數據庫連接池，是一種相當實用的應用程序。它可以保存、維護及創建用戶所需的數據庫連接。從而使得用戶得到一個連接的時間降低90%以上。大大提升了數據庫訪問的反應時間。

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這個是一個開源的代碼。大家可以修改它、使用它。

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希望我的代碼能對大家有用。

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此代碼，經過1000數量級的多線程并發訪問測試。在四核CPU下也進行了多線程測試。保證了連接池在真多線程上同步訪問的安全性。

里面包含了一個公開的接口。使用這個接口里面的函數。可以輕易創建使用數據庫連接池服務。

使用一個守護線程維護這個連接池，完全自動化。

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下載連接：http://download.csdn.net/user/lauo1188

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連接池接口類：

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[java]?view plaincopy

package?mysql;??

import?java.sql.*;??

import?java.sql.ResultSet;??

public?interface?Pool??

{??

????public?boolean?start(String?dbname,String?user,String?psw);??//啟動數據庫連接池服務??

????//以下start函數將允許用戶設置最低空閑連接數，最高空閑連接數,最大連接數??

????public?boolean?start(int?lows,int?maxs,int?maxc,String?dbname,String?user,String?psw);??

????public?Connection?getConnection();??//得到連接器??

????public?boolean?freeConnection(Connection?con);//將連接返回到連接池中??

????public?boolean?close();?//清除連接池，并且關閉它（使之變得不可用）??

}??

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?

第一個實現類：VectorPool

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?

[java]?view plaincopy

/**?

?*?@(#)Pool.java?

?*?

?*?

?*?@author??lauo?

?*?@version?1.00?2010/5/15?

?*?

?*?測試完成于2010-5-16??22:40分?

?*/??

package?mysql;??

import?mysql.*;??

import?java.sql.*;??

import?java.util.*;??

/*?

?*這里將實現ConnectionPool接口?

?*/??

public?class?VectorPool?extends?Thread?implements?Pool???

{??

????protected?final?boolean?debug?=?false;?//是否debug態（如是??輸出debug狀態信息)??

????protected?boolean?init?=?false;//是否已經將setting初始化??

????//timeDiff???一個連接超過此時間未使用過，則需要更新此連接----1小時??

????protected?final?long?timeDiff?=??60*60*1000?;//1小時60分鐘，1分鐘60秒，1秒1000毫秒??

????protected?int?lows?=?20?;?//連接池的最小空閑連接數??

????protected?int?maxs?=?100?;?//連接池的最大空閑連接數??

????protected?int?maxc?=?100;??

????protected?String?dbname?=?null;??

????protected?String?user?=?null;??

????protected?String?psw?=?null;??

??????

????protected?Integer?conCount?=?0;?//這個是靜態的。當前連接數??

????//下面是連接保存的池??

????protected?Vector<ConInfo>?pool?=?new?Vector<ConInfo>();??

????public?VectorPool()???

????{??

????}??

????public?void?start()??

????{??

??????????

????}??

????//得到當前連接數??

????protected?int?getConCount()??

????{??

????????return?conCount;??

????}??

????/*?

?????*設置數據庫連接的基本參數?

?????*/??

????public??synchronized??boolean?start(String?db,String?u,String?p)??

????{??

????????if(false?==?init?&&?null?!=?pool)//如果未初始化，且連接池可用??

????????{??

????????????dbname??=???db;??

????????????user????=???u;??

????????????psw?????=???p;??

????????????if(test())??

????????????{??

????????????????init????=???true;??

????????????????super.start();???

????????????????return?true;??

????????????}??

????????????else?return?false;??

????????}??

????????else??

????????????return?false;??

????}??

????public?synchronized?boolean?start(int?l,int?m,int?mc,String?db,String?u,String?p)??

????{??

????????if(l<0?||?m<0?||l>=m?||?m>mc)//0<l<m<=mc??

????????????return?false;??

????????if(false?==?init?&&?null?!=?pool)//如果未初始化，且連接池可用??

????????{??

????????????dbname??=???db;??

????????????user????=???u;??

????????????psw?????=???p;??

????????????if(test())??

????????????{??

????????????????init????=???true;??

????????????????lows?=?l<5?5:l;??//這里允許的最小的值為5??

????????????????maxs?=?m<10?10:m;?//這里允許的最小的值為10??

????????????????maxc?=?mc<20??20:mc;//這里允許的連接數??

