锘??xml version="1.0" encoding="utf-8" standalone="yes"?>免费成人在线电影,污污的网站在线看,精品福利在线http://www2.blogjava.net/machilansing/category/13689.htmlLansing--Coding 涓嶆槸姊? zh-cnWed, 28 Feb 2007 20:20:10 GMTWed, 28 Feb 2007 20:20:10 GMT60Java 鐨凧DBC 鏁版嵁搴撹繛鎺ユ睜瀹炵幇鏂規硶http://www.aygfsteel.com/machilansing/archive/2006/08/04/61776.htmlLansingLansingFri, 04 Aug 2006 07:56:00 GMThttp://www.aygfsteel.com/machilansing/archive/2006/08/04/61776.htmlhttp://www.aygfsteel.com/machilansing/comments/61776.htmlhttp://www.aygfsteel.com/machilansing/archive/2006/08/04/61776.html#Feedback0http://www.aygfsteel.com/machilansing/comments/commentRss/61776.htmlhttp://www.aygfsteel.com/machilansing/services/trackbacks/61776.html
鍏抽敭瀛? Java, JDBC, Connection Pool, Database, 鏁版嵁搴撹繛鎺ユ睜, sourcecode

聽聽铏界劧 J2EE 紼嬪簭鍛樹竴鑸兘鏈夌幇鎴愮殑搴旂敤鏈嶅姟鍣ㄦ墍甯︾殑JDBC 鏁版嵁搴撹繛鎺ユ睜錛屼笉榪囧浜庡紑鍙戜竴鑸殑 Java Application 銆?Applet 鎴栬?JSP銆乿elocity 鏃訛紝鎴戜滑鍙敤鐨凧DBC 鏁版嵁搴撹繛鎺ユ睜騫朵笉澶氾紝騫朵笖涓鑸ц兘閮戒笉濂姐?Java 紼嬪簭鍛橀兘寰堢盡鎱?Windows ADO 錛屽彧闇瑕?new Connection 灝卞彲浠ョ洿鎺ヤ粠鏁版嵁搴撹繛鎺ユ睜涓繑鍥?Connection銆傚茍涓?ADO Connection 鏄嚎紼嬪畨鍏ㄧ殑錛屽涓嚎紼嬪彲浠ュ叡鐢ㄤ竴涓?Connection錛?鎵浠?ASP 紼嬪簭涓鑸兘鎶?getConnection 鏀懼湪 Global.asa 鏂囦歡涓紝鍦?IIS 鍚姩鏃跺緩绔嬫暟鎹簱榪炴帴銆侫DO 鐨?Connection 鍜?Result 閮芥湁寰堝ソ鐨勭紦鍐詫紝騫朵笖寰堝鏄撲嬌鐢ㄣ?br />
鍏跺疄鎴戜滑鍙互鑷繁鍐欎竴涓狫DBC 鏁版嵁搴撹繛鎺ユ睜銆傚啓 JDBC connection pool 鐨勬敞鎰忎簨欏規湁錛?br />
1. 鏈変竴涓畝鍗曠殑鍑芥暟浠庤繛鎺ユ睜涓緱鍒頒竴涓?Connection銆?
2. close 鍑芥暟蹇呴』灝?connection 鏀懼洖 鏁版嵁搴撹繛鎺ユ睜銆?
3. 褰撴暟鎹簱榪炴帴姹犱腑娌℃湁絀洪棽鐨?connection錛?鏁版嵁搴撹繛鎺ユ睜蹇呴』鑳藉鑷姩澧炲姞 connection 涓暟銆?
4. 褰撴暟鎹簱榪炴帴姹犱腑鐨?connection 涓暟鍦ㄦ煇涓涓壒鍒殑鏃墮棿鍙樺緱寰堝ぇ錛屼絾鏄互鍚庡緢闀挎椂闂村彧鐢ㄥ叾涓竴灝忛儴鍒嗭紝搴旇鍙互鑷姩灝嗗浣欑殑 connection 鍏抽棴鎺夈?
5. 濡傛灉鍙兘錛屽簲璇ユ彁渚沝ebug 淇℃伅鎶ュ憡娌℃湁鍏抽棴鐨?new Connection 銆?

