protocol.java

This is a resource based on j2me embedded,if you dont understand,you can connection with me .

        if (deviceName != null) {
            checkPermission(deviceName);
	    /* 6231661: before checking if port is already open, 
	       check if no open Streams (ensureNoStreamsOpen).  This is 
	       done to throw the correct exception: IOException when 
	       open Streams exist */
	    ensureNoStreamsOpen();

            /* 6227981: before opening, check to see if the port is already 
	       opened" */
            if (openedPorts.contains(deviceName)) {
                throw new IOException("Connection already open");
            }
	    handle = native_openByName(deviceName, baud,
				       bbc|stop|parity|rts|cts);
        } else {
            checkPermission("comm:" + portNumber);
	    handle = native_openByNumber(portNumber, baud,
					 bbc|stop|parity|rts|cts);
        }
        /* 6227970: if open fails throw an IOException */
        if (handle < 0) {
            throw new IOException("Could not open connection");
        }
        openedPorts.addElement(deviceName);
	thisDeviceName = new String(deviceName);
        registerCleanup();
    }

    /** 
     * Gets the baudrate for the serial port connection.
     * @return the baudrate of the connection
     * @see #setBaudRate
     */
    public int getBaudRate() {
	return baud;
    }

    /** 
     * Sets the baudrate for the serial port connection.
     * If the requested <code>baudrate</code> is not supported 
     * on the platform, then the system MAY use an alternate valid setting.
     * The alternate value can be accessed using the 
     * <code>getBaudRate</code> method.
     * @param baudrate the baudrate for the connection
     * @return the previous baudrate of the connection
     * @see #getBaudRate
     */
    public int setBaudRate(int baudrate) {
	int temp = baud;

	/*
	 * If the baudrate is not supported, select one
	 * that is allowed.
	 */
	if (baudrate < 299) {
            baudrate = 110;
        } else if (baudrate < 599) {
            baudrate = 300;
        } else if (baudrate < 1199) {
            baudrate = 600;
        } else if (baudrate < 2399) {
            baudrate = 1200;
        } else if (baudrate < 4799) {
            baudrate = 2400;
        } else if (baudrate < 9599) {
            baudrate = 4800;
        } else if (baudrate < 14399) {
            baudrate = 9600;
        } else if (baudrate < 19199) {
            baudrate = 14400;
        } else if (baudrate < 38399) {
            baudrate = 19200;
        } else if (baudrate < 55999) {
            baudrate = 38400;
        } else if (baudrate < 57599) {
            baudrate = 56000;
        } else if (baudrate < 115199) {
            baudrate = 57600;
        } else if (baudrate < 127999) {
            baudrate = 115200;
        } else if (baudrate < 255999) {
            baudrate = 128000;
        } else {
            baudrate = 256000;
	}
	try {
	    /* Set the new baudrate. */ 
	    ///*	    native_configurePort(handle, baudrate,
	    ///*				 bbc|stop|parity|rts|cts);
	    native_configurePort(handle, baudrate,
			       bbc|stop|parity|rts|cts);
	    /* If successful, update the local baud variable. */
	    baud = baudrate;
	} catch (IOException ioe) {
	    // NYI - could not set baudrate as requested.
	}
	return temp;
    }

    /**
     * Override close the GCF connection
     *
     *
     * @exception  IOException  if an I/O error occurs when closing the
     *                          connection.
     */
    public void close() throws IOException {
	if ((thisDeviceName != null) && 
	    (openedPorts.contains(thisDeviceName))) {
	    openedPorts.remove(thisDeviceName);
	}
	super.close();
    }
      
    /**
     * Close the native serial port.
     *
     * @exception  IOException  if an I/O error occurs.
     */
    protected void disconnect() throws IOException {
	try {
	    ///*	    native_close(handle);
	    native_close(handle);
	} finally {
	    /* Reset handle to prevent resgistered cleanup close. */
	    handle = -1;
	}
    }

    /**
     * Reads up to <code>len</code> bytes of data from the input stream into
     * an array of bytes, blocks until at least one byte is available,
     * if blocking is turned on.
     * Sets the <code>eof</code> field of the connection when the native read
     * returns -1.
     * <p>
     * Polling the native code is done here to avoid the need for
     * asynchronous native methods to be written. Not all implementations
     * work this way (they block in the native code) but the same
     * Java code works for both.
     *
     * @param      b     the buffer into which the data is read
     * @param      off   the start offset in array <code>b</code>
     *                   at which the data is written
     * @param      len   the maximum number of bytes to read
     * @return     the total number of bytes read into the buffer, or
     *             <code>-1</code> if there is no more data because the end of
     *             the stream has been reached
     * @exception  IOException  if an I/O error occurs
     */
    protected int nonBufferedRead(byte b[], int off, int len)
        throws IOException {

        int bytesRead = 0;

