Android Location and Maps

//未写完 1 Maps API Key申请

要使用Google提供的map服务，必须先申请一个Maps API Key。步骤如下：

Step1：申请MD5
(1)打开eclipse，然后选择Window-->Preferences-->Android-->Build,这时候我们可以查找debug.keystore的路径，如下图：

(2)将debug.keystore拷贝到keytool所在目录，如果安装JDK是按默认路径安装，keytool是在C:\Program Files\Java\jdk1.6.0_25\bin下。

(3)运行cmd,进入到keytool的目录下，输入 keytool -list -keystore debug.keystore,提示输入密码时直接回车，得到MD5。

Step2：利用MD5申请API Key。

登陆http://code.google.com/intl/zh-CN/android/maps-api-signup.html，输入获取的MD5，Generate API Key即可(需要gmail邮箱)。

注：申请API Key的官网文档见http://code.google.com/intl/zh-CN/android/add-ons/google-apis/mapkey.html

2 Maps开发

Map开发最好的学习资料：

(1)http://developer.android.com/guide/tutorials/views/hello-mapview.html

(2)Demo：<sdk>/add-ons/google_apis-<api-level>/samples/MapsDemo

(3)Package com.google.android.maps （<sdk>/add-ons/google_apis-<api-level>/docs/reference/index.html）

2.1 建立工程

Android maps开发建立工程时需要选择Google API，如果没有相应版本的Google API，打开Windows>Android SDK and AVD Manager>Available package里面下载相应的add-ons，如下图：

下载完成后，在android-sdk-windows\add-ons\addon_google_apis_google_inc_10\docs\reference\index.html里面查阅map相关的API,也可以在官网(http://code.google.com/intl/zh-CN/android/add-ons/google-apis/reference/com/google/android/maps/package-summary.html)上查询。

2.2 编写mapView.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/mainlayout"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <com.google.android.maps.MapView
        android:id="@+id/mapview"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:clickable="true"
        android:apiKey="Your Maps API Key"
    />

</RelativeLayout>

2.3 添加mapActivity

public class MappingOverlayActivity extends MapActivity {  
private MapView mapView;

@Override
public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
        mapView = (MapView) findViewById(R.id.mapview); 
} 

@Override
protected boolean isLocationDisplayed() {  
        return false;  
}

}

2.4 AndroidManifest.xml

(1)application element里面添加uses-library
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.package.name">
...
<application android:name="MyApplication" >
   <uses-library android:name="com.google.android.maps" />
...
</application>

(2)添加网络权限
<uses-permission android:name="android.permission.INTERNET" />

3 Location

Android gives your applications access to the location services supported by the device through the classes in the android.location package. The central component of the location framework is the LocationManager system service, which provides APIs to determine location and bearing of the underlying device (if available).

As with other system services, you do not instantiate a LocationManager directly. Rather, you request an instance from the system by calling getSystemService(Context.LOCATION_SERVICE). The method returns a handle to a new LocationManager

Location相关的最关键的三个class是：LocationManager，LocationListener，LocationProvider.具体内容请查阅SDK文档。另外Geocoder里面有曾经令人鸡动的API，但是暂时还无法获得服务(The Geocoder class requires a backend service that is not included in the core android framework. The Geocoder query methods will return an empty list if there no backend service in the platform. Use the isPresent() method to determine whether a Geocoder implementation exists.)。

3.1 获取当前位置信息

LocationManager locMan = (LocationManager)context.getSystemService(Context.LOCATION_SERVICE); 

Location location = locMan.getLastKnownLocation(LocationManager.GPS_PROVIDER); 

if(null == location){ 

   location = locMan.getLastKnownLocation(LocationManager.NETWORK_PROVIDER); 

}

注：此处只是为了比较清晰的说明如何使用Location Service，事实上这样做getLastKnownLocation的返回值为null，解决方法见5.1.

3.2 监听位置变化

(1)实例化LocationListener

LocationListener mLocationListener1 = new LocationListener() { 

    @Override 
    public void onLocationChanged(Location location) {}      

    @Override 
     public void onProviderDisabled(String provider) {} 

    @Override  
    public void onProviderEnabled(String provider) {}       

    @Override  
    public void onStatusChanged(String provider, int status, Bundle extras) {} 

};

(2)注册监听

locMan.requestLocationUpdates(LocationManager.GPS_PROVIDER, 60000, 1, mLocationListener1);//激活LocationListener对象mLocationListener1

(3)注销监听

locMan.removeUpdates(mLocationListener1);

4 Search 5 问题汇总及解决办法 5.1 geoCoder.getFromLocationName returns null 5.2 onLocationChanged never triggered 5.3 getLastKnownLocation Failed 5.4 addProximityAlert doesn’t fired 5.5 debug.keystor过期 6 Reference

Google Projects for Android
http://developer.android.com/guide/topics/location/index.html (android-sdk-windows\docs\guide\index.html>Dev Guide>Location and Maps)