# IVS 聊天功能客户端消息收发 SDK：React 和 React Native 最佳实践
<a name="chat-sdk-react-best-practices"></a>

此文档说明了使用适用于 React 和 React Native 的 Amazon IVS 聊天功能消息收发 SDK 的最重要实践。利用这些信息，您应该能够在 React 应用程序中构建典型的聊天功能，此外还包括相关的背景知识，以帮助您更深入了解 IVS 聊天功能消息收发 SDK 的更高级部分。

## 创建聊天室初始化程序挂钩
<a name="chatroom-initializer-hook"></a>

`ChatRoom` 类包含核心的聊天方法和侦听器，用于管理连接状态和侦听各种事件，例如已收到消息和已删除消息。我们将在本教程中演示如何在挂钩中正确地存储聊天实例。

### 实施
<a name="chatroom-initializer-hook-implementation"></a>

------
#### [ TypeScript ]

```
// useChatRoom.ts

import React from 'react';
import { ChatRoom, ChatRoomConfig } from 'amazon-ivs-chat-messaging';

export const useChatRoom = (config: ChatRoomConfig) => {
  const [room] = React.useState(() => new ChatRoom(config));

  return { room };
};
```

------
#### [ JavaScript ]

```
import React from 'react';
import { ChatRoom } from 'amazon-ivs-chat-messaging';

export const useChatRoom = (config) => {
  const [room] = React.useState(() => new ChatRoom(config));

  return { room };
};
```

------

注意：我们不会使用来自 `setState` 挂钩的 `dispatch` 方法，因为您无法即时更新配置参数。SDK 会一次性创建实例，并且无法更新令牌提供者。

**重要提示**：一次使用 `ChatRoom` 初始化程序挂钩来初始化一个新的聊天室实例。

### 示例
<a name="chatroom-initializer-hook-example"></a>

**TypeScript/JavaScript**：

```
// ...

const MyChatScreen = () => {
  const userId = 'Mike';
  const { room } = useChatRoom({
    regionOrUrl: SOCKET_URL,
    tokenProvider: () => tokenProvider(ROOM_ID, ['SEND_MESSAGE']),
  });

  const handleConnect = () => {
    room.connect();
  };

  // ...
};

// ...
```

### 侦听连接状态
<a name="chatroom-initializer-hook-connection-state"></a>

您还可以在聊天室挂钩中订阅连接状态更新。

#### 实施
<a name="connection-state-implementation"></a>

------
#### [ TypeScript ]

```
// useChatRoom.ts

import React from 'react';
import { ChatRoom, ChatRoomConfig, ConnectionState } from 'amazon-ivs-chat-messaging';

export const useChatRoom = (config: ChatRoomConfig) => {
  const [room] = useState(() => new ChatRoom(config));

  const [state, setState] = React.useState<ConnectionState>('disconnected');

  React.useEffect(() => {
    const unsubscribeOnConnecting = room.addListener('connecting', () => {
      setState('connecting');
    });

    const unsubscribeOnConnected = room.addListener('connect', () => {
      setState('connected');
    });

    const unsubscribeOnDisconnected = room.addListener('disconnect', () => {
      setState('disconnected');
    });

    return () => {
      unsubscribeOnConnecting();
      unsubscribeOnConnected();
      unsubscribeOnDisconnected();
    };
  }, []);

  return { room, state };
};
```

------
#### [ JavaScript ]

```
// useChatRoom.js

import React from 'react';
import { ChatRoom } from 'amazon-ivs-chat-messaging';

export const useChatRoom = (config) => {
  const [room] = useState(() => new ChatRoom(config));

  const [state, setState] = React.useState('disconnected');

  React.useEffect(() => {
    const unsubscribeOnConnecting = room.addListener('connecting', () => {
      setState('connecting');
    });

    const unsubscribeOnConnected = room.addListener('connect', () => {
      setState('connected');
    });

    const unsubscribeOnDisconnected = room.addListener('disconnect', () => {
      setState('disconnected');
    });

    return () => {
      unsubscribeOnConnecting();
      unsubscribeOnConnected();
      unsubscribeOnDisconnected();
    };
  }, []);

  return { room, state };
};
```

