Flutter学习(8)——CheckBox多选框使用及动态更改多选框数据

原文地址:Flutter学习(8)——CheckBox多选框使用及动态更改多选框数据 | Stars-One的杂货小窝

最近项目需求需要调整页面,记录一下实现过程

这次主要是要实现个评价页面,选择不同的星级显示不同的多选框数据,加上之前也没有使用过CheckBox,今天便是一起讲吧

效果预览

效果看似有点复杂,我们一步步来实现吧

1.星级组件使用

首先,我们有使用到星级评分组件在pubspec.yaml文件中添加下面依赖

flutter_simple_rating_bar: ^0.0.3

使用的话页面也是有个例子介绍,我们直接拿来即可使用

RatingBar(

		//默认选择5星

		rating: 5,

        //总星星数目

        starCount: 5,

        //星星图标

        icon: Icon(

            Icons.star,

            size: 40,

            color: Colors.grey,

        ),

        spacing: 5.0,

        size: 40,

        isIndicator: false,

        //是否可选半星

        allowHalfRating: true,

        onRatingCallback:(double value, ValueNotifier<bool> isIndicator) {

	        //value是点击后选中的星星数(即评分),范围为1-rating(我们上面rating为5)

        },

        color: Colors.amber,

)

现在我们要根据选择的数目不同,从而显示不同的文字,这过程是动态的,所以我们选择使用StatefulWidget作为页面继承的基类

我们先在State类中加上相应的数据,如下所示

//显示的文字信息

List typeList = ["非常不满意", "不满意", "基本满意", "满意", "非常满意"];

//当前选择type的下标

int selectType = 4;

我们文字显示内容是typeList[selectType],我们在星级评分选择的回调函数,更改selecType即可实现更改UI的功能

Column(

    children: [

        RatingBar(

            rating: 5,

            //默认选择5星

            starCount: 5,

            //总星星数目

            //星星图标

            icon: Icon(

                Icons.star,

                size: 40,

                color: Colors.grey,

            ),

            spacing: 5.0,

            size: 40,

            isIndicator: false,

            //是否可选半星

            allowHalfRating: true,

            onRatingCallback:

            (double value, ValueNotifier<bool> isIndicator) {

                //更改数据同时也要更改UI,所以使用setState方法

                setState(() {

                    //注意 星级从1开始,selectType是下标,从0开始,需要减1

                    selectType = value.toInt() - 1;

                });

            },

            color: Colors.amber,

        ),

        //取指定下标的文字内容展示

        Text(typeList[selectType])

    ],

)

