feat:增加消息记录功能

lib/models/im_message.dart

@@ -0,0 +1,61 @@
+import 'dart:convert';
+
+enum ImMessageType {
+  chatPrivate('CHAT_PRIVATE'),
+  chatGroup('CHAT_GROUP'),
+  online('ONLINE'),
+  heartbeat('HEARTBEAT'),
+  system('SYSTEM'),
+  notice('NOTICE');
+
+  final String value;
+
+  const ImMessageType(this.value);
+}
+
+class ImMessage {
+  final ImMessageType type;
+  final String from;
+  final String to;
+  final String content;
+
+  ImMessage({
+    required this.type,
+    required this.from,
+    required this.to,
+    required this.content,
+  });
+
+  factory ImMessage.fromJsonString(String json) {
+    return ImMessage.fromJson(jsonDecode(json));
+  }
+
+  factory ImMessage.fromJson(Map<String, dynamic> json) {
+    return ImMessage(
+      type: ImMessageType.values.firstWhere((e) => e.value == json['type']),
+      from: json['from'],
+      to: json['to'],
+      content: json['content'],
+    );
+  }
+
+  Map<String, dynamic> toJson() => {
+    'type': type.value,
+    'from': from,
+    'to': to,
+    'content': content,
+  };
+
+  String toJsonString() {
+    return jsonEncode(toJson());
+  }
+
+  static ImMessage online(int userId) {
+    return ImMessage(
+      type: ImMessageType.online,
+      from: userId.toString(),
+      to: 'SYSTEM',
+      content: '',
+    );
+  }
+}