Android - Lecture 17 - LBS With Google API

8/2/2019 Android - Lecture 17 - LBS With Google API

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ANDROID

Location Based Services with Google Map API


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Creating your Android Project

When Creating a Project

with Google Maps you need

to pick a Target that

includes Google APIs


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Editing your Manifest

Specify that you will use the Google Maps Library:

Then add the permissions for Internet, coarse, and

fine location:


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Well need an API to utilize Google Maps and

have our Map show in our Application

Google Maps API Key


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Google Maps API key

In order to show our google map we need toinclude an api key

First you need to location your debug.keystore in

your directory structure (Likely here): C:\Users\portia\.android

Record the file path (We will use it shortly)

Replace with yourown name


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Google Maps API Key

Run the Command Prompt

Start -> Run -> cmd


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Google Maps API Key

Now we will utlize the keytool to get your MD5

Fingerprint

keytool.exe is likely located at:

C:\Program Files\Java\jre6\bin

Well first change directory on the command prompt

to the location of keytools execute the line on the command prompt

cd C:\Program Files\Java\jre6\bin


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Google Maps API Key

Now you will execute a line similar to the following but with

your directory path (FYI: this is all one line):

keytool -list -alias androiddebugkey -storepass android -

keypass androidkeystore

C:\Users\portia\.android\debug.keystore


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Google Maps API Key

On your command prompt you should now see:

MD5 Certificate


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Google Maps API Key

Now go to the following site:

http://code.google.com/android/maps-api-signup.html

Accept the Terms and Conditions and enter your

MD5 fingerprint in the text box.

Click Generate API Key
http://code.google.com/android/maps-api-signup.htmlhttp://code.google.com/android/maps-api-signup.htmlhttp://code.google.com/android/maps-api-signup.htmlhttp://code.google.com/android/maps-api-signup.htmlhttp://code.google.com/android/maps-api-signup.htmlhttp://code.google.com/android/maps-api-signup.html


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Google Maps API Key

Now you have your API key KEEP IT

Your Key is good for all apps on your computer as

long as you keep normal settings, but once you

transfer to another computer youll have to changethe key to use your maps. However, itll work fine

on the device.


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Now that we have an API Key we can generate

our Map

Showing your Map


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Creating Map in Layout File

Well use the com.google.android.maps.MapView tag to

generate the map

Make sure to include an id for your map and the api key

Note we still need to add some Java code for the map to show!


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Our MapActivity

Now rather than simply extending Activity in your

class you now need to extend MapActivity

Your map should now

appear


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Customizing your Map

We will now add to instance attributes for the class:

And create a method for initializing the map and

call it from onCreate()


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MapView and MapController

Setup your MapView and MapController

Now you can specify Street or Satellite view,

Add your Zoom Controls, and

Specify how much you zoom by


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Looking good

Zoom controls should now appear when you click the

bottom of the screen


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Lets now make the map Appear at your location

Your Location


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Location Listener

We need to now listen for location changes so that

we can find out where we currently are

To do so our class now needs to implement

LocationListener


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Location Manager & Service Provider

Add the following two instance variables

Now initialize them in your onCreate() method

The service provider (gps, network) will be the

best connection we can get


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Requesting Location Updates

We now need to listen for location updates from the

location manager:


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Current Location

Now well use the location manager to get your last

known location. This may not be where you

currently are though:

Then call a function to show the specified location

We will make this function


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Show Location

Create your showLocation method

if the location is not empty then get its latitude and

longitude


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Show Location

Then you will create a point with the given latitude

and longitude

And pass it to the mapController so it animates to

that place


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Testing Current Location

To test this on the emulator you need to send the

phone a location using the DDMS perspective then

reload the app:

Windows -> Open Perspective -> Other -> DDMS


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Testing Current Location

Now under the Location Controls section put in a

Longitude and Latitude and Send it to your app


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Now youll see your Location

You will have to re-open your app when you send in

a new location to test it as we are only showing

data onCreate()


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We now want the map to change locations when

your location changes

Updating Location on Change


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onLocationChanged

We now will change the location every time the

onLocationChanged method is called rather than

having an explicit showLocation method.

Copy the code from showLocation toonLocationChanged

Delete showLocation method

call onLocationChanged(location) rather thanshowLocation from onCreate()


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Location Should Change!

Now every time you send a new longitude /

latitude pair through the DDMS your locations

should update on the emulator


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We now want to add a pin to illustrate your

location on the map

Adding A Pin


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Adding a Pin

The Pins on maps used to highlight certain locations

are called Overlays

We will create an Overlay to pin your location


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CurrentLocationOverlay

Create a new class called CurrentLocationOverlay

and have it extend ItimizedOverlay

Create an OveralyItem instance variable of theclass used to hold the current location Overlay


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CurrentLocationOverlay Constructor

Modify the constructor as such to get the drawable

graphic in a state ready to be a pin


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CreateItem

This method will return the current Overlay

and size() will return 1 because we only have 1 Overlay


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addItem

We will use this method to create our Overlay, given a point,

what we want the title of the point to be, and the service

provider

We then call populate to do all the processing of our Overlay


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Adding Instance Variables

We will now add the following instance variables to

reference our CurrentLocationOverlay, and

to hold the list of all Overlays on the Map


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Adding a Marker

Before we initialize our overlays we need to add a

pin icon to our drawable directory to hold the

image that will be drawn on our screen for the

overlays Call it map_pin_current


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Initializing the Overlays

Call the initCurrentLocationMarkerOverlays() from

the onCreate() method after setting up the map

This method captures the mapoverlays

Gets the image for the pin and creates the itimizedOverlay to hold our overlay in

the future


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When to reset the Pin?

We will want to reset the pin every time the lcoation

is changed

Hence in our onLocationChanged method after

getting our point well update the itimizedOverlay

reset the maps overlays


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Now lets add another set of Overlays to keep

track of special places

Adding More Overlays


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Holding the Overlays

Now we need to keep track of a set of Overlays

rather than just one of the current place.

To do this we will create another ItimizedOverlay

that contains an ArrayList to hold all theOverlayItems


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Start from CurrentLocationOverlay

Make a copy of CurrentLocationOverlay and call it

SpecialLocationOverlay.

Rename the class accordingly

Replace the instance variable with an ArrayList

becomes


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Change methods for ArrayList


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Adding your Overlays

In your Main Activity after initializing your

CurrentLocationOverlays call a method

addSpecialLocationOverlays() which we will make


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addSpecialLocationOverlays()

Here well get our pin from drawable (Make sure to

add a new icon to the drawable directory)

Initialize the SpecialLocationOverlay

Add location

Show them in the Map


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addSpecialLocationOverlays()

Well make this

method


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addSpecialOverlay()

This method makes a point from the specified

longitude / latitude and adds it to the

specialoverlays


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Special Points Appear Now

Android - Lecture 17 - LBS With Google API

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