????????????????super.start();???

????????????????return?true;??

????????????}??

????????????else???

????????????????return?false;??

????????}??

????????else??

????????????return?false;??

????}??

????/*?

?????*從連接池得到一個連接?

?????*/??

????public?synchronized?Connection?getConnection()??

????{??

??????????

????????if(init)??

????????{??

????????????ConInfo?c?=?getOneConnection();??

????????????return?c!=null?c.con:null;//安全得到一個連接??

????????}??

????????else??

????????????return?null;??

????}??

????/*?

?????*得到一個連接，包含了lastTime信息?

?????*/??

????protected?synchronized?ConInfo?getOneConnection()??

????{??

????????if(pool.size()!=0)??

????????{??

????????????return?pool.remove(0);??

????????}??

????????else?//如果連接池為空，創建新的連接??

????????{??

????????????if(debug)?System.out.println("new?connection!");??

????????????return?newConInfo();??

????????}??

????}??

????/*?

?????*將一個連接放回到連接池中?

?????*/??

????public?synchronized?boolean?freeConnection(Connection?con)??

????{??

????????if(init==false?||?con?==?null?)//當沒有init或者已經close之后?不應該free它進來。??

????????????return?false;??

????????ConInfo?c?=??new?ConInfo(con);//調用了ConInfo的構造函數??

????????pool.addElement(c);??

????????return?true;??

????}??

????/*?

?????*將內容清空?

?????*且將本連接池對象置為無用狀態?

?????*/??

????public?synchronized??boolean?close()??

????{??

????????if(init)??

????????{??

????????????init?=?false;??

????????????for(int?i?=?0;?i?<pool.size();i++)??

????????????????pool.get(i).close();??

????????????pool.clear();??

????????????pool????=???null;//將此連接池置為無用狀態。如果要新的鏈接池，重新創建鏈接池對象??

????????????dbname??=???null;??

????????????user????=???null;??

????????????psw?????=???null;??

????????????return?true;??

????????}??

????????else???

????????????return?false;??

????}??

?????

??

????/*?

?????*下面將是一個一線程執行體，當start連接池服務之后，由它來維護?

?????*連接池里面的連接，從而保證他們能被正確的創建、注銷?

?????*?

?????*/??

????public?void?run()??

????{??

????????final?long?sleepTime?=?2*1000??;?//2秒???

????????final?long?refreshTime?=?10*60*1000;?//10分鐘運行一次。連接是否應該被更新??

????????final?long?lowsCheckTime?=?2*1000;//10秒檢查一次。最低連接數檢查間隔時間??

????????final?long?maxsCheckTime?=?60*1000;//1分鐘檢查一次。最大連接數時間??

????????long?loop?=?0;??

????????while(true)??

????????{??

????????????if(loop%refreshTime?==?0)??

????????????{??

????????????????if(debug)?System.out.println("call?refresh:"+pool.size());??

????????????????refreshByTimeDiff();??

????????????}??

????????????if(loop%maxsCheckTime?==?0)??

????????????{??

????????????????if(debug)?System.out.println("call?toMaxs:"+pool.size());??

????????????????toMaxs();??

????????????}??

????????????if(loop%lowsCheckTime?==?0)??

????????????{??

????????????????if(debug)?System.out.println("conCnt:"+conCount+"?call?toLows:"+pool.size());??

????????????????toLows();??

????????????}??

????????????loop?+=?sleepTime;//更新loop的時間。??

????????????try{??

????????????????sleep(sleepTime);??

????????????}??

????????????catch(Exception?e){??

????????????????e.printStackTrace();??

????????????????stop();??

????????????}??

??????????????

????????}??

??????????

????}??

????/*?

?????*使過小的空閑連接數恢復到lows?

?????*/??

????protected?void?toLows()??

????{??

????????int?size?=?pool.size();??

????????/*?

?????????*這里要避免直接使用pool.size進行判斷?

?????????*當連接一直被get出去之后，size很難達到lows，故此?

?????????*/??

????????for(;size<lows;size++)??

????????{??

????????????if(debug)?System.out.println("toLows?is?running!");??

????????????ConInfo?c?=??newConInfo();??

????????????if(c!=null)??

????????????????synchronized(pool)??

????????????????{??

????????????????????pool.addElement(c);??

????????????????}??

????????}??

????}??

????/*?

?????*使過多的空閑連接數恢復到maxs;?

?????*/??

