Java Web中使用数据库连接池proxool配置详解

使用proxool数据库连接池步骤：

在WEB-INF的lib中导入proxool-0.9.0RC3.jar
在WEB-INF中新建一个XML文件，取名为proxool.xml
在proxool.xml中的内容如下：

    <?xml version="1.0" encoding="UTF-8"?> 
    <!-- 
    the proxool configuration can be embedded within your own application's. Anything outside the "proxool"  
     
    tag is ignored. 
    --> 
    <something-else-entirely> 
         <proxool> 
                    <alias>smms</alias> <!--数据源的别名--> 
                    <driver-url>jdbc:mysql://127.0.0.1:3306/smms</driver-url><!--url连接串--> 
                    <driver-class>com.mysql.jdbc.Driver</driver-class><!--驱动类--> 
                    <driver-properties> 
                            <property name="user" value="root" /><!--用户名--> 
                            <property name="password" value="root" /><!--密码--> 
                    </driver-properties>          
                    <!--最大连接数(默认 5个),超过了这个连接数,再有请求时,就排在队列中等候,最大的等待请求数由 
     
    maximum-new-connections决定--> 
                    <maximum-connection-count>100</maximum-connection-count> 
                    <!--最小连接数(默认2个)--> 
                    <minimum-connection-count>10</minimum-connection-count> 
                    <!--proxool自动侦察各个连接状态的时间间隔(毫秒),侦察到空闲的连接就马上回收,超时的销毁  默 
     
    认30秒--> 
                    <house-keeping-sleep-time>90000</house-keeping-sleep-time> 
                    <!--没有空闲连接可以分配而在队列中等候的最大请求数,超过这个请求数的用户连接就不会被接受- 
     
    -> 
                    <maximum-new-connections>10</maximum-new-connections> 
                    <!--最少保持的空闲连接数(默认2个)--> 
                    <prototype-count>5</prototype-count> 
                    <!--在使用之前测试--> 
                    <test-before-use>true</test-before-use> 
                    <!--用于保持连接的测试语句  --> 
                    <house-keeping-test-sql>select id from t_sysadmin</house-keeping-test-sql> 
         </proxool> 
    </something-else-entirely> 

在web.xml中添加以下节点：

    <servlet>      
     <servlet-name>ServletConfigurator</servlet-name>      
     <servlet-class>      
       org.logicalcobwebs.proxool.configuration.ServletConfigurator</servlet-class>      
     <init-param>      
       <param-name>xmlFile</param-name>      
       <param-value>WEB-INF/proxool.xml</param-value>      
     </init-param>      
     <load-on-startup>1</load-on-startup>      
    t;/servlet> 

数据库操作类如下：

    package cn.edu.hbcit.smms.dao.databasedao; 
     
    import java.sql.Connection; 
    import java.sql.DriverManager; 
    import java.sql.PreparedStatement; 
    import java.sql.ResultSet; 
    import java.sql.SQLException; 
     
    import org.apache.log4j.Logger; 
     
    import org.logicalcobwebs.proxool.ProxoolException;        
    import org.logicalcobwebs.proxool.ProxoolFacade;        
    import org.logicalcobwebs.proxool.admin.SnapshotIF; 
    /**
     * 数据库操作类
     * @author lw
     *
     */ 
    public class DBConn { 
        private static Connection conn; 
        private static ResultSet rs; 
        private static PreparedStatement ps; 
        private static String driverClass = "org.logicalcobwebs.proxool.ProxoolDriver";//proxool驱动类  
        //private static String url = "jdbc:mysql://localhost:3306/bbs?user=root&password=123";  
        private static int activeCount = 0; //活动连接数  
        protected final Logger log = Logger.getLogger(DBConn.class.getName()); 
         
        /**
         * 获取数据库连接
         * @return Connection
         */ 
        public Connection getConn() { 
            try { 
                Class.forName(driverClass);  
                conn = DriverManager.getConnection("proxool.smms"); //此处的smms是在proxool.xml中配置的连接池别名  
                this.showSnapshotInfo(); //查看连接池信息  
            } catch (Exception e) { 
                log.error(e.getMessage()); 
                log.debug("数据库连接错误！"); 
                //System.out.println(e.getMessage());  
                //System.out.println("数据库连接错误！");  
            } 
            return conn; 
        } 
         
        /**     
         * 释放连接     
         * freeConnection     
         * @param conn     
         */ 
        public void freeConnection(Connection conn){ 
            if(conn!=null){ 
                try { 
                    conn.close(); 
                } catch (SQLException e) { 
                    e.printStackTrace(); 
                } 
            } 
        } 
         
     
        /**
         * 获取连接池中的连接信息
         */ 
        private void showSnapshotInfo(){ 
            try{        
                SnapshotIF snapshot = ProxoolFacade.getSnapshot("smms", true);        
                int curActiveCount=snapshot.getActiveConnectionCount();//获得活动连接数         
                int availableCount=snapshot.getAvailableConnectionCount();//获得可得到的连接数         
                int maxCount=snapshot.getMaximumConnectionCount() ;//获得总连接数         
                if(curActiveCount!=activeCount)//当活动连接数变化时输出的信息         
                { 
                    log.debug("活动连接数:"+curActiveCount+"(active)；可得到的连接数:"+availableCount+"(available)；总连接数:"+maxCount+"(max)"); 
                 //System.out.println("活动连接数:"+curActiveCount+"(active)；可得到的连接数:"+availableCount+"(available)；总连接数:"+maxCount+"(max)");                      
                 activeCount=curActiveCount;        
                } 
            }catch(ProxoolException e){        
                e.printStackTrace();        
            }        
        }   
     
    }