【Java入門】HttpURLConnectionでGET送信して結果をJacksonでJSONに変換して受け取る

public static void main( String[] args ) {

    String baseUrl = "http://httpbin.org/get";
    HttpURLConnection  con = null;
    try {
        URL url = new URL(baseUrl);
        con = (HttpURLConnection) url.openConnection();
        con.setRequestMethod("GET");
        con.setInstanceFollowRedirects(false);
        con.connect();

        int status = con.getResponseCode();

        // HTTPステータスが200の場合、JSONを受け取る
        if (status == HttpURLConnection.HTTP_OK) {

            try (InputStreamReader in = new InputStreamReader(con.getInputStream());
                BufferedReader reader = new BufferedReader(in);) {
                StringBuilder output = new StringBuilder();
                String line;

                while ((line = reader.readLine()) != null) {
                    output.append(line);
                }
                // 一旦、返り値のJSONを確認
                System.out.println(output.toString());

                ObjectMapper mapper = new ObjectMapper();

                // JSONに変換
                ResponseBody hoge = mapper.readValue(output.toString(), ResponseBody.class);
                // JSONに変換後に試しに出力
                System.out.println(hoge.getHeadersData().getHost());
            }
        }
    } catch (MalformedURLException e) {

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

        e.printStackTrace();
    } finally {
        con.disconnect();
    }
}

public class ResponseBody {
	@JsonProperty("args")
	private Args args;

	@JsonProperty("headers")
	private HeadersData headersData;

	@JsonProperty("origin")
	private String origin;

	@JsonProperty("url")
	private String url;
}

public class HeadersData {

	@JsonProperty("Accept")
	private String accept;

	@JsonProperty("Host")
	private String host;

	@JsonProperty("User-Agent")
	private String userAgent;

	@JsonProperty("Content-Type")
	private String contentType;

	@JsonProperty("X-Amzn-Trace-Id")
	private String xAmznTraceId;
}

ResponseBody body = new ResponseBody();
HeadersData headersData = new HeadersData();
Args args = new Args();
body.setArgs(args);
body.setHeadersData(headersData);
headersData.setAccept("text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2");
headersData.setHost("httpbin.org");
headersData.setUserAgent("Java/1.8.0_60");
headersData.setUserAgent("application/json; charset=utf-8");
headersData.setxAmznTraceId("Root=1-64169ad1-3d6687174f0166035a7bea81");
body.setOrigin("122.209.27.26");
body.setUrl("http://httpbin.org/get");

ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(body);
System.out.println("出力して確認ーーー");
System.out.println(json);