????protected?void?toMaxs()??

????{??

????????int?size?=?pool.size();??

????????for(;size>maxs;size--)??

????????{??

????????????if(debug)?System.out.println("toMaxs?is?running!");??

????????????try{??

????????????????getConnection().close();??

????????????????synchronized(conCount)//這里修改要同步好。??

????????????????{??

????????????????????conCount?--;??

????????????????}??

????????????}??

????????????catch(Exception?e)??

????????????{??

????????????????e.printStackTrace();??

????????????}??

????????}??

????}??

????/*?

?????*查找當前的連接池，找到timeDiff時間內未使用過的連接，刪除它們，如果連接數不足，將由toLows補齊?

?????*一個危險的線程不安全函數?

?????*/??

????public?void?refreshByTimeDiff()??

????{??

????????Calendar?nowTime?=?Calendar.getInstance();??

????????long?now?=?nowTime.getTimeInMillis();??

????????for(int?i=0;i<pool.size();i++)??

????????{??

????????????ConInfo?c?=?getOneConnection();??

????????????if(now??-?c.lastTime.getTimeInMillis()?>=timeDiff)//刪除它們??

????????????{??

????????????????if(debug)?System.out.println("refresh?the?pool!,,,,,,,,");??

????????????????synchronized(pool)//獲得pool的鎖??

????????????????{??

????????????????????pool.remove(i).close();//使用了ConInfo中的關閉函數??

????????????????}??

????????????}??

????????}??

????}??

????/*?

?????*一個測試數據庫連接是否可用的函數?

?????*/??

????protected?boolean?test()??

????{??

????????int?cnt?=?10;??

????????Connection?c;??

????????do{??

????????????c?=?newConnection();??

????????????cnt?--?;??

????????}while(c==null?&&?cnt>=0);??

????????if(c!=null)??

????????{??

????????????(new?ConInfo(c)).close();??

????????????return?true;??

????????}??

????????else??

????????????return?false;??

??????????????

????}??

??

????/*?

?????*下面為內置的類，用于表明一個連接最后使用時間?

?????*/??

????class?ConInfo??

????{??

????????protected?Calendar?lastTime;????//連接最后使用時間??

????????protected?Connection?con?=?null;????//對應的connection??

????????public?ConInfo(Connection?c)??

????????{??

????????????con?=???c;??

????????????lastTime?=?Calendar.getInstance();??

????????}??

????????public?synchronized?void?close()??

????????{??

????????????try??

????????????{??

????????????????if(con!=null)??

????????????????????con.close();??

????????????????synchronized(conCount)??

????????????????{??

????????????????????conCount-=con!=null?1:0;??

????????????????}??

????????????????lastTime?=?null;??

????????????}??

????????????catch(Exception?e)??

????????????{??

????????????????e.printStackTrace();??

????????????}??

????????}??

????}??

????/*?

?????*創建一個新的連接?

?????*/??

????protected??Connection?newConnection()??

????{??

????????try??

????????{??

????????????Class.forName("com.mysql.jdbc.Driver");??

????????????int?cnt?=?0;??

????????????Connection?c?=?null;??

????????????synchronized(conCount)??

????????????{??

????????????????if(conCount<=maxc)//當連接數沒超過既定最大連接數時??

????????????????do??

????????????????{??

????????????????????try{??

????????????????????c?=?DriverManager.getConnection(dbname,user,psw);??

????????????????????}catch(Exception?es){c=null;if(debug)?System.out.println("create?new?connection?error!");}??

????????????????????cnt++;??

????????????????}while(null?==?c??&&?cnt<3);??

????????????????conCount+=c!=null?1:0;??

????????????}??

????????????return?c;//創建一個新的connection??

????????}??

????????catch(Exception?e)??

????????{??

????????????e.printStackTrace();??

????????????return?null;??

????????}??

????}??

????/*?

?????*得到一個新的連接?

?????*/??

????protected?ConInfo?newConInfo()??

????{??

????????Connection?c?=?newConnection();??

????????if(c==null)??

????????????return?null;??

????????return?new?ConInfo(c);??

????}??

??

????/*?

?????*測試函數main?

?????*/??

????public?static?void?main(String[]?argvs)??

????{??

????????VectorPool?pool?=?new?VectorPool();??

????????Connection?con?=?null;??

????????boolean?flag?=?pool.start("jdbc:mysql://localhost/finance","root","");??

