Question

在我的 flutter 项目中，我需要在调用 API 时发生套接字异常时显示一些插图图像。我该怎么做？

提前致谢

Answer 1

这取决于您想在小部件树中的哪个位置显示它。一个简单的例子是将一个新屏幕推送到导航堆栈上。您将需要在可能发生异常的函数中使用 BuildContext。

 {
      artist: { mbid: '', '#text': 'Tyler, The Creator' },
      '@attr': { nowplaying: 'true' },
      mbid: '',
      album: { mbid: '', '#text': 'CALL ME IF YOU GET LOST' },
      streamable: '0',
      url: 'https://www.last.fm/music/Tyler,+The+Creator/_/SWEET+%2F+I+THOUGHT+YOU+WANTED+TO+DANCE+(feat.+Brent+Faiyaz+&+Fana+Hues)',
      name: 'SWEET / I THOUGHT YOU WANTED TO DANCE (feat. Brent Faiyaz & Fana Hues)',
      image: [
        {
          size: 'small',
          '#text': 'https://lastfm.freetls.fastly.net/i/u/34s/8bed6cc4a2f68d3bb2228fbe6654b887.gif'
        },
        {
          size: 'medium',
          '#text': 'https://lastfm.freetls.fastly.net/i/u/64s/8bed6cc4a2f68d3bb2228fbe6654b887.gif'
        },
        {
          size: 'large',
          '#text': 'https://lastfm.freetls.fastly.net/i/u/174s/8bed6cc4a2f68d3bb2228fbe6654b887.gif'
        },
        {
          size: 'extralarge',
          '#text': 'https://lastfm.freetls.fastly.net/i/u/300x300/8bed6cc4a2f68d3bb2228fbe6654b887.gif'
        }
      ]
    }

另一个示例是根据布尔值将其添加到您的小部件树中。抛出异常时，您将该 bool 设置为 true。

void someMethod(BuildContext context) {
    try {
      //some code that might throw an exception
    } on Exception catch (_) {
      Navigator.pushNamed(context, "Your illustration view");
    }
  }

在您的小部件树中使用它，如下所示：

void someOtherMethod() {
    try {
      //some code that might throw an exception
    } on Exception catch (_) {
      setState(() {
      hasThrownError = true; 
      });
    }
  }

Answer 2

这将有助于解决套接字异常和格式异常。

为 httpresponse 创建模型类

class HTTPResponse<T> {
  bool isSuccessful;
  T data;
  String message;
  int responseCode;
  HTTPResponse(this.isSuccessful, this.data, {this.message, this.responseCode});
}

然后像这样在 api 响应中使用这个模型

Future<HTTPResponse<List<Post>>> getPosts(
      {int limit = 20, int page = 1}) async {
    String url =
        'https://jsonplaceholder.typicode.com/posts?_limit=$limit&_page=$page';
    Uri uri = Uri.parse(url);

    try {
      var response = await http.get(uri);
      if (response.statusCode == 200) {
        var body = json.decode(response.body);
        List<Post> postsList = [];
        body.forEach((e) {
          Post post = Post.fromJson(e);
          postsList.add(post);
        });
        return HTTPResponse(
          true,
          postsList,
          responseCode: response.statusCode,
        );
      } else {
        return HTTPResponse(false, null,
            message: 'Invalid response from server',
            responseCode: response.statusCode);
      }
    } on SocketException {
      return HTTPResponse(false, [], message: 'Unable to reach the internet');
    } on FormatException {
      return HTTPResponse(false, [], message: 'Invalid response from server');
    } catch (e) {
      return HTTPResponse(false, [],
          message: "Something went wrong please try in a minute or two");
    }
  }

如何在颤振中创建套接字异常的屏幕？

2 个答案: