前言

在地图的使用中，尤其在导航场景下，进行GPS轨迹录制是十分必要并且有用的，本文会对于安卓系统下的轨迹录制部分做一个分享。

系统架构

对于一个GPSRecordSystem（GPS轨迹录制系统）主要分成3个部分：开始录制，录制GPS定位，结束录制并存储，如上图右方所示。在实际应用中，以导航系统为例：（1）在开始导航时（start navi）,进行录制工作的相关配置；（2）收到安卓系统的onLocationChanged的callback进行GPSLocation的记录；（3）结束导航（stop navi）时，停止记录并存入文件。

相关代码展示

用到的相关变量

	private LocationManager mLocationManager;   // 系统locationManager
	private LocationListener mLocationListener; // 系统locationListener
	
	private boolean mIsRecording = false;       // 是否正在录制 

	private List<String> mGpsList;              // 记录gps的list
	private String mRecordFileName;             // gps文件名称

• 开始录制

开始录制一般是在整个系统工作之初，比如在导航场景下，当“开始导航”时，可以开始进行“startRecordLocation” 的配置

	public void startRecordLocation(Context context, String fileName) {
		// 已经在录制中不进行录制
		if (mIsRecording) {
			return;
		}
		Toast.makeText(context, "start record location...", Toast.LENGTH_SHORT).show();
		
		// 初始化locationManager和locationListener
		mLocationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
		mLocationListener = new MyLocationListener();
		try {
			// 添加listener
			mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, mLocationListener);
		} catch (SecurityException e) {
			Toast.makeText(context, "start record location error!!!", Toast.LENGTH_SHORT).show();
            Log.e(TAG, "startRecordLocation Exception", e);
			e.printStackTrace();
		}

// 记录文件名称，笔者这里使用“realLocationRecord + routeID”形式进行记录
		mRecordFileName = fileName;
		if (!mRecordFileName.endsWith(".gps")) {
			mRecordFileName += ".gps";
		}

		mIsRecording = true;
	}

• 录制中记录轨迹
  记录location一般是在获取安卓系统onLocationChanged回调时调用“recordGPSLocation”

	public void recordGPSLocation(Location location) {
		if (mIsRecording && location != null) {
		// 记录location to list
			mGpsList.add(locationToString(location));
		}
	}

locationToString工具方法

驱动导航工作的GPS轨迹点一般要包含以下几个要素，经度，纬度，精度，角度，速度，时间，海拔高度，所以在此记录下，为后期轨迹回放做准备。

	private String locationToString(Location location) {
		StringBuilder sb = new StringBuilder();
		
		long time = System.currentTimeMillis();
		String timeStr = gpsDataFormatter.format(new Date(time));

		sb.append(location.getLatitude());
		sb.append(",");
		sb.append(location.getLongitude());
		sb.append(",");
		sb.append(location.getAccuracy());
		sb.append(",");
		sb.append(location.getBearing());
		sb.append(",");
		sb.append(location.getSpeed());
		sb.append(",");
		sb.append(timeStr);
		sb.append(",");
		sb.append(df.format((double) time / 1000.0));
		// sb.append(df.format(System.currentTimeMillis()/1000.0));
		// sb.append(df.format(location.getTime()/1000.0));
		sb.append(",");
		sb.append(location.getAltitude());
		sb.append("\n");
		return sb.toString();
	}

• 结束录制并保存gps文件

结束录制一般作用在整个系统的结尾，例如在导航场景下，“结束导航”时停止录制调用“stopRecordLocation”

	public void stopRecordLocation(Context context) {
        Toast.makeText(context, "stop record location, save to file...", Toast.LENGTH_SHORT).show();
        
        // 移除listener
		mLocationManager.removeUpdates(mLocationListener);
		String storagePath = StorageUtil.getStoragePath(context); // 存储的路径
		String filePath = storagePath + mRecordFileName;

		saveGPS(filePath);
		mIsRecording = false;
	}

GPS轨迹存储工具方法

	private void saveGPS(String path) {
		OutputStreamWriter writer = null;
		try {
			File outFile = new File(path);
			File parent = outFile.getParentFile();
			if (parent != null && !parent.exists()) {
				parent.mkdirs();
			}
			OutputStream out = new FileOutputStream(outFile);
			writer = new OutputStreamWriter(out);
			for (String line : mGpsList) {
				writer.write(line);
			}
		} catch (Exception e) {
			Log.e(TAG, "saveGPS Exception", e);
			e.printStackTrace();
		} finally {
			if (writer != null) {
				try {
					writer.flush();
				} catch (IOException e) {
					e.printStackTrace();
					Log.e(TAG, "Failed to flush output stream", e);
				}
				try {
					writer.close();
				} catch (IOException e) {
					e.printStackTrace();
					Log.e(TAG, "Failed to close output stream", e);
				}
			}
		}
	}
	

StorageUtil的getStoragePath工具方法

// 存储在跟路径下/TencentMapSDK/navigation
    private static final String NAVIGATION_PATH = "/tencentmapsdk/navigation";

// getStoragePath工具方法
    public static String getStoragePath(Context context) {
        if (context == null) {
            return null;
        }
        String strFolder;
        boolean hasSdcard;
        try {
            hasSdcard = Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
        } catch (Exception e) {
            Log.e(TAG, "getStoragePath Exception", e);
            e.printStackTrace();
            hasSdcard = false;
        }
        if (!hasSdcard) {
            strFolder = context.getFilesDir().getPath() + NAVIGATION_PATH;
            File file = new File(strFolder);
            if (!file.exists()) {
                file.mkdirs();
            }
        } else {
            strFolder = Environment.getExternalStorageDirectory().getPath() + NAVIGATION_PATH;
            File file = new File(strFolder);
            if (!file.exists()) { // 目录不存在，创建目录
                if (!file.mkdirs()) {
                    strFolder = context.getFilesDir().getPath() + NAVIGATION_PATH;
                    file = new File(strFolder);
                    if (!file.exists()) {
                        file.mkdirs();
                    }
                }
            } else { // 目录存在，创建文件测试是否有权限
                try {
                    String newFile = strFolder + "/.test";
                    File tmpFile = new File(newFile);
                    if (tmpFile.createNewFile()) {
                        tmpFile.delete();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                    Log.e(TAG, "getStoragePath Exception", e);
                    strFolder = context.getFilesDir().getPath() + NAVIGATION_PATH;
                    file = new File(strFolder);
                    if (!file.exists()) {
                        file.mkdirs();
                    }
                }
            }
        }
        return strFolder;
    }

结果展示

最终存储在了手机目录下的navigation目录

后续工作

后续可以对于录制的gps文件讲解在导航场景下进行轨迹回放的分享