자바 HTTP 로드밸런싱 서버의 리다이렉션 캡처

HttpUtil.java

이어서 작성한다.

// Apache HttpCore » 4.4.15 필요
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpResponseInterceptor;

// Apache HttpClient » 4.5.13 필요 
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClients;
import org.apache.http.impl.client.HttpClients;

connectCaptureGET() : GET요청 후 캡처한 응답별 String 얻기

	/*********************
	 * GET 요청 후 타서버 접속하여 응답결과를 String 으로 받는다.
	 * 타겟 서버측 내부에서 로드밸런싱 등의 리다이렉트 처리가 일어나면
   * 중간에서 응답을 캡처한다.
   * 
	 * @param 요청 URL주소
	 * @return String
	 * @throws IOException 
	 * @throws ClientProtocolException
	 *********************/
	public static String connectCaptureGET(String containParamURL) throws ClientProtocolException, IOException 
	{
    final boolean[] isRedirect = {false};
	  StringBuilder builder = new StringBuilder();
    HttpGet get = null;

    // Yarn Resource 서버측 로드밸런싱으로 인한 HTTP 응답 인터셉터 캡처 구현
    HttpResponseInterceptor responseInterceptor = new HttpResponseInterceptor() {
      @Override
      public void process(HttpResponse response, HttpContext context) throws HttpException, IOException {
        int statusCode = response.getStatusLine().getStatusCode();
        if (statusCode == 307) isRedirect[0] = true; //리다이렉트 캡처
      }
    };

    //HttpClient 생성 및 응답 인터셉터 등록
    CloseableHttpClient httpClient = HttpClient.custom();
            .addInterceptorLast(responseInterceptor);
            .build();
	  try
	  {
	    get = new HttpGet(containParamURL);

	    HttpResponse response = httpClient.execute(get);
	    int status = response.getStatusLine().getStatusCode();

	    if(status >= 200 && status < 300) 
	    {
        if(isRedirect[0]) return null; //307 로드밸런싱시 return
	      HttpEntity entity = response.getEntity();

        // try-with-resources 자원해제
        try (BufferedReader br = new BufferedReader(new InputStreamReader(entitiy.getContent()));) {
          String line = null;
          while((line = br.readLine()) != null) {
	          builder.append(line);
	        }
        }	      
	    }
	  }
	  finally
	  {
      try {
        httpClient.close();
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
	  return builder.toString();
	}