poolelement.java

JAVA平台下优秀的CHART开源代码,可以实现类似EXCEL中的二维或三维的饼图/椎图功能.

/**
 * Copyright (C) 2003  Manfred Andres
 * 
 * This program 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 2
 * of the License, or (at your option) any later version.
 * 
 * This program is 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
package freecs.auth.sqlConnectionPool;

import freecs.Server;
import java.sql.*;

public class PoolElement {
   java.sql.Connection con = null;
   int statements, sCnt=0, id;
   long validUntil;
   boolean isActive = false;
   Statement read, write;

   PoolElement (Connection con, int statements, long validUntil, int id) throws Exception {
      if (con == null) throw new Exception ("no connection supplied");
      this.id = id;
      this.con = con;
      con.setAutoCommit (false);
      this.statements = statements;
      if (validUntil == 0) this.validUntil = 0;
      else this.validUntil = System.currentTimeMillis () + validUntil;
      initRead ();
      initWrite ();
      Server.log ("PoolElement.construct: Created new Connection", Server.MSG_STATE, Server.LVL_MINOR);
   }

	/**
	 * mark this PoolElement as active
	 */
	synchronized void setActive () {
      isActive = true;
   }

	/**
	 * initialize the write-cursor of this PoolElement
	 * @throws Exception
	 */
   private void initWrite () throws Exception {
      write = con.createStatement (ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_UPDATABLE);
      // write.setCursorName ("write"+id);
   }
   /**
    * initialize the read-cursor of this PoolElement
    * @throws Exception
    */
   private void initRead () throws Exception {
      read = con.createStatement (ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
      read.setMaxRows(2);
   }

	/**
	 * get the Result for the given parameters
	 * @param t the table name
	 * @param data the data-columns to retrieve
	 * @param cond the condition to match
	 * @return the resultset containing the data
	 * @throws Exception
	 */
   public synchronized ResultSet getResultSet (String t, String data, String cond, String timeout) throws Exception {
      StringBuffer tsb = new StringBuffer ("select ").append (data);
      tsb.append (" FROM ").append (t);
      tsb.append (" WHERE ").append (cond);
      if (read == null) initRead ();
		if (timeout != null) {
		  int tout = Integer.parseInt(timeout, 10);
		  read.setQueryTimeout(tout);
		}
      ResultSet rs = read.executeQuery (tsb.toString ());
      if (Server.checkLogLvl (Server.MSG_AUTH, Server.LVL_VERY_VERBOSE)) {
         tsb.insert (0, "PoolElement.getResultSet: returning result for statement\r\n");
         Server.log (tsb.toString (), Server.MSG_AUTH, Server.LVL_VERY_VERBOSE);
      }
      sCnt++;
		checkWarnings (read);
      isActive = false;
      return rs;
   }

	/**
	 * close the read-cursor
	 */
   public synchronized void closeRead () {
      try {
         read.close ();
         read = null;
      } catch (SQLException se) {
         Server.debug ("PoolElement.closeRead:", se, Server.MSG_ERROR, Server.LVL_MINOR);
      }
   }
   /**
	* close the read-cursor
	*/
   public synchronized void closeWrite () {
 	  try {
 		 write.close ();
 		 write = null;
 	  } catch (SQLException se) {
		 Server.debug ("PoolElement.closeWrite:", se, Server.MSG_ERROR, Server.LVL_MINOR);
	  }
   }

	/**
	 * commit changes
	 * @throws Exception
	 */
   public synchronized void commit () throws Exception {
      con.commit ();
      write.close ();
      write = null;
      isActive = false;
   }
   
   /**
    * rollback changes
    * @throws Exception
    */
   public synchronized void rollback () throws Exception {
      con.rollback ();
      write.close ();
      write = null;
      isActive = false;
   }

	/**
	 * cause the datarecords to be updated
	 * @param t the table to update
	 * @param data the data update
	 * @param cond the condition to match
	 * @return the number of updated records
	 * @throws Exception
	 */
   public synchronized int setData (String t, String data, String cond, String timeout) throws Exception {
      StringBuffer tsb = new StringBuffer ("update ").append (t).append (" set ");
      tsb.append (data);
      tsb.append (" where ");
      tsb.append (cond);
      if (write == null) initWrite ();
	  if (timeout != null) {
  		 int tout = Integer.parseInt(timeout, 10);
  		 read.setQueryTimeout(tout);
	  }
      int count = write.executeUpdate (tsb.toString ());
      if (Server.checkLogLvl (Server.MSG_AUTH, Server.LVL_VERY_VERBOSE)) {
         tsb.insert (0, "PoolElement.setData: Executed update\r\n");
         Server.log (tsb.toString (), Server.MSG_AUTH, Server.LVL_VERY_VERBOSE);
      }
		checkWarnings (write);
      return count;
   }

	/**
	 * check if this PoolElement is active
	 * @return true if active, false if not
	 */
   public synchronized boolean isActive () {
      return isActive;
   }

	/**
	 * checks if this PoolElement is valid
	 * @return true if this element is valid, false if not
	 */
	synchronized boolean isValid () {
      if (con == null) return false;
      try {
         if (con.isClosed ()) return false;
         if (read == null) {
            initRead ();
            if (read == null) return false;
         }
         if (write == null) {
            initWrite ();
            if (write == null) return false;
         }
         if (sCnt > statements ||
             (validUntil < System.currentTimeMillis () && validUntil != 0) ||
             con.isClosed ()) {
            cleanup ();
            return false;
         }
      } catch (Exception e) {
         Server.debug ("error during db-connection-cleanup", e, Server.MSG_ERROR, Server.LVL_MAJOR);
         con = null;
         read = write = null;
         return false;
      }
      return true;
   }

	/**
	 * causes this PoolElement to close all open cursors and the connection to it's jdbc-source
	 * @throws Exception
	 */
   public synchronized void cleanup () throws Exception {
      if (read != null) read.close ();
      read = null;
      if (write != null) write.close ();
      write = null;
      if (con != null && !con.isClosed ()) con.close ();
      con = null;
      Server.log ("PoolElement.cleanup: Cleanup done", Server.MSG_STATE, Server.LVL_VERBOSE);
   }

	public synchronized void checkWarnings(Statement s) throws Exception {
		SQLWarning sqlW = s.getWarnings();
		while (sqlW != null) {
			  StringBuffer sb = new StringBuffer("PoolElement.getResultSet: Encountered SQLWarning: ");
			  sb.append (sqlW.getErrorCode());
			  sb.append (": ");
			  sb.append (sqlW.getCause());
			  Server.log (sb.toString (), Server.MSG_ERROR, Server.LVL_MAJOR);
			  sqlW = sqlW.getNextWarning();
		}
	}
}