濡傛灉瑕?new Connection 灝卞彲浠ョ洿鎺ヤ粠鏁版嵁搴撹繛鎺ユ睜涓繑鍥?Connection錛?鍙互榪欐牱鍐? Mediator pattern ) (浠ヤ笅浠g爜涓嬌鐢ㄤ簡涓枃鍏ㄨ絀烘牸)錛?br />
public class EasyConnection implements java.sql.Connection{
銆銆private Connection m_delegate = null;

銆銆public EasyConnection(){
銆銆銆銆m_delegate = getConnectionFromPool();
銆銆}

銆銆public void close(){
銆銆銆銆putConnectionBackToPool(m_delegate);
銆銆}

銆銆public PreparedStatement prepareStatement(String sql) throws SQLException{
銆銆銆銆m_delegate.prepareStatement(sql);
銆銆}

銆銆//...... other method

}


鐪嬫潵騫朵笉闅俱備笉榪囦笉寤鴻榪欑鍐欐硶錛屽洜涓哄簲璇ュ敖閲忛伩鍏嶄嬌鐢?Java Interface, 鍏充簬 Java Interface 鐨勭己鐐規垜鍙﹀鍐嶅啓鏂囩珷璁ㄨ銆傚ぇ瀹跺叧娉ㄧ殑鏄?Connection Pool 鐨勫疄鐜版柟娉曘備笅闈㈢粰鍑轟竴縐嶅疄鐜版柟娉曘?

import java.sql.*;
import java.lang.reflect.*;
import java.util.*;
import java.io.*;

public class SimpleConnetionPool {
銆銆private static LinkedList m_notUsedConnection = new LinkedList();
銆銆private static HashSet m_usedUsedConnection = new HashSet();
銆銆private static String m_url = "";
銆銆private static String m_user = "";
銆銆private static String m_password = "";
銆銆static final boolean DEBUG = true;
銆銆static private long m_lastClearClosedConnection = System.currentTimeMillis();
銆銆public static long CHECK_CLOSED_CONNECTION_TIME = 4 * 60 * 60 * 1000; //4 hours

銆銆static {
銆銆銆銆initDriver();
銆銆}

銆銆private SimpleConnetionPool() {
銆銆}

銆銆private static void initDriver() {
銆銆銆銆Driver driver = null;
銆銆銆銆//load mysql driver
銆銆銆銆try {
銆銆銆銆銆銆driver = (Driver) Class.forName("com.mysql.jdbc.Driver").newInstance();
銆銆銆銆銆銆installDriver(driver);
銆銆銆銆} catch (Exception e) {
銆銆銆銆}

銆銆銆銆//load postgresql driver
銆銆銆銆try {
銆銆銆銆銆銆driver = (Driver) Class.forName("org.postgresql.Driver").newInstance();
銆銆銆銆銆銆installDriver(driver);
銆銆銆銆} catch (Exception e) {
銆銆銆銆}
銆銆}

銆銆public static void installDriver(Driver driver) {
銆銆銆銆try {
銆銆銆銆銆銆DriverManager.registerDriver(driver);
銆銆銆銆} catch (Exception e) {
銆銆銆銆銆銆e.printStackTrace();
銆銆銆銆}
銆銆}


