單實(shí)例模式數(shù)據(jù)庫(kù)連接池+log4j//DBConnectionManager.java 連接池類 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; /** * * <p>Title: IFNIC</p> * * <p>Description: 類DBConnectionManager，連接池的管理類</p> * * <p>Copyright: Copyright (c) 2005 www.</p> * * <p>Company: IFNIC.CN</p> * * @author IFNIC * @version 1.1.0 */ /** * 管理類DBConnectionManager支持對(duì)一個(gè)或多個(gè)由屬性文件定義的數(shù)據(jù)庫(kù)連接 * 池的訪問.客戶程序可以調(diào)用getInstance()方法訪問本類的唯一實(shí)例. */ public class DBConnectionManager { static private DBConnectionManager instance; // 唯一實(shí)例 static private int clients; private Vector drivers = new Vector();
private Logger logger; //private PrintWriter log; private Hashtable pools = new Hashtable(); /**
* 返回唯一實(shí)例.如果是第一次調(diào)用此方法,則創(chuàng)建實(shí)例 * * @return DBConnectionManager 唯一實(shí)例 */ static synchronized public DBConnectionManager getInstance() { if (instance == null) { instance = new DBConnectionManager(); } clients++; return instance; } /**
* 建構(gòu)函數(shù)私有以防止其它對(duì)象創(chuàng)建本類實(shí)例 */ private DBConnectionManager() { init(); } /**
* 將連接對(duì)象返回給由名字指定的連接池 * * @param name 在屬性文件中定義的連接池名字 * @param con 連接對(duì)象 */ public void freeConnection(String name, Connection con) { DBConnectionPool pool = (DBConnectionPool) pools.get(name); if (pool != null) { pool.freeConnection(con); } } /**
* 獲得一個(gè)可用的(空閑的)連接.如果沒有可用連接,且已有連接數(shù)小于最大連接數(shù) * 限制,則創(chuàng)建并返回新連接 * * @param name 在屬性文件中定義的連接池名字 * @return Connection 可用連接或null */ public Connection getConnection(String name) { DBConnectionPool pool = (DBConnectionPool) pools.get(name); if (pool != null) { return pool.getConnection(); } return null; } /**
* 獲得一個(gè)可用連接.若沒有可用連接,且已有連接數(shù)小于最大連接數(shù)限制, * 則創(chuàng)建并返回新連接.否則,在指定的時(shí)間內(nèi)等待其它線程釋放連接. * * @param name 連接池名字 * @param time 以毫秒計(jì)的等待時(shí)間 * @return Connection 可用連接或null */ public Connection getConnection(String name, long time) { DBConnectionPool pool = (DBConnectionPool) pools.get(name); if (pool != null) { return pool.getConnection(time); } return null; } /**
* 關(guān)閉所有連接,撤銷驅(qū)動(dòng)程序的注冊(cè) */ public synchronized void release() { // 等待直到最后一個(gè)客戶程序調(diào)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("撤銷JDBC驅(qū)動(dòng)程序 " + driver.getClass().getName() + "的注冊(cè)"); } catch (SQLException e) { logger.error("無法撤銷下列JDBC驅(qū)動(dòng)程序的注冊(cè): " + driver.getClass().getName(), e.getNextException()); } } } /**
* 根據(jù)指定屬性創(chuàng)建連接池實(shí)例. * * @param props 連接池屬性 */ 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("沒有為連接池" + 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("錯(cuò)誤的最大連接數(shù)限制: " + maxconn + " .連接池: " + poolName); max = 0; } DBConnectionPool pool = new DBConnectionPool(poolName, url, user, password, max); pools.put(poolName, pool); logger.info("成功創(chuàng)建連接池" + poolName); } } } /**
* 讀取屬性完成初始化 */ 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; } }
/**
* 裝載和注冊(cè)所有JDBC驅(qū)動(dòng)程序 * * @param props 屬性 */ 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("成功注冊(cè)JDBC驅(qū)動(dòng)程序" + driverClassName); } catch (Exception e) { logger.error("無法注冊(cè)JDBC驅(qū)動(dòng)程序: " + driverClassName + ", 錯(cuò)誤: " + e); } } } /**