------

## 聊天室实例提供者
<a name="chatroom-instance-provider"></a>

要在其他组件中使用挂钩（以避免道具钻取），您可以使用 React `context` 创建聊天室提供者。

### 实施
<a name="chatroom-instance-provider-implementation"></a>

------
#### [ TypeScript ]

```
// ChatRoomContext.tsx

import React from 'react';
import { ChatRoom } from 'amazon-ivs-chat-messaging';

const ChatRoomContext = React.createContext<ChatRoom | undefined>(undefined);

export const useChatRoomContext = () => {
  const context = React.useContext(ChatRoomContext);

  if (context === undefined) {
    throw new Error('useChatRoomContext must be within ChatRoomProvider');
  }

  return context;
};

export const ChatRoomProvider = ChatRoomContext.Provider;
```

------
#### [ JavaScript ]

```
// ChatRoomContext.jsx

import React from 'react';
import { ChatRoom } from 'amazon-ivs-chat-messaging';

const ChatRoomContext = React.createContext(undefined);

export const useChatRoomContext = () => {
  const context = React.useContext(ChatRoomContext);

  if (context === undefined) {
    throw new Error('useChatRoomContext must be within ChatRoomProvider');
  }

  return context;
};

export const ChatRoomProvider = ChatRoomContext.Provider;
```

------

### 示例
<a name="chatroom-instance-provider-example"></a>

创建 `ChatRoomProvider` 后，您可以通过 `useChatRoomContext` 来使用您的实例。

**重要提示**：请仅在您需要访问聊天屏幕和中间的其他组件之间的 `context` 时，才将提供者置于根级别，以避免在侦听连接时进行不必要的重新渲染。否则，应将提供者放置在尽可能靠近聊天屏幕的位置。

**TypeScript/JavaScript**：

```
// AppContainer

const AppContainer = () => {
  const { room } = useChatRoom({
    regionOrUrl: SOCKET_URL,
    tokenProvider: () => tokenProvider(ROOM_ID, ['SEND_MESSAGE']),
  });

  return (
    <ChatRoomProvider value={room}>
      <MyChatScreen />
    </ChatRoomProvider>
  );
};

// MyChatScreen

const MyChatScreen = () => {
  const room = useChatRoomContext();

  const handleConnect = () => {
    room.connect();
  };
  // ...
};

// ...
```

## 创建消息侦听器
<a name="message-listener"></a>

要及时了解所有传入的消息，您需要订阅 `message` 和 `deleteMessage` 事件。以下是一些为您的组件提供聊天消息的代码。

**重要提示**：为确保理想的性能，我们将 `ChatMessageContext` 与 `ChatRoomProvider` 分开，因为当聊天消息侦听器更新其消息状态时，我们可能会进行多次重新渲染。请记住要在您要使用 `ChatMessageProvider` 的组件中应用 `ChatMessageContext`。

### 实施
<a name="message-listener-implementation"></a>

------
#### [ TypeScript ]

```
// ChatMessagesContext.tsx

import React from 'react';
import { ChatMessage } from 'amazon-ivs-chat-messaging';
import { useChatRoomContext } from './ChatRoomContext';

const ChatMessagesContext = React.createContext<ChatMessage[] | undefined>(undefined);

export const useChatMessagesContext = () => {
  const context = React.useContext(ChatMessagesContext);

  if (context === undefined) {
    throw new Error('useChatMessagesContext must be within ChatMessagesProvider);
  }

  return context;
};

export const ChatMessagesProvider = ({ children }: { children: React.ReactNode }) => {
  const room = useChatRoomContext();

  const [messages, setMessages] = React.useState<ChatMessage[]>([]);

  React.useEffect(() => {
    const unsubscribeOnMessageReceived = room.addListener('message', (message) => {
      setMessages((msgs) => [message, ...msgs]);
    });

    const unsubscribeOnMessageDeleted = room.addListener('messageDelete', (deleteEvent) => {
      setMessages((prev) => prev.filter((message) => message.id !== deleteEvent.messageId));
    });

    return () => {
      unsubscribeOnMessageDeleted();
      unsubscribeOnMessageReceived();
    };
  }, [room]);

  return <ChatMessagesContext.Provider value={messages}>{children}</ChatMessagesContext.Provider>;
};
```

