如何使用http库捕获SocketException？

这个问题已经被其他人指出过（比如here https://stackoverflow.com/questions/32810051/cannot-catch-socketexception）。虽然我可能已经明白了原因，但是在使用更高级别的时候仍然没有找到解决方案http图书馆。 例如：

import 'package:http/http.dart';

// yes, pwd is String, it's just a test...
Future<Response> login(String user, String pwd) {
  final authHeader = encodeBasicCredentials(user, pwd);
  return get(
    'http://192.168.0.100:8080/login',
    headers: <String, String>{
    HttpHeaders.AUTHORIZATION: authHeader,
    },
  ));
}

我找不到捕捉的方法SocketException例如，如果无法访问主机（在我的例子中，主机 IP 错误），则会抛出该错误。 我尝试过包裹await in try/catch，或使用Future.catchError.

这是异常的堆栈跟踪：

[ERROR:topaz/lib/tonic/logging/dart_error.cc(16)] Unhandled exception:
E/flutter ( 4036): SocketException: OS Error: Connection refused, errno = 111, address = 192.168.0.100, port = 35588
E/flutter ( 4036): #0      IOClient.send (package:http/src/io_client.dart:30:23)
E/flutter ( 4036): <asynchronous suspension>
E/flutter ( 4036): #1      BaseClient._sendUnstreamed (package:http/src/base_client.dart:171:38)
E/flutter ( 4036): <asynchronous suspension>
E/flutter ( 4036): #2      BaseClient.get (package:http/src/base_client.dart:34:5)
E/flutter ( 4036): #3      get.<anonymous closure> (package:http/http.dart:47:34)
E/flutter ( 4036): #4      _withClient (package:http/http.dart:167:20)
E/flutter ( 4036): <asynchronous suspension>
E/flutter ( 4036): #5      get (package:http/http.dart:47:3)

你可以改变login to be async以便您可以等待回复。这允许您捕获异常（例如，返回null而不是Response).

Future<Response> login(String user, String pwd) async {
  final String authHeader = encodeBasicCredentials(user, pwd);
  try {
    return await get(
        'http://192.168.0.100:8080/login',
        headers: {
          HttpHeaders.AUTHORIZATION: authHeader,
        },
      );
  } catch (e) {
    print(e);
    return null;
  }
}