wso2bpel-ext/wso2bpel-core/BPEL4RESTLight/src/main/java/org/opentosca/bpel4restlight/rest/LowLevelRestApi.java

   1 /**
   2  * This static-class eases HTTP-method execution by self-managed fault-handling
   3  * and automated Response-information processing
   4  */
   5 package org.opentosca.bpel4restlight.rest;
   6
   7 import java.io.IOException;
   8 import java.util.Map;
   9 import java.util.Set;
  10
  11 import org.apache.commons.httpclient.Header;
  12 import org.apache.commons.httpclient.HttpClient;
  13 import org.apache.commons.httpclient.HttpMethod;
  14 import org.apache.commons.logging.Log;
  15 import org.apache.commons.logging.LogFactory;
  16 import org.json.simple.JSONArray;
  17 import org.json.simple.JSONObject;
  18 import org.json.simple.parser.JSONParser;
  19 import org.json.simple.parser.ParseException;
  20
  21
  22 public class LowLevelRestApi {
  23
  24   protected static final Log log = LogFactory.getLog(LowLevelRestApi.class);
  25         // Local HttpClient used for every communication (Singleton implementation)
  26 //      private static HttpClient httpClient = new HttpClient();
  27
  28         /**
  29          * Executes a passed HttpMethod (Method type is either PUT, POST, GET or
  30          * DELETE) and returns a HttpResponseMessage
  31          *
  32          * @param method Method to execute
  33          * @return HttpResponseMessage which contains all information about the
  34          *         execution
  35          */
  36         public static HttpResponseMessage executeHttpMethod(HttpMethod method) {
  37
  38                 HttpResponseMessage responseMessage = null;
  39
  40                 try {
  41                         log.debug("Method invocation on URI: \n");
  42                         log.debug(method.getURI().toString());
  43
  44                         // Execute Request
  45                         HttpClient httpClient = new HttpClient();
  46                         httpClient.executeMethod(method);
  47                         responseMessage = LowLevelRestApi.extractResponseInformation(method);
  48
  49                 } catch (Exception e) {
  50                   log.error("call rest error:", e);
  51                 } finally {
  52                         // Release Connection anyway
  53                         method.releaseConnection();
  54                 }
  55
  56                 // Extract response information and return
  57                 return responseMessage;
  58         }
  59
  60         /**
  61          * Extracts the response information from an executed HttpMethod
  62          *
  63          * @param method Executed Method
  64          * @return Packaged response information
  65          */
  66         private static HttpResponseMessage extractResponseInformation(HttpMethod method) {
  67                 // Create and return HttpResponseMethod
  68                 HttpResponseMessage responseMessage = new HttpResponseMessage();
  69                 responseMessage.setStatusCode(method.getStatusCode());
  70                 try {
  71                         responseMessage.setResponseBody(getResponseBody(method));
  72                 } catch (Exception e) {
  73                     log.error(e);
  74                 }
  75                 return responseMessage;
  76
  77         }
  78
  79         /**
  80          * getResponseBody
  81          *
  82          * get response body info, if response body is a json object, then translate json object to xml
  83          * if the rest request failed, i.e. the response body is a 404 error page, then response the body with header <root>
  84          * @param method
  85          * @return
  86          * @throws ParseException
  87          */
  88         private static String getResponseBody(HttpMethod method) throws ParseException
  89         {
  90           String result = null;
  91           try {
  92             result = method.getResponseBodyAsString();
  93                 log.debug("result:");
  94                 log.debug(result);
  95           } catch (IOException e) {
  96             log.error(e);
  97           }
  98
  99           Header header = method.getRequestHeader("Accept");
 100           if ("application/json".equals(header.getValue())) {
 101             StringBuilder sb = new StringBuilder();
 102             sb.append("<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>");
 103             sb.append("<root>");
 104             if(result != null && !"".equals(result)) {
 105               /**
 106                   if(result.startsWith("<html>")) {
 107                 sb.append("<![CDATA[");
 108                 sb.append(result);
 109                 sb.append("]]>");
 110               } else {
 111                 Object json = new JSONParser().parse(result);
 112                 json2Xml(sb, "obj", json);
 113               }
 114                   */
 115
 116                   try {
 117                         Object json = new JSONParser().parse(result);
 118                 json2Xml(sb, "obj", json);
 119                   } catch (Exception e) {
 120                         log.error(e);
 121                         sb.append("<![CDATA[");
 122                 sb.append(result);
 123                 sb.append("]]>");
 124                   }
 125             }
 126             sb.append("</root>");
 127
 128                 log.debug("responseBody:");
 129                 log.debug(sb.toString());
 130             return sb.toString();
 131           }
 132           return result;
 133         }
 134
 135
 136         @SuppressWarnings("unchecked")
 137         public static void json2Xml(StringBuilder sb, String key,  Object jsonObject) {
 138           if(jsonObject == null) {
 139             sb.append("<error>empty</error>");
 140             return;
 141           }
 142
 143           if(jsonObject instanceof JSONArray) {
 144             JSONArray array = (JSONArray) jsonObject;
 145             sb.append("<").append(key).append("s").append(">");
 146             for(int i=0, len=array.size(); i<len; i++) {
 147               json2Xml(sb, key, array.get(i));
 148             }
 149             sb.append("</").append(key).append("s").append(">");
 150
 151             return;
 152           } else if(jsonObject instanceof JSONObject) {
 153             sb.append("<").append(key).append(">");
 154             JSONObject json = (JSONObject) jsonObject;
 155             for(Map.Entry<String, Object> entry : (Set<Map.Entry<String, Object>>)json.entrySet()) {
 156               json2Xml(sb, entry.getKey(), entry.getValue());
 157             }
 158             sb.append("</").append(key).append(">");
 159             return;
 160           } else {
 161             sb.append("<").append(key).append(">");
 162             sb.append("<![CDATA[");
 163             sb.append(jsonObject.toString());
 164             sb.append("]]>");
 165             sb.append("</").append(key).append(">");
 166
 167             return;
 168           }
 169         }
 170
 171 }