Chinaunix首页 | 论坛 | 博客
  • 博客访问: 240082
  • 博文数量: 22
  • 博客积分: 512
  • 博客等级: 下士
  • 技术积分: 242
  • 用 户 组: 普通用户
  • 注册时间: 2012-02-17 09:48
文章分类

全部博文(22)

文章存档

2013年(1)

2012年(21)

我的朋友

分类: Java

2012-02-23 20:12:34

package cn.ifnic.db;
import java.io.*;
import java.sql.*;
import java.util.*;
import java.util.Date;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;
import cn.ifnic.util.Common;
import cn.ifnic.util.GetProperties;
/**
 *
 *

Title: IFNIC


 *
 *

Description: 类DBConnectionManager,连接池的管理类


 *
 *

Copyright: Copyright (c) 2005
 *
 *

Company: IFNIC.CN


 *
 * @author IFNIC
 * @version 1.1.0
 */
/**
 * 管理类DBConnectionManager支持对一个或多个由属性文件定义的数据库连接
 * 池的访问.客户程序可以调用getInstance()方法访问本类的唯一实例.
 */
public class DBConnectionManager {
    static private DBConnectionManager instance; // 唯一实例
    static private int clients;
    private Vector drivers = new Vector();
    private Logger logger;
    //private PrintWriter log;
    private Hashtable pools = new Hashtable();
    /**
     * 返回唯一实例.如果是第一次调用此方法,则创建实例
     *
     * @return DBConnectionManager 唯一实例
     */
    static synchronized public DBConnectionManager getInstance() {
        if (instance == null) {
            instance = new DBConnectionManager();
        }
        clients++;
        return instance;
    }
    /**
     * 建构函数私有以防止其它对象创建本类实例
     */
    private DBConnectionManager() {
        init();
    }
    /**
     * 将连接对象返回给由名字指定的连接池
     *
     * @param name 在属性文件中定义的连接池名字
     * @param con 连接对象
     */
    public void freeConnection(String name, Connection con) {
        DBConnectionPool pool = (DBConnectionPool) pools.get(name);
        if (pool != null) {
            pool.freeConnection(con);
        }
    }
    /**
     * 获得一个可用的(空闲的)连接.如果没有可用连接,且已有连接数小于最大连接数
     * 限制,则创建并返回新连接
     *
     * @param name 在属性文件中定义的连接池名字
     * @return Connection 可用连接或null
     */
    public Connection getConnection(String name) {
        DBConnectionPool pool = (DBConnectionPool) pools.get(name);
        if (pool != null) {
            return pool.getConnection();
        }
        return null;
    }
    /**
     * 获得一个可用连接.若没有可用连接,且已有连接数小于最大连接数限制,
     * 则创建并返回新连接.否则,在指定的时间内等待其它线程释放连接.
     *
     * @param name 连接池名字
     * @param time 以毫秒计的等待时间
     * @return Connection 可用连接或null
     */
    public Connection getConnection(String name, long time) {
        DBConnectionPool pool = (DBConnectionPool) pools.get(name);
        if (pool != null) {
            return pool.getConnection(time);
        }
        return null;
    }
    /**
     * 关闭所有连接,撤销驱动程序的注册
     */
    public synchronized void release() {
        // 等待直到最后一个客户程序调用
        if (--clients != 0) {
            return;
        }
        Enumeration allPools = pools.elements();
        while (allPools.hasMoreElements()) {
            DBConnectionPool pool = (DBConnectionPool) allPools.nextElement();
            pool.release();
        }
        Enumeration allDrivers = drivers.elements();
        while (allDrivers.hasMoreElements()) {
            Driver driver = (Driver) allDrivers.nextElement();
            try {
                DriverManager.deregisterDriver(driver);
                logger.info("撤销JDBC驱动程序 " + driver.getClass().getName() + "的注册");
            } catch (SQLException e) {
                logger.error("无法撤销下列JDBC驱动程序的注册: " + driver.getClass().getName(),
                             e.getNextException());
            }
        }
    }
    /**
     * 根据指定属性创建连接池实例.
     *
     * @param props 连接池属性
     */
    private void createPools(Properties props) {
        Enumeration propNames = props.propertyNames();
        while (propNames.hasMoreElements()) {
            String name = (String) propNames.nextElement();
            if (name.endsWith(".url")) {
                String poolName = name.substring(0, name.lastIndexOf("."));
                String url = props.getProperty(poolName + ".url");
                if (url == null) {
                    logger.error("没有为连接池" + poolName + "指定URL");
                    continue;
                }
                String user = props.getProperty(poolName + ".user");
                String password = props.getProperty(poolName + ".password");
                String maxconn = props.getProperty(poolName + ".maxconn", "0");
                int max;
                try {
                    max = Integer.valueOf(maxconn).intValue();
                } catch (NumberFormatException e) {
                    logger.error("错误的最大连接数限制: " + maxconn + " .连接池: " +
                                 poolName);
                    max = 0;
                }
                DBConnectionPool pool =
                        new DBConnectionPool(poolName, url, user, password, max);
                pools.put(poolName, pool);
                logger.info("成功创建连接池" + poolName);
            }
        }
    }
    /**
     * 读取属性完成初始化
     */
    private void init() {
        GetProperties getProperties = new GetProperties();
        if (getProperties.getProperties("DBConnectionManager") != null) {
            PropertyConfigurator.configure(getProperties.getProperties(
                    "DBConnectionManager"));
        }
        logger = Logger.getLogger(Common.class.getName());
        if (getProperties.getProperties("db") != null) {
            Properties pp=getProperties.getProperties("db");
            loadDrivers(pp);
            createPools(pp);
        } else {
            return;
        }
    }
    /**
     * 装载和注册所有JDBC驱动程序
     *
     * @param props 属性
     */
    private void loadDrivers(Properties props) {
        String driverClasses = props.getProperty("drivers");
        StringTokenizer st = new StringTokenizer(driverClasses);
        while (st.hasMoreElements()) {
            String driverClassName = st.nextToken().trim();
            try {
                Driver driver = (Driver)
                                Class.forName(driverClassName).newInstance();
                DriverManager.registerDriver(driver);
                drivers.addElement(driver);
                logger.info("成功注册JDBC驱动程序" + driverClassName);
            } catch (Exception e) {
                logger.error("无法注册JDBC驱动程序: " +
                             driverClassName + ", 错误: " + e);
            }
        }
    }
 