????????int?cnt?=?10000;//1萬次??

????????long?t0??=?Calendar.getInstance().getTimeInMillis();??

????????/測試選項??

????????final?boolean?tflag?=?true?;//如為true?為使用連接池??否則直接創建一個新連接。??

????????//??

????????while(flag){??

??????????

????????????con?=?tflag???pool.getConnection():pool.newConnection();//;??

????????????try??

????????????{?????

????????????????Statement?stm?=?con.createStatement();??

????????????????ResultSet?rev?=?stm.executeQuery("select?*?from?user");??

????????????????while(false?&&?rev!=null?&&?rev.next())??

????????????????{??

????????????????????System.out.println(rev.getString("id"));??

????????????????}??

????????????????stm.close();??

????????????}??

????????????catch(Exception?e)??

????????????{??

????????????????e.printStackTrace();??

??????????????????

????????????}??

????????//??if(Math.abs(Math.random())%10<4)??

????????????if(tflag)//使用完之后要釋放，否則會出大問題??

????????????????pool.freeConnection(con);??

????????????try{??

????????????????if(!tflag)??

????????????????????con.close();//釋放連接?當不用pool時??

????????????}??

????????????catch(Exception?exx)??

????????????{??

????????????????exx.printStackTrace();??

????????????}??

????????????/*?

????????????try{?

????????????????sleep(100);?///間隔時間?

????????????}?

????????????catch(Exception?ee)?

????????????{?

????????????????ee.printStackTrace();?

????????????}?

????????????*/??

????????????//System.out.println("cnt:"+cnt);??

????????//??System.out.println("con_Cnt:"+pool.getConCount());??

????????????if(--cnt<0)??

????????????????break;??

????????}??

????????System.out.println("used?time:"+(Calendar.getInstance().getTimeInMillis()-t0));??

????}??

}??

/*?

?*?

use?the?pool;?

cnt:3?

cnt:2?

cnt:1?

cnt:0?

used?time:11286?

---用了11.286秒?

cnt:9?

cnt:8?

cnt:7?

cnt:6?

cnt:5?

cnt:4?

cnt:3?

cnt:2?

cnt:1?

cnt:0?

used?time:129376?

用了129.376秒（多了整整十倍）。?

再測試一次：?

cnt:1?

cnt:0?

used?time:7871??

---used?the?pool??7.871秒?

cnt:4?

cnt:3?

cnt:2?

cnt:1?

cnt:0?

used?time:100084??

----create?the?connection?one?by?one???100.084秒?

*/??

?

?

?

第二個實現類：ListPool

?

?

[java]?view plaincopy

/*?

?*?@(#)Pool.java?

?*?

?*?

?*?@author??

?*?@version?1.00?2010/5/15?

?*/??

package?mysql;??

import?mysql.*;??

import?java.sql.*;??

import?java.util.*;??

/*?

?*這里將實現ConnectionPool接口?

?*/??

public?class?ListPool?extends?Thread?implements?Pool???

{??

????protected?final?boolean?debug?=?false;?//是否debug態（如是??輸出debug狀態信息)??

????protected?boolean?init?=?false;//是否已經將setting初始化??

????//timeDiff???一個連接超過此時間未使用過，則需要更新此連接----1小時??

????protected?final?long?timeDiff?=??60*60*1000?;//1小時60分鐘，1分鐘60秒，1秒1000毫秒??

????protected?int?lows?=?20?;?//連接池的最小空閑連接數??

????protected?int?maxs?=?100?;?//連接池的最大空閑連接數??

????protected?int?maxc?=?100;??

????protected?String?dbname?=?null;??

????protected?String?user?=?null;??

????protected?String?psw?=?null;??

??????

????protected?Integer?conCount?=?0;?//這個是靜態的。當前連接數??

????//下面是連接保存的池??

????protected?LinkedList<ConInfo>?pool?=?new?LinkedList<ConInfo>();??

????public?ListPool()???

????{??

????}??

????public?void?start()??

????{??

??????????

????}??

????//得到當前連接數??

????protected?int?getConCount()??

????{??

????????return?conCount;??

????}??

????/*?

?????*設置數據庫連接的基本參數?

?????*/??

????public??synchronized??boolean?start(String?db,String?u,String?p)??

????{??

????????if(false?==?init?&&?null?!=?pool)//如果未初始化，且連接池可用??

????????{??

????????????dbname??=???db;??

????????????user????=???u;??