------
#### [ JavaScript ]

```
// ChatMessagesContext.jsx

import React from 'react';
import { useChatRoomContext } from './ChatRoomContext';

const ChatMessagesContext = React.createContext(undefined);

export const useChatMessagesContext = () => {
  const context = React.useContext(ChatMessagesContext);

  if (context === undefined) {
    throw new Error('useChatMessagesContext must be within ChatMessagesProvider);
  }

  return context;
};

export const ChatMessagesProvider = ({ children }) => {
  const room = useChatRoomContext();

  const [messages, setMessages] = React.useState([]);

  React.useEffect(() => {
    const unsubscribeOnMessageReceived = room.addListener('message', (message) => {
      setMessages((msgs) => [message, ...msgs]);
    });

    const unsubscribeOnMessageDeleted = room.addListener('messageDelete', (deleteEvent) => {
      setMessages((prev) => prev.filter((message) => message.id !== deleteEvent.messageId));
    });

    return () => {
      unsubscribeOnMessageDeleted();
      unsubscribeOnMessageReceived();
    };
  }, [room]);

  return <ChatMessagesContext.Provider value={messages}>{children}</ChatMessagesContext.Provider>;
};
```

------

### React 示例
<a name="message-listener-example-react"></a>

**重要提示**：请记住要用 `ChatMessagesProvider` 打包您的消息容器。`Message` 行是一个显示消息内容的示例组件。

**TypeScript/JavaScript**：

```
// your message list component...

import React from 'react';
import { useChatMessagesContext } from './ChatMessagesContext';

const MessageListContainer = () => {
  const messages = useChatMessagesContext();

  return (
    <React.Fragment>
      {messages.map((message) => (
        <MessageRow message={message} />
      ))}
    </React.Fragment>
  );
};
```

### React Native 示例
<a name="message-listener-example-react-native"></a>

`ChatMessage` 会默认包含 `id`，后者将在 `FlatList` 中自动用作每行的 React 键；因此，您无需传递 `keyExtractor`。

------
#### [ TypeScript ]

```
// MessageListContainer.tsx

import React from 'react';
import { ListRenderItemInfo, FlatList } from 'react-native';
import { ChatMessage } from 'amazon-ivs-chat-messaging';
import { useChatMessagesContext } from './ChatMessagesContext';

const MessageListContainer = () => {
  const messages = useChatMessagesContext();

  const renderItem = useCallback(({ item }: ListRenderItemInfo<ChatMessage>) => <MessageRow />, []);

  return <FlatList data={messages} renderItem={renderItem} />;
};
```

------
#### [ JavaScript ]

```
// MessageListContainer.jsx

import React from 'react';
import { FlatList } from 'react-native';
import { useChatMessagesContext } from './ChatMessagesContext';

const MessageListContainer = () => {
  const messages = useChatMessagesContext();

  const renderItem = useCallback(({ item }) => <MessageRow />, []);

  return <FlatList data={messages} renderItem={renderItem} />;
};
```

------

## 一个应用程序中的多个聊天室实例
<a name="multiple-chatroom-instances"></a>

如果您在应用程序中使用多个并发聊天室，我们建议为每个聊天创建一个提供者，并在聊天提供者中使用该提供者。在此例中，我们将创建一个帮助机器人和客户帮助聊天。我们将为两者分别创建了一个提供者。

