stat字段中显示的值为The requested protocol does not exist comm:0。
为什么midlet没有用？