[Android] the principle of mobile location of mobile guards

There are three ways of mobile phone positioning: network positioning, base station positioning and GPS positioning

For network positioning, when the mobile phone is connected to WiFi 2g 3g, the mobile phone will have an IP, with great error

The accuracy of base station positioning is related to the number of base stations, with an error of tens of meters to several kilometers

GPS positioning requires at least three satellites to locate accurately in open places

The mobile phone uses A-GPS and needs the network to assist in positioning. The positioning speed is fast. The network records the last satellite orbit,

Get the locationmanager object through getsystemservice (location_service)

Call the requestlocationupdates() method of the locationmanager object to request location updates. Parameters:

Positioning method ("GPS"), update time (60000), update distance (50), locationlistener object

Locationlistener is an interface, and its implementation class needs to be made

Define mylocationlistener and implement the following methods

Onlocationchanged(), when the location changes, the callback passes in a location object

Call the getlongitude () method of the location object to get the longitude

Call the getlatitude () method of the location object to get the dimension

Call the getaccuracy () method of the location object to get the accuracy

Onstatus changed(), when the status changes, the callback is turned off and on

Onproviderenabled(), when a location provider is available

Onproviderdisabled(), when a location provider is unavailable

When the activity is destroyed, the listening location is cancelled

Override the ondestroy () method of the activity

Call removeupdates() of locationmanager object to cancel listening. Parameter: locationlistener object

Set the locationlistener object to null and garbage collection

Required permissions

android.permission.ACCESS_ FINE_ Location get accurate location

android.permission.ACCESS_ COARSE_ Location gets the rough location

android.permission.ACCESS_ MOCK_ Location get the location of the simulation (when the simulator is developed)

On the simulator, the following positions can be displayed only after being sent in DDMS

The state has biased the coordinates and turned them into Martian coordinates, which requires the plug-in of the National Bureau of Surveying and mapping. There is a Martian coordinate conversion code on the Internet