Okhttp3 请求返回空响应以及与 Postman 不同的标头

Question

我正在尝试从这个 URL https://fantasy.premierleague.com/drf/elements 解析 JSON，但我从 okhttp 和 Postman 得到的响应是不同的。我还使用了在线 API 测试器，并且在那里我得到了完整的 JSON 响应。我不确定为什么我的代码不起作用。

谁能帮我解决这个问题？

这是我用于快速测试的代码。

    val request = Request.Builder()
            .url("https://fantasy.premierleague.com/drf/elements")
            .get()
            .addHeader("accept", "*/*")
            .addHeader("accept-encoding", "gzip, deflate")
            .addHeader("cache-control", "no-cache")
            .addHeader("connection", "keep-alive")
            .cacheControl(CacheControl.FORCE_NETWORK)
            .build()

    val httpClient = OkHttpClient()
    httpClient.newCall(request).enqueue(object : okhttp3.Callback {
        override fun onFailure(call: okhttp3.Call?, e: IOException?) {
            Timber.d("FPL response failed = " + e?.message.toString())
        }

        override fun onResponse(call: okhttp3.Call?, response: okhttp3.Response?) {
            if (response!!.isSuccessful) {

                val responseBody = response.body()?.string()
                try {
                    val obj = JSONObject(responseBody)
                    Timber.d("FPL response = " + obj.toString())
                } catch (t: Throwable) {
                    Timber.e("Could not parse malformed JSON: " + t.message)
                }

                Timber.d("FPL response = $response")
                Timber.d("FPL headers = " + response.headers())
                Timber.d("FPL body = " + responseBody)
            } else {
                Timber.d("FPL response failed = " + response.body().toString())
            }
        }
    })

我尝试复制 Postman 的代码 sn-p 标头，它们是：

Request request = new Request.Builder()
  .url("https://fantasy.premierleague.com/drf/elements")
  .get()
  .addHeader("cache-control", "no-cache")
  .addHeader("postman-token", "05ae03ef-cf44-618c-a82c-5762e245b771")
  .build();

但遗憾的是那里也没有运气。

日志：

D/HomeController$onAttach:L135: FPL response = Response{protocol=http/1.1, code=200, message=OK, url=https://fantasy.premierleague.com/drf/elements}

D/HomeController$onAttach:L138: FPL headers = 
Server: Varnish
Retry-After: 0
Content-Type: application/json
Content-Length: 0
Accept-Ranges: bytes
Date: Tue, 15 Aug 2017 22:17:18 GMT
Via: 1.1 varnish
Connection: close
X-Served-By: cache-jfk8123-JFK
X-Cache: MISS
X-Cache-Hits: 0
X-Timer: S1502835438.419014,VS0,VE0

D/HomeController$onAttach:L139: FPL body = 

如您所见，主体为空，“连接”已关闭。

这是 Postman 获得的响应标头，大不相同。

Accept-Ranges →bytes
Age →14
Allow →GET, HEAD, OPTIONS
Cache-Control →no-cache, no-store, must-revalidate, max-age=0
Connection →keep-alive
Content-Encoding →gzip
Content-Language →plfplen
Content-Length →39518
Content-Type →application/json
Date →Tue, 15 Aug 2017 00:54:32 GMT
Edge-Control →max-age=60
Fastly-Debug-Digest →fdb44d2dd7c0b26c639a8b3476f8c63661c68707cc3b9446f8ed3941cd3fe01e
Server →nginx
Vary →Accept-Encoding
Via →1.1 varnish
Via →1.1 varnish
X-Cache →HIT, MISS
X-Cache-Hits →1, 0
X-Frame-Options →DENY
X-Served-By →cache-lcy1146-LCY, cache-jfk8143-JFK
X-Timer →S1502758472.116470,VS0,VE82

如您所见，“连接”表示保持活动状态。

我的 Request.Builder() 中是否缺少某些东西以使其正常工作？

编辑：

因此，我决定尝试使用AsyncTask 发出请求，并返回完整的 JSON，如下面的日志所示。我不明白为什么Okhttp3 不起作用。

            val url = params[0]
            var stream: InputStream? = null
            var connection: HttpsURLConnection? = null
            var result: String? = null
            try {
                connection = url?.openConnection() as HttpsURLConnection?
                // Timeout for reading InputStream arbitrarily set to 3000ms.
                connection?.readTimeout = 3000
                // Timeout for connection.connect() arbitrarily set to 3000ms.
                connection?.connectTimeout = 3000
                // For this use case, set HTTP method to GET.
                connection?.requestMethod = "GET"
                // Already true by default but setting just in case; needs to be true since this request
                // is carrying an input (response) body.
                connection?.doInput = true
                // Open communications link (network traffic occurs here).
                connection?.connect()

                val responseCode = connection?.responseCode

                if (responseCode != HttpsURLConnection.HTTP_OK) {
                    throw IOException("HTTP error code: " + responseCode)
                }
                // Retrieve the response body as an InputStream.
                stream = connection?.inputStream

                Timber.d("httpurl stream = " + connection?.inputStream.toString())

                if (stream != null) {
                    // Converts Stream to String with max length of 500.
                result = readStream(stream, 500)
                }
            } finally {
                // Close Stream and disconnect HTTPS connection.
                if (stream != null) {
                    stream.close()
                }
                if (connection != null) {
                    connection.disconnect()
                }
            }

            return result

日志：

 D/HomeController$NetworkA:L266: httpurl response = [{"id":1,"photo":"48844.jpg","web_name":"Ospina","team_code":3,"status":"a","code":48844,"first_name":"David","second_name":"Ospina","squad_number":13,"news":"","now_cost":50, .... }]

Answer 1

您的问题是User-Agent 标头。这是一个工作示例：

fun syncGetOkHttp() {
    println("\n===")
    println("OkHttp")
    println("===")
    val client = OkHttpClient().newBuilder()
            .addNetworkInterceptor { chain ->
                val (request, response) = chain.request().let {
                    Pair(it, chain.proceed(it))
                }

                println("--> ${RequestLine.get(request, Proxy.Type.HTTP)})")
                println("Headers: (${request.headers().size()})")
                request.headers().toMultimap().forEach { k, v -> println("$k : $v") }

                println("<-- ${response.code()} (${request.url()})")

                val body = if (response.body() != null)
                    GZIPInputStream(response.body()!!.byteStream()).use {
                        it.readBytes(50000)
                    } else null

                println("Response: ${StatusLine.get(response)}")
                println("Length: (${body?.size ?: 0})")

                println("""Body: ${if (body != null && body.isNotEmpty()) String(body) else "(empty)"}""")
                println("Headers: (${response.headers().size()})")
                response.headers().toMultimap().forEach { k, v -> println("$k : $v") }

                response
            }
            .build()

    Request.Builder()
            .url(url)
            .header("Accept", "application/json")
            .header("User-Agent", "Mozilla/5.0")
            .build()
            .let { client.newCall(it).execute() }
}