feat：优化网络异常处理

lib/api/base_dio.dart

@@ -105,7 +105,7 @@ abstract class BaseDio {
       );
       onNetSuccess(response, successCallback, errorCallback);
     } on DioException catch (e) {
-      var result = await _handleHttpException(e.response);
+      var result = await _handleHttpException(e);
       // result 为null时，已调用重新登录方法 onLoginExpire，onLoginExpire需重写
       if (result != null) {
         await errorCallback?.call(result["code"], result["message"]);
@@ -146,7 +146,7 @@ abstract class BaseDio {
         return {"code": 400, "message": "数据解析错误"};
       }
     } on DioException catch (e) {
-      var result = await _handleHttpException(e.response);
+      var result = await _handleHttpException(e);
       // result 为null时，已调用重新登录方法 onLoginExpire，onLoginExpire需重写
       if (result != null) {
         return result;
@@ -184,7 +184,24 @@ abstract class BaseDio {
   }
 
   /// 处理http异常
-  Future<Map<String, dynamic>?> _handleHttpException(Response? response) async {
+  Future<Map<String, dynamic>?> _handleHttpException(DioException e) async {
+    switch (e.type) {
+      case DioExceptionType.connectionError:
+        return {"code": -500, "message": "网络连接异常，请检查网络设置"};
+      case DioExceptionType.connectionTimeout:
+        return {"code": -500, "message": "连接服务器超时，请稍后再试"};
+      case DioExceptionType.sendTimeout:
+        return {"code": -500, "message": "发送数据超时，请重试"};
+      case DioExceptionType.receiveTimeout:
+        return {"code": -500, "message": "接收数据超时，请重试"};
+      default:
+        return _handleHttpOtherException(e.response);
+    }
+  }
+
+  /// 其他异常处理
+  Future<Map<String, dynamic>?> _handleHttpOtherException(
+      Response? response) async {
     if (response == null) {
       return {"code": -500, "message": "网络请求错误，请稍后重试"};
     }