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davidgyoungdavidgyoung
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make distance calculations specific to Android model
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‎src/main/java/org/altbeacon/beacon/distance/AndroidModel.java

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package org.altbeacon.beacon.distance;
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import android.os.Build;
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/**
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* Created by dyoung on 8/28/14.
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*/
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public class AndroidModel {
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String mVersion;
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String mBuildNumber;
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String mModel;
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String mManufacturer;
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public AndroidModel(String version, String buildNumber,
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String model,
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String manufacturer) {
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mVersion = version;
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mBuildNumber = buildNumber;
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mModel = model;
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mManufacturer = manufacturer;
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}
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public static AndroidModel forThisDevice() {
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return new AndroidModel(
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Build.VERSION.RELEASE,
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Build.ID,
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Build.MODEL,
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Build.MANUFACTURER);
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}
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public String getVersion() {
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return mVersion;
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}
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public void setVersion(String mVersion) {
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this.mVersion = mVersion;
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}
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public String getBuildNumber() {
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return mBuildNumber;
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}
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public String getModel() {
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return mModel;
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}
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public String getManufacturer() {
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return mManufacturer;
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}
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public int matchScore(AndroidModel otherModel) {
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int score = 0;
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if (this.mManufacturer.equals(otherModel.mManufacturer)) {
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score = 1;
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}
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if (this.mModel.equals(otherModel.mModel)) {
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score = 2;
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}
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if (this.mBuildNumber.equals(otherModel.mBuildNumber)) {
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score = 3;
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}
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if (this.mVersion.equals(otherModel.mVersion)) {
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score = 4;
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}
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return score;
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}
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}

‎src/main/java/org/altbeacon/beacon/distance/CurveFittedDistanceCalculator.java

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package org.altbeacon.beacon.distance;
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import org.altbeacon.beacon.BeaconManager;
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/**
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* Created by dyoung on 8/28/14.
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*/
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public class CurveFittedDistanceCalculator implements DistanceCalculator {
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public static final String TAG = "CurveFittedDistanceCalculator";
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private double mCoefficient1;
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private double mCoefficient2;
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private double mCoefficient3;
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public CurveFittedDistanceCalculator(double coefficient1, double coefficient2, double coefficient3) {
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mCoefficient1 = coefficient1;
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mCoefficient2 = coefficient2;
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mCoefficient3 = coefficient3;
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}
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/**
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* Calculated the estimated distance in meters to the beacon based on a reference rssi at 1m
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* and the known actual rssi at the current location
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* @param txPower
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* @param rssi
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* @return estimated distance
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*/
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@Override
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public double calculateDistance(int txPower, double rssi) {
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if (rssi == 0) {
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return -1.0; // if we cannot determine accuracy, return -1.
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}
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BeaconManager.logDebug(TAG, "calculating distance based on mRssi of " + rssi + " and txPower of " + txPower);
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double ratio = rssi*1.0/txPower;
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double distance;
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if (ratio < 1.0) {
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distance = Math.pow(ratio,10);
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}
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else {
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distance = (0.42093)*Math.pow(ratio,6.9476) + 0.54992;
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}
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BeaconManager.logDebug(TAG, " avg mRssi: "+rssi+" distance: "+distance);
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return distance;
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}
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}

‎src/main/java/org/altbeacon/beacon/distance/DistanceCalculator.java

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package org.altbeacon.beacon.distance;
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/**
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* Created by dyoung on 8/28/14.
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*/
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public interface DistanceCalculator {
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public double calculateDistance(int txPower, double rssi);
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}

‎src/main/java/org/altbeacon/beacon/distance/ModelSpecificDistanceCalculator.java