2.多选框使用及数据更改

CheckBox多选框的使用需要定义一个bool类型的数据,每次点击需要更改此数据来改变CheckBox的选择状态

由于我们是使用的列表数据，所以每个数据写个变量不太现实,而且繁琐,所以可以考虑在实体类中加个bool类型的字段,用来存储CheckBox选择的状态

这里,数据我就暂且写死,实际上是要通过调用接口获取的

void initTagData() {

    var data = """{

    "code":200,

    "error":"",

    "ReturnValue":[{"generalstars":"1","tagid":"109759610348409856","tagname":"无理由超过法定办理时间","updatetime":"2020-06-12 17:38:00"},{"generalstars":"1","tagid":"6176177900787350","tagname":"在办事指南之外增加新的审批条件","updatetime":"2020-08-27 00:00:00"},{"generalstars":"1","tagid":"6176177900787351","tagname":"需提供办事指南之外的申报材料","updatetime":"2020-08-27 00:00:00"},{"generalstars":"1","tagid":"7176177890787535","tagname":"无理由超过法定办理时间","updatetime":"2020-08-27 00:00:00"},{"generalstars":"2","tagid":"6176177900787349","tagname":"未在承诺时间内办结","updatetime":"2020-08-27 00:00:00"},{"generalstars":"2","tagid":"6176177900787347","tagname":"没有提供材料样本","updatetime":"2020-08-27 00:00:00"},{"generalstars":"2","tagid":"6176177900787348","tagname":"没有提供材料清单","updatetime":"2020-08-27 00:00:00"},{"generalstars":"3","tagid":"119596473292723200","tagname":"22222","updatetime":"2020-06-12 17:38:00"},{"generalstars":"3","tagid":"6176177900787346","tagname":"在承诺的时间内办结","updatetime":"2020-08-27 00:00:00"},{"generalstars":"3","tagid":"6176177900787345","tagname":"提供申报材料样本","updatetime":"2020-08-27 00:00:00"},{"generalstars":"3","tagid":"6176177900787344","tagname":"一次性告知需要补正的材料","updatetime":"2020-08-27 00:00:00"},{"generalstars":"4","tagid":"6176177900787340","tagname":"填写一张表单就可以完成申报","updatetime":"2020-08-27 00:00:00"},{"generalstars":"4","tagid":"6176177900787341","tagname":"在线提交材料窗口核验","updatetime":"2020-08-27 00:00:00"},{"generalstars":"4","tagid":"6176177900787342","tagname":"一张清单告知全部申报材料","updatetime":"2020-08-27 00:00:00"},{"generalstars":"5","tagid":"7176177890787335","tagname":"一窗受理一次办结","updatetime":"2020-08-27 00:00:00"},{"generalstars":"5","tagid":"7176177890787235","tagname":"可以先受理后补材料","updatetime":"2020-08-27 00:00:00"},{"generalstars":"5","tagid":"7176177890787435","tagname":"不用提交证明","updatetime":"2020-08-27 00:00:00"}]

    }""";

    Map<String, dynamic> responseData = jsonDecode(data);

    var tagListModel = TagListModel.fromJson(responseData);

    if (tagListModel.code == 200) {

      //注意要使用setState,才会使UI发生变化(因为网络请求是耗时任务,可能界面渲染完毕后才能请求到数据)

      setState(() {

        tagList.addAll(tagListModel.tagItems);

      });

    }

  }

TagListModel是生成的实体类,生成的步骤已经在上篇文章讲解到,这里就不在赘述了

按照上面说的思路,我们在TagListModel的实体类中(其实是在TagItem中),添加一个bool类型的字段,用来作为存储CheckBox选择的状态,

这里使用插件生成的实体类(TagListModel里面还包含有个实体类),原本应该是ReturnValue,但为了方便,我将其改了个名字TagItem

Flutter中的CheckBox是只有一个框,并不包含文字,所以我们得组合一个文本,拼成一个Widget,_tagView()这个方法就是每个选项

Widget _tagView(item) {

    var str = item.tagname;

    return InkWell(

        child: Row(

            children: <Widget>[

                Checkbox(

                    value: item.flag,

                    activeColor: Colors.blue,

                    onChanged: (bool val) {

                        // val 是布尔值

                        this.setState(() {

                            item.flag = val;

                        });

                    },

                ),

                Text(str),

            ],

        ),

        onTap: () {

            setState(() {

                item.flag = !item.flag;

            });

        },

   );

这里最外层使用了InkWell,是因为其有onTag的点击事件方法 点击整行都可以去改变CheckBox的状态,用户体验比较友好,如果没有的话,只能点击CheckBox的框来改变状态

有了上面的一个子项,现在我们需要构建一个多选选项列表(列表包含N个_tagView组件)

先声明两个数组,用来存放数据

//标签数据(存放所有数据)

List<TagItem> tagList = [];

//临时存放的数据,后面评价提交需要

List<TagItem> tempTagList = [];

这里为什么需要两个数组呢?

