gsmspotter.java

一个基于PlaceLab的室内和室外的智能导航系统

/*
 * Created on Jun 29, 2004
 */
package org.placelab.midp;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.microedition.io.Connector;
import javax.microedition.io.SocketConnection;

import org.placelab.core.BeaconMeasurement;
import org.placelab.core.BeaconReading;
import org.placelab.core.Measurement;
import org.placelab.spotter.SpotterException;
import org.placelab.spotter.SyncSpotter;
import org.placelab.util.StringUtil;

/**
 * This spotter polls a localhost server running on the phone. This is a
 * synchronous spotter that makes a blocking read request to the server, returning
 * when the read completes.
 * 
 * NEW: The GSMSpotter now supports operation in the emulator by using log files that
 * were uploaded by the StumbleUploadProxy placed inside the jar to get the Measurements.
 * The build.xml helps here by only placing those log files in the jar when the do-emulate
 * target is selected.
 */
public class GSMSpotter extends SyncSpotter {
	//the server passes back parameterNumber values
	//cellId,areaId,signalStrength,MCC,MNC,networkName
	private int parameterNumber = 6;

	private long scanIntervalMillis;

	SocketConnection sc = null;
	DataInputStream is = null;
	DataOutputStream dos = null;
	
	private boolean simulated;
	private InputStream logReader = null;

	/**
	 * Construct a GSMSpotter with default scan time of 1 second
	 *
	 */
	public GSMSpotter() {
		this(1000);
	}

	/**
	 * Construct a GSMSpotter
	 * @param intervalMillis time between scans
	 */
	public GSMSpotter(long intervalMillis) {
		super();
		scanIntervalMillis = intervalMillis;
		if(setupLogReader()) {
			simulated = true;
		} else {
			simulated = false;
		}
	}
	
	/*
	 * The idea here is to go through the jar file, looking for uploaded-log-i files.
	 * If none are found, then it is assumed we are running on the actual device.
	 * If some are found, then it is assumed that we are running in the simulator.
	 * The build script ties in here by only putting in the log files when the emulate
	 * target is specified.
	 * 
	 * The most recent log file in the jar is used.
	 */
	private boolean setupLogReader() {
		int i = 0;
		InputStream stream1 = this.getClass().getResourceAsStream("/compressed-log-" + i + ".txt");
		InputStream stream2;
		if(stream1 == null) {
			System.out.println("GSMSpotter LogReader: cannot find resource");
			return false;
		} else {
			System.out.println("GSMSpotter LogReader: found resource");
		}
		i++;
		while(true) {
			stream2 = stream1;
			stream1 = this.getClass().getResourceAsStream("/compressed-log-" + i + ".txt");
			if(stream1 != null) {
				try {
					stream2.close();
				} catch (IOException ioe) { }
			} else {
				logReader = stream2;
				return true;
			}
		}
	}

	/*
	 *  (non-Javadoc)
	 * @see org.placelab.spotter.Spotter#open()
	 */
	public void open() throws SpotterException {
		if(simulated) return;
		try {
			//native server runs on port 4040
			sc = (SocketConnection) Connector.open("socket://127.0.0.1:4040");
			if(sc == null) throw new SpotterException("Cannot open socket to native GSM spotter");
			sc.setSocketOption(SocketConnection.DELAY, 0);
			is = sc.openDataInputStream();
			dos = sc.openDataOutputStream();
		} catch (IOException ioe) {
			throw new SpotterException("Cannot open stream to native GSM spotter");
		}
	}

	/*
	 *  (non-Javadoc)
	 * @see org.placelab.spotter.Spotter#close()
	 */
	public void close() throws SpotterException {
		try {
			if (is != null)
				is.close();
			if (sc != null)
				sc.close();
			if (dos != null)
				dos.close();
			if (logReader != null) 
				logReader.close();
		} catch (IOException ioe) {
			throw new SpotterException("Cannot close stream to native GSM spotter");
		}
	}

	/**
	 * Polls the native server for a GSM reading
	 * @return Measurement containing a GSM reading
	 * @throws IOException
	 * @throws SpotterException
	 */
	private Measurement queryServer() throws IOException,SpotterException {
		
		StringBuffer message = new StringBuffer("");

		//open connection
		if(dos == null) throw new SpotterException("GSMSpotter.query: output stream  not open");
		if(is == null) throw new SpotterException("GSMSpotter.query: input stream not open");
		
		byte[] b = { 1 };
		dos.write(b);
		dos.flush();

