dbconnpool.java~1~

流言板 用JBUILDER开发的 实用方便 需要的尽管拿去用

package com.test.DB;

import java.sql.*;
import java.util.*;

/*连接池类.能够根据要求创建新连接,直到最大连接数为止.*/
public class DBConnPool {
        //实际使用中的连接数
        private int inUse=0;
        //空闲连接
        private Vector connections = new Vector();
        //连接池名
        private String poolname;
        //数据库标识
        private String dbid;
        //驱动程序名
        private String drivername;
        //数据库账号
        private String username;
        //数据库密码
        private String passwd;
        //最大连接数
        private int maxconn;

        public DBConnPool(String poolname, String drivername, String dbid, String username, String passwd, int maxconn) {
                this.poolname = poolname;
                this.dbid = dbid;
                this.drivername = drivername;
                this.username = username;
                this.passwd = passwd;
                this.maxconn = maxconn;
        }

        /*将连接返回给连接池*/
        public synchronized void releaseConnection(Connection con) {
                // 将指定连接加入到向量末尾
                connections.addElement(con);
                //连接数减一
                inUse--;
        }

        /*从连接池得到一个连接*/
        public synchronized Connection getConnection() {
                Connection con = null;
                if (connections.size() > 0) {
                        // 获取连接列表中获得第一个连接
                        con = (Connection) connections.elementAt(0);
                        connections.removeElementAt(0);
                        //如果此连接已关闭，则继续获取
         try {
            if (con.isClosed())
               con = getConnection();
         }
         catch (Exception ex) {
            ex.printStackTrace();
         }
                }
                //如果实际使用的连接小于最大连接数，就新创建一个连接
                else if (maxconn == 0 || inUse < maxconn) {
                        con = newConnection();
                }
                if (con != null) {
                        //连接数增一
                        inUse++;
                }
                //返回一个连接
                return con;
        }

        /*创建新的连接*/
        private Connection newConnection() {
                Connection con = null;
                try {
                        //加载驱动程序
                        Class.forName(drivername);
                        //建立连接
                        con = DriverManager.getConnection(dbid, username, passwd);
                }
                catch (Exception e) {
                        e.printStackTrace();
                        return null;
                }
                //返回该连接
                return con;
        }

        /*关闭所有连接*/
        public synchronized void closeConn() {
                Enumeration allConnections = connections.elements();
                while (allConnections.hasMoreElements()) {
                        Connection con = (Connection) allConnections.nextElement();
                        try {
                                con.close();
                        }
                        catch (SQLException e) {
                                e.printStackTrace();
                        }
                }
                connections.removeAllElements();
        }
}