如何在flutter中使用url编码的正文发出HTTP POST请求?

问题描述：

我正在尝试以 url 编码的内容类型在 flutter 中发出 post 请求.当我编写 body : json.encode(data) 时，它会编码为纯文本.

I'm trying to make an post request in flutter with content type as url encoded. When I write body : json.encode(data), it encodes to plain text.

如果我写 body: data 我得到错误 type '_InternalLinkedHashMap'不是类型转换中String"类型的子类型

If I write body: data I get the error type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'String' in type cast

这是数据对象

var match = {
  "homeTeam": {"team": "Team A"},
  "awayTeam": {"team": "Team B"}
};

还有我的要求

var response = await post(Uri.parse(url),
    headers: {
      "Accept": "application/json",
      "Content-Type": "application/x-www-form-urlencoded"
    },
    body: match,
    encoding: Encoding.getByName("utf-8"));

答

您需要添加三个额外的步骤:首先，您需要将 JSON 映射转换为字符串(使用 json.encode)然后，如果要将其作为 application/x-www-form-urlencoded 发送，则需要对其进行 Uri 编码.最后，您需要为要发布的参数指定名称.

You need to add three additional steps: First, you need to convert the JSON map to a String (using json.encode) Then you need to Uri encode it if you want to send it as application/x-www-form-urlencoded. Lastly, you need to give the parameter that you are posting a name.

例如(注意，这里使用的是dart:io HttpClient，但基本相同):

For example (note, this is using the dart:io HttpClient, but it's basically the same):

  Future<HttpClientResponse> foo() async {
    Map<String, dynamic> jsonMap = {
      'homeTeam': {'team': 'Team A'},
      'awayTeam': {'team': 'Team B'},
    };
    String jsonString = json.encode(jsonMap); // encode map to json
    String paramName = 'param'; // give the post param a name
    String formBody = paramName + '=' + Uri.encodeQueryComponent(jsonString);
    List<int> bodyBytes = utf8.encode(formBody); // utf8 encode
    HttpClientRequest request =
        await _httpClient.post(_host, _port, '/a/b/c');
    // it's polite to send the body length to the server
    request.headers.set('Content-Length', bodyBytes.length.toString());
    // todo add other headers here
    request.add(bodyBytes);
    return await request.close();
  }

以上是针对dart:io版本的(当然，你可以在Flutter中使用)如果您想坚持使用 package:http 版本，那么您需要稍微调整一下您的 Map.body 必须是 Map.你需要决定你想要什么作为你的 POST 参数.你想要两个:homeTeam 和 awayTeam?或者一个，比如说teamJson?

The above is for the dart:io version (which, of course, you can use in Flutter) If you would like to stick with the package:http version, then you need to tweak your Map a bit. body must be a Map<String, String>. You need to decide what you want as your POST parameters. Do you want two: homeTeam and awayTeam? or one, say, teamJson?

此代码

  Map<String, String> body = {
    'name': 'doodle',
    'color': 'blue',
    'homeTeam': json.encode(
      {'team': 'Team A'},
    ),
    'awayTeam': json.encode(
      {'team': 'Team B'},
    ),
  };

  Response r = await post(
    url,
    body: body,
  );

在电线上产生这个

name=doodle&color=blue&homeTeam=%7B%22team%22%3A%22Team+A%22%7D&awayTeam=%7B%22team%22%3A%22Team+B%22%7D>

name=doodle&color=blue&homeTeam=%7B%22team%22%3A%22Team+A%22%7D&awayTeam=%7B%22team%22%3A%22Team+B%22%7D

或者，这个

  Map<String, String> body = {
    'name': 'doodle',
    'color': 'blue',
    'teamJson': json.encode({
      'homeTeam': {'team': 'Team A'},
      'awayTeam': {'team': 'Team B'},
    }),
  };

  Response r = await post(
    url,
    body: body,
  );

在电线上产生这个

name=doodle&color=blue&teamJson=%7B%22homeTeam%22%3A%7B%22team%22%3A%22Team+A%22%7D%2C%22awayTeam%22%3A%7B%22team%22%3A%22团队+B%22%7D%7D

name=doodle&color=blue&teamJson=%7B%22homeTeam%22%3A%7B%22team%22%3A%22Team+A%22%7D%2C%22awayTeam%22%3A%7B%22team%22%3A%22Team+B%22%7D%7D

package:http 客户端负责:对 Uri.encodeQueryComponent 进行编码，utf8 编码(注意这是默认的，所以不需要指定它)并在 Content-Length 中发送长度标题.您仍然必须进行json编码.

the package:http client takes care of: encoding the Uri.encodeQueryComponent, utf8 encoding (note that that's the default, so no need to specify it) and sending the length in the Content-Length header. You must still do the json encoding.

如何在flutter中使用url编码的正文发出HTTP POST请求?

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