为什么我在 Android post 之后一直收到错误 400？

Question

我正在构建一个使用用户凭据登录 Spotify 的应用程序。我关注这个 API 调用：https://developer.spotify.com/web-api/authorization-guide/#client_credentials_flow

这是实现代码：

@Override
protected Session doInBackground(String... params) {

    Session session = new Session();



    try {
        String response = "";
        URL url = new URL(GET_TOKEN_URL);
        HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();

        String credentials = params[0]+":"+params[1];
        String basicAuth ="Basic "+new String(android.util.Base64.encode(credentials.getBytes(), Base64.DEFAULT));

        Uri.Builder builder = new Uri.Builder()
                .appendQueryParameter(GRANT_TYPE, CLIENT_CREDENTIALS);
        String query = builder.build().getEncodedQuery();
        httpURLConnection.setRequestProperty(AUTH, basicAuth);
        httpURLConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
        httpURLConnection.setRequestProperty("Content-Language", "en-US");
        httpURLConnection.setDoInput(true);
        httpURLConnection.setUseCaches(false);
        httpURLConnection.setDoOutput(true);
        httpURLConnection.setRequestMethod(POST);


        httpURLConnection.connect();

        OutputStream os = httpURLConnection.getOutputStream();
        BufferedWriter writer = new BufferedWriter(
                new OutputStreamWriter(os, "UTF-8"));

        writer.write(query);
        writer.flush();
        writer.close();
        os.close();

        int responseCode=httpURLConnection.getResponseCode();

        session.setResponseCode(responseCode);

        if (responseCode == HttpsURLConnection.HTTP_OK) {
            String line;
            BufferedReader br=new BufferedReader(new InputStreamReader(httpURLConnection.getInputStream()));
            while ((line=br.readLine()) != null) {
                response+=line;
            }
        }else{
            Log.e(getClass().getSimpleName(), "RESPONSE:" + responseCode);
           // response = "Something went wrong";
        }
        Log.d(getClass().getSimpleName(), response);

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally{

    }
    return session;
}

但无论我更改什么，我总是收到错误 400。

我做错了什么？

更新：

我按照 Spotify Developer 网页的确切语法使用在线工具执行了 curl，我仍然有 HTTP STATUS 400

Answer 1

尝试更正以下错误

1) 更正您 else 中的拼写错误。 else后面不能有semi-colon。

2) 删除计算内容长度并添加 header 的代码。长度应该是 body 的长度，而不是您编码的查询字符串。如果您只是删除此代码，HttpUrlConnection class 应该会为您生成此 header。

3) 将授权类型参数放在body中。那就是文档所说的地方。你在查询字符串中有它。您应该可以使用以下代码：

String body =  GRANT_TYPE + "=" + CLIENT_CREDENTIALS;
byte[] bodyBytes = body.getBytes("UTF-8");
OutputStream stream = httpURLConnection.getOutputStream();
stream.write(bodyBytes);    
stream.close();

为什么我在 Android post 之后一直收到错误 400？

Why do I keep getting Error 400 after post in Android?

android

http-post

spotify

httpconnection