我正在尝试在flutter上运行插件flutter_map。代码如下：
import 'package:flutter_map/flutter_map.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new FlutterMap(
layers: [
new TileLayerOptions(urlTemplate:'https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png')
],
);
}
}
但是在设备上运行代码后，出现以下错误：
Performing hot reload...
Syncing files to device SM J510FN...
I/flutter (14355): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (14355): The following NoSuchMethodError was thrown building LayoutBuilder:
I/flutter (14355): The getter 'plugins' was called on null.
I/flutter (14355): Receiver: null
I/flutter (14355): Tried calling: plugins
I/flutter (14355):
I/flutter (14355): When the exception was thrown, this was the stack:
I/flutter (14355): #0 Object.noSuchMethod (dart:core/runtime/libobject_patch.dart:50:5)
I/flutter (14355): #1 FlutterMapState.build.<anonymous closure>.<anonymous closure> (package:flutter_map/src/map/flutter_map_state.dart:53:62)
I/flutter (14355): #2 MappedListIterable.elementAt (dart:_internal/iterable.dart:414:29)
I/flutter (14355): #3 ListIterable.toList (dart:_internal/iterable.dart:219:19)
I/flutter (14355): #4 FlutterMapState.build.<anonymous closure> (package:flutter_map/src/map/flutter_map_state.dart:54:12)
I/flutter (14355): #5 _LayoutBuilderElement._layout.<anonymous closure> (package:flutter/src/widgets/layout_builder.dart:111:26)
I/flutter (14355): #6 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2253:19)
I/flutter (14355): #7 _LayoutBuilderElement._layout (package:flutter/src/widgets/layout_builder.dart:107:11)
I/flutter (14355): #8 RenderObject.invokeLayoutCallback.<anonymous closure> (package:flutter/src/rendering/object.dart:1728:58)
I/flutter (14355): #9 PipelineOwner._enableMutationsToDirtySubtrees (package:flutter/src/rendering/object.dart:797:15)
I/flutter (14355): #10 RenderObject.invokeLayoutCallback (package:flutter/src/rendering/object.dart:1728:13)
I/flutter (14355): #11 _RenderLayoutBuilder.performLayout (package:flutter/src/widgets/layout_builder.dart:205:5)
I/flutter (14355): #12 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (14355): #13 RenderView.performLayout (package:flutter/src/rendering/view.dart:151:13)
I/flutter (14355): #14 RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1507:7)
I/flutter (14355): #15 PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:766:18)
I/flutter (14355): #16 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:329:19)
I/flutter (14355): #17 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:701:13)
I/flutter (14355): #18 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:268:5)
I/flutter (14355): #19 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:988:15)
I/flutter (14355): #20 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:928:9)
I/flutter (14355): #21 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:749:7)
I/flutter (14355): #23 _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)
I/flutter (14355): #24 _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)
I/flutter (14355): #25 _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
I/flutter (14355): (elided one frame from package dart:async)
I/flutter (14355): ════════════════════════════════════════════════════════════════════════════════════════════════════
Reloaded 206 of 637 libraries in 7,394ms.
我在做什么错？请注意，我是flutter的新手，这是我在flutter主页提供的教程之后的第一次试用。
答案 0 :(得分：3)
首先确保pubspec.yaml具有：
dependencies:
flutter:
sdk: flutter
flutter_map: ^0.8.1
...并且您已经在Android Studio中运行了GET PACKAGES（我认为那是您在此处使用的功能）
然后，使用ESRI地图进行尝试，例如：
Widget build(BuildContext context) {
return new FlutterMap(
options: new MapOptions(
center: new LatLng(40.0, -120.0),
zoom: 8.0,
),
layers: [
TileLayerOptions(
urlTemplate:
'https://server.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer/tile/{z}/{y}/{x}',
subdomains: ['a', 'b', 'c'],
tileProvider: CachedNetworkTileProvider(),
),
],
);
}
此外，这是与传单一起使用的地图的绝佳资源：
答案 1 :(得分：0)
MaterialApp(
debugShowCheckedModeBanner: false,
home: Scaffold(
body: Center(
child: Container(
child: FlutterMap(
options: MapOptions(
plugins: [
DragMarkerPlugin(),
],
center: LatLng(23.77441, 90.41153),
zoom: 16.4,
),
layers: [
TileLayerOptions(
urlTemplate:
//'https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',
'https://www.gebco.net/data_and_products/gebco_web_services/north_polar_view_wms/mapserv?',
subdomains: [
'a',
'b',
'c',
],
),
PolylineLayerOptions(polylines: _polylines),
DragMarkerPluginOptions(
markers: <DragMarker>[
DragMarker(
point: LatLng(23.7744, 90.4115),
width: 80.0,
height: 80.0,
offset: Offset(0.0, -8.0),
builder: (ctx) => Container(
child: Icon(Icons.location_on,
size: 50, color: Colors.blueAccent),
),
onDragStart: (details, point) =>
print("Drag Start point $point"),
onDragEnd: (details, point) =>
print("Drag End point $point"),
// onDragUpdate: (details, point) {
// print("on Drag Update $point");
// },
// onTap: (point) {
// print("on tap $point");
// },
// onLongPress: (point) {
// print("on long press $point");
// },
feedbackBuilder: (ctx) => Container(
child: Icon(
Icons.edit_location,
size: 75,
color: Colors.redAccent,
),
),
feedbackOffset: Offset(0.0, -18.0),
updateMapNearEdge: false,
nearEdgeRatio: 2.0,
nearEdgeSpeed: 1.0,
),
DragMarker(
point: LatLng(23.7745, 90.4116),
width: 80.0,
height: 80.0,
builder: (ctx) => Container(
child: Icon(
Icons.location_on,
color: Colors.green,
size: 50,
),
),
onDragStart: (details, point) =>
print("Drag Start point $point"),
onDragEnd: (details, point) {
print('Finished Drag $details $point');
},
updateMapNearEdge: false,
),
],
),
// PolylineLayerOptions(
// polylines: [
// Polyline(
// points: points,
// strokeWidth: 2.0,
// color: Colors.red,
// )
// ],
// ),
],
children: [
Align(
alignment: Alignment.bottomRight,
child: Column(
children: <Widget>[
button(_onMapTypeButtonPressed, Icons.map, "btn1"),
SizedBox(
height: 16.0,
),
button(_getCurrentLocation, Icons.location_searching,
"btn3"),
],
),
),
],
),
),
),
),
);