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我知道在J2ME中CommConnection是使用serial port時要使用的連接。我知道有openInputStream和openOutputStream方法，但事實上我不知道如何將數據從我的MIDLet傳輸到COM端口（手機電纜插入的USB端口，手機是Alcatel OT-806D）。例如，我想發送文本「Hello world」。如何實現這一目標？如何將數據傳輸到串口？
下面是代碼：
J2ME：
import java.io.IOException;
import java.io.OutputStream;
import javax.microedition.io.CommConnection;
import javax.microedition.io.Connector;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.midlet.*;
public class SerialPortMidlet extends MIDlet implements CommandListener, Runnable {
private Command upload = new Command("upload", Command.SCREEN, 0);
private Command exit = new Command("exit", Command.SCREEN, 1);
private Form f = new Form("test serial port");
private Thread uploadThread;
private CommConnection com;
private OutputStream os;
public SerialPortMidlet()
{
f.addCommand(upload);
f.addCommand(exit);
f.setCommandListener(this);
uploadThread = new Thread(this);
}
public void startApp() {
Display.getDisplay(this).setCurrent(f);
}
public void pauseApp() {
}
public void destroyApp(boolean unconditional) {
notifyDestroyed();
}
public void commandAction(Command c, Displayable d) {
if (c == upload)
{
uploadThread.start();
f.removeCommand(upload);
}
else if (c == exit)
{
if (uploadThread.isAlive())
{
uploadThread.interrupt();
try {
uploadThread.join();
} catch (InterruptedException ex) {
ex.printStackTrace();
}
}
destroyApp(true);
}
}
public void run() {
try
{
String s = new String("andrana mandefa lavaka");
com = (CommConnection) Connector.open("comm:COM4");
os = com.openOutputStream();
os.write(s.getBytes());
os.close();
}
catch (IOException ex)
{
ex.printStackTrace();
}
}
}
J2SE：（Eclipse的）
import gnu.io.CommPort;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
public class TwoWaySerialComm
{
public TwoWaySerialComm()
{
super();
}
void connect (String portName) throws Exception
{
CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(portName);
if (portIdentifier.isCurrentlyOwned())
{
System.out.println("Error: Port is currently in use");
}
else
{
CommPort commPort = portIdentifier.open(this.getClass().getName(),2000);
if (commPort instanceof SerialPort)
{
SerialPort serialPort = (SerialPort) commPort;
serialPort.setSerialPortParams(57600,SerialPort.DATABITS_8,SerialPort.STOPBITS_1,SerialPort.PARITY_NONE);
InputStream in = serialPort.getInputStream();
OutputStream out = serialPort.getOutputStream();
(new Thread(new SerialWriter(out))).start();
serialPort.addEventListener(new SerialReader(in));
serialPort.notifyOnDataAvailable(true);
}
else
{
System.out.println("Error: Only serial ports are handled by this example.");
}
}
}
public static class SerialReader implements SerialPortEventListener
{
private InputStream in;
private byte[] buffer = new byte[1024];
public SerialReader (InputStream in)
{
this.in = in;
}
public void serialEvent(SerialPortEvent arg0) {
int data;
try
{
int len = 0;
while ((data = in.read()) > -1)
{
if (data == '\n') {
break;
}
buffer[len++] = (byte) data;
}
System.out.print(new String(buffer,0,len));
}
catch (IOException e)
{
e.printStackTrace();
System.exit(-1);
}
}
}
public static class SerialWriter implements Runnable
{
OutputStream out;
public SerialWriter (OutputStream out)
{
this.out = out;
}
public void run()
{
try
{
int c = 0;
while ((c = System.in.read()) > -1)
{
this.out.write(c);
}
}
catch (IOException e)
{
e.printStackTrace();
System.exit(-1);
}
}
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
try
{
(new TwoWaySerialComm()).connect("COM1");
}
catch (Exception e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
我運行J2SE程序，我插入移動電話線插入電腦（在USB插槽中），我點擊了J2M中的upload命令E應用程序，但在eclipse的輸出屏幕中沒有任何東西！
那麼問題是什麼？
我運行此J2SE代碼來檢測在其手機的電纜端口：
import gnu.io.*;
public class SerialPortLister {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
listPorts();
}
private static void listPorts()
{
@SuppressWarnings("unchecked")
java.util.Enumeration<CommPortIdentifier> portEnum = CommPortIdentifier.getPortIdentifiers();
while (portEnum.hasMoreElements())
{
CommPortIdentifier portIdentifier = portEnum.nextElement();
System.out.println(portIdentifier.getName() + " - " + getPortTypeName(portIdentifier.getPortType()));
}
}
private 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";
}
}
}
這也表明COM4，因爲當我拆下電纜則只有COM1和LPT1顯示。
那麼問題是什麼？
在手機中，您只能找到COM1或COM2，而這些端口在計算機系統中總是處於忙碌狀態以用於其他目的。 – Lucifer
但是我發現COM4是手機使用的端口！ – pheromix
這是一個好兆頭。只有您需要在計算機系統中搜索文件。它必須在某個目錄中。或者你可以在你的J2SE代碼中給出一個物理路徑。 – Lucifer