主要是考虑到后面需要获取勾选的数据,所以才考虑再多加一个临时的列表

每次改变星级的时候,列表选项的数据就会改变,之后我们只需要去这个临时列表中筛选状态为true的数据即可

List<Widget> _tagList() {

    List<Widget> widgetList = [];

    var list = this.tagList;

    tempTagList.clear();

    var star = selectType.toInt() + 1;

    //匹配相同星级数据

    for (var i = 0; i < list.length; i++) {

      var item = list[i];

      if (item.generalstars == star.toString()) {

        //存在临时表中,之后可以快速查找用户的选择

        tempTagList.add(item);

        var row = _tagView(item);

        widgetList.add(row);

      }

    }

    return widgetList;

}

由于数据较少,可以使用Column用来包裹上面的组件_tagList

//标签选项

Container(

    decoration: BoxDecoration(color: Colors.white),

    padding: EdgeInsets.fromLTRB(10, 0, 15, 5),

    child: Column(

    	children: _tagList(),

    )

)

由于提交标签需要传标签的id,而且需要逗号隔开,所以需要遍历临时选项列表,处理一下即可

//处理标签

var tagId = "";

for (var i = 0; i < tempTagList.length; i++) {

    var item = tempTagList[i];

    //查找选择的标签数据

    if (item.flag) {

        tagId += item.tagid + ",";

    }

}

if (tagId.length>0) {

	tagId = tagId.substring(0, tagId.length - 1);

}

print(tagId);

源码

import 'dart:convert';

import 'package:flutter/material.dart';

import 'package:flutter_demo/model/tag_list_model.dart';

import 'package:flutter_simple_rating_bar/flutter_simple_rating_bar.dart';

class CheckBoxPage extends StatefulWidget {

  @override

  State<StatefulWidget> createState() {

    return new CheckBoxState();

  }

}

class CheckBoxState extends State<CheckBoxPage> {

  //标签数据

  List<TagItem> tagList = [];

  //临时标签,后面评价提交需要

  List<TagItem> tempTagList = [];

  List typeList = ["非常不满意", "不满意", "基本满意", "满意", "非常满意"];

  //当前选择type的下标

  int selectType = 4;

  @override

  void initState() {

    //初始化数据(这里是暂时写死,实际中这里是调用接口)

    initTagData();

  }

  void initTagData() {

    var data = """{

    "code":200,

    "error":"",

    "ReturnValue":[{"generalstars":"1","tagid":"109759610348409856","tagname":"无理由超过法定办理时间","updatetime":"2020-06-12 17:38:00"},{"generalstars":"1","tagid":"6176177900787350","tagname":"在办事指南之外增加新的审批条件","updatetime":"2020-08-27 00:00:00"},{"generalstars":"1","tagid":"6176177900787351","tagname":"需提供办事指南之外的申报材料","updatetime":"2020-08-27 00:00:00"},{"generalstars":"1","tagid":"7176177890787535","tagname":"无理由超过法定办理时间","updatetime":"2020-08-27 00:00:00"},{"generalstars":"2","tagid":"6176177900787349","tagname":"未在承诺时间内办结","updatetime":"2020-08-27 00:00:00"},{"generalstars":"2","tagid":"6176177900787347","tagname":"没有提供材料样本","updatetime":"2020-08-27 00:00:00"},{"generalstars":"2","tagid":"6176177900787348","tagname":"没有提供材料清单","updatetime":"2020-08-27 00:00:00"},{"generalstars":"3","tagid":"119596473292723200","tagname":"22222","updatetime":"2020-06-12 17:38:00"},{"generalstars":"3","tagid":"6176177900787346","tagname":"在承诺的时间内办结","updatetime":"2020-08-27 00:00:00"},{"generalstars":"3","tagid":"6176177900787345","tagname":"提供申报材料样本","updatetime":"2020-08-27 00:00:00"},{"generalstars":"3","tagid":"6176177900787344","tagname":"一次性告知需要补正的材料","updatetime":"2020-08-27 00:00:00"},{"generalstars":"4","tagid":"6176177900787340","tagname":"填写一张表单就可以完成申报","updatetime":"2020-08-27 00:00:00"},{"generalstars":"4","tagid":"6176177900787341","tagname":"在线提交材料窗口核验","updatetime":"2020-08-27 00:00:00"},{"generalstars":"4","tagid":"6176177900787342","tagname":"一张清单告知全部申报材料","updatetime":"2020-08-27 00:00:00"},{"generalstars":"5","tagid":"7176177890787335","tagname":"一窗受理一次办结","updatetime":"2020-08-27 00:00:00"},{"generalstars":"5","tagid":"7176177890787235","tagname":"可以先受理后补材料","updatetime":"2020-08-27 00:00:00"},{"generalstars":"5","tagid":"7176177890787435","tagname":"不用提交证明","updatetime":"2020-08-27 00:00:00"}]