* 此內(nèi)部類定義了一個(gè)連接池.它能夠根據(jù)要求創(chuàng)建新連接,直到預(yù)定的最 * 大連接數(shù)為止.在返回連接給客戶程序之前,它能夠驗(yàn)證連接的有效性. */ 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; /**
* 創(chuàng)建新的連接池 * * @param name 連接池名字 * @param URL 數(shù)據(jù)庫(kù)的JDBC URL * @param user 數(shù)據(jù)庫(kù)賬號(hào),或 null * @param password 密碼,或 null * @param maxConn 此連接池允許建立的最大連接數(shù) */ 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; } }
/**
* 將不再使用的連接返回給連接池 * * @param con 客戶程序釋放的連接 */ public synchronized void freeConnection(Connection con) { // 將指定連接加入到向量末尾 freeConnections.addElement(con); checkedOut--; notifyAll(); } /**
* 從連接池獲得一個(gè)可用連接.如沒有空閑的連接且當(dāng)前連接數(shù)小于最大連接 * 數(shù)限制,則創(chuàng)建新連接.如原來登記為可用的連接不再有效,則從向量刪除之, * 然后遞歸調(diào)用自己以嘗試新的可用連接. */ public synchronized Connection getConnection() { Connection con = null; if (freeConnections.size() > 0) { // 獲取向量中第一個(gè)可用連接 con = (Connection) freeConnections.firstElement(); freeConnections.removeElementAt(0); try { if (con.isClosed()) { logger.info("從連接池" + name + "刪除一個(gè)無效連接"); // 遞歸調(diào)用自己,嘗試再次獲取可用連接 con = getConnection(); } } catch (SQLException e) { logger.warn("從連接池" + name + "刪除一個(gè)無效連接"); // 遞歸調(diào)用自己,嘗試再次獲取可用連接 con = getConnection(); } } else if (maxConn == 0 || checkedOut < maxConn) { con = newConnection(); } if (con != null) { checkedOut++; } return con; } /**
* 從連接池獲取可用連接.可以指定客戶程序能夠等待的最長(zhǎng)時(shí)間 * 參見前一個(gè)getConnection()方法. * * @param timeout 以毫秒計(jì)的等待時(shí)間限制 */ 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()返回的原因是超時(shí) return null; } } return con; } /**
* 關(guān)閉所有連接 */ public synchronized void release() { Enumeration allConnections = freeConnections.elements(); while (allConnections.hasMoreElements()) { Connection con = (Connection) allConnections.nextElement(); try { con.close(); logger.info("關(guān)閉連接池" + name + "中的一個(gè)連接"); } catch (SQLException e) { logger.error("無法關(guān)閉連接池" + name + "中的連接", e.getNextException()); } } freeConnections.removeAllElements(); } /**
* 創(chuàng)建新的連接 */ private Connection newConnection() { Connection con = null; try { if (user == null) { con = DriverManager.getConnection(URL); } else { con = DriverManager.getConnection(URL, user, password); } logger.info("連接池" + name + "創(chuàng)建一個(gè)新的連接"); } catch (SQLException e) { logger.error("無法創(chuàng)建下列URL的連接: " + URL, e.getNextException()); return null; } return con; } } } //PropertiesLoader.java 配置文件讀取類
package cn.ifnic.util;
import java.util.Properties;
import java.io.InputStream; import java.io.*; /**
* * <p>Title: IFNIC</p> * * <p>Description: 類GetProperties，用來獲取*.properties配置文件的</p> * * <p>Copyright: Copyright (c) 2005 www.</p> * * <p>Company: IFNIC.CN</p> * * @author IFNIC * @version 1.1.0 */ public class PropertiesLoader {
//db.properties 連接池配置文件
drivers=net.sourceforge.jtds.jdbc.Driver #為連接池指定一個(gè)數(shù)據(jù)庫(kù)連接驅(qū)動(dòng)程序 jtds_root.url=jdbc:jtds:sqlserver://localhost/root #數(shù)據(jù)庫(kù)連接URL //DBConnectionManager.properties Log4j配置文件 log4j.rootLogger=INFO, Common #定義被日志捕獲的信息級(jí)別
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