一个从底部弹出的省市三级联动选择器，直接上图
Screenshot_1542595177.png
直接贴代码
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'dart:convert';
typedef void ChangeData(Map map);
typedef List CreateWidgetList();
class CityPicker {
static void showCityPicker(
BuildContext context, {
ChangeData selectProvince,
ChangeData selectCity,
ChangeData selectArea,
}) {
rootBundle.loadString('data/province.json').then((v) {
List data = json.decode(v);
Navigator.push(
context,
new _CityPickerRoute(
data: data,
selectProvince: selectProvince,
selectCity: selectCity,
selectArea: selectArea,
theme: Theme.of(context, shadowThemeOnly: true),
barrierLabel:
MaterialLocalizations.of(context).modalBarrierDismissLabel),
);
});
}
}
class _CityPickerRoute extends PopupRoute {
final ThemeData theme;
final String barrierLabel;
final List data;
final ChangeData selectProvince;
final ChangeData selectCity;
final ChangeData selectArea;
_CityPickerRoute({
this.theme,
this.barrierLabel,
this.data,
this.selectProvince,
this.selectCity,
this.selectArea,
});
@override
Duration get transitionDuration => Duration(milliseconds: 2000);
@override
@override
Color get barrierColor => Colors.black54;
@override
bool get barrierDismissible => true;
AnimationController _animationController;
@override
AnimationController createAnimationController() {
assert(_animationController == null);
_animationController =
BottomSheet.createAnimationController(navigator.overlay);
return _animationController;
}
@override
Widget buildPage(BuildContext context, Animation animation,
Animation secondaryAnimation) {
Widget bottomSheet = new MediaQuery.removePadding(
removeTop: true,
context: context,
child: new _CityPickerWidget(
route: this,
data: data,
selectProvince: selectProvince,
selectCity: selectCity,
selectArea: selectArea,
),
);
if (theme != null) {
bottomSheet = new Theme(data: theme, child: bottomSheet);
}
return bottomSheet;
}
}
class _CityPickerWidget extends StatefulWidget {
final _CityPickerRoute route;
final List data;
final ChangeData selectProvince;
final ChangeData selectCity;
final ChangeData selectArea;
_CityPickerWidget(
{Key key,
@required this.route,
this.data,
this.selectProvince,
this.selectCity,
this.selectArea});
@override
State createState() {
return new _CityPickerState();
}
}
class _CityPickerState extends State<_CityPickerWidget> {
FixedExtentScrollController provinceController;
FixedExtentScrollController cityController;
FixedExtentScrollController areaController;
int provinceIndex = 0, cityIndex = 0, areaIndex = 0;
List province = new List();
List city = new List();
List area = new List();
@override
void initState() {
super.initState();
provinceController = new FixedExtentScrollController();
cityController = new FixedExtentScrollController();
areaController = new FixedExtentScrollController();
setState(() {
province = widget.data;
city = widget.data[provinceIndex]['sub'];
area = widget.data[provinceIndex]['sub'][cityIndex]['sub'];
});
}
Widget _bottomView() {
return new Container(
width: double.infinity,
color: Colors.white,
child: new Column(
children: [
new Expanded(
child: new Row(
children: [
FlatButton(
onPressed: () {
Navigator.pop(context);
},
child: new Text(
'取消',
style: new TextStyle(
color: Theme.of(context).primaryColor,
),
),
),
FlatButton(
onPressed: () {
Map provinceMap = {
"code": province[provinceIndex]['code'],
"name": province[provinceIndex]['name']
};
Map cityMap = {
"code": province[provinceIndex]['sub'][cityIndex]
['code'],
"name": province[provinceIndex]['sub'][cityIndex]
['name']
};
Map areaMap = {
"code": province[provinceIndex]['sub'][cityIndex]['sub']
[areaIndex]['code'],
"name": province[provinceIndex]['sub'][cityIndex]['sub']
[areaIndex]['name']
};
if (widget.selectProvince != null) {
widget.selectProvince(provinceMap);
}
if (widget.selectCity != null) {
widget.selectCity(cityMap);
}
