Adding the View Logged in Users functionality to core

api/src/main/java/org/openmrs/util/CurrentUsers.java

@@ -0,0 +1,69 @@
+package org.openmrs.util;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+
+import javax.servlet.http.HttpSession;
+
+public class CurrentUsers {
+
+
+	/**
+	 * Initialize the current users list.
+	 * 
+	 * @param servletContext
+	 */
+
+	public static Map<String,String> init(ServletContext servletContext){
+		Map<String,String> currentUserMap = Collections.synchronizedMap(new TreeMap<String,String>());
+		servletContext.setAtrribute(WebConstants.CURRENT_USERS,currentUserMap);
+		return currentUserMap;
+	}
+
+	/**
+	 * Get the current list of map of users stored in the session
+	 * 
+	 * @param httpSession the current session
+	 * @return map of users logged in
+	 */
+	private static Map<String,String> getCurrentUsers(HttpSession httpSession){
+
+		Map<String,String> currentUsers = (Map <String,String>) httpSession.getServletContext().getAttribute(WebConstants.CURRENT_USERS);
+		if(currentUsers == null) {
+
+			currentUsers = init(httpSession.getServletContext());
+		}
+
+		return currentUsers;
+	}
+
+	/**
+	 * Get sorted user names list.
+	 * 
+	 * @param httpSession
+	 * @return sorted user names
+	 */
+
+	public static List<String> getCurrentUsernames(HttpSession httpSession){
+
+		Map<String,String> currentUsers = getCurrentUsers(httpSession);
+
+		List<String> userNames = new ArrayList<String>();
+		synchronized(currentUsers){
+
+			for(String value:currentUsers.values()) {
+
+				userNames.add(value);
+			}
+
+		}
+
+		Collections.sort(userNames);
+		return userNames;
+	}
+
+
+}