Merge branch 'issue_74' into 0.9.0

src/android/src/main/java/com/RNFetchBlob/RNFetchBlobReq.java

                 Uri uri = Uri.parse(url);
                 DownloadManager.Request req = new DownloadManager.Request(uri);
                 req.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
-
-                if (options.addAndroidDownloads.hasKey("title")) {
+                if(options.addAndroidDownloads.hasKey("title")) {
                     req.setTitle(options.addAndroidDownloads.getString("title"));
                 }
-                if (options.addAndroidDownloads.hasKey("description")) {
+                if(options.addAndroidDownloads.hasKey("description")) {
                     req.setDescription(options.addAndroidDownloads.getString("description"));
                 }
+                if(options.addAndroidDownloads.hasKey("path")) {
+                    req.setDestinationUri(Uri.parse("file://" + options.addAndroidDownloads.getString("path")));
+                }
                 // set headers
                 ReadableMapKeySetIterator it = headers.keySetIterator();
                 while (it.hasNextKey()) {
                     String contentUri = c.getString(c.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));
                     Uri uri = Uri.parse(contentUri);
                     Cursor cursor = appCtx.getContentResolver().query(uri, new String[]{android.provider.MediaStore.Images.ImageColumns.DATA}, null, null, null);
+                    // use default destination of DownloadManager
                     if (cursor != null) {
                         cursor.moveToFirst();
                         String filePath = cursor.getString(0);
                         cursor.close();
                         this.callback.invoke(null, RNFetchBlobConst.RNFB_RESPONSE_PATH, filePath);
                     }
-                    else
-                        this.callback.invoke(null, null, null);
+                    // custom destination
+                    else {
+                        if(options.addAndroidDownloads.hasKey("path")) {
+                            try {
+                                String customDest = options.addAndroidDownloads.getString("path");
+                                boolean exists = new File(customDest).exists();
+                                if(!exists)
+                                    throw new Exception("Download manager download failed, the file does not downloaded to destination.");
+                                callback.invoke(null, RNFetchBlobConst.RNFB_RESPONSE_PATH, customDest);
+
+                            } catch(Exception ex) {
+                                this.callback.invoke(ex.getLocalizedMessage(), null, null);
+                            }
+                        }
+                    }
                 }
             }
         }

test/test-android.js

   })
 
 })
+
+// issue #74
+describe('download file to specific location using DownloadManager', (report, done) => {
+  let dest = dirs.DCIMDir + '/android-download-test-' +Date.now() + '.png'
+  RNFetchBlob.config({
+    addAndroidDownloads : {
+      useDownloadManager : true,
+      path : dest,
+      mime : 'image/png',
+      title : 'android-download-path-test.png',
+      description : 'download to specific path #74'
+    }
+  })
+  .fetch('GET', `${TEST_SERVER_URL}/public/github.png`)
+  .then((res) => fs.stat(res.path()))
+  .then((stat) => {
+    report(
+      <Assert key="file exists at the path"
+        expect={true} actual={true}/>,
+      <Assert key="file size correct"
+        expect="23975" actual={stat.size}/>)
+    done()
+  })