		//get data
		int ch;
		while ((ch = is.read()) != -1) {
			if (ch == '\n')
				break;
			message = message.append((char) ch);
		}
		//parse data
		String data[] = StringUtil.split(message.toString(), ',');
		if (data.length == parameterNumber) {

			String cellId = data[0];
			String areaId = data[1];
			String signalStrength = data[2];
			String MCC = data[3];
			String MNC = data[4];
			String networkName = data[5];

			//construct a GSM Reading
			GSMReading[] grs = new GSMReading[1];
			GSMReading gr = new GSMReading(cellId, areaId, signalStrength, MCC,
					MNC, networkName);
			grs[0] = gr;

			//construct a beaconmeasurement
			return new BeaconMeasurement(System.currentTimeMillis(), grs);
		}
		return null;
	}
	
	private BeaconMeasurement currentMeasurement = null;
	private BeaconMeasurement nextMeasurement = null;
	private long sampleTime = 0;
	private long timeToWait = 0;
	
	/*
	 * The phone stores the logs in such a way that it only records the Measurements
	 * when they change in order to save space.  Given that, I continue to return
	 * the same Measurement until it is time for the next Measurement
	 */
	private Measurement readLog() throws IOException, SpotterException {
		if(sampleTime == 0) {
			sampleTime = System.currentTimeMillis();
			currentMeasurement = readGSMMeasurement();
			if(currentMeasurement != null) {
				nextMeasurement = readGSMMeasurement();
			}
		} else if(timeToWait != -1 && (System.currentTimeMillis() - sampleTime) > timeToWait) {
				currentMeasurement = nextMeasurement;
				nextMeasurement = readGSMMeasurement();
		} else {
			return currentMeasurement;
		}
		
		if(nextMeasurement == null) {
			logReader.close();
			logReader = null;
			// current measurement is the last measurement, so it lasts forever
			timeToWait = -1;
		} else if(timeToWait != -1) {
			timeToWait = nextMeasurement.getTimestamp() - 
				currentMeasurement.getTimestamp();
		}
		// this may be null if the log is empty.  hope this is ok.
		return currentMeasurement;
	}
	
	// helper method.  simply reads a contigous BeaconMeasurement from the log
	// other types of measurements or readings are just ignored
	// returns null if the file is done
	private BeaconMeasurement readGSMMeasurement() throws IOException {
		while(true) {
			byte[] byteLine = new byte[256];
			boolean checkNext = false;
			for(int i=0;i<byteLine.length;i++) {
				int value = logReader.read();
				if(value == -1) {
					// EOF
					return null;
				}
				byte b = (byte)value;
				if (((char) b) == '\r') {
					checkNext = true;
				} else if (checkNext) {
					if (((char) b) == '\n') {
						byte[] tempBytes = byteLine;
						//array needs to be exact length
						byteLine = new byte[i - 1];
						System.arraycopy(tempBytes, 0, byteLine, 0, i - 1);
						break;
					}
					checkNext = false;
				}
				byteLine[i] = b;
			}		
			String line = new String(byteLine,0,byteLine.length);
			if(line == null) return null;
			if(line.startsWith("#")) { //this would be the #Placelab v2 string
				// do it again, its the first line
				continue;
			} else if(line.equals("DONE")) { //we're done here
				System.out.println("GSMSpotter: Log is done");
				return null;
			} else { //it must be a measurement
				Measurement m = Measurement.fromCompressedBytes(byteLine);
				if (m != null) {
					if(m instanceof BeaconMeasurement) {
						// cull non-gsm readings
						BeaconMeasurement ret = new BeaconMeasurement(m.getTimestamp());
						BeaconReading[] readings = ((BeaconMeasurement)m).getReadings();
						for(int j = 0; j < readings.length; j++) {
							if(readings[j] instanceof GSMReading) {
								ret.addReading(readings[j]);
							}
						}
						return ret;
					}
					else continue;
				} else {
					continue;
				}
			}
		}
	}

	/*
	 *  (non-Javadoc)
	 * @see org.placelab.spotter.SyncSpotter#getMeasurementImpl()
	 */
	protected Measurement getMeasurementImpl() throws SpotterException {
		try {
			if(!simulated) {
				return queryServer();
			} else {
				return readLog();
			}
		} catch (IOException e) {
			throw new SpotterException(e.getMessage());
		}
	}

	/**
	 * Returns the scan interval for polling the native server
	 * @return nextScanInterval
	 */
	protected long nextScanInterval() {
		return scanIntervalMillis;
	}
}