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package org.altbeacon.beacon.distance;
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import android.os.Build;
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import android.util.Log;
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import org.json.JSONArray;
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import org.json.JSONObject;
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import java.io.BufferedReader;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.Properties;
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/**
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* Created by dyoung on 8/28/14.
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*/
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public class ModelSpecificDistanceCalculator implements DistanceCalculator {
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Map<AndroidModel,DistanceCalculator> mModelMap;
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//private static final String CONFIG_FILE = "/model-distance-calculations.json";
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private static final String CONFIG_FILE = "test.properties";
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private static final String TAG = "ModelSpecificDistanceCalculator";
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private DistanceCalculator mDefaultDistanceCalculator;
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private DistanceCalculator mDistanceCalculator;
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public ModelSpecificDistanceCalculator() {
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this(AndroidModel.forThisDevice());
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}
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public ModelSpecificDistanceCalculator(AndroidModel model) {
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loadModelMap();
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mDistanceCalculator = findCalculatorForModel(model);
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}
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private DistanceCalculator findCalculatorForModel(AndroidModel model) {
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Log.d(TAG, "Finding best distance calculator for "+model.getVersion()+","+
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model.getBuildNumber()+","+model.getModel()+"," +
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""+model.getManufacturer());
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int highestScore = 0;
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AndroidModel bestMatchingModel = null;
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for (AndroidModel candidateModel : mModelMap.keySet()) {
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if (candidateModel.matchScore(model) > highestScore) {
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highestScore = candidateModel.matchScore(model);
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bestMatchingModel = candidateModel;
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}
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}
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if (bestMatchingModel != null) {
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Log.d(TAG, "found a match with score "+highestScore);
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Log.d(TAG, "Finding best distance calculator for "+bestMatchingModel.getVersion()+","+
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bestMatchingModel.getBuildNumber()+","+bestMatchingModel.getModel()+"," +
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""+bestMatchingModel.getManufacturer());
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return mModelMap.get(bestMatchingModel);
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}
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Log.d(TAG, "Cannot find match for this device. Using default");
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return mDefaultDistanceCalculator;
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}
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private void loadModelMap() {
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mModelMap = new HashMap<AndroidModel, DistanceCalculator>();
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try {
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JSONObject jsonObject = new JSONObject(stringFromFilePath(CONFIG_FILE));
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JSONArray array = jsonObject.getJSONArray("models");
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for (int i = 0; i < array.length(); i++) {
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JSONObject modelObject = array.getJSONObject(i);
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boolean defaultFlag = modelObject.getBoolean("default");
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Double coefficient1 = modelObject.getDouble("coefficient1");
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Double coefficient2 = modelObject.getDouble("coefficient2");
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Double coefficient3 = modelObject.getDouble("coefficient3");
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String version = modelObject.getString("version");
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String buildNumber = modelObject.getString("build_number");
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String model = modelObject.getString("model");
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String manufacturer = modelObject.getString("manufacturer");
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CurveFittedDistanceCalculator distanceCalculator =
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new CurveFittedDistanceCalculator(coefficient1,coefficient2,coefficient3);
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AndroidModel androidModel = new AndroidModel(version, buildNumber, model, manufacturer);
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mModelMap.put(androidModel, distanceCalculator);
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if (defaultFlag) {
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mDefaultDistanceCalculator = distanceCalculator;
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}
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}
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}
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catch (Exception e) {
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throw new RuntimeException("Cannot build model distance calculations", e);
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}
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}
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private String stringFromFilePath(String path) throws IOException {
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InputStream stream = ModelSpecificDistanceCalculator.class.getResourceAsStream(path);
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if (stream == null) {
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throw new RuntimeException("Cannot load resource at "+path);
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}
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StringBuilder inputStringBuilder = new StringBuilder();
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BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(stream, "UTF-8"));
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String line = bufferedReader.readLine();
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while(line != null){
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inputStringBuilder.append(line);inputStringBuilder.append('\n');
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line = bufferedReader.readLine();
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}
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return inputStringBuilder.toString();
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}
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@Override
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public double calculateDistance(int txPower, double rssi) {
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return mDistanceCalculator.calculateDistance(txPower, rssi);
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}
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}

‎src/main/resources/model-distance-calculations.json

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{
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"models":
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[
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{
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"coefficient1": 0.42093,
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"coefficient2": 6.9476,
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"coefficient3": 0.54992,
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"version":"4.4.2",
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"build_number":"KOT49H",
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"model":"Nexus 4",
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"manufacturer":"LGE",
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"default": true
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},
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{
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"coefficient1": 0.42093,
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"coefficient2": 6.9476,
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"coefficient3": 0.54992,
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"version":"4.4.2",
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"build_number":"LPV79",
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"model":"Nexus 5",
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"manufacturer":"LGE",
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}
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]
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}

‎src/main/resources/test.properties

Whitespace-only changes.

‎src/test/java/org/altbeacon/beacon/distance/ModelSpecificDistanceCalculatorTest.java

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package org.altbeacon.beacon.distance;
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import android.os.Parcel;
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import static android.test.MoreAsserts.assertNotEqual;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertNotNull;
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import static org.junit.Assert.assertTrue;
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import org.altbeacon.beacon.AltBeacon;
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import org.altbeacon.beacon.AltBeaconParser;
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import org.altbeacon.beacon.Beacon;
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import org.robolectric.RobolectricTestRunner;
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import org.junit.runner.RunWith;
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import org.junit.Test;
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import org.robolectric.annotation.Config;
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@Config(emulateSdk = 18)
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@RunWith(RobolectricTestRunner.class)
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/*
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HOW TO SEE DEBUG LINES FROM YOUR UNIT TESTS:
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1. set a line like this at the start of your test:
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org.robolectric.shadows.ShadowLog.stream = System.err;
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2. run the tests from the command line
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3. Look at the test report file in your web browser, e.g.
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file:///Users/dyoung/workspace/AndroidProximityLibrary/build/reports/tests/index.html
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4. Expand the System.err section
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/**
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* Created by dyoung on 8/28/14.
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*/
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public class ModelSpecificDistanceCalculatorTest {
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@Test
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public void testRecognizeBeacon() {
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ModelSpecificDistanceCalculator distanceCalculator = new ModelSpecificDistanceCalculator();
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Double distance = distanceCalculator.calculateDistance(-59, -59);
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assertEquals("Distance should be 1.0 for same power and rssi", 1.0, (double) distance, 0.001);
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}
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}

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