1 | package de.ugoe.cs.autoquest.htmlmonitor; |
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2 | |
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3 | import java.io.IOException; |
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4 | import java.io.InputStreamReader; |
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5 | import java.net.MalformedURLException; |
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6 | import java.net.URL; |
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7 | import java.util.ArrayList; |
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8 | import java.util.List; |
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9 | import java.util.Map; |
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10 | import java.util.Set; |
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11 | |
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12 | import javax.servlet.ServletException; |
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13 | import javax.servlet.http.HttpServletRequest; |
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14 | import javax.servlet.http.HttpServletResponse; |
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15 | |
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16 | import org.json.simple.JSONArray; |
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17 | import org.json.simple.JSONObject; |
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18 | import org.json.simple.JSONValue; |
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19 | import org.json.simple.parser.ParseException; |
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20 | import org.mortbay.jetty.servlet.DefaultServlet; |
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21 | |
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22 | import de.ugoe.cs.util.console.Console; |
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23 | |
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24 | /** |
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25 | * <p> |
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26 | * the servlet deployed in the web server that receives all client messages. The messages are |
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27 | * parsed, validated, and forwarded to the provided message listener. If a message is not valid, |
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28 | * it is discarded. If an event in a message is not valid, it is discarded. Messages are only |
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29 | * received via the POST HTTP method. |
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30 | * </p> |
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31 | * |
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32 | * @author Patrick Harms |
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33 | */ |
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34 | class HtmlMonitorServlet extends DefaultServlet { |
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35 | |
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36 | /** */ |
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37 | private static final long serialVersionUID = 1L; |
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38 | |
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39 | /** |
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40 | * the message listener to forward received messages to. |
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41 | */ |
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42 | private HtmlMonitorMessageListener messageListener; |
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43 | |
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44 | /** |
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45 | * <p> |
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46 | * initializes the servlet with the message listener to which all events shall be forwarded |
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47 | * </p> |
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48 | * |
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49 | * @param messageListener the message listener that shall receive all client events |
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50 | */ |
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51 | HtmlMonitorServlet(HtmlMonitorMessageListener messageListener) { |
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52 | this.messageListener = messageListener; |
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53 | } |
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54 | |
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55 | /* (non-Javadoc) |
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56 | * @see org.mortbay.jetty.servlet.DefaultServlet#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse) |
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57 | */ |
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58 | @Override |
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59 | protected void doPost(HttpServletRequest request, HttpServletResponse response) |
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60 | throws ServletException, IOException |
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61 | { |
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62 | Object value = null; |
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63 | try { |
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64 | value = JSONValue.parseWithException(new InputStreamReader(request.getInputStream())); |
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65 | |
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66 | if (!(value instanceof JSONObject)) { |
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67 | Console.printerrln("incoming data is not of the expected type --> discarding it"); |
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68 | } |
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69 | else { |
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70 | handleJSONObject((JSONObject) value); |
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71 | } |
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72 | } |
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73 | catch (ParseException e) { |
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74 | Console.printerrln |
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75 | ("could not parse incoming data --> discarding it (" + e.toString() + ")"); |
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76 | } |
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77 | } |
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78 | |
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79 | /** |
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80 | * <p> |
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81 | * processes a received JSON object and validates it. If the message is ok, it is forwarded |
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82 | * to the message listener |
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83 | * </p> |
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84 | * |
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85 | * @param object the JSON object that contains a client message |
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86 | */ |
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87 | private void handleJSONObject(JSONObject object) { |
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88 | dumpJSONObject(object, ""); |
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89 | |
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90 | JSONObject message = assertValue(object, "message", JSONObject.class); |
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91 | |
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92 | if (message == null) { |
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93 | Console.printerrln("incoming data is no valid message --> discarding it"); |
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94 | } |
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95 | else { |
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96 | HtmlClientInfos clientInfos = extractClientInfos(message); |
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97 | |
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98 | if (clientInfos == null) { |
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99 | Console.printerrln |
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100 | ("incoming message does not contain valid client infos --> discarding it"); |
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101 | } |
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102 | else { |
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103 | HtmlEvent[] events = extractHtmlEvents(message, clientInfos); |
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104 | if (events == null) { |
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105 | Console.printerrln |
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106 | ("incoming message does not contain valid events --> discarding it"); |
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107 | } |
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108 | else { |
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109 | messageListener.handleMessage(clientInfos, events); |
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110 | } |
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111 | } |
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112 | } |
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113 | } |
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114 | |
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115 | /** |
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116 | * <p> |
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117 | * tries to extract the client infos out of the received JSON object. If this is not fully |
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118 | * possible, an appropriate message is dumped and the whole message is discarded (the method |
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119 | * return null). |
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120 | * </p> |
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121 | * |