    /**
     * 此内部类定义了一个连接池.它能够根据要求创建新连接,直到预定的最
     * 大连接数为止.在返回连接给客户程序之前,它能够验证连接的有效性.
     */
    class DBConnectionPool {
        private int checkedOut;
        private Vector freeConnections = new Vector();
        private int maxConn;
        private String name;
        private String password;
        private String URL;
        private String user;
        private Logger logger;
        /**
         * 创建新的连接池
         *
         * @param name 连接池名字
         * @param URL 数据库的JDBC URL
         * @param user 数据库帐号,或 null
         * @param password 密码,或 null
         * @param maxConn 此连接池允许建立的最大连接数
         */
        public DBConnectionPool(String name, String URL, String user,
                                String password,
                                int maxConn) {
            this.name = name;
            this.URL = URL;
            this.user = user;
            this.password = password;
            this.maxConn = maxConn;
            GetProperties getProperties = new GetProperties();
            if (getProperties.getProperties("DBConnectionManager") != null) {
                PropertyConfigurator.configure(getProperties.getProperties(
                        "DBConnectionManager"));
                logger = Logger.getLogger(Common.class.getName());
            } else {
                return;
            }
        }
        /**
         * 将不再使用的连接返回给连接池
         *
         * @param con 客户程序释放的连接
         */
        public synchronized void freeConnection(Connection con) {
            // 将指定连接加入到向量末尾
            freeConnections.addElement(con);
            checkedOut--;
            notifyAll();
        }
        /**
         * 从连接池获得一个可用连接.如没有空闲的连接且当前连接数小于最大连接
         * 数限制,则创建新连接.如原来登记为可用的连接不再有效,则从向量删除之,
         * 然后递归调用自己以尝试新的可用连接.
         */
        public synchronized Connection getConnection() {
            Connection con = null;
            if (freeConnections.size() > 0) {
                // 获取向量中第一个可用连接
                con = (Connection) freeConnections.firstElement();
                freeConnections.removeElementAt(0);
                try {
                    if (con.isClosed()) {
                        logger.info("从连接池" + name + "删除一个无效连接");
                        // 递归调用自己,尝试再次获取可用连接
                        con = getConnection();
                    }
                } catch (SQLException e) {
                    logger.warn("从连接池" + name + "删除一个无效连接");
                    // 递归调用自己,尝试再次获取可用连接
                    con = getConnection();
                }
            } else if (maxConn == 0 || checkedOut < maxConn) {
                con = newConnection();
            }
            if (con != null) {
                checkedOut++;
            }
            return con;
        }
        /**
         * 从连接池获取可用连接.可以指定客户程序能够等待的最长时间
         * 参见前一个getConnection()方法.
         *
         * @param timeout 以毫秒计的等待时间限制
         */
        public synchronized Connection getConnection(long timeout) {
            long startTime = new Date().getTime();
            Connection con;
            while ((con = getConnection()) == null) {
                try {
                    wait(timeout);
                } catch (InterruptedException e) {}
                if ((new Date().getTime() - startTime) >= timeout) {
                    // wait()返回的原因是超时
                    return null;
                }
            }
            return con;
        }
        /**
         * 关闭所有连接
         */
        public synchronized void release() {
            Enumeration allConnections = freeConnections.elements();
            while (allConnections.hasMoreElements()) {
                Connection con = (Connection) allConnections.nextElement();
                try {
                    con.close();
                    logger.info("关闭连接池" + name + "中的一个连接");
                } catch (SQLException e) {
                    logger.error("无法关闭连接池" + name + "中的连接", e.getNextException());
                }
            }
            freeConnections.removeAllElements();
        }
        /**
         * 创建新的连接
         */
        private Connection newConnection() {
            Connection con = null;
            try {
                if (user == null) {
                    con = DriverManager.getConnection(URL);
                } else {
                    con = DriverManager.getConnection(URL, user, password);
                }
                logger.info("连接池" + name + "创建一个新的连接");
            } catch (SQLException e) {
                logger.error("无法创建下列URL的连接: " + URL, e.getNextException());
                return null;
            }
            return con;
        }
    }
}
 


