View Javadoc
   /*
    * Created by IntelliJ IDEA.
    * User: birchfield
    * Date: Aug 18, 2002
    * Time: 4:55:54 PM
    * To change template for new class use
    * Code Style | Class Templates options (Tools | IDE Options).
    */
   package net.plugin.sql.util;
  
  import net.plugin.sql.listeners.QueryListener;
  
  import java.util.*;
  
  public class QueryManager implements QueryListener {
  
      public static QueryManager instance = null;
  
      private List queries = null;
      private Collection listeners = null;
  
      private QueryManager() {
          queries = new ArrayList();
          listeners = new ArrayList();
      }
  
      public static QueryManager getInstance() {
          if (instance == null) {
              instance = new QueryManager();
          }
          return instance;
      }
  
      public synchronized void addQuery(String query) {
          if (queries.contains(query))
              return;
          //ifwe are at 50, pop the first one off
          if (queries.size() == 50) {
              queries.remove(0);
          }
          //add to the end. We will loop backwards to build the list
          queries.add(0, query);
          notifyListeners(query);
      }
  
      public List getQueries() {
          List copy = new ArrayList(queries);
          return copy;
      }
  
  
      private void notifyListeners(String query) {
          for (Iterator iterator = listeners.iterator(); iterator.hasNext();) {
              QueryListener queryListener = (QueryListener) iterator.next();
              queryListener.queryPerformed(query);
          }
      }
  
      public void queryPerformed(String query) {
          addQuery(query);
      }
  
      public void removeQueryListener(QueryListener listener) {
          listeners.remove(listener);
      }
      public void addQueryListener(QueryListener listener) {
          listeners.add(listener);
      }
  
  }