Advanced android Development (III)-exploration of positioning service (GPS) on the Android platform)

 

Exploration of positioning service (GPS) on Android platform)

 

Note: Do not forget to add permissions for all of the following operations:

   <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />    <uses-permission android:name="android.permission.INTERNET" />    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> 

Locationmanager

You can use locationmanager to locate, track, and approaching devices. It does not need to be instantiated directly. We can use context. getsystemservice (context. location_service). To obtain the locationmanager instance.

Common attributes and Methods

Attributes and Methods	Description
Gps_provider	Static String constant, indicating that locationprovider is GPS
Network_provider	Static String constant, indicating that locationprovider is a network
Addgpsstatuslistener (gpsstatus. Listener listener)	Add a GPS status listener
Addproximityalert (double latitude, double longpolling, float radius, long expiration, pendingintent intent)	Add a approaching warning
Getallproviders ()	Obtain the list of all locationproviders
Getbestprovider (Criteria, Boolean enabledonly)	Return the most suitable locationprovider based on criteria
Getlastknownlocation (string provider)	Obtain location information based on the provider
Getprovider (string name)	Obtain the locationprovider with the specified name
Getprovider (Boolean enableonly)	Obtain the list of available locationproviders
Removeproximityalert (pendingintent intent)	Delete approaching warning
Requestlocationupdates (string provider, long mintime, float mindistance, pendingintent intent)	Periodically notifies the current activity by the specified provider name
Requestlocationupdates (string provider, long mintime, float mindistance, locationlistener listener)	Bind the specified locationlistener listener to the specified provider name

 

Locationprovider

Locationprovider is used to describe the location provider and set some attributes of the location provider. You can use the criteria class to set conditions for the locationprovider to obtain the appropriate locationprovider.

Attribute or method name	Description
Available	Static integer constant, indicating whether it is usable
Out_of_service	Static integer constant, out of service
Temporaily_unavailable	Static integer constant, temporarily unavailable
Getaccuarcy ()	Accuracy
Getname ()	Get name
Getpowerrequirement ()	Power supply requirements
Hasmonetarycost ()	The cost is still free.
Requirescell ()	Access Base Station Network?
Requiresnetwork ()	Whether intent network data is required
Requiressatelite ()	Satellite access required?
Supportsaltitude ()	Whether high information can be provided
Supportsbearing ()	Provide direction information?
Supportsspeed ()	Whether speed information can be provided

Instance: Get all locationproviders on the device

Locationmanager = (locationmanager) locationmanagerdemoactivity. this. getsystemservice (context. location_service); // obtain all locationprovider lists <string> allproviders = locationmanager. getallproviders (); For (string: allproviders) {system. out. println (string );}

 

Location class

It is used to describe the geographic location information of the current device, including latitude and longitude, direction, height and speed. You can use the locationmanager. getlastknownlocation (string provider) method to obtain the location instance.

Common methods and attributes:

Method	Description
Public float getaccuracy ()	Accuracy
Public double getaltitude ()	Gain height
Public float getbearing ()	Direction
Public double getlatitude ()	Obtain longitude
Public double getlongpolling ()	Obtain latitude
Public float getspeed ()	Acquisition speed

Instance: Get your location

// Obtain your position btngetposition. setonclicklistener (new view. onclicklistener () {@ override public void onclick (view v) {system. out. println ("Get current location"); locationmanager = (locationmanager) locationmanagerdemoactivity. this. getsystemservice (context. location_service); location = locationmanager. getlastknownlocation (locationmanager. gps_provider); system. out. println ("your current location:"); stringbuilder sb = new stringbuilder ("your current location (longitude and latitude):"); sb. append ("("); sb. append (location. getlatitude (); sb. append (","); sb. append (location. getlongpolling (); sb. append (")"); system. out. println (location. getlatitude (); system. out. println (location. getlongpolling (); txtpostion. settext (SB );}});

 

Instance: Tracking Location:

Requestlocationupdates (string provider, long mintime, float mindistance, locationlistener listener)

About the mintime parameter, the mindistance parameter indicates how long the user's location will be updated when the user's location changes.

   locationManager.requestLocationUpdates(                     LocationManager.GPS_PROVIDER, 500, 500, new listener());

Instance: Get the best locationproivider

LocationManager.getBasetProvider(Criteria criteria,boolean is)

Criteria class

It encapsulates the conditions used to obtain the locationprovider. You can filter and obtain the locationprovider according to the specified criteria conditions.

And common attributes and methods are as follows:

Attribute or access name	Description
Acceracy_coarse	Rough precision
Accuracy_fine	High Accuracy
Power_hing	High power usage
Power_low	Low Power Consumption
Isalitituderequried ()	Returns whether the provider requires height information.
Isbearingrequired ()	Returns whether the provider requires location information.
Isspeedrequried ()	Returns whether the provider requires speed information.
Iscostallowed ()	Allow fees
Setaccuracy (INT accuracy)	Set provider precision
Setaltituderequired (Boolean altituderequired)	Sets whether the provider requires height information.
Setbearingrequired (Boolean bearingrequired)	Sets whether the provider requires orientation information.
Setcostallowed (Boolean costallowed)	Set whether the provider generates fees
Setspeedaccuracy (INT accuracy)	Set whether the provider requires speed information
Getaccuracy ()	Accuracy

// Obtain the best provider btnbestprovider. setonclicklistener (new view. onclicklistener () {@ override public void onclick (view v) {string bestproviders = ""; locationmanager = (locationmanager) locationmanagerdemoactivity. this. getsystemservice (context. location_service); // Create a New Criteria = new criteria (); // set the accuracy of criteria. setaccuracy (criteria. accuracy_coarse); criteria. setpowerrequirement (criteria. power_low); criteria. setaltituderequired (false); criteria. setbearingrequired (false); criteria. setspeedrequired (false); criteria. setcostallowed (false); // obtain the qualified provider bestproviders = locationmanager. getbestprovider (criteria, false); txtcrerita. settext ("best provider:" + bestproviders );}});

Conclusion (see GPS again ):

From the above knowledge, we can know that we need to use the locationmanager System Service to use the GPS service on the Android platform. We can use the context. getsystemservice (context. location_servier) to get the locationmanager object instance. With such a service, we can use locationprovider to describe the location provider, for some reason, we have used another criteria class to set our own best requirements. When everything is done, we use the location class to get our own location, this class is used to obtain our own location, such as longitude and latitude.