if (widget.selectArea != null) {
widget.selectArea(areaMap);
}
Navigator.pop(context);
},
child: new Text(
'确定',
style: new TextStyle(
color: Theme.of(context).primaryColor,
),
),
),
],
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
),
flex: 1,
),
new Row(
children: [
new _MyCityPicker(
key: Key('province'),
controller: provinceController,
createWidgetList: () {
return province.map((v) {
return new Align(
child: new Text(
v['name'],
textScaleFactor: 1.2,
),
alignment: Alignment.centerLeft,
);
}).toList();
},
changed: (index) {
setState(() {
provinceIndex = index;
cityIndex = 0;
areaIndex = 0;
cityController.jumpToItem(0);
areaController.jumpToItem(0);
city = widget.data[provinceIndex]['sub'];
area =
widget.data[provinceIndex]['sub'][cityIndex]['sub'];
});
},
),
new _MyCityPicker(
key: Key('city'),
controller: cityController,
createWidgetList: () {
return city.map((v) {
return new Align(
child: new Text(
v['name'],
textScaleFactor: 1.2,
),
alignment: Alignment.centerLeft,
);
}).toList();
},
changed: (index) {
setState(() {
cityIndex = index;
areaIndex = 0;
areaController.jumpToItem(0);
area =
widget.data[provinceIndex]['sub'][cityIndex]['sub'];
});
},
),
new _MyCityPicker(
key: Key('area'),
controller: areaController,
createWidgetList: () {
return area.map((v) {
return new Align(
child: new Text(
v['name'],
textScaleFactor: 1.2,
),
alignment: Alignment.centerLeft,
);
}).toList();
},
changed: (index) {
setState(() {
areaIndex = index;
});
},
),
],
)
],
));
}
@override
Widget build(BuildContext context) {
return new GestureDetector(
child: new AnimatedBuilder(
animation: widget.route.animation,
builder: (BuildContext context, Widget child) {
return new ClipRect(
child: new CustomSingleChildLayout(
delegate: new _BottomPickerLayout(widget.route.animation.value),
child: new GestureDetector(
child: new Material(
color: Colors.transparent,
child: new Container(
width: double.infinity,
height: 260.0,
child: _bottomView(),
),
),
),
),
);
},
),
);
}
}
class _MyCityPicker extends StatefulWidget {
final CreateWidgetList createWidgetList;
final Key key;
final FixedExtentScrollController controller;
final ValueChanged changed;
_MyCityPicker(
{this.createWidgetList, this.key, this.controller, this.changed});
@override
State createState() {
return new _MyCityPickerState();
}
}
class _MyCityPickerState extends State<_MyCityPicker> {
List children;
@override
Widget build(BuildContext context) {
return new Expanded(
child: new Container(
padding: const EdgeInsets.all(6.0),
alignment: Alignment.center,
height: 220.0,
child: CupertinoPicker(
backgroundColor: Colors.white,
scrollController: widget.controller,
key: widget.key,
itemExtent: 30.0,
onSelectedItemChanged: (index) {
if (widget.changed != null) {
widget.changed(index);
}
},
children: widget.createWidgetList().length > 0
? widget.createWidgetList()
: [new Text('')],
),
),
flex: 1,
);
}
}
class _BottomPickerLayout extends SingleChildLayoutDelegate {
_BottomPickerLayout(this.progress, {this.itemCount, this.showTitleActions});
final double progress;
final int itemCount;
final bool showTitleActions;
@override
BoxConstraints getConstraintsForChild(BoxConstraints constraints) {
double maxHeight = 300.0;
return new BoxConstraints(
minWidth: constraints.maxWidth,
maxWidth: constraints.maxWidth,
minHeight: 0.0,
maxHeight: maxHeight,
);
}
@override
Offset getPositionForChild(Size size, Size childSize) {
double height = size.height - childSize.height * progress;
return new Offset(0.0, height);
}
@override
bool shouldRelayout(_BottomPickerLayout oldDelegate) {
return progress != oldDelegate.progress;
}
}
调用方式,采用接口回调的方式，当确定后可以返回选中的省市区信息，返回的具体数据格式Map
CityPicker.showCityPicker(
context,
selectProvince: (province) {
print(province);
},
selectCity: (city) {
print(city);
},
selectArea: (area) {
print(area);
},
);
选择具体的省市县后返回的具体数据格式可以在控制台查看
image.png
例子 代码