Flutter Widget之DataTable

Widget：https://flutter.io/docs/development/ui/widgets
DataTable：https://docs.flutter.io/flutter/material/DataTable-class.html
PaginatedDataTable：https://docs.flutter.io/flutter/material/PaginatedDataTable-class.html
DataColumn：https://docs.flutter.io/flutter/material/DataColumn-class.html
DataRow：https://docs.flutter.io/flutter/material/DataRow-class.html
DataCell：https://docs.flutter.io/flutter/material/DataCell-class.html

import 'package:flutter/material.dart';

class DataTableDemoPage extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => new _DataTableDemoPagePageState();
}

class _DataTableDemoPagePageState extends State<DataTableDemoPage> {
  //默认的行数
  int _defalutRowPageCount = PaginatedDataTable.defaultRowsPerPage;
  int _sortColumnIndex;
  bool _sortAscending = true;
  MyTable table = MyTable();

  //排序关联_sortColumnIndex,_sortAscending
  void _sort(Comparable getField(Shop s), int index, bool b) {
    table._sort(getField, b);
    setState(() {
      this._sortColumnIndex = index;
      this._sortAscending = b;
    });
  }

  List<DataColumn> getColumn() {
    return [
      DataColumn(label: Text('商品名'), onSort: (i, b) {_sort((Shop p) => p.name, i, b);}),
      DataColumn(label: Text('价格'), onSort: (i, b) {_sort((Shop p) => p.price, i, b);}),
      DataColumn(label: Text('库存'), onSort: (i, b) {_sort((Shop p) => p.number, i, b);}),
      DataColumn(label: Text('类型'), onSort: (i, b) {_sort((Shop p) => p.type, i, b);}),
    ];
  }

  @override
  void initState() {
    super.initState();
  }

  Widget build(BuildContext context) {
    return Scaffold(
        appBar: new AppBar(
          title: new Text('DataTable Demo'),
        ),
        body: getPaginatedDataTable(),
    );
  }

  Widget getPaginatedDataTable() {
    return SingleChildScrollView(
      child: PaginatedDataTable(
        rowsPerPage: _defalutRowPageCount,
        onRowsPerPageChanged: (value) {
          setState(() {
            _defalutRowPageCount = value;
          });
        },
        sortColumnIndex: _sortColumnIndex,
        initialFirstRowIndex: 0,
        sortAscending: _sortAscending,
        availableRowsPerPage: [
          5,10
        ],
        onPageChanged: (value) {
          print('$value');
        },
        onSelectAll: table.selectAll,
        header: Text('商品库存'),
        columns: getColumn(),
        source: table,
      ),
    );
  }
}

class MyTable extends DataTableSource {
  List _shops = [
    Shop('小米8', 100, '手机', 1699.0),
    Shop('华为P20', 50, '手机', 4999.0),
    Shop('华硕a61', 50, '电脑', 5700.0),
    Shop('iPhone7Plus耳机', 9999, '耳机', 60.0),
    Shop('iPhone7Plus256G', 1, '手机', 4760.0),
    Shop('金士顿8g内存条', 66, '内存条', 399.0),
    Shop('西门子洗衣机9.0kg', 890, '家电', 10399.0),
    Shop('三星66寸液晶智能电视', 800, '家电', 20389.0),
  ];

  int _selectCount = 0; //当前选中的行数
  bool _isRowCountApproximate = false; //行数确定

  @override
  DataRow getRow(int index) {
    //根据索引获取内容行
    if (index >= _shops.length || index < 0) throw FlutterError('Data Error!');
    //如果索引不在商品列表里面，抛出一个异常
    final Shop shop = _shops[index];
    return DataRow.byIndex(
        cells: [
          DataCell(Text(shop.name)),
          DataCell(Text('${shop.price}')),
          DataCell(Text('${shop.number}')),
          DataCell(Text(shop.type)),
        ],
        selected: shop.selected,
        index: index,
        onSelectChanged: (isSelected) {
          selectOne(index, isSelected);
        });
  }

  @override //是否行数不确定
  bool get isRowCountApproximate => _isRowCountApproximate;

  @override //有多少行
  int get rowCount => _shops.length;

  @override //选中的行数
  int get selectedRowCount => _selectCount;

  //选中单个
  void selectOne(int index, bool isSelected) {
    Shop shop = _shops[index];
    if (shop.selected != isSelected) {
      //如果选中就选中数量加一，否则减一
      _selectCount = _selectCount += isSelected ? 1 : -1;
      shop.selected = isSelected;
      //更新
      notifyListeners();
    }
  }
  //选中全部
  void selectAll(bool checked) {
    for (Shop _shop in _shops) {
      _shop.selected = checked;
    }
    _selectCount = checked ? _shops.length : 0;
    notifyListeners(); //通知监听器去刷新
  }

  //排序,
  void _sort(Comparable getField(Shop shop), bool b) {
    _shops.sort((s1, s2) {
      if (!b) { //两个项进行交换
        final Shop temp = s1;
        s1 = s2;
        s2 = temp;
      }
      final Comparable s1Value = getField(s1);
      final Comparable s2Value = getField(s2);
      return Comparable.compare(s1Value, s2Value);
    });
    notifyListeners();
  }
}

class Shop {
  final String name;
  final int number;
  final String type;
  final double price;
  bool selected = false; // 默认为未选中
  Shop(this.name, this.number, this.type, this.price,);
}