//PropertiesLoader.java 配置文件读取类
 
package cn.ifnic.util;
import java.util.Properties;
import java.io.InputStream;
import java.io.*;
/**
 *
 *

Title: IFNIC


 *
 *

Description: 类GetProperties,用来获取*.properties配置文件的


 *
 *

Copyright: Copyright (c) 2005
 *
 *

Company: IFNIC.CN


 *
 * @author IFNIC
 * @version 1.1.0
 */
public class PropertiesLoader {
    /**
     * 用法:getProperties(*.properties配置文件名),返回一个Properties对象
     * @param propertiesName String
     * @return Properties
     */
    public Properties getProperties(String propertiesName) {
        InputStream is = getClass().getResourceAsStream("/" + propertiesName +
                ".properties");
        Properties dbProps = new Properties();
        try {
            dbProps.load(is);
            return dbProps;
        } catch (IOException ex) {
            System.out.println("不能读取属性文件. " +
                               "请确保" + propertiesName +
                               ".properties 在CLASSPATH指定的路径中");
            return null;
        }
    }
}


 

//db.properties 连接池配置文件

 

drivers=net.sourceforge.jtds.jdbc.Driver #为连接池指定一个数据库连接驱动程序

jtds_root.url=jdbc:jtds:sqlserver://localhost/root #数据库连接URL
jtds_root.maxconn=0 #连接最大数 为0表示没有限制
jtds_root.user=sa #数据库用户名
jtds_root.password=sa #数据库密码

//DBConnectionManager.properties Log4j配置文件

log4j.rootLogger=INFO, Common #定义被日志捕获的信息级别
#ERROR、WARN、INFO、DEBUG
log4j.appender.Common=org.apache.log4j.RollingFileAppender #定义日志的存储方式
log4j.appender.Common.File = logs/DBConnectionManagerLog.html #定义日志文件路径
log4j.appender.Common.Append=true #定义是否追加 否为覆盖
log4j.appender.Common.MaxFileSize = 1024kb #定义文件大小
log4j.appender.Common.MaxBackupIndex=10 #定义最大备份文件数log4j.appender.Common.layout=org.apache.log4j.HTMLLayout #定义输出格式为HTML格式

阅读(3064) | 评论(0) | 转发(0) |
给主人留下些什么吧!~~