????????????psw?????=???p;??

????????????if(test())??

????????????{??

????????????????init????=???true;??

????????????????super.start();???

????????????????return?true;??

????????????}??

????????????else?return?false;??

????????}??

????????else??

????????????return?false;??

????}??

????public?synchronized?boolean?start(int?l,int?m,int?mc,String?db,String?u,String?p)??

????{??

????????if(l<0?||?m<0?||l>=m?||?m>mc)//0<l<m<=mc??

????????????return?false;??

????????if(false?==?init?&&?null?!=?pool)//如果未初始化，且連接池可用??

????????{??

????????????dbname??=???db;??

????????????user????=???u;??

????????????psw?????=???p;??

????????????if(test())??

????????????{??

????????????????init????=???true;??

????????????????lows?=?l<5?5:l;??//這里允許的最小的值為5??

????????????????maxs?=?m<10?10:m;?//這里允許的最小的值為10??

????????????????maxc?=?mc<20??20:mc;//這里允許的連接數??

????????????????super.start();???

????????????????return?true;??

????????????}??

????????????else???

????????????????return?false;??

????????}??

????????else??

????????????return?false;??

????}??

????/*?

?????*從連接池得到一個連接?

?????*/??

????public?synchronized?Connection?getConnection()??

????{??

??????????

????????if(init)??

????????{??

????????????ConInfo?c?=?getOneConnection();??

????????????return?c!=null?c.con:null;//安全得到一個連接??

????????}??

????????else??

????????????return?null;??

????}??

????/*?

?????*得到一個連接，包含了lastTime信息?

?????*/??

????protected?synchronized?ConInfo?getOneConnection()??

????{??

????????if(pool.size()!=0)??

????????{??

????????????return?pool.remove(0);??

????????}??

????????else?//如果連接池為空，創建新的連接??

????????{??

????????????if(debug)?System.out.println("new?connection!");??

????????????return?newConInfo();??

????????}??

????}??

????/*?

?????*將一個連接放回到連接池中?

?????*/??

????public?synchronized?boolean?freeConnection(Connection?con)??

????{??

????????if(init==false?||?con?==?null?)//當沒有init或者已經close之后?不應該free它進來。??

????????????return?false;??

????????ConInfo?c?=??new?ConInfo(con);//調用了ConInfo的構造函數??

????????pool.add(c);??

????????return?true;??

????}??

????/*?

?????*將內容清空?

?????*且將本連接池對象置為無用狀態?

?????*/??

????public?synchronized??boolean?close()??

????{??

????????if(init)??

????????{??

????????????init?=?false;??

????????????for(int?i?=?0;?i?<pool.size();i++)??

????????????????pool.get(i).close();??

????????????pool.clear();??

????????????pool????=???null;//將此連接池置為無用狀態。如果要新的鏈接池，重新創建鏈接池對象??

????????????dbname??=???null;??

????????????user????=???null;??

????????????psw?????=???null;??

????????????return?true;??

????????}??

????????else???

????????????return?false;??

????}??

?????

??

????/*?

?????*下面將是一個一線程執行體，當start連接池服務之后，由它來維護?

?????*連接池里面的連接，從而保證他們能被正確的創建、注銷?

?????*?

?????*/??

????public?void?run()??

????{??

????????final?long?sleepTime?=?2*1000??;?//2秒???

????????final?long?refreshTime?=?10*60*1000;?//10分鐘運行一次。連接是否應該被更新??

????????final?long?lowsCheckTime?=?2*1000;//10秒檢查一次。最低連接數檢查間隔時間??

????????final?long?maxsCheckTime?=?60*1000;//1分鐘檢查一次。最大連接數時間??

????????long?loop?=?0;??

????????while(true)??

????????{??

????????????if(loop%refreshTime?==?0)??

????????????{??

????????????????if(debug)?System.out.println("call?refresh:"+pool.size());??

????????????????refreshByTimeDiff();??

????????????}??

????????????if(loop%maxsCheckTime?==?0)??

????????????{??

????????????????if(debug)?System.out.println("call?toMaxs:"+pool.size());??

????????????????toMaxs();??

????????????}??

????????????if(loop%lowsCheckTime?==?0)??

????????????{??

????????????????if(debug)?System.out.println("conCnt:"+conCount+"?call?toLows:"+pool.size());??

????????????????toLows();??

????????????}??

????????????loop?+=?sleepTime;//更新loop的時間。??

