谷歌地圖API的Android V2檢查，如果谷歌地圖安裝在設備

Question

在使用谷歌地圖API的Android V2我正在關注的Google Play Services setup documentation進行檢查，以確保谷歌Play服務，安裝，使用我的主要活動如下代碼：

@Override 
public void onResume() 
{ 
     checkGooglePlayServicesAvailability(); 

     super.onResume(); 
} 

public void checkGooglePlayServicesAvailability() 
    { 
     int resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this); 
     if(resultCode != ConnectionResult.SUCCESS) 
     { 
      Dialog dialog = GooglePlayServicesUtil.getErrorDialog(resultCode, this, 69); 
      dialog.setCancelable(false); 
      dialog.setOnDismissListener(getOnDismissListener()); 
      dialog.show(); 
     } 

     Log.d("GooglePlayServicesUtil Check", "Result is: " + resultCode); 
    } 

這工作正常。但是，我注意到一些較舊的Android手機（主要是2.2版本）缺少GooglePlayServices以及Google地圖應用程序本身。

的logcat會報告這個錯誤： 谷歌地圖API的Android：谷歌地圖應用程序丟失。

問題 - 我怎麼能執行一個類似的檢查上面的一個谷歌地圖的設備上的可用性？其次，如果用戶已經安裝了Google地圖，我認爲該檢查需要確保他們的安裝版本與Android Maps API的V2兼容。

更新 這是我的setupMapIfNeeded（）方法，它在onCreate（）的末尾被調用。這是我想，我會想確定是否安裝了谷歌地圖，並提醒用戶，看到別的塊：

private void setUpMapIfNeeded() 
{ 
    // Do a null check to confirm that we have not already instantiated the map. 
    if (mMap == null) 
    { 
     // Try to obtain the map from the SupportMapFragment. 
     mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.basicMap)).getMap(); 

     if (mMap != null) 
     { 
      mMap.setLocationSource(this); 

      mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(44.9800, -93.2636), 10.0f)); 
      setUpMap(); 
     } 
     else 
     { 
      //THIS CODE NEVER EXECUTES - mMap is non-null even when Google Maps are not installed 
      MapConstants.showOkDialogWithText(this, R.string.installGoogleMaps); 
     } 
    } 
} 

Answer 1

好了之後更戳，並慫恿我意識到我只需要問PackageManager如果安裝了谷歌地圖。 IMO應該真的包含在Google Maps Android API V2開發人員指南中......將會有很多開發人員錯過了這種情況，並且讓用戶感到沮喪。

以下是如何檢查是否谷歌地圖的安裝和重新引導用戶到Play商店，如果不是安裝了谷歌地圖列表（見isGoogleMapsInstalled()）：

private void setUpMapIfNeeded() { 
    // Do a null check to confirm that we have not already instantiated the map. 
    if (mMap == null) 
    { 
     // Try to obtain the map from the SupportMapFragment. 
     mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.basicMap)).getMap(); 

     if(isGoogleMapsInstalled()) 
     { 
      if (mMap != null) 
      { 
       setUpMap(); 
      } 
     } 
     else 
     { 
      Builder builder = new AlertDialog.Builder(this); 
      builder.setMessage("Install Google Maps"); 
      builder.setCancelable(false); 
      builder.setPositiveButton("Install", getGoogleMapsListener()); 
      AlertDialog dialog = builder.create(); 
      dialog.show(); 
     } 
    } 
} 

public boolean isGoogleMapsInstalled() 
{ 
    try 
    { 
     ApplicationInfo info = getPackageManager().getApplicationInfo("com.google.android.apps.maps", 0); 
     return true; 
    } 
    catch(PackageManager.NameNotFoundException e) 
    { 
     return false; 
    } 
} 

public OnClickListener getGoogleMapsListener() 
{ 
    return new OnClickListener() 
    { 
     @Override 
     public void onClick(DialogInterface dialog, int which) 
     { 
      Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=com.google.android.apps.maps")); 
      startActivity(intent); 

      //Finish the activity so they can't circumvent the check 
      finish(); 
     } 
    }; 
} 

我寫了一個簡短的博客文章這些細節：How to check if Google Maps are installed and redirect user to the Play Store

Answer 2

您可以驗證的GoogleMap可通過調用MapFragment.getMap（）或MapView.getMap（）方法並檢查返回的對象是否爲空。

public GoogleMap getMap()

The GoogleMap. Null if the view of the fragment is not yet ready. This can happen if the fragment lifecyle have not gone through onCreateView(LayoutInflater, ViewGroup, Bundle) yet. This can also happen if Google Play services is not available. If Google Play services becomes available afterwards and the fragment have gone through onCreateView(LayoutInflater, ViewGroup, Bundle), calling this method again will initialize and return the GoogleMap.

你可以閱讀有關verify map availability here。

Answer 3

From Google guide

if (mapIntent.resolveActivity(getPackageManager()) != null) { 
    ... 
}