Java freebase查询

Question

我正在尝试用Java读取freebase查询的结果：

URL url = null;
String inputLine;

try{
  url = new URL("https://www.googleapis.com/freebase/v1/mqlread?query={\"id\":\"/en/madonna\", \"name\": null, \"type\":\"/base/popstra/celebrity\",\"/base/popstra/celebrity/friendship\": [{\"participant\": [] }] }");

} catch (MalformedURLException e) {
  e.printStackTrace();
}
BufferedReader in;
try {
  URLConnection con = url.openConnection();
  con.setReadTimeout( 1000 ); //1 second
  in = new BufferedReader(new InputStreamReader(con.getInputStream()));
  while ((inputLine = in.readLine()) != null) {
  System.out.println(inputLine);
}
in.close();

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

但是，我得到了以下错误：

java.io.IOException: Server returned HTTP response code: 400 for URL:     https://www.googleapis.com/freebase/v1/mqlread?query={ "id":"/en/madonna", "name": null, "type": "/base/popstra/celebrity","/base/popstra/celebrity/friendship": [{ "participant": [] }] }

at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unknown Source)
at FreebaseCelebrities.main(FreebaseCelebrities.java:66)

我以前已经这样做了(对于其他请求)，并且它起作用了，那么这里的问题是什么呢？

Answer 1

如果你成功了！

api不能正确解析emply空格，请使用以下内容：

    url = new URL("https://www.googleapis.com/freebase/v1/mqlread?query={\"id\":\"/en/madonna\", \"name\": null, \"type\":\"/base/popstra/celebrity\",\"/base/popstra/celebrity/friendship\": [{\"participant\": [] }] }".replace(" ", ""));

Answer 2

在创建URL时尝试以下代码：

try {
  String query = "{\"id\":\"/en/madonna\", \"name\": null, \"type\":\"/base/popstra/celebrity\",\"/base/popstra/celebrity/friendship\": [{\"participant\": [] }] }";
  url = new URL("https://www.googleapis.com/freebase/v1/mqlread?query="+URLEncoder.encode(query, "UTF-8"));
} catch (UnsupportedEncodingException e) {
  e.printStackTrace();
} catch (MalformedURLException e) {
  e.printStackTrace();
}

您需要对查询字符串参数进行URL编码。