Flutter (Dart 2) 访问推特 GET api

Question

我在 Flutter 应用程序中调用 Twitter api 时遇到问题。我已经使用 Twitter 登录库来获取我的令牌和秘密令牌，并且我有我的消费者和消费者秘密。但我无法正确形成 https 请求。我尝试过使用 Oauth2 客户端和直接请求，但都没有用。

我发现 this 带有 dart 1 Twitter 和 Oauth 实现的 repo，但我一直无法弄清楚如何将其转换为 Dart 2。非常感谢所有帮助。

编辑：这是最新的代码：

final response = await http.get(new Uri.https(
        "api.twitter.com", "/1.1/statuses/home_timeline.json", {
      "count": "200",
      "tweet_mode": "extended",
      "exclude_replies": "false"
    }), headers: {
      "Authorization": 'Bearer ${twitter.token}', //twitter.token is the token recieved from Twitter sign in process
      "Content-Type": "application/json"
    });

returns "errors":[{"code":89,"message":"Invalid or expired token."}] 我知道令牌有效

编辑 2：

Future<List<Tweet>> getTimeline() async {
    print("Getting timeline");
    var query = https.get(
        "https://api.twitter.com/1.1/statuses/home_timeline.json?count=2&tweet_mode=extended&exclude_replies=false",
    headers: {
      "Authorization":
          'oauth_consumer_key="$_consumerKey", oauth_token="${twitter.token}"',
      "Content-Type": "application/json"
    }).timeout(Duration(seconds: 15));

    print("Before await");
    final response = await query;
    print("code: ${response.statusCode}");
    ...
}

经过更多调试后，twitter.token 可能出现空异常。修复后，我仍然收到错误的授权数据。我会继续尝试向 header 添加更多信息，看看是否有帮助。

编辑 3：

这是我生成签名的方法：

static String generateSignature(String method, String base, List<String> sortedItems) {
    String sig = '$method&${Uri.encodeComponent(base)}&';
    String param = '';

    for (int i = 0; i < sortedItems.length; i++) {
      if (i == 0)
        param = sortedItems[i];
      else
        param += '&${sortedItems[i]}';
    }

    sig += Uri.encodeComponent(param);
    String key = '${Uri.encodeComponent(_secretKey)}&${Uri.encodeComponent(twitter.secret)}';
    var digest = Hmac(sha1, utf8.encode(key)).convert(utf8.encode(sig));
    print("base: ${digest.bytes}");
    print("sig: ${base64.encode(digest.bytes)}");
    return base64.encode(digest.bytes);
  }

时间线方法如下：

Future<List<Tweet>> getTimeline() async {
    print("Getting timeline");
    Future<http.Response> query;

    try {
      String base = 'https://api.twitter.com/1.1/statuses/home_timeline.json';
      String count = 'count=2';
      String mode = 'tweet_mode=extended';
      String replies = 'exclude_replies=false';
      String oauthConsumer = 'oauth_consumer_key="$_consumerKey"';
      String oauthToken = 'oauth_token="${twitter.token}"';
      String oauthNonce = 'oauth_nonce="${randomAlphaNumeric(20)}"';
      String oauthVersion = 'oauth_version="1.0"';
      String oauthTime =
      'oauth_timestamp="${DateTime.now().millisecondsSinceEpoch}"';
      String oauthMethod = 'oauth_signature_method="HMAC-SHA1"';
      String oauthSig = 'oauth_signature="${generateSignature("GET", base, [
    count,
    replies,
    oauthConsumer,
    oauthNonce,
    oauthTime,
    oauthToken,
    oauthVersion,
    mode
  ])}"';

  query = http.get(
      new Uri.https("api.twitter.com", "/1.1/statuses/home_timeline.json", {
        "count": "2",
        "tweet_mode": "extended",
        "exclude_replies": "false"
      }),
      headers: {
        "Authorization": '$oauthConsumer, $oauthToken, $oauthVersion, $oauthTime, $oauthNonce, $oauthMethod, $oauthSig',
        "Content-Type": "application/json"
      }).timeout(Duration(seconds: 15));
} catch (e) {
  print(e);
}

谢谢！

Answer 1

这是 Twitter 用户身份验证的文档：https://developer.twitter.com/en/docs/basics/authentication/overview/3-legged-oauth

前 3 个步骤由 flutter_twitter_login 处理。看看最后一个例子：

Step 4: Using these credentials for app-user required requests

Example POST statuses/update

Request includes:

