Apache HttpClient - Rest call Client

다른 시스템에 접근하거나 결과값을 받아와 후처리를 해야 할경우, java.io.net 페키지에있는 URL 을 사용해도 좋으나,

오픈소스인 Apache HttpClient를 사용하여 구현해 보았다.

(Spring Framework 을사용중이라면 RestTemplate(http://blog.springsource.org/2009/03/27/rest-in-spring-3-resttemplate/) 을 사용할수도 있다.)

URIBuilder.java source google github - 

1. https://github.com/SpringSource/spring-social/blob/master/spring-social-core/src/main/java/org/springframework/social/support/URIBuilder.java

Apache Software Foundation -

1. http://hc.apache.org/httpcomponents-client-ga/examples.html

2. http://hc.apache.org/httpcomponents-client-ga/tutorial/html/caching.html

3. http://hc.apache.org/httpcomponents-client-ga/tutorial/pdf/httpclient-tutorial.pdf

사용자 블로그

1. http://naleejang.tistory.com/category/Java

2. http://dyutiman.wordpress.com/2011/04/13/rest-template-using-apache-httpclient/

Method Type

HttpGet    : 데이터 조회

HttpHead   : 조회하고자 하는 데이터의 메타데이터나 인증정보, 혹은 세션값 확인

HttpPost   : 새로운 메타데이 수정 및 등록

HttpPut    : 새로운 데이터 생성시

HttpDelete : 데이터 삭제시

사용방법

pom.xml library 등록

  <dependency>

            <groupId>org.apache.httpcomponents</groupId>

            <artifactId>httpcore</artifactId>

            <version>4.1</version>

        </dependency>

    

        <dependency>

            <groupId>org.apache.httpcomponents</groupId>

            <artifactId>httpclient</artifactId>

            <version>4.0.3</version>

        </dependency>

JavaCode

1. PostCall Sample

public boolean externalPostURLCall(String url , Map<Object,Object> parameters) throws Exception {

            HttpClient client = new DefaultHttpClient();

             try {

                  

                   if (parameters == null ) {

                        parameters = parameterMap ;    

                  }

                  

                  HttpPost httpPost = new HttpPost(url);

                  List<NameValuePair> paramList = super .parameterGenerator(parameters);

                  

                   //케릭터셋 인코딩 처리

                  httpPost.setEntity( new UrlEncodedFormEntity(paramList, charset ));

                  httpPost.addHeader( "Connection" , "close" );

                   try {

                        

                         //ResponseHandler<String> responseHandler = new BasicResponseHandler();

                         //String responseBodyStr = client.execute(httpPost ,responseHandler);

                         //System.out.println(responseBodyStr);

                        

                        HttpContext localContext = new BasicHttpContext();

                         super .response   = client.execute(httpPost);

                        

                  } catch (HttpHostConnectException e) {

                         super .urlCall = false;

                        System. out .println( super. response);

                         //서버가 동장되지 않는경우에도 재호출??

                         //throw new HttpClientError("");

                  }

                  

                  System. out .println("getStatusCode :: " + super .response .getStatusLine().getStatusCode());

                  

                   if (super .response .getStatusLine().getStatusCode() != 200) {

                         super .urlCall = false;

                         //실패시 3초간격으로 3번간 재호출 한다.

                         while (DEFAULT_CONNECTION_COUNT > RECONNECT_COUNT ) {

                               RECONNECT_COUNT ++;

                               try {

                                    Thread. sleep(3000);

                                    System. out .println("========================method call is externalPostURLCall======================== \n\n\n");

                                    System. out .println("ExternalURLCallUtils.java  parameters : " + parameters.toString());

                                    System. out .println("ExternalURLCallUtils.java  setCharset : " + charset );

                                    

                                    System. out .println("urlCall :: " + super .urlCall );

                                     super .urlCall = externalPostURLCall(url, parameters);

                                    

                              } catch (InterruptedException e) {

                                    e.printStackTrace();

                              }

                              

                        }

                  } else {

                         super .urlCall = true;

                  }

                  

            } catch (Exception e) {

                  e.printStackTrace();

            } finally {

                  client.getConnectionManager().closeExpiredConnections();

            }

            

             return super .urlCall ;

      }

2. parameter를 전송하기위한 NameValue List method

/**

       * 파라미터전송을 위한 NameValuePair List 제너레이터  

       * POST, PUT, DELETE method 에 사용된다.

       * @param parameters

       * @return

       */

       public List<NameValuePair> parameterGenerator(Map<Object,Object> parameters) throws Exception {

            List<org.apache.http.NameValuePair> paramList = new ArrayList<org.apache.http.NameValuePair>();

             for (@SuppressWarnings ( "unused") Entry<Object, Object> entry : parameters.entrySet()) {

                  paramList.add( new BasicNameValuePair((String)entry.getKey(), (String) entry.getValue()));

            }

            

             return paramList;

      }

3. 응답받은 response의 Entity Contents 확인하기.

     - response된 결과를 BufferReader를 이용하여, 페이지를 읽어 확인한다. 확인 전 Status 코드를 확인해도 된다.

     - org.apache.http.util.EntityUtils. toString(response.getEntity()); 와 같이 사용하여도 된다.  (BufferReader가 텍스트 읽을땐 제일 빠르다고 하니,, 여기선 BufferedReader를 구현해서 사용.)

     /**

       * 호출된 URL의 Contents 를 String 으로 Return

       * @param response

       * @return

       * @throws Exception

       */

       public String responseEntityStr(HttpResponse response) throws Exception {

            HttpEntity entity = response.getEntity();

            InputStream is = entity.getContent();

            StringBuilder sb = new StringBuilder();

             try {

             /** convert response to string */

            BufferedReader reader = new BufferedReader( new InputStreamReader(is/*, " iso-8859-1"*/ ), 8);

            String line = null ;

             while ((line = reader.readLine()) != null) {

                  sb.append(line).append( "\n" );

            }

            } catch (IOException e) {

                  e.printStackTrace();

            } finally {

                  is.close();

            }

             return sb.toString();

      }

Abstract Class와 implement Class는 첨부파일을 확인하세요.

Get Method 를 만들어 호출 할경우에는 ___________.do?parameter 을 보내면된다.

생성할때는 URIBuilder를 사용하면 좀더 편하게 사용할수 있다.