Do not resolve filename from Uri

It was observed by one user on another app that uses
the same code that the Uri to filename lookup
can fail with an IllegalStateException. The code which
converts a Uri to a file path may not be that great,
especially now that the app is expected to not receive
file Uris.

Instead of determining the best way to lookup the file
names, as it is not that important, the Uri is used directly.
This is both for printing the location after the import,
and determinimg the mimetype.

Author: brarcher

app/src/main/java/protect/budgetwatch/ImportExportActivity.java

@@ -2,18 +2,17 @@
 
 import android.Manifest;
 import android.content.ActivityNotFoundException;
+import android.content.ContentResolver;
 import android.content.Context;
 import android.content.DialogInterface;
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.content.pm.ResolveInfo;
-import android.database.Cursor;
 import android.net.Uri;
 import android.os.AsyncTask;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Environment;
-import android.provider.OpenableColumns;
 import android.support.annotation.NonNull;
 import android.support.v4.app.ActivityCompat;
 import android.support.v4.content.ContextCompat;
@@ -25,6 +24,7 @@
 import android.util.Log;
 import android.view.MenuItem;
 import android.view.View;
+import android.webkit.MimeTypeMap;
 import android.widget.ArrayAdapter;
 import android.widget.Button;
 import android.widget.Spinner;
@@ -203,21 +203,17 @@ public void onTaskComplete(boolean success)
             }
         };
 
-        String filename = fileNameFromUri(targetUri);
-        if(filename == null)
-        {
-            filename = targetUri.getPath();
-        }
+        String mimetype = getMimeType(targetUri);
 
-        if(format == null && filename != null)
+        if(format == null && mimetype != null)
         {
             // Attempt to guess the data format based on the extension
-            Log.d(TAG, "Attempting to determine file type for: " + filename);
+            Log.d(TAG, "Attempting to determine file type for: " + mimetype);
 
             for(Map.Entry<String, DataFormat> item : _fileFormatMap.entrySet())
             {
-                String key = item.getKey();
-                if(filename.toLowerCase().endsWith(key.toLowerCase()))
+                DataFormat value = item.getValue();
+                if(mimetype.toLowerCase().equals(value.mimetype()))
                 {
                     format = item.getValue();
                     break;
@@ -227,15 +223,15 @@ public void onTaskComplete(boolean success)
 
         if(format != null)
         {
-            Log.d(TAG, "Starting import of file: " + filename);
+            Log.d(TAG, "Starting import of file");
             importExporter = new ImportExportTask(ImportExportActivity.this,
                     format, target, listener);
             importExporter.execute();
         }
         else
         {
             // If format is still null, then we do not know what to import
-            Log.w(TAG, "Could not import " + filename + ", could not determine extension");
+            Log.w(TAG, "Could not import file because mimetype could not get determined");
             onImportComplete(false, targetUri);
 
             try
@@ -318,31 +314,39 @@ public boolean onOptionsItemSelected(MenuItem item)
         return super.onOptionsItemSelected(item);
     }
 
-    private String fileNameFromUri(Uri uri)
+    public String getMimeType(Uri uri)
     {
-        if("file".equals(uri.getScheme()))
-        {
-            return uri.getPath();
-        }
+        String mimeType = null;
 
-        Cursor returnCursor =
-                getContentResolver().query(uri, null, null, null, null);
-        if(returnCursor == null)
+        String fileExtension = MimeTypeMap.getFileExtensionFromUrl(uri.toString());
+        if(fileExtension != null)
         {
-            return null;
+            fileExtension = fileExtension.toLowerCase();
+            for(DataFormat format : DataFormat.values())
+            {
+                if(fileExtension.equals(format.name().toLowerCase()))
+                {
+                    mimeType = format.mimetype();
+                    break;
+                }
+            }
         }
 
-        int nameIndex = returnCursor.getColumnIndex(OpenableColumns.DISPLAY_NAME);
-        if(returnCursor.moveToFirst() == false)
+        if(mimeType == null && uri.getScheme() != null && uri.getScheme().equals(ContentResolver.SCHEME_CONTENT))
         {
-            returnCursor.close();
-            return null;
-        }
+            ContentResolver cr = getContentResolver();
+            mimeType = cr.getType(uri);
 
-        String name = returnCursor.getString(nameIndex);
-        returnCursor.close();
+            if(mimeType != null)
+            {
+                if(mimeType.equals("text/comma-separated-values"))
+                {
+                    mimeType = "text/csv";
+                }
+            }
+        }
 
-        return name;
+        return mimeType;
     }
 
     private void onImportComplete(boolean success, Uri path)
@@ -359,15 +363,10 @@ private void onImportComplete(boolean success, Uri path)
         }
 
         int messageId = success ? R.string.importedFrom : R.string.importFailed;
-
         final String template = getResources().getString(messageId);
 
         // Get the filename of the file being imported
-        String filename = fileNameFromUri(path);
-        if(filename == null)
-        {
-            filename = "(unknown)";
-        }
+        String filename = path.toString();
 
         final String message = String.format(template, filename);
         builder.setMessage(message);
@@ -495,13 +494,24 @@ protected void onActivityResult(int requestCode, int resultCode, Intent data)
 
         try
         {
-            InputStream reader = getContentResolver().openInputStream(uri);
+            InputStream reader;
+
+            if(uri.getScheme() != null)
+            {
+                reader = getContentResolver().openInputStream(uri);
+            }
+            else
+            {
+                reader = new FileInputStream(new File(uri.toString()));
+            }
+
             Log.e(TAG, "Starting file import with: " + uri.toString());
             startImport(null, reader, uri);
         }
-        catch (FileNotFoundException e)
+        catch(FileNotFoundException e)
         {
             Log.e(TAG, "Failed to import file: " + uri.toString(), e);
+            onImportComplete(false, uri);
         }
     }
 }