JSP数据库连接池连接实例

/** * @author youyongming * */ import java.util.LinkedHashSet; import java.sql.*; import java.util.Iterator; public class ConnectionFactory { private static ConnectionFactory m_instance = null; //在使用的连接池 private LinkedHashSet ConnectionPool = null; //空闲连接池 private LinkedHashSet FreeConnectionPool = null; //最大连接数 private int MaxConnectionCount = 4; //最小连接数 private int MinConnectionCount = 2; //当前连接数 private int current_conn_count = 0; //连接参数 private ConnectionParam connparam = null; //是否创建工厂的标志 private boolean isflag = false; //是否支持事务 private boolean supportTransaction = false; //定义管理策略 private int ManageType = 0; private ConnectionFactory() { ConnectionPool = new LinkedHashSet(); FreeConnectionPool = new LinkedHashSet(); } /** * 使用指定的参数创建一个连接池 */ public ConnectionFactory(ConnectionParam param, FactoryParam fparam) throws SQLException { //不允许参数为空 if ((param == null)||(fparam == null)) throw new SQLException("ConnectionParam和FactoryParam不能为空"); if (m_instance == null) { synchronized(ConnectionFactory.class){ if (m_instance == null) { //new instance //参数定制 m_instance = new ConnectionFactory(); m_instance.connparam = param; m_instance.MaxConnectionCount = fparam.getMaxConn(); m_instance.MinConnectionCount = fparam.getMinConn(); m_instance.ManageType = fparam.getType(); m_instance.isflag = true; //初始化，创建MinConnectionCount个连接 System.out.println("connection factory 创建！"); try{ for (int i=0; i < m_instance.MinConnectionCount; i++) { _Connection _conn = _Connection.getConnection(m_instance, m_instance.connparam); if (_conn == null) continue; System.out.println("connection创建"); m_instance.FreeConnectionPool.add(_conn);//加入空闲连接池 m_instance.current_conn_count ++; //标志是否支持事务 m_instance.supportTransaction = _conn.isSupportTransaction(); } } catch(Exception e) { e.printStackTrace(); } //根据策略判断是否需要查询 if (m_instance.ManageType != 0) { Thread t = new Thread(new FactoryMangeThread(m_instance)); t.start(); } } } } } /** * 标志工厂是否已经创建 * @return boolean */ public boolean isCreate() { return m_instance.isflag; } /** * 从连接池中取一个空闲的连接 * @return Connection * @throws SQLException */ public synchronized Connection getFreeConnection() throws SQLException { Connection conn = null; //获取空闲连接 Iterator iter = m_instance.FreeConnectionPool.iterator(); while(iter.hasNext()){ _Connection _conn = (_Connection)iter.next(); //找到未用连接 if(!_conn.isFree()){ conn = _conn.getFreeConnection(); _conn.setIsFree(true); //移出空闲区 m_instance.FreeConnectionPool.remove(_conn); //加入连接池 m_instance.ConnectionPool.add(_conn); break; } } //检查空闲池是否为空 if (m_instance.FreeConnectionPool.isEmpty()) { //再检查是否能够分配 if (m_instance.current_conn_count < m_instance.MaxConnectionCount) { //新建连接到空闲连接池 int newcount = 0 ; //取得要建立的数目 if (m_instance.MaxConnectionCount - m_instance.current_conn_count >=m_instance.MinConnectionCount) { newcount = m_instance.MinConnectionCount; } else { newcount = m_instance.MaxConnectionCount - m_instance.current_conn_count; } //创建连接 for (int i=0;i <newcount; i++) { _Connection _conn = _Connection.getConnection(m_instance, m_instance.connparam); m_instance.FreeConnectionPool.add(_conn); m_instance.current_conn_count ++; } } else {//如果不能新建，检查是否有已经归还的连接 iter = m_instance.ConnectionPool.iterator(); while(iter.hasNext()){ _Connection _conn = (_Connection)iter.next(); if(!_conn.isFree()){ conn = _conn.getFreeConnection(); _conn.setIsFree(false); m_instance.ConnectionPool.remove(_conn); m_instance.FreeConnectionPool.add(_conn); break; } } } }//if (FreeConnectionPool.isEmpty()) //再次检查是否能分配连接 if(conn == null){ iter = m_instance.FreeConnectionPool.iterator(); while(iter.hasNext()){ _Connection _conn = (_Connection)iter.next(); if(!_conn.isFree()){ conn = _conn.getFreeConnection(); _conn.setIsFree(true); m_instance.FreeConnectionPool.remove(_conn); m_instance.ConnectionPool.add(_conn); break; } } if(conn == null)//如果不能则说明无连接可用 throw new SQLException("没有可用的数据库连接"); } System.out.println("get connection"); return conn; } /** * 关闭该连接池中的所有数据库连接 * @throws SQLException */ public synchronized void close() throws SQLException { this.isflag = false; SQLException excp = null; //关闭空闲池 Iterator iter = m_instance.FreeConnectionPool.iterator(); while(iter.hasNext()){ try{ ((_Connection)iter.next()).close(); System.out.println("close connection:free"); m_instance.current_conn_count --; }catch(Exception e){ if(e instanceof SQLException) excp = (SQLException)e; } } //关闭在使用的连接池 iter = m_instance.ConnectionPool.iterator(); while(iter.hasNext()){ try{ ((_Connection)iter.next()).close(); System.out.println("close connection:inused"); m_instance.current_conn_count --; }catch(Exception e){ if(e instanceof SQLException) excp = (SQLException)e; } } if(excp != null) throw excp; } /** * 返回是否支持事务 * @return boolean */ public boolean isSupportTransaction() { return m_instance.supportTransaction; } /** * 连接池调度管理 * */ public void schedule() { Connection conn = null; //再检查是否能够分配 Iterator iter = null; //检查是否有已经归还的连接 { iter = m_instance.ConnectionPool.iterator(); while(iter.hasNext()){ _Connection _conn = (_Connection)iter.next(); if(!_conn.isFree()){ conn = _conn.getFreeConnection(); _conn.setIsFree(false); m_instance.ConnectionPool.remove(_conn); m_instance.FreeConnectionPool.add(_conn); break; } } } if (m_instance.current_conn_count < m_instance.MaxConnectionCount) { //新建连接到空闲连接池 int newcount = 0 ; //取得要建立的数目 if (m_instance.MaxConnectionCount - m_instance.current_conn_count >=m_instance.MinConnectionCount) { newcount = m_instance.MinConnectionCount; } else { newcount = m_instance.MaxConnectionCount - m_instance.current_conn_count; } //创建连接 for (int i=0;i <newcount; i++) { _Connection _conn = _Connection.getConnection(m_instance, m_instance.connparam); m_instance.FreeConnectionPool.add(_conn); m_instance.current_conn_count ++; } } } }