java - 无法从 URLConnection 获取 JSON 响应

Question

我正在尝试使用 java URLConnection 读取 googleapi 的响应。

在浏览器中如果我查询“https://www.googleapis.com/pagespeedonline/v2/runPagespeed?url=https%3A%2F%2Fwww.zauq.se&strategy=mobilez”

我得到 JSON 格式的响应。

{
 "error": {
  "errors": [
   {
    "domain": "global",
    "reason": "invalidParameter",
    "message": "Invalid string value: 'mobilez'. Allowed values: [desktop, mobile]",
    "locationType": "parameter",
    "location": "strategy"
   }
  ],
  "code": 400,
  "message": "Invalid string value: 'mobilez'. Allowed values: [desktop, mobile]"
 }
}

但是当我使用以下代码时。

URL url = null;
            System.setProperty("http.agent", "");

            url = new URL("https://www.googleapis.com/pagespeedonline/v2/runPagespeed?url=https%3A%2F%2Fwww.zauq.se&strategy=mobilez");//"https://www.googleapis.com/pagespeedonline/v2/runPagespeed?url=" + paramUrl + "&strategy=" + paramStrategy);
            URLConnection conn = url.openConnection();
            conn.setRequestProperty("Accept", "application/json");
            conn.setRequestProperty("User-Agent", "Mozilla/5.0");
            BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            String strTemp = "";
            StringBuilder sb = new StringBuilder();

            while ((null != (strTemp = br.readLine())))
            {
                sb.append(strTemp);
                if (dump)
                {
                    System.out.println(strTemp);
                }
            }

我收到 IO 异常

java.io.IOException: Server returned HTTP response code: 400 for URL: https://www.googleapis.com/pagespeedonline/v2/runPagespeed?url=https%3A%2F%2Fwww.zauq.se&strategy=mobilez
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1627)
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
    at amirTest.PageSpeedCheck.main(PageSpeedCheck.java:62)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

/但我需要获取 JSON 响应。

请建议我需要进行哪些更改才能获取 JSON 作为响应。

Answer 1

将连接转换为 Http(s)URLConnection，并调用 getErrorStream()在发生错误时获取流。