[FEATURE] First implementation of the configuration

src/main/java/net/sourceforge/plantuml/servlet/PlantUmlServlet.java

@@ -30,6 +30,7 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import javax.servlet.RequestDispatcher;
+import javax.servlet.ServletConfig;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
@@ -41,6 +42,7 @@ import net.sourceforge.plantuml.SourceStringReader;
 import net.sourceforge.plantuml.StringUtils;
 import net.sourceforge.plantuml.code.Transcoder;
 import net.sourceforge.plantuml.code.TranscoderUtil;
+import net.sourceforge.plantuml.servlet.utility.Configuration;
 import net.sourceforge.plantuml.api.PlantumlUtils;
 
 /*
@@ -121,7 +123,11 @@ public class PlantUmlServlet extends HttpServlet {
         dispatcher.forward(request, response);
         return;
     }
-
+    
+	public void init(ServletConfig config) throws ServletException {
+		config.getServletContext().setAttribute("cfg", Configuration.get());
+	}
+    
     private Transcoder getTranscoder() {
         return TranscoderUtil.getDefaultTranscoder();
     }

src/main/java/net/sourceforge/plantuml/servlet/utility/Configuration.java

@@ -0,0 +1,84 @@
+/* ========================================================================
+ * PlantUML : a free UML diagram generator
+ * ========================================================================
+ *
+ * Project Info:  http://plantuml.sourceforge.net
+ * 
+ * This file is part of PlantUML.
+ *
+ * PlantUML is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * PlantUML distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+ * USA.
+ */
+package net.sourceforge.plantuml.servlet.utility;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import java.util.Properties;
+
+public class Configuration {
+
+	private static Configuration instance;
+	private Properties config;
+
+	/**
+	 * Singleton constructor
+	 */
+	private Configuration() {
+		Properties config = new Properties();
+		
+		// Default values
+		config.setProperty("SHOW_SOCIAL_BUTTONS", "off");
+		config.setProperty("USE_GOOGLE_TRACKER", "off");
+		// End of default values
+		
+		try {
+			InputStream is = Thread.currentThread().getContextClassLoader().
+	            getResourceAsStream("config.properties");
+			if (is != null) {
+			    config.load(is);
+				is.close();
+			}
+		} catch (IOException e) {
+			// Just log a warning
+			e.printStackTrace();
+		}
+	}
+
+	/**
+	 * Get the configuration
+	 * 
+	 * @return the complete configuration
+	 */
+	public static Properties get() {
+		if (instance == null) {
+			instance = new Configuration();
+		}
+		return instance.config;
+	}
+	
+	/**
+	 * Get a boolean configuration value
+	 * 
+	 * @return true if the value is "on"
+	 */
+	public static boolean get(String key) {
+		if (instance.config.getProperty(key) == null) {
+			return false;
+		}
+		return instance.config.getProperty(key).startsWith("on");
+	}
+
+}

src/main/resources/config.properties

@@ -0,0 +1,3 @@
+#PlantUML configuration file
+#
+#USE_GOOGLE_TRACKER=on

src/main/webapp/index.jsp

@@ -1,6 +1,7 @@
 <%@ page info="index" contentType="text/html; charset=utf-8" pageEncoding="utf-8" session="false" %>
 <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
 
+<c:set var="cfg" value="${applicationScope['cfg']}" />
 <c:set var="contextroot" value="${pageContext.request.contextPath}" />
 <c:set var="hostpath" value="http://${pageContext.request.serverName}:${pageContext.request.serverPort}${contextroot}" />
 <c:if test="${pageContext.request.serverPort == 80 }">
@@ -32,6 +33,9 @@
     <%-- PAGE TITLE --%>
     <h1>PlantUML Server</h1>
     <p>This application provides a servlet which serves images created by <a href="http://plantuml.sourceforge.net">PlantUML</a>.</p>
+    <c:if test="${cfg['SHOW_SOCIAL_BUTTONS'] == 'on' }">
+        <p>SOCIAL BUTTONS</p>
+    </c:if>
 </div>
 <div id="content">
     <%-- CONTENT --%>