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122 | * @param message the message to parse the client infos from |
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123 | * |
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124 | * @return the client infos, if the message is valid in this respect, or null if not |
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125 | */ |
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126 | private HtmlClientInfos extractClientInfos(JSONObject message) { |
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127 | HtmlClientInfos clientInfos = null; |
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128 | |
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129 | JSONObject infos = assertValue(message, "clientInfos", JSONObject.class); |
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130 | |
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131 | if (infos != null) { |
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132 | String clientId = assertValue((JSONObject) infos, "clientId", String.class); |
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133 | String userAgent = assertValue((JSONObject) infos, "userAgent", String.class); |
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134 | URL url = assertValue((JSONObject) infos, "url", URL.class); |
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135 | String title = assertValue((JSONObject) infos, "title", String.class); |
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136 | |
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137 | if (clientId == null) { |
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138 | Console.printerrln("client infos do not contain a valid client id"); |
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139 | } |
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140 | else if (userAgent == null) { |
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141 | Console.printerrln("client infos do not contain a valid user agent"); |
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142 | } |
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143 | else if (url == null) { |
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144 | Console.printerrln("client infos do not contain a valid URL"); |
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145 | } |
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146 | else if (title == null) { |
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147 | Console.printerrln("client infos do not contain a valid title"); |
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148 | } |
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149 | else { |
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150 | clientInfos = new HtmlClientInfos(clientId, userAgent, url, title); |
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151 | } |
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152 | } |
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153 | |
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154 | return clientInfos; |
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155 | } |
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156 | |
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157 | /** |
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158 | * <p> |
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159 | * tries to extract the events out of the received JSON object. If this is not fully |
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160 | * possible, an appropriate message is dumped and the errorprone event is discarded. If no |
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161 | * valid event is found, the whole message is discarded. |
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162 | * </p> |
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163 | * |
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164 | * @param object the message to parse the events from |
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165 | * @param clientInfos the infos about the client that send the events |
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166 | * |
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167 | * @return the valid events stored in the message, or null if there are none |
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168 | */ |
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169 | private HtmlEvent[] extractHtmlEvents(JSONObject object, HtmlClientInfos clientInfos) { |
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170 | List<HtmlEvent> events = null; |
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171 | |
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172 | JSONArray eventArray = assertValue(object, "events", JSONArray.class); |
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173 | |
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174 | if (eventArray != null) { |
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175 | events = new ArrayList<HtmlEvent>(); |
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176 | |
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177 | for (int i = 0; i < eventArray.size(); i++) { |
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178 | Object eventObj = eventArray.get(i); |
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179 | if (!(eventObj instanceof JSONObject)) { |
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180 | Console.printerrln("event number " + (i + 1) + " is not a valid event object"); |
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181 | } |
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182 | else { |
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183 | Long time = assertValue(((JSONObject) eventObj), "time", Long.class); |
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184 | String path = assertValue(((JSONObject) eventObj), "path", String.class); |
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185 | String eventType = |
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186 | assertValue(((JSONObject) eventObj), "eventType", String.class); |
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187 | Integer[] coordinates = |
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188 | assertValue(((JSONObject) eventObj), "coordinates", Integer[].class); |
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189 | Integer key = assertValue(((JSONObject) eventObj), "key", Integer.class); |
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190 | Integer scrollPosition = |
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191 | assertValue(((JSONObject) eventObj), "scrollPosition", Integer.class); |
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192 | |
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193 | if (time == null) { |
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194 | Console.printerrln("event number " + (i + 1) + " has no valid timestamp"); |
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195 | } |
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196 | else if (path == null) { |
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197 | Console.printerrln("event number " + (i + 1) + " has no valid path"); |
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198 | } |
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199 | else if (eventType == null) { |
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200 | Console.printerrln("event number " + (i + 1) + " has no valid event type"); |
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201 | } |
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202 | else if ((coordinates != null) && (coordinates.length != 2)) { |
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203 | Console.printerrln("event number " + (i + 1) + " has no valid coordinates"); |
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204 | } |
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205 | else if (checkEventParameterCombinations |
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206 | (eventType, coordinates, key, scrollPosition)) |
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207 | { |
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208 | events.add(new HtmlEvent(clientInfos, time, path, eventType, coordinates, |
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209 | key, scrollPosition)); |
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210 | } |
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211 | else { |
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212 | Console.printerrln |
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213 | ("event number " + (i + 1) + " has no valid parameter combination"); |
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214 | } |
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215 | } |
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216 | } |
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217 | |
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218 | } |
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219 | |
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220 | if ((events != null) && (events.size() > 0)) { |
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221 | return events.toArray(new HtmlEvent[events.size()]); |
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222 | } |
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223 | else { |
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224 | return null; |
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225 | } |
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226 | } |
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227 | |
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228 | /** |
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229 | * <p> |
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230 | * validates if for the given event type the parameter combination of coordinates, key, and |
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231 | * scroll position is valid. As an example, an onclick event should usually not have an |
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232 | * associated scroll position. |
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233 | * </p> |
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234 | * |
