Android GPS学习 (二) ：GPS 服务启动以及初始化流程

扫码关注，一起学习

1、GPS 服务启动

SystemServer.java的startOtherServices方法中添加LocationManagerService方法的代码如下,

frameworks/base/services/java/com/android/server/SystemServer.java

traceBeginAndSlog("StartLocationManagerService");
try {
    
    
    location = new LocationManagerService(context);
    ServiceManager.addService(Context.LOCATION_SERVICE, location);

添加gps服务到系统之后, SystemServer.java的startOtherServices方法中

final LocationManagerService locationF = location;

try {
    
    
    if (locationF != null) locationF.systemRunning();

调用LocationManagerService的systemRunning方法,完成LocationManagerService服务的初始化。

2、函数调用

frameworks/base/services/core/java/com/android/server/LocationManagerService.java

systemRunning方法中会调用loadProvidersLocked方法,

public void systemRunning() {
    
    
    synchronized (mLock) {
    
    
        // prepare providers
        loadProvidersLocked();
        updateProvidersLocked();
    }

loadProvidersLocked方法主要是添加设备上支持的GPS定位Provider,

private void loadProvidersLocked() {
    
    
    // create a passive location provider, which is always enabled
    PassiveProvider passiveProvider = new PassiveProvider(this);
    addProviderLocked(passiveProvider);
    mEnabledProviders.add(passiveProvider.getName());
    mPassiveProvider = passiveProvider;

    if (GnssLocationProvider.isSupported()) {
    
    
        // Create a gps location provider
        GnssLocationProvider gnssProvider = new GnssLocationProvider(mContext, this,
                mLocationHandler.getLooper());
        mGnssSystemInfoProvider = gnssProvider.getGnssSystemInfoProvider();
        mGnssBatchingProvider = gnssProvider.getGnssBatchingProvider();
        mGnssMetricsProvider = gnssProvider.getGnssMetricsProvider();
        mGnssStatusProvider = gnssProvider.getGnssStatusProvider();
        mNetInitiatedListener = gnssProvider.getNetInitiatedListener();
        addProviderLocked(gnssProvider);
        mRealProviders.put(LocationManager.GPS_PROVIDER, gnssProvider);
        mGnssMeasurementsProvider = gnssProvider.getGnssMeasurementsProvider();
        mGnssNavigationMessageProvider = gnssProvider.getGnssNavigationMessageProvider();
        mGpsGeofenceProxy = gnssProvider.getGpsGeofenceProxy();
    }

2.1、Framework调用JNI层方法

GnssLocationProvider.java -> com_android_server_location_GnssLocationProvider.cpp

2.2 、JNI层调用Framework方法

com_android_server_location_GnssLocationProvider.cpp -> GnssLocationProvider.java