引入 Rust \\TODO 使用 rust 实现的下载器

lib/common/rust/ffi.dart

@@ -0,0 +1,23 @@
+// This file initializes the dynamic library and connects it with the stub
+// generated by flutter_rust_bridge_codegen.
+
+import 'dart:ffi';
+
+import 'bridge_generated.dart';
+import 'bridge_definitions.dart';
+export 'bridge_definitions.dart';
+
+// Re-export the bridge so it is only necessary to import this file.
+export 'bridge_generated.dart';
+import 'dart:io' as io;
+
+
+const _base = 'rust';
+
+// On MacOS, the dynamic library is not bundled with the binary,
+// but rather directly **linked** against the binary.
+final _dylib = io.Platform.isWindows ? '$_base.dll' : 'lib$_base.so';
+
+final Rust rustFii = RustImpl(io.Platform.isIOS || io.Platform.isMacOS
+    ? DynamicLibrary.executable()
+    : DynamicLibrary.open(_dylib));