POST statuses/update.json

oauth_consumer_key=cChZNFj6T5R0TigYB9yd1w

oauth_token=7588892-kagSNqWge8gB1WwE3plnFsJHAZVfxWD7Vb57p0b4

另一个例子可以在这里找到：https://developer.twitter.com/en/docs/tweets/post-and-engage/api-reference/post-statuses-update

$ curl --request POST 
--url 'https://api.twitter.com/1.1/statuses/update.json?
status=Test%20tweet%20using%20the%20POST%20statuses%2Fupdate%20endpoint' 
--header 'authorization: OAuth oauth_consumer_key="YOUR_CONSUMER_KEY",
oauth_nonce="AUTO_GENERATED_NONCE", oauth_signature="AUTO_GENERATED_SIGNATURE",
oauth_signature_method="HMAC-SHA1", oauth_timestamp="AUTO_GENERATED_TIMESTAMP",
oauth_token="USERS_ACCESS_TOKEN", oauth_version="1.0"' 
--header 'content-type: application/json'

我不确定您是否需要所有这些参数，但是 header 对于一个简单的 get 请求可能至少需要这个：

headers: {
  "Authorization": 'oauth_consumer_key="${consumerKey}", oauth_token="${twitter.token}"', 
  "Content-Type": "application/json"
}

Answer 2

这是最终运行的代码：

生成字符串方法：

static String generateSignature(
      String method, String base, List<String> sortedItems) {
    String param = '';

    for (int i = 0; i < sortedItems.length; i++) {
      if (i == 0)
        param = sortedItems[i];
      else
        param += '&${sortedItems[i]}';
    }

    String sig =
        '$method&${Uri.encodeComponent(base)}&${Uri.encodeComponent(param)}';
    String key =
        '${Uri.encodeComponent(_secretKey)}&${Uri.encodeComponent(twitter.secret)}';
    var digest = Hmac(sha1, utf8.encode(key)).convert(utf8.encode(sig));
    return base64.encode(digest.bytes);
  }

twitter get 调用的便捷方法：

Future<http.Response> _twitterGet(
      String base, List<List<String>> params) async {
    if (twitter == null) await _startSession();

    String oauthConsumer =
        'oauth_consumer_key="${Uri.encodeComponent(_consumerKey)}"';
    String oauthToken = 'oauth_token="${Uri.encodeComponent(twitter.token)}"';
    String oauthNonce =
        'oauth_nonce="${Uri.encodeComponent(randomAlphaNumeric(42))}"';
    String oauthVersion = 'oauth_version="${Uri.encodeComponent("1.0")}"';
    String oauthTime =
        'oauth_timestamp="${(DateTime.now().millisecondsSinceEpoch / 1000).toString()}"';
    String oauthMethod =
        'oauth_signature_method="${Uri.encodeComponent("HMAC-SHA1")}"';
    var oauthList = [
      oauthConsumer.replaceAll('"', ""),
      oauthNonce.replaceAll('"', ""),
      oauthMethod.replaceAll('"', ""),
      oauthTime.replaceAll('"', ""),
      oauthToken.replaceAll('"', ""),
      oauthVersion.replaceAll('"', "")
    ];
    var paramMap = Map<String, String>();

    for (List<String> param in params) {
      oauthList.add(
          '${Uri.encodeComponent(param[0])}=${Uri.encodeComponent(param[1])}');
      paramMap[param[0]] = param[1];
    }

    oauthList.sort();
    String oauthSig =
        'oauth_signature="${Uri.encodeComponent(generateSignature("GET", "https://api.twitter.com$base", oauthList))}"';

    return await http
        .get(new Uri.https("api.twitter.com", base, paramMap), headers: {
      "Authorization":
          'Oauth $oauthConsumer, $oauthNonce, $oauthSig, $oauthMethod, $oauthTime, $oauthToken, $oauthVersion',
      "Content-Type": "application/json"
    }).timeout(Duration(seconds: 15));
  }

调用示例：

Future<User> getUser(String tag) async {
    String base = '/1.1/users/show.json';
    final response = await _twitterGet(base, [
      ["screen_name", tag],
      ["tweet_mode", "extended"]
    ]);

    if (response.statusCode == 200) {
      try {
        return User(json.decode(response.body));
      } catch (e) {
        print(e);
        return null;
      }
    } else {
      print("Error retrieving user");
      print(response.body);
      return null;
    }
  }

Flutter (Dart 2) 访问推特 GET api

Flutter (Dart 2) accessing twitter GET api

twitter

flutter

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