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235 | * @param eventType the type of the event |
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236 | * @param coordinates the coordinates of the event |
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237 | * @param key the key of the event |
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238 | * @param scrollPosition the scroll position of the event |
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239 | * |
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240 | * @return true, if the combination of the parameters is valid, false else |
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241 | */ |
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242 | private boolean checkEventParameterCombinations(String eventType, |
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243 | Integer[] coordinates, |
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244 | Integer key, |
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245 | Integer scrollPosition) |
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246 | { |
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247 | boolean result = false; |
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248 | |
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249 | if ("onscroll".equals(eventType)) { |
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250 | if ((coordinates == null) && (key == null) && (scrollPosition != null)) { |
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251 | result = true; |
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252 | } |
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253 | else { |
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254 | Console.printerrln(eventType + " event has invalid parameters"); |
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255 | } |
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256 | } |
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257 | else if ("onclick".equals(eventType) || "ondblclick".equals(eventType)) { |
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258 | if ((coordinates != null) && (key == null) && (scrollPosition == null)) { |
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259 | result = true; |
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260 | } |
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261 | else { |
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262 | Console.printerrln(eventType + " event has invalid parameters"); |
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263 | } |
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264 | } |
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265 | else if ("onkeypress".equals(eventType) || "onkeydown".equals(eventType) || |
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266 | "onkeyup".equals(eventType)) |
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267 | { |
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268 | if ((coordinates == null) && (key != null) && (scrollPosition == null)) { |
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269 | result = true; |
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270 | } |
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271 | else { |
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272 | Console.printerrln(eventType + " event has invalid parameters"); |
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273 | } |
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274 | } |
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275 | else if ("onfocus".equals(eventType) || "onmouseout".equals(eventType) || |
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276 | "onmousemove".equals(eventType) || "onunload".equals(eventType)) |
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277 | { |
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278 | if ((coordinates == null) && (key == null) && (scrollPosition == null)) { |
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279 | result = true; |
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280 | } |
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281 | else { |
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282 | Console.printerrln(eventType + " event has invalid parameters"); |
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283 | } |
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284 | } |
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285 | else { |
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286 | Console.printerrln("'" + eventType + "' is not a valid event type"); |
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287 | } |
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288 | |
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289 | return result; |
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290 | } |
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291 | |
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292 | /** |
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293 | * <p> |
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294 | * converts a value in the provided object matching the provided key to the provided type. If |
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295 | * there is no value with the key or if the value can not be transformed to the provided type, |
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296 | * the method returns null. |
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297 | * </p> |
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298 | * |
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299 | * @param object the object to read the value from |
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300 | * @param key the key of the value |
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301 | * @param clazz the type to which the value should be transformed |
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302 | * |
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303 | * @return the value or null if either the value does not exist or if it can not be transformed |
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304 | * to the expected type |
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305 | */ |
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306 | @SuppressWarnings("unchecked") |
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307 | private <T> T assertValue(JSONObject object, String key, Class<T> clazz) { |
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308 | Object value = object.get(key); |
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309 | T result = null; |
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310 | |
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311 | if (clazz.isInstance(value)) { |
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312 | result = (T) value; |
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313 | } |
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314 | else if (value instanceof String) { |
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315 | if (URL.class.equals(clazz)) { |
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316 | try { |
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317 | result = (T) new URL((String) value); |
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318 | } |
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319 | catch (MalformedURLException e) { |
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320 | e.printStackTrace(); |
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321 | Console.printerrln("retrieved malformed URL for key '" + key + "': " + value + |
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322 | " (" + e.toString() + ")"); |
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323 | } |
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324 | } |
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325 | else if ((int.class.equals(clazz)) || (Integer.class.equals(clazz))) { |
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326 | try { |
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327 | result = (T) new Integer(Integer.parseInt((String) value)); |
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328 | } |
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329 | catch (NumberFormatException e) { |
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330 | Console.printerrln |
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331 | ("retrieved malformed integer for key '" + key + "': " + value); |
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332 | } |
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333 | } |
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334 | else if ((long.class.equals(clazz)) || (Long.class.equals(clazz))) { |
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335 | try { |
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336 | result = (T) new Long(Long.parseLong((String) value)); |
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337 | } |
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338 | catch (NumberFormatException e) { |
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339 | Console.printerrln |
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340 | ("retrieved malformed long for key '" + key + "': " + value); |
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341 | } |
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342 | } |
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343 | } |
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344 | else if (value instanceof Long) { |
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345 | if ((int.class.equals(clazz)) || (Integer.class.equals(clazz))) { |
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346 | result = (T) (Integer) ((Long) value).intValue(); |
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347 | } |
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348 | } |
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349 | else if (value instanceof JSONArray) { |
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350 | if ((int[].class.equals(clazz)) || (Integer[].class.equals(clazz))) { |
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351 | Integer[] resultArray = new Integer[((JSONArray) value).size()]; |