    }""";

    Map<String, dynamic> responseData = jsonDecode(data);

    var tagListModel = TagListModel.fromJson(responseData);

    if (tagListModel.code == 200) {

      //注意要使用setState,才会使UI发生变化(因为网络请求是耗时任务,可能界面渲染完毕后才能请求到数据)

      setState(() {

        tagList.addAll(tagListModel.tagItems);

      });

    }

  }

  @override

  Widget build(BuildContext context) {

    return Scaffold(

      appBar: AppBar(

        title: Text("评价"),

      ),

      body: Column(

        children: [

          Container(

            decoration: BoxDecoration(color: Colors.white),

            padding: EdgeInsets.fromLTRB(15, 0, 15, 10),

            child: Wrap(

              spacing: 10,

              children: [

                Center(

                  child: Column(

                    children: [

                      RatingBar(

                        rating: 5,

                        //默认选择5星

                        starCount: 5,

                        //总星星数目

                        //星星图标

                        icon: Icon(

                          Icons.star,

                          size: 40,

                          color: Colors.grey,

                        ),

                        spacing: 5.0,

                        size: 40,

                        isIndicator: false,

                        //是否可选半星

                        allowHalfRating: true,

                        onRatingCallback:

                            (double value, ValueNotifier<bool> isIndicator) {

                          //更改数据同时也要更改UI,所以使用setState方法

                          setState(() {

                            //注意 星级从1开始,selectType是下标,从0开始,需要减1

                            selectType = value.toInt() - 1;

                          });

                        },

                        color: Colors.amber,

                      ),

                      _tipText()

                    ],

                  ),

                )

              ],

            ),

          ),

          //标签选项

          Container(

              decoration: BoxDecoration(color: Colors.white),

              padding: EdgeInsets.fromLTRB(10, 0, 15, 5),

              child: Column(

                children: _tagList(),

              )),

          Container(

              decoration: BoxDecoration(color: Colors.white),

              padding: EdgeInsets.fromLTRB(10, 0, 15, 5),

              child: FlatButton(

                child: Text("提交"),

                onPressed: () {

                  //处理标签

                  var tagId = "";

                  for (var i = 0; i < tempTagList.length; i++) {

                    var item = tempTagList[i];

                    //查找选择的标签数据

                    if (item.flag) {

                      tagId += item.tagid + ",";

                    }

                  }

                  if (tagId.length>0) {

                    tagId = tagId.substring(0, tagId.length - 1);

                  }

                  print(tagId);

                },

              )),

        ],

      ),

    );

  }

  Widget _tipText() {

    //根据selectType变更UI

    return Text(typeList[selectType]);

  }

  List<Widget> _tagList() {

    List<Widget> widgetList = [];

    var list = this.tagList;

    tempTagList.clear();

    var star = selectType.toInt() + 1;

    for (var i = 0; i < list.length; i++) {

      var item = list[i];

      if (item.generalstars == star.toString()) {

        //存在临时表中,之后可以快速查找用户的选择

        tempTagList.add(item);

        var row = _tagView(item);

        widgetList.add(row);

      }

    }

    return widgetList;

  }

  Widget _tagView(item) {

    var str = item.tagname;

    return InkWell(

      child: Row(

        children: <Widget>[

          Checkbox(

            value: item.flag,

            activeColor: Colors.blue,

            onChanged: (bool val) {

              // val 是布尔值

              this.setState(() {

                item.flag = val;

              });

            },

          ),

          Text(str),

        ],

      ),

      onTap: () {

        setState(() {

          item.flag = !item.flag;

        });

      },

    );

  }

}