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Question

我想在长度为 2 的名为“Need Help”和“Help Requests”的应用程序中实现 Tab Bar。在“需要帮助”选项卡中，我想要我的第一个容器（即将数据上传到 Firestore 数据库），在“帮助请求”选项卡中，我想要我的第二个容器（即从 Firestore 数据库中检索数据）。我是 flutter 的新手，如果你能帮助我，我将不胜感激。

源代码：

import 'package:chat_app/group_chats/group_info.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';


import '../constants.dart';
import '../global_data.dart';

class FinancialRoom extends StatelessWidget {
  final String groupChatId, groupName;

  FinancialRoom({required this.groupName, required this.groupChatId, Key? key})
      : super(key: key);

  final FirebaseFirestore _firestore = FirebaseFirestore.instance;
  final FirebaseAuth _auth = FirebaseAuth.instance;
  final _formKey = GlobalKey<FormState>();
  TextEditingController amountValue = TextEditingController();

  void onSend() async {
    Map<String, dynamic> data = {
      "amount": amountValue.text,
      "sendBy": _auth.currentUser!.displayName,
      "type": "text",
      "time": FieldValue.serverTimestamp(),
    };

    amountValue.clear();

    await _firestore
        .collection('groups')
        .doc(groupChatId)
        .collection('chats')
        .add(data);
  }


  @override
  Widget build(BuildContext context) {
    final Size size = MediaQuery.of(context).size;

    return Scaffold(
      appBar: AppBar(
        title: Text(groupName),
        actions: [
          IconButton(
              onPressed: () => Navigator.of(context).push(
                MaterialPageRoute(
                  builder: (_) => GroupInfo(
                    groupName: groupName,
                    groupId: groupChatId,
                  ),
                ),
              ),
              icon: Icon(Icons.more_vert)),
        ],
      ),
      body: SafeArea(
        child: ListView(padding: EdgeInsets.all(20.0), children: [
          Container(
            key: _formKey,
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                SizedBox(
                  height: 10.0,
                ),
                TextFormField(
                  controller: amountValue,
                  decoration: InputDecoration(
                    hintText: 'Enter the amount you want',
                    labelText: 'Enter the amount you want',
                    prefixIcon: Icon(Icons.account_balance_wallet_outlined),
                    enabledBorder: kEnabledBorder,
                    focusedBorder: kFocusedBorder,
                    errorBorder: kErrorBorder,
                    focusedErrorBorder: kErrorBorder,
                  ),
                  onTap: () {
                  },
                  // The validator receives the text that the user has entered.
                  validator: (value) {
                    if (value!.isEmpty) {
                      return 'Please enter the amount you want';
                    }
                    return null;
                  },
                ),

                SizedBox(
                  height: kInputSpacing,
                ),
                SizedBox(
                  width: double.infinity,
                  child: FlatButton(
                    shape: RoundedRectangleBorder(
                        borderRadius: BorderRadius.circular(10.0)),
                    color: Colors.blue,
                    textColor: Colors.white,
                    padding: EdgeInsets.only(top: 16.0, bottom: 16.0),
                    onPressed: onSend,
                    child: Text(
                      'SEND',
                      style: kButtonTextStyle,
                    ),
                  ),
                ),
              ],
            ),
          ),
          Container(
            height: size.height / 1.27,
            width: size.width,
            child: StreamBuilder<QuerySnapshot>(
              stream: _firestore
                  .collection('groups')
                  .doc(groupChatId)
                  .collection('chats')
                  .orderBy('time')
                  .snapshots(),
              builder: (context, snapshot) {
                if (snapshot.hasData) {
                  return ListView.builder(
                    itemCount: snapshot.data!.docs.length,
                    itemBuilder: (context, index) {
                      Map<String, dynamic> data =
                      snapshot.data!.docs[index].data()
                      as Map<String, dynamic>;

                      return messageTile(size, data);
                    },
                  );
                } else {
                  return Container();
                }
              },
            ),
          ),
        ]),
      ),
    );
  }
  Widget messageTile(Size size, Map<String, dynamic> data) {
    return Builder(builder: (_) {
      if (data['type'] == "text") {
        return Container(
          width: size.width,
          alignment: data['sendBy'] == _auth.currentUser!.displayName
              ? Alignment.centerRight
              : Alignment.centerLeft,
          child: Container(
              padding: EdgeInsets.symmetric(vertical: 8, horizontal: 14),
              margin: EdgeInsets.symmetric(vertical: 5, horizontal: 8),
              decoration: BoxDecoration(
                borderRadius: BorderRadius.circular(15),
                color: Colors.blue,
              ),
              child: Column(
                children: [
                  Text(
                    data['sendBy'],
                    style: TextStyle(
                      fontSize: 12,
                      fontWeight: FontWeight.w500,
                      color: Colors.white,
                    ),
                  ),
                  SizedBox(
                    height: size.height / 200,
                  ),
                  Text(
                    data['amount'],
                    style: TextStyle(
                      fontSize: 16,
                      fontWeight: FontWeight.w500,
                      color: Colors.white,
                    ),
                  ),
                ],
              )),
        );
      } else if (data['type'] == "img") {
        return Container(
          width: size.width,
          alignment: data['sendBy'] == _auth.currentUser!.displayName
              ? Alignment.centerRight
              : Alignment.centerLeft,
          child: Container(
            padding: EdgeInsets.symmetric(vertical: 10, horizontal: 14),
            margin: EdgeInsets.symmetric(vertical: 5, horizontal: 8),
            height: size.height / 2,
            child: Image.network(
              data['amount'],
            ),
          ),
        );
      } else if (data['type'] == "notify") {
        return Container(
          width: size.width,
          alignment: Alignment.center,
          child: Container(
            padding: EdgeInsets.symmetric(vertical: 8, horizontal: 8),
            margin: EdgeInsets.symmetric(vertical: 5, horizontal: 8),
            decoration: BoxDecoration(
              borderRadius: BorderRadius.circular(5),
              color: Colors.black38,
            ),
            child: Text(
              data['message'],
              style: TextStyle(
                fontSize: 14,
                fontWeight: FontWeight.bold,
                color: Colors.white,
              ),
            ),
          ),
        );
      } else {
        return SizedBox();
      }
    });
  }

}

Answer 1

在您的应用中实现一个简单的 TabBar 非常简单。您只需要一个 TabController 和两个名为 TabBar 和 TabBarView 的小部件。这是一个简单的例子：

DefaultTabController(
  length: 2,
  child: Scaffold(
    appBar: AppBar(
      bottom: TabBar(tabs: [
        Tab(text: 'Tab 1'),
        Tab(text: 'Tab 2'),
      ]),
    ),
    body: TabBarView(children: [
      // Tab 1
      Container(color: Colors.red),
      // Tab 2
      Container(color: Colors.blue),
    ]),
  ),
);

现在您需要做的就是将 TabBarView 中的 children 替换为您想要显示的内容。

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Tab Bar in Flutter

tabs

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