銆銆public static synchronized Connection getConnection() {
銆銆銆銆clearClosedConnection();
銆銆銆銆while (m_notUsedConnection.size() > 0) {
銆銆銆銆銆銆try {
銆銆銆銆銆銆銆銆ConnectionWrapper wrapper = (ConnectionWrapper) m_notUsedConnection.removeFirst();
銆銆銆銆銆銆銆銆if (wrapper.connection.isClosed()) {
銆銆銆銆銆銆銆銆銆銆continue;
銆銆銆銆銆銆銆銆}
銆銆銆銆銆銆銆銆m_usedUsedConnection.add(wrapper);
銆銆銆銆銆銆銆銆if (DEBUG) {
銆銆銆銆銆銆銆銆銆銆wrapper.debugInfo = new Throwable("Connection initial statement");
銆銆銆銆銆銆銆銆}
銆銆銆銆銆銆銆銆return wrapper.connection;
銆銆銆銆銆銆} catch (Exception e) {
銆銆銆銆銆銆}
銆銆銆銆}
銆銆銆銆int newCount = getIncreasingConnectionCount();
銆銆銆銆LinkedList list = new LinkedList();
銆銆銆銆ConnectionWrapper wrapper = null;
銆銆銆銆for (int i = 0; i < newCount; i++) {
銆銆銆銆銆銆wrapper = getNewConnection();
銆銆銆銆銆銆if (wrapper != null) {
銆銆銆銆銆銆銆銆list.add(wrapper);
銆銆銆銆銆銆}
銆銆銆銆}
銆銆銆銆if (list.size() == 0) {
銆銆銆銆銆銆return null;
銆銆銆銆}
銆銆銆銆wrapper = (ConnectionWrapper) list.removeFirst();
銆銆銆銆m_usedUsedConnection.add(wrapper);

銆銆銆銆m_notUsedConnection.addAll(list);
銆銆銆銆list.clear();

銆銆銆銆return wrapper.connection;
銆銆}

銆銆private static ConnectionWrapper getNewConnection() {
銆銆銆銆try {
銆銆銆銆銆銆Connection con = DriverManager.getConnection(m_url, m_user, m_password);
銆銆銆銆銆銆ConnectionWrapper wrapper = new ConnectionWrapper(con);
銆銆銆銆銆銆return wrapper;
銆銆銆銆} catch (Exception e) {
銆銆銆銆銆銆e.printStackTrace();
銆銆銆銆}
銆銆銆銆return null;
銆銆}

銆銆static synchronized void pushConnectionBackToPool(ConnectionWrapper con) {
銆銆銆銆boolean exist = m_usedUsedConnection.remove(con);
銆銆銆銆if (exist) {
銆銆銆銆銆銆m_notUsedConnection.addLast(con);
銆銆銆銆}
銆銆}

銆銆public static int close() {
銆銆銆銆int count = 0;

銆銆銆銆Iterator iterator = m_notUsedConnection.iterator();
銆銆銆銆while (iterator.hasNext()) {
銆銆銆銆銆銆try {
銆銆銆銆銆銆銆銆( (ConnectionWrapper) iterator.next()).close();
銆銆銆銆銆銆銆銆count++;
銆銆銆銆銆銆} catch (Exception e) {
銆銆銆銆銆銆}
銆銆銆銆}
銆銆銆銆m_notUsedConnection.clear();

銆銆銆銆iterator = m_usedUsedConnection.iterator();
銆銆銆銆while (iterator.hasNext()) {
銆銆銆銆銆銆try {
銆銆銆銆銆銆銆銆ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next();
銆銆銆銆銆銆銆銆wrapper.close();
銆銆銆銆銆銆銆銆if (DEBUG) {
銆銆銆銆銆銆銆銆銆銆wrapper.debugInfo.printStackTrace();
銆銆銆銆銆銆銆銆}
銆銆銆銆銆銆銆銆count++;
銆銆銆銆銆銆} catch (Exception e) {
銆銆銆銆銆銆}
銆銆銆銆}
銆銆銆銆m_usedUsedConnection.clear();

銆銆銆銆return count;
銆銆}

銆銆private static void clearClosedConnection() {
銆銆銆銆long time = System.currentTimeMillis();
銆銆銆銆//sometimes user change system time,just return
銆銆銆銆if (time < m_lastClearClosedConnection) {
銆銆銆銆銆銆time = m_lastClearClosedConnection;
銆銆銆銆銆銆return;
銆銆銆銆}
銆銆銆銆//no need check very often
銆銆銆銆if (time - m_lastClearClosedConnection < CHECK_CLOSED_CONNECTION_TIME) {
銆銆銆銆銆銆return;
銆銆銆銆}
銆銆銆銆m_lastClearClosedConnection = time;

