环信即时通讯 im_flutter_sdk 快速入门

通过本文可以实现一个集成聊天 SDK 的简单 app。

实现原理

下图展示在客户端发送和接收一对一文本消息的工作流程。

img

如上图所示,发送和接收单聊消息的步骤如下:

  1. 客户端向你的应用服务器请求 Token,你的应用服务器返回 Token。
  2. 客户端 A 和客户端 B 使用获得的 Token 登录环信即时通讯系统。
  3. 客户端 A 发送消息到环信即时通讯服务器。
  4. 环信即时通讯服务器将消息发送到客户端 B,客户端 B 接收消息。

前提条件

如果你的目标平台是iOS,你需要满足一下要求:

  • Flutter 2.10 或 以上版本;
  • Dart 2.16 或 以上版本;
  • macOS;
  • Xcode 12.4 或 以上版本;
  • CocoaPods;
  • iOS 10 或以上版本模拟器或真机。

如果你的目标平台是Android,需要满足以下要求:

  • Flutter 2.10 或 以上版本;
  • Dart 2.16 或 以上版本;
  • macOS 或 windows;
  • Android Studio 4.0 或以上版本,包括 JDK 1.8 或以上版本;
  • Android SDK API 等级 21 或以上版本;

配置开发或者运行环境如果遇到问题,请参考这里

项目设置

使用命令创建项目

打开终端,进入需要创建项目的目录,输入命令进行 flutter create 项目创建:

flutter create quick_start

设置 Android

  1. 打开文件 quick_start/android/app/build.gradle 在文件最后添加:
android {
    defaultConfig {
        minSdkVersion 21
    }
}
  1. quick_start/android/app/proguard-rules.pro 中设置免混淆规则:
-keep class com.hyphenate.** {*;}
-dontwarn  com.hyphenate.**

设置 iOS

打开文件 quick_start/ios/Runner.xcodeproj,然后:

  1. 找到 TARGETS > RunnerGeneralDeployment Info 中修改最低版本为 iOS 10.0

集成 SDK

在终端命令行,输入命令添加依赖:

cd quick_start
flutter pub add im_flutter_sdk
flutter pub get

添加示例代码

打开 quick_start/lib/main.dart 文件,引入头文件:

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

修改 _MyHomePageState 代码:

class _MyHomePageState extends State<MyHomePage> {
  // 测试用 Appkey
  final String appKey = "easemob-demo#easeim";
  ScrollController scrollController = ScrollController();
  String _username = "";
  String _password = "";
  String _messageContent = "";
  String _chatId = "";
  final List<String> _logText = [];

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Container(
        padding: const EdgeInsets.only(left: 10, right: 10),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          mainAxisSize: MainAxisSize.max,
          children: [
            TextField(
              decoration: const InputDecoration(hintText: "Enter username"),
              onChanged: (username) => _username = username,
            ),
            TextField(
              decoration: const InputDecoration(hintText: "Enter password"),
              onChanged: (password) => _password = password,
            ),
            const SizedBox(height: 10),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
              children: [
                Expanded(
                  flex: 1,
                  child: TextButton(
                    onPressed: _signIn,
                    child: const Text("SIGN IN"),
                    style: ButtonStyle(
                      foregroundColor: MaterialStateProperty.all(Colors.white),
                      backgroundColor:
                          MaterialStateProperty.all(Colors.lightBlue),
                    ),
                  ),
                ),
                const SizedBox(width: 10),
                Expanded(
                  child: TextButton(
                    onPressed: _signOut,
                    child: const Text("SIGN OUT"),
                    style: ButtonStyle(
                      foregroundColor: MaterialStateProperty.all(Colors.white),
                      backgroundColor:
                          MaterialStateProperty.all(Colors.lightBlue),
                    ),
                  ),
                ),
                const SizedBox(width: 10),
                Expanded(
                  child: TextButton(
                    onPressed: _signUp,
                    child: const Text("SIGN UP"),
                    style: ButtonStyle(
                      foregroundColor: MaterialStateProperty.all(Colors.white),
                      backgroundColor:
                          MaterialStateProperty.all(Colors.lightBlue),
                    ),
                  ),
                ),
              ],
            ),
            const SizedBox(height: 10),
            TextField(
              decoration: const InputDecoration(
                  hintText: "Enter recipient's user name"),
              onChanged: (chatId) => _chatId = chatId,
            ),
            TextField(
              decoration: const InputDecoration(hintText: "Enter message"),
              onChanged: (msg) => _messageContent = msg,
            ),
            const SizedBox(height: 10),
            TextButton(
              onPressed: _sendMessage,
              child: const Text("SEND TEXT"),
              style: ButtonStyle(
                foregroundColor: MaterialStateProperty.all(Colors.white),
                backgroundColor: MaterialStateProperty.all(Colors.lightBlue),
              ),
            ),
            Flexible(
              child: ListView.builder(
                controller: scrollController,
                itemBuilder: (_, index) {
                  return Text(_logText[index]);
                },
                itemCount: _logText.length,
              ),
            ),
          ],
        ),
      ),
    );
  }

  void _initSDK() async {
  }

  void _addChatListener() {
  }

  void _signIn() async {
  }

  void _signOut() async {
  }

  void _signUp() async {
  }

  void _sendMessage() async {
  }

  void _addLogToConsole(String log) {
    _logText.add(_timeString + ": " + log);
    setState(() {
      scrollController.jumpTo(scrollController.position.maxScrollExtent);
    });
  }

  String get _timeString {
    return DateTime.now().toString().split(".").first;
  }
}