????????????try{??

????????????????sleep(sleepTime);??

????????????}??

????????????catch(Exception?e){??

????????????????e.printStackTrace();??

????????????????stop();??

????????????}??

??????????????

????????}??

??????????

????}??

????/*?

?????*使過小的空閑連接數恢復到lows?

?????*/??

????protected?void?toLows()??

????{??

????????int?size?=?pool.size();??

????????/*?

?????????*這里要避免直接使用pool.size進行判斷?

?????????*當連接一直被get出去之后，size很難達到lows，故此?

?????????*/??

????????for(;size<lows;size++)??

????????{??

????????????if(debug)?System.out.println("toLows?is?running!");??

????????????ConInfo?c?=??newConInfo();??

????????????if(c!=null)??

????????????????synchronized(pool)??

????????????????{??

????????????????????pool.add(c);??

????????????????}??

????????}??

????}??

????/*?

?????*使過多的空閑連接數恢復到maxs;?

?????*/??

????protected?void?toMaxs()??

????{??

????????int?size?=?pool.size();??

????????for(;size>maxs;size--)??

????????{??

????????????if(debug)?System.out.println("toMaxs?is?running!");??

????????????try{??

????????????????getConnection().close();??

????????????????synchronized(conCount)//這里修改要同步好。??

????????????????{??

????????????????????conCount?--;??

????????????????}??

????????????}??

????????????catch(Exception?e)??

????????????{??

????????????????e.printStackTrace();??

????????????}??

????????}??

????}??

????/*?

?????*查找當前的連接池，找到timeDiff時間內未使用過的連接，刪除它們，如果連接數不足，將由toLows補齊?

?????*一個危險的線程不安全函數?

?????*/??

????public?void?refreshByTimeDiff()??

????{??

????????Calendar?nowTime?=?Calendar.getInstance();??

????????long?now?=?nowTime.getTimeInMillis();??

????????for(int?i=0;i<pool.size();i++)??

????????{??

????????????ConInfo?c?=?getOneConnection();??

????????????if(now??-?c.lastTime.getTimeInMillis()?>=timeDiff)//刪除它們??

????????????{??

????????????????if(debug)?System.out.println("refresh?the?pool!,,,,,,,,");??

????????????????synchronized(pool)//獲得pool的鎖??

????????????????{??

????????????????????pool.remove(i).close();//使用了ConInfo中的關閉函數??

????????????????}??

????????????}??

????????}??

????}??

????/*?

?????*一個測試數據庫連接是否可用的函數?

?????*/??

????protected?boolean?test()??

????{??

????????int?cnt?=?10;??

????????Connection?c;??

????????do{??

????????????c?=?newConnection();??

????????????cnt?--?;??

????????}while(c==null?&&?cnt>=0);??

????????if(c!=null)??

????????{??

????????????(new?ConInfo(c)).close();??

????????????return?true;??

????????}??

????????else??

????????????return?false;??

??????????????

????}??

??

????/*?

?????*下面為內置的類，用于表明一個連接最后使用時間?

?????*/??

????class?ConInfo??

????{??

????????protected?Calendar?lastTime;????//連接最后使用時間??

????????protected?Connection?con?=?null;????//對應的connection??

????????public?ConInfo(Connection?c)??

????????{??

????????????con?=???c;??

????????????lastTime?=?Calendar.getInstance();??

????????}??

????????public?synchronized?void?close()??

????????{??

????????????try??

????????????{??

????????????????if(con!=null)??

????????????????????con.close();??

????????????????synchronized(conCount)??

????????????????{??

????????????????????conCount-=con!=null?1:0;??

????????????????}??

????????????????lastTime?=?null;??

????????????}??

????????????catch(Exception?e)??

????????????{??

????????????????e.printStackTrace();??

????????????}??

????????}??

????}??

????/*?

?????*創建一個新的連接?

?????*/??

????protected??Connection?newConnection()??

????{??

????????try??

????????{??

????????????Class.forName("com.mysql.jdbc.Driver");??

????????????int?cnt?=?0;??

????????????Connection?c?=?null;??

????????????synchronized(conCount)??

????????????{??

????????????????if(conCount<=maxc)//當連接數沒超過既定最大連接數時??

????????????????do??

????????????????{??

????????????????????try{??

????????????????????c?=?DriverManager.getConnection(dbname,user,psw);??