銆銆銆銆//begin check
銆銆銆銆Iterator iterator = m_notUsedConnection.iterator();
銆銆銆銆while (iterator.hasNext()) {
銆銆銆銆銆銆ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next();
銆銆銆銆銆銆try {
銆銆銆銆銆銆銆銆if (wrapper.connection.isClosed()) {
銆銆銆銆銆銆銆銆銆銆iterator.remove();
銆銆銆銆銆銆銆銆}
銆銆銆銆銆銆} catch (Exception e) {
銆銆銆銆銆銆銆銆iterator.remove();
銆銆銆銆銆銆銆銆if (DEBUG) {
銆銆銆銆銆銆銆銆銆銆System.out.println("connection is closed, this connection initial StackTrace");
銆銆銆銆銆銆銆銆銆銆wrapper.debugInfo.printStackTrace();
銆銆銆銆銆銆銆銆}
銆銆銆銆銆銆}
銆銆銆銆}

銆銆銆銆//make connection pool size smaller if too big
銆銆銆銆int decrease = getDecreasingConnectionCount();
銆銆銆銆if (m_notUsedConnection.size() < decrease) {
銆銆銆銆銆銆return;
銆銆銆銆}

銆銆銆銆while (decrease-- > 0) {
銆銆銆銆銆銆ConnectionWrapper wrapper = (ConnectionWrapper) m_notUsedConnection.removeFirst();
銆銆銆銆銆銆try {
銆銆銆銆銆銆銆銆wrapper.connection.close();
銆銆銆銆銆銆} catch (Exception e) {
銆銆銆銆銆銆}
銆銆銆銆}
銆銆}

銆銆/**
銆銆 * get increasing connection count, not just add 1 connection
銆銆 * @return count
銆銆 */
銆銆public static int getIncreasingConnectionCount() {
銆銆銆銆int count = 1;
銆銆銆銆int current = getConnectionCount();
銆銆銆銆count = current / 4;
銆銆銆銆if (count < 1) {
銆銆銆銆銆銆count = 1;
銆銆銆銆}
銆銆銆銆return count;
銆銆}

銆銆/**
銆銆 * get decreasing connection count, not just remove 1 connection
銆銆 * @return count
銆銆 */
銆銆public static int getDecreasingConnectionCount() {
銆銆銆銆int count = 0;
銆銆銆銆int current = getConnectionCount();
銆銆銆銆if (current < 10) {
銆銆銆銆銆銆return 0;
銆銆銆銆}
銆銆銆銆return current / 3;
銆銆}

銆銆public synchronized static void printDebugMsg() {
銆銆銆銆printDebugMsg(System.out);
銆銆}

銆銆public synchronized static void printDebugMsg(PrintStream out) {
銆銆銆銆if (DEBUG == false) {
銆銆銆銆銆銆return;
銆銆銆銆}
銆銆銆銆StringBuffer msg = new StringBuffer();
銆銆銆銆msg.append("debug message in " + SimpleConnetionPool.class.getName());
銆銆銆銆msg.append("\r\n");
銆銆銆銆msg.append("total count is connection pool: " + getConnectionCount());
銆銆銆銆msg.append("\r\n");
銆銆銆銆msg.append("not used connection count: " + getNotUsedConnectionCount());
銆銆銆銆msg.append("\r\n");
銆銆銆銆msg.append("used connection, count: " + getUsedConnectionCount());
銆銆銆銆out.println(msg);
銆銆銆銆Iterator iterator = m_usedUsedConnection.iterator();
銆銆銆銆while (iterator.hasNext()) {
銆銆銆銆銆銆ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next();
銆銆銆銆銆銆wrapper.debugInfo.printStackTrace(out);
銆銆銆銆}
銆銆銆銆out.println();
銆銆}

銆銆public static synchronized int getNotUsedConnectionCount() {
銆銆銆銆return m_notUsedConnection.size();
銆銆}

銆銆public static synchronized int getUsedConnectionCount() {
銆銆銆銆return m_usedUsedConnection.size();
銆銆}