------
#### [ TypeScript ]

```
// SupportChatProvider.tsx

import React from 'react';
import { SUPPORT_ROOM_ID, SOCKET_URL } from '../../config';
import { tokenProvider } from '../tokenProvider';
import { ChatRoomProvider } from './ChatRoomContext';
import { useChatRoom } from './useChatRoom';

export const SupportChatProvider = ({ children }: { children: React.ReactNode }) => {
  const { room } = useChatRoom({
    regionOrUrl: SOCKET_URL,
    tokenProvider: () => tokenProvider(SUPPORT_ROOM_ID, ['SEND_MESSAGE']),
  });

  return <ChatRoomProvider value={room}>{children}</ChatRoomProvider>;
};

// SalesChatProvider.tsx

import React from 'react';
import { SALES_ROOM_ID, SOCKET_URL } from '../../config';
import { tokenProvider } from '../tokenProvider';
import { ChatRoomProvider } from './ChatRoomContext';
import { useChatRoom } from './useChatRoom';

export const SalesChatProvider = ({ children }: { children: React.ReactNode }) => {
  const { room } = useChatRoom({
    regionOrUrl: SOCKET_URL,
    tokenProvider: () => tokenProvider(SALES_ROOM_ID, ['SEND_MESSAGE']),
  });

  return <ChatRoomProvider value={room}>{children}</ChatRoomProvider>;
};
```

------
#### [ JavaScript ]

```
// SupportChatProvider.jsx

import React from 'react';
import { SUPPORT_ROOM_ID, SOCKET_URL } from '../../config';
import { tokenProvider } from '../tokenProvider';
import { ChatRoomProvider } from './ChatRoomContext';
import { useChatRoom } from './useChatRoom';

export const SupportChatProvider = ({ children }) => {
  const { room } = useChatRoom({
    regionOrUrl: SOCKET_URL,
    tokenProvider: () => tokenProvider(SUPPORT_ROOM_ID, ['SEND_MESSAGE']),
  });

  return <ChatRoomProvider value={room}>{children}</ChatRoomProvider>;
};

// SalesChatProvider.jsx

import React from 'react';
import { SALES_ROOM_ID, SOCKET_URL } from '../../config';
import { tokenProvider } from '../tokenProvider';
import { ChatRoomProvider } from './ChatRoomContext';
import { useChatRoom } from './useChatRoom';

export const SalesChatProvider = ({ children }) => {
  const { room } = useChatRoom({
    regionOrUrl: SOCKET_URL,
    tokenProvider: () => tokenProvider(SALES_ROOM_ID, ['SEND_MESSAGE']),
  });

  return <ChatRoomProvider value={room}>{children}</ChatRoomProvider>;
};
```

------

### React 示例
<a name="multiple-chatroom-instances-example-react"></a>

您现在可以使用具有相同 `ChatRoomProvider` 的不同聊天提供者。稍后您可以在每个屏幕/视图中重复使用相同的 `useChatRoomContext`。

**TypeScript/JavaScript**：

```
// App.tsx / App.jsx

const App = () => {
  return (
    <Routes>
      <Route
        element={
          <SupportChatProvider>
            <SupportChatScreen />
          </SupportChatProvider>
        }
      />
      <Route
        element={
          <SalesChatProvider>
            <SalesChatScreen />
          </SalesChatProvider>
        }
      />
    </Routes>
  );
};
```

### React Native 示例
<a name="multiple-chatroom-instances-example-react-native"></a>

**TypeScript/JavaScript**：

```
// App.tsx / App.jsx

const App = () => {
  return (
    <Stack.Navigator>
      <Stack.Screen name="SupportChat">
        <SupportChatProvider>
          <SupportChatScreen />
        </SupportChatProvider>
      </Stack.Screen>
      <Stack.Screen name="SalesChat">
        <SalesChatProvider>
          <SalesChatScreen />
        </SalesChatProvider>
      </Stack.Screen>
    </Stack.Navigator>
  );
};
```

**TypeScript/JavaScript**：

```
// SupportChatScreen.tsx / SupportChatScreen.jsx

// ...

const SupportChatScreen = () => {
  const room = useChatRoomContext();

  const handleConnect = () => {
    room.connect();
  };

  return (
    <>
      <Button title="Connect" onPress={handleConnect} />
      <MessageListContainer />
    </>
  );
};

// SalesChatScreen.tsx / SalesChatScreen.jsx

// ...

const SalesChatScreen = () => {
  const room = useChatRoomContext();

  const handleConnect = () => {
    room.connect();
  };

  return (
    <>
      <Button title="Connect" onPress={handleConnect} />
      <MessageListContainer />
    </>
  );
};
```