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352 | boolean allCouldBeParsed = true; |
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353 | |
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354 | for (int i = 0; i < ((JSONArray) value).size(); i++) { |
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355 | try { |
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356 | if (((JSONArray) value).get(i) instanceof Long) { |
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357 | resultArray[i] = (int) (long) (Long) ((JSONArray) value).get(i); |
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358 | } |
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359 | else if (((JSONArray) value).get(i) instanceof String) { |
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360 | try { |
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361 | resultArray[i] = |
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362 | (int) Long.parseLong((String) ((JSONArray) value).get(i)); |
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363 | } |
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364 | catch (NumberFormatException e) { |
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365 | Console.printerrln |
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366 | ("retrieved malformed integer array for key '" + key + "': " + |
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367 | value); |
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368 | |
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369 | allCouldBeParsed = false; |
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370 | break; |
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371 | } |
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372 | } |
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373 | else { |
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374 | Console.printerrln |
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375 | ("can not handle type of value in expected integer array '" + key + |
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376 | "': " + value); |
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377 | } |
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378 | } |
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379 | catch (ClassCastException e) { |
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380 | e.printStackTrace(); |
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381 | Console.printerrln("expected integer array for key '" + key + |
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382 | "' but it was something else: " + value); |
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383 | |
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384 | allCouldBeParsed = false; |
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385 | break; |
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386 | } |
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387 | } |
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388 | |
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389 | if (allCouldBeParsed) { |
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390 | result = (T) resultArray; |
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391 | } |
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392 | } |
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393 | } |
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394 | |
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395 | return result; |
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396 | } |
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397 | |
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398 | /** |
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399 | * <p> |
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400 | * convenience method for dumping an object to std out. If the object is a JSON object, it is |
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401 | * deeply analyzed and its internal structure is dumped as well. |
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402 | * </p> |
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403 | * |
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404 | * @param object the object to dump |
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405 | * @param indent the indentation to be used. |
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406 | */ |
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407 | private void dumpJSONObject(Object object, String indent) { |
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408 | if (object instanceof JSONArray) { |
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409 | boolean arrayContainsJSONObjects = false; |
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410 | for (Object arrayElem : (JSONArray) object) { |
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411 | if (arrayElem instanceof JSONObject) { |
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412 | arrayContainsJSONObjects = true; |
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413 | break; |
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414 | } |
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415 | } |
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416 | |
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417 | if (arrayContainsJSONObjects) { |
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418 | System.out.println(); |
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419 | System.out.print(indent); |
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420 | System.out.println('['); |
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421 | System.out.print(indent); |
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422 | System.out.print(' '); |
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423 | } |
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424 | else { |
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425 | System.out.print(' '); |
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426 | System.out.print('['); |
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427 | } |
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428 | |
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429 | int index = 0; |
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430 | for (Object arrayElem : (JSONArray) object) { |
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431 | if (index++ > 0) { |
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432 | System.out.print(","); |
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433 | if (arrayContainsJSONObjects) { |
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434 | System.out.println(); |
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435 | System.out.print(indent); |
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436 | } |
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437 | |
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438 | System.out.print(' '); |
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439 | } |
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440 | |
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441 | dumpJSONObject(arrayElem, indent + " "); |
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442 | } |
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443 | |
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444 | if (arrayContainsJSONObjects) { |
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445 | System.out.println(); |
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446 | System.out.print(indent); |
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447 | } |
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448 | |
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449 | System.out.print(']'); |
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450 | } |
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451 | else if (object instanceof JSONObject) { |
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452 | System.out.println(" {"); |
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453 | |
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454 | @SuppressWarnings("unchecked") |
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455 | Set<Map.Entry<?,?>> entrySet = ((JSONObject) object).entrySet(); |
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456 | |
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457 | int index = 0; |
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458 | for (Map.Entry<?,?> entry : entrySet) { |
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459 | if (index++ > 0) { |
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460 | System.out.println(","); |
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461 | } |
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462 | System.out.print(indent); |
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463 | System.out.print(" \""); |
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464 | System.out.print(entry.getKey()); |
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465 | System.out.print("\":"); |
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466 | dumpJSONObject(entry.getValue(), indent + " "); |
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467 | } |
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468 | |
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469 | System.out.println(); |
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470 | System.out.print(indent); |
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471 | System.out.print('}'); |
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472 | } |
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473 | else { |
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474 | System.out.print('"'); |
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475 | System.out.print(object); |
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476 | System.out.print('"'); |
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477 | } |
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478 | } |
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479 | |
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480 | } |
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