銆銆public static synchronized int getConnectionCount() {
銆銆銆銆return m_notUsedConnection.size() + m_usedUsedConnection.size();
銆銆}

銆銆public static String getUrl() {
銆銆銆銆return m_url;
銆銆}

銆銆public static void setUrl(String url) {
銆銆銆銆if (url == null) {
銆銆銆銆銆銆return;
銆銆銆銆}
銆銆銆銆m_url = url.trim();
銆銆}

銆銆public static String getUser() {
銆銆銆銆return m_user;
銆銆}

銆銆public static void setUser(String user) {
銆銆銆銆if (user == null) {
銆銆銆銆銆銆return;
銆銆銆銆}
銆銆銆銆m_user = user.trim();
銆銆}

銆銆public static String getPassword() {
銆銆銆銆return m_password;
銆銆}

銆銆public static void setPassword(String password) {
銆銆銆銆if (password == null) {
銆銆銆銆銆銆return;
銆銆銆銆}
銆銆銆銆m_password = password.trim();
銆銆}

}

class ConnectionWrapper implements InvocationHandler {
銆銆private final static String CLOSE_METHOD_NAME = "close";
銆銆public Connection connection = null;
銆銆private Connection m_originConnection = null;
銆銆public long lastAccessTime = System.currentTimeMillis();
銆銆Throwable debugInfo = new Throwable("Connection initial statement");

銆銆ConnectionWrapper(Connection con) {
銆銆銆銆Class[] interfaces = {java.sql.Connection.class};
銆銆銆銆this.connection = (Connection) Proxy.newProxyInstance(
銆銆銆銆銆銆con.getClass().getClassLoader(),
銆銆銆銆銆銆interfaces, this);
銆銆銆銆m_originConnection = con;
銆銆}

銆銆void close() throws SQLException {
銆銆銆銆m_originConnection.close();
銆銆}

銆銆public Object invoke(Object proxy, Method m, Object[] args) throws Throwable {
銆銆銆銆Object obj = null;
銆銆銆銆if (CLOSE_METHOD_NAME.equals(m.getName())) {
銆銆銆銆銆銆SimpleConnetionPool.pushConnectionBackToPool(this);
銆銆銆銆}
銆銆銆銆else {
銆銆銆銆銆銆obj = m.invoke(m_originConnection, args);
銆銆銆銆}
銆銆銆銆lastAccessTime = System.currentTimeMillis();
銆銆銆銆return obj;
銆銆}
}


浣跨敤鏂規硶

public class TestConnectionPool{
銆銆public static void main(String[] args) {
銆銆銆銆SimpleConnetionPool.setUrl(DBTools.getDatabaseUrl());
銆銆銆銆SimpleConnetionPool.setUser(DBTools.getDatabaseUserName());
銆銆銆銆SimpleConnetionPool.setPassword(DBTools.getDatabasePassword());

銆銆銆銆Connection con = SimpleConnetionPool.getConnection();
銆銆銆銆Connection con1 = SimpleConnetionPool.getConnection();
銆銆銆銆Connection con2 = SimpleConnetionPool.getConnection();

銆銆銆銆//do something with con ...

銆銆銆銆try {
銆銆銆銆銆銆con.close();
銆銆銆銆} catch (Exception e) {}

銆銆銆銆try {
銆銆銆銆銆銆con1.close();
銆銆銆銆} catch (Exception e) {}

銆銆銆銆try {
銆銆銆銆銆銆con2.close();
銆銆銆銆} catch (Exception e) {}

銆銆銆銆con = SimpleConnetionPool.getConnection();
銆銆銆銆con1 = SimpleConnetionPool.getConnection();
銆銆銆銆try {
銆銆銆銆銆銆con1.close();
銆銆銆銆} catch (Exception e) {}

銆銆銆銆con2 = SimpleConnetionPool.getConnection();
銆銆銆銆SimpleConnetionPool.printDebugMsg();

銆銆}
}


Lansing 2006-08-04 15:56 鍙戣〃璇勮
]]>
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