????????????????????}catch(Exception?es){c=null;if(debug)?System.out.println("create?new?connection?error!");}??

????????????????????cnt++;??

????????????????}while(null?==?c??&&?cnt<3);??

????????????????conCount+=c!=null?1:0;??

????????????}??

????????????return?c;//創建一個新的connection??

????????}??

????????catch(Exception?e)??

????????{??

????????????e.printStackTrace();??

????????????return?null;??

????????}??

????}??

????/*?

?????*得到一個新的連接?

?????*/??

????protected?ConInfo?newConInfo()??

????{??

????????Connection?c?=?newConnection();??

????????if(c==null)??

????????????return?null;??

????????return?new?ConInfo(c);??

????}??

??

????/*?

?????*測試函數main?

?????*/??

????public?static?void?main(String[]?argvs)??

????{??

????????ListPool?pool?=?new?ListPool();??

????????Connection?con?=?null;??

????????boolean?flag?=?pool.start("jdbc:mysql://localhost/finance","root","");??

????????int?cnt?=?10000;//1萬次??

????????long?t0??=?Calendar.getInstance().getTimeInMillis();??

????????/測試選項??

????????final?boolean?tflag?=?true?;//如為true?為使用連接池??否則直接創建一個新連接。??

????????//??

????????while(flag){??

??????????

????????????con?=?tflag???pool.getConnection():pool.newConnection();//;??

????????????try??

????????????{?????

????????????????Statement?stm?=?con.createStatement();??

????????????????ResultSet?rev?=?stm.executeQuery("select?*?from?user");??

????????????????while(false?&&?rev!=null?&&?rev.next())??

????????????????{??

????????????????????System.out.println(rev.getString("id"));??

????????????????}??

????????????????stm.close();??

????????????}??

????????????catch(Exception?e)??

????????????{??

????????????????e.printStackTrace();??

??????????????????

????????????}??

????????//??if(Math.abs(Math.random())%10<4)??

????????????if(tflag)//使用完之后要釋放，否則會出大問題??

????????????????pool.freeConnection(con);??

????????????try{??

????????????????if(!tflag)??

????????????????????con.close();//釋放連接?當不用pool時??

????????????}??

????????????catch(Exception?exx)??

????????????{??

????????????????exx.printStackTrace();??

????????????}??

????????????/*?

????????????try{?

????????????????sleep(100);?///間隔時間?

????????????}?

????????????catch(Exception?ee)?

????????????{?

????????????????ee.printStackTrace();?

????????????}?

????????????*/??

????????//??System.out.println("cnt:"+cnt);??

????????//??System.out.println("con_Cnt:"+pool.getConCount());??

????????????if(--cnt<0)??

????????????????break;??

????????}??

????????System.out.println("used?time:"+(Calendar.getInstance().getTimeInMillis()-t0));??

????}??

}??

/*?

?*?

use?the?pool;?

cnt:3?

cnt:2?

cnt:1?

cnt:0?

used?time:11286?

---用了11.286秒?

cnt:9?

cnt:8?

cnt:7?

cnt:6?

cnt:5?

cnt:4?

cnt:3?

cnt:2?

cnt:1?

cnt:0?

used?time:129376?

用了129.376秒（多了整整十倍）。?

-------listPool?

used?time:10995?

*/??

?

?

?

?

?

一個測試類：testPool

?

[java]?view plaincopy

/**?

?*?@(#)testPool.java?

?*?

?*?

?*?@author??

?*?@version?1.00?2010/5/15?

?*/??

package??mysql;??

import?java.sql.*;??

import?java.util.*;??

import?mysql.*;??

public?class?testPool?extends?Thread??

{??

????protected??String?dbname?=?null,??

????????????????????????user?=?null,??

????????????????????????psw??=?null;??

????Pool?pool=?null;??

????boolean?flag?=?true;??

????public?testPool(Pool?p,boolean?f,String?d,String?u,String?pw)???

????{??

????????pool?=?p;??

????????flag?=?f;??

????????dbname?=?d;??

????????user?=?u;??

????????psw?=?pw;??

????}??

????public?void?start(int?n)??

????{??

????????while(n-->0)??

????????{??

????????????super.start();??

????????}??

????}??

????public?void?run()??

????{??

????????long?id?=?this.getId();??

????????Connection?con?=?null;??

????????int?cnt?=?100;//1萬次??

????????long?t0??=?Calendar.getInstance().getTimeInMillis();??

????????/測試