flutter-shared_preferences（持久化）

https://github.com/flutter/plugins/tree/master/packages/shared_preferences/shared_preferences

1.import 'package:shared_preferences/shared_preferences.dart';

2.

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';



class CartPage extends StatefulWidget {
  @override
  _CartPageState createState() => _CartPageState();
}

class _CartPageState extends State<CartPage> {

  List<String> testList=[];

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Column(
        children: <Widget>[
          Container(
            height: 500,
            child: ListView.builder(
              itemCount: testList.length,
              itemBuilder: (context,index){
                return ListTile(
                  title: Text('${testList[index]}'),
                );
              }
            ),
          ),
          RaisedButton(
            onPressed: (){_add();},
            child: Text('增加'),
          ),
          RaisedButton(
            onPressed: (){_delete();},
            child: Text('清空'),
          )
        ],
      ),
    );
  }

  //增加方法
  void _add() async{
    SharedPreferences prefs= await SharedPreferences.getInstance();
    String tem='吳夢嬌';
    testList.add(tem);
    prefs.setStringList('testInfo', testList);
    _show();
  }
  //顯示方法
  void _show() async{
    SharedPreferences prefs= await SharedPreferences.getInstance();
    setState(() {
      if(prefs.getStringList('testInfo') != null){
        testList=prefs.getStringList('testInfo');
      }
    });
  }
  // 刪除
  void _delete() async{
    SharedPreferences prefs= await SharedPreferences.getInstance();
    // prefs.clear();//刪除所有
    prefs.remove('testInfo');
    setState(() {
      testList=[];
    });
  }
}