初始化 SDK

_initSDK 方法中添加 SDK 初始化:

  void _initSDK() async {
    EMOptions options = EMOptions(
      appKey: appKey,
      autoLogin: false,
    );
    await EMClient.getInstance.init(options);
    // 告诉sdk ui已经准备好,执行后才会收到`EMChatRoomManagerListener`, `EMContactManagerListener`, `EMGroupManagerListener` 回调。
    await EMClient.getInstance.startCallback();
  }

添加 注册环信Id 代码

Demo 中使用 sdk 注册环信id,在真实环境中,可以由你的后台调用环信rest api,

_signUp 方法中添加登录代码。

void _signUp() async {
  if (_username.isEmpty || _password.isEmpty) {
    _addLogToConsole("username or password is null");
    return;
  }

  try {
    _addLogToConsole("begin create account...");
    await EMClient.getInstance.createAccount(_username, _password);
    _addLogToConsole("create account succeed, username: $_username");
  } on EMError catch (e) {
    _addLogToConsole(
        "create account failed, code: ${e.code}, desc: ${e.description}");
  }
}

添加登录

_signIn 方法中添加登录代码。

  void _signIn() async {
    if (_username.isEmpty || _password.isEmpty) {
      _addLogToConsole("username or password is null");
      return;
    }

    String? agoraToken = await HttpRequestManager.loginToAppServer(
      username: _username,
      password: _password,
    );
    if (agoraToken != null) {
      _addLogToConsole("fetch agora token succeed, begin login");
      try {
        await EMClient.getInstance.loginWithAgoraToken(_username, agoraToken);
        _addLogToConsole("login succeed, username: $_username");
      } on EMError catch (e) {
        _addLogToConsole(
            "login failed, code: ${e.code}, desc: ${e.description}");
      }
    } else {
      _addLogToConsole("fetch agora token failed");
    }
  }

添加退出

_signOut 方法中添加退出代码。

  void _signOut() async {
    try {
      await EMClient.getInstance.logout(true);
      _addLogToConsole("sign out succeed");
    } on EMError catch (e) {
      _addLogToConsole(
          "sign out failed, code: ${e.code}, desc: ${e.description}");
    }
  }

添加发消息

_sendMessage 方法中添加发消息代码。

  void _sendMessage() async {
    if (_chatId.isEmpty || _messageContent.isEmpty) {
      _addLogToConsole("single chat id or message content is null");
      return;
    }

    var msg = EMMessage.createTxtSendMessage(
      targetId: _chatId,
      content: _messageContent,
    );
    msg.setMessageStatusCallBack(MessageStatusCallBack(
      onSuccess: () {
        _addLogToConsole("send message succeed");
      },
      onError: (e) {
        _addLogToConsole(
          "send message failed, code: ${e.code}, desc: ${e.description}",
        );
      },
    ));
    EMClient.getInstance.chatManager.sendMessage(msg);
  }

添加收消息监听

_addChatListener 方法中添加代码。

  void _addChatListener() {
    EMClient.getInstance.chatManager.addChatManagerListener(this);
  }

移除消息监听

iniState 方法下方添加代码移除监听:

  @override
  void dispose() {
    EMClient.getInstance.chatManager.removeChatManagerListener(this);
    super.dispose();
  }

接收消息

接收消息需要对象继承 EMChatManagerDelegate 并实现相关的回调方法,同时将对象加入到监听列表中。

示例代码如下:

class _MyHomePageState extends State<MyHomePage>
    implements EMChatManagerListener {

  ...

@override
  void onCmdMessagesReceived(List<EMMessage> messages) {}

  @override
  void onConversationRead(String from, String to) {}

  @override
  void onConversationsUpdate() {}

  @override
  void onGroupMessageRead(List<EMGroupMessageAck> groupMessageAcks) {}

  @override
  void onMessagesDelivered(List<EMMessage> messages) {}

  @override
  void onMessagesRead(List<EMMessage> messages) {}

  @override
  void onMessagesRecalled(List<EMMessage> messages) {}

  @override
  void onMessageReactionDidChange(List<EMMessageReactionEvent> list) {}
  
  @override
  void onMessagesReceived(List<EMMessage> messages) {
    for (var msg in messages) {
      switch (msg.body.type) {
        case MessageType.TXT:
          {
            EMTextMessageBody body = msg.body as EMTextMessageBody;
            _addLogToConsole(
              "receive text message: ${body.content}, from: ${msg.from}",
            );
          }
          break;
        case MessageType.IMAGE:
          {
            _addLogToConsole(
              "receive image message, from: ${msg.from}",
            );
          }
          break;
        case MessageType.VIDEO:
          {
            _addLogToConsole(
              "receive video message, from: ${msg.from}",
            );
          }
          break;
        case MessageType.LOCATION:
          {
            _addLogToConsole(
              "receive location message, from: ${msg.from}",
            );
          }
          break;
        case MessageType.VOICE:
          {
            _addLogToConsole(
              "receive voice message, from: ${msg.from}",
            );
          }
          break;
        case MessageType.FILE:
          {
            _addLogToConsole(
              "receive image message, from: ${msg.from}",
            );
          }
          break;
        case MessageType.CUSTOM:
          {
            _addLogToConsole(
              "receive custom message, from: ${msg.from}",
            );
          }
          break;
        case MessageType.CMD:
          {
            // 当前回调中不会有 CMD 类型消息,CMD 类型消息通过 `EMChatManagerListener#onCmdMessagesReceived` 回调接收
          }
          break;
      }
    }
  }
}

运行项目

以 iOS 为例,首先打开模拟器,之后在终端输入。

flutter run

Libraries

im_flutter_sdk