使用DataInputStream / socket从GPS设备读取数据

Question

How to read data From GPS Device?

I am reading data from GPS device using socket & DataInputStream but while i am fetching data i am getting something ASCII encoded string and at the end of that string i have my answer string which i want to use. So how can i get continuously data without such complex character set and get exact string. I have also tried using serial port.

Here what I have tried.

//Using Serial Port //

CommPortIdentifier portId = CommPortIdentifier.getPortIdentifier(portname);
System.out.println("fired");
// Open port
// Requires owner name and timeout
CommPort port = portId.open("Java Printing", 3000);

// Setup reading from file
FileInputStream fis = new FileInputStream(filename);
BufferedInputStream bis = new BufferedInputStream(fis);

// Setup output
OutputStream os = port.getOutputStream();
BufferedOutputStream bos = new BufferedOutputStream(os);

int c;
while ((c = bis.read()) != -1) 
{
bos.write(c);
System.out.print((char)c);
}

// Close
bos.close();`enter code here`
bis.close();
port.close();

//Using Normal Socket //

char[] inputChars = new char[1024];
byte[] data = new byte[1024];
int charsRead = 0;
BufferedReader inputStream = null;

System.out.println("1 1 1 1 1");
InputStreamReader isr = new InputStreamReader( s1.getInputStream() );
System.out.println("2 2 2 2 2 2");
inputStream = new BufferedReader( isr );

//Read 1024 characters. Note: This will pause the thread when stream is empty.

System.out.println("Reading from stream:");
while ((charsRead =  inputStream.read(inputChars)) != -1)
{
System.out.println("Chars read from stream: " + charsRead);  
System.out.println("inputChars = "+inputChars);
data = new String(inputChars).getBytes("US-ASCII");
System.out.flush();
}
byte[] decodedBytes = Base64.encodeBase64(data);
System.out.println("decodedBytes " + new String(decodedBytes));

Answer 1

You can communicate with the GPS chip either in normed NMEA format, or with the chips manufaturer custom binary protocol.
Make sure that you have setup the baud rate and (virtual) com port correctly.

The default protocoll is always NMEA. NMEA messages start with a "$". You always should get a $GPRMC message