        try {
            if (b == null) {
                int chunk = 256;
                b = new byte[chunk];
                int end = off + len;
                int tmp = chunk;
                for (; off < end && tmp == chunk; off += chunk) {
                    if (off + chunk > end) {
                        chunk = end - off;
                    }
                    tmp = native_readBytes(handle, b, 0, chunk);
                    if (tmp > 0) {
                        bytesRead += tmp;
                    }
                }
                if (tmp < 0) {
                    eof = true;
                }
            } else {
                bytesRead = native_readBytes(handle, b, off, len);
            }
        } finally {
            if (iStreams == 0) {
                throw new InterruptedIOException("Stream closed");
            }
        }

        if (bytesRead == -1) {
            eof = true;
        }

        ///            GeneralBase.iowait(); 
        return(bytesRead);
    }

    /**
     * Reads up to <code>len</code> bytes of data from the input stream into
     * an array of bytes, but does not block if no bytes available.
     * Sets the <code>eof</code> flag if the end of stream is reached.
     * <p>
     * This is implemented so the <code>available</code> method of
     * <code>BufferedConnectionBaseAdapter</code> will return more than
     * zero if the buffer is empty.
     *
     * @param      b     the buffer into which the data is read
     * @param      off   the start offset in array <code>b</code>
     *                   at which the data is written
     * @param      len   the maximum number of bytes to read
     * @return     the total number of bytes read into the buffer, or
     *             <code>-1</code> if there is no more data because the end of
     *             the stream has been reached
     * @exception  IOException  if an I/O error occurs
     */
    protected int readBytesNonBlocking(byte b[], int off, int len)
            throws IOException {
        int bytesRead;

        try {
            // the native read does not block
	    ///*            bytesRead = native_readBytes(handle, b, off, len);
	    bytesRead = native_readBytes(handle, b, off, len);
        } finally {
            if (iStreams == 0) {
                throw new InterruptedIOException("Stream closed");
            }
        }

        if (bytesRead == -1) {
            eof = true;
        }

        return bytesRead;
    }

    /**
     * Writes <code>len</code> bytes from the specified byte array
     * starting at offset <code>off</code> to this output stream.
     * <p>
     * Polling the native code is in the stream object handed out by
     * our parent helper class. This done to avoid the need for
     * asynchronous native methods to be written. Not all implementations
     * work this way (they block in the native code) but the same
     * Java code works for both.
     *
     * @param      b     the data
     * @param      off   the start offset in the data
     * @param      len   the number of bytes to write
     *
     * @return     number of bytes written
     * @exception  IOException  if an I/O error occurs. In particular,
     *             an <code>IOException</code> is thrown if the output
     *             stream is closed.
     */
    public int writeBytes(byte b[], int off, int len) throws IOException {
	///* return native_writeBytes(handle, b, off, len);
        return native_writeBytes(handle, b, off, len);
    }

    /*
     * Real primitive methods
     */

    /**
     * Open a serial port by logical number.
     *
     * @param port logical number of the port 0 being the first
     * @param baud baud rate to set the port at
     * @param flags options for the serial port
     *
     * @return handle to a native serial port
     *
     * @exception  IOException  if an I/O error occurs.
     */
    private static native int native_openByNumber(int port, int baud,
						  int flags) 
	throws IOException;

    /**
     * Open a serial port by system dependent device name.
     *
     * @param name device name of the port
     * @param baud baud rate to set the port at
     * @param flags options for the serial port
     *
     * @return handle to a native serial port
     *
     * @exception  IOException  if an I/O error occurs.
     */
    private static native int native_openByName(String name, int baud,
        int flags) throws IOException;

    /**
     * Configure a serial port optional parameters.
     *
     * @param port device port returned from open
     * @param baud baud rate to set the port at
     * @param flags options for the serial port
     *
     * @exception  IOException  if an I/O error occurs
     */
    private static native void native_configurePort(int port, int baud,
						    int flags) 
	throws IOException;

    /**
     * Close a serial port.
     *
     * @param hPort handle to a native serial port
     *
     * @exception  IOException  if an I/O error occurs
     */
    private static native void native_close(int hPort) throws IOException;


    /** Register this object's native cleanup function. */
    private native void registerCleanup();

    /**
     * Read from a serial port without blocking.
     *
     * @param hPort handle to a native serial port
     * @param b I/O buffer
     * @param off starting offset for data
     * @param len length of data
     *
     * @return number of bytes read
     *
     * @exception  IOException  if an I/O error occurs
     */
    private static native int native_readBytes(int hPort, byte b[], int off,
        int len) throws IOException;

    /**
     * Write to a serial port without blocking.
     *
     * @param hPort handle to a native serial port
     * @param b I/O buffer
     * @param off starting offset for data
     * @param len length of data
     *
     * @return number of bytes that were written
     *
     * @exception  IOException  if an I/O error occurs.
     */
    private static native int native_writeBytes(int hPort, byte b[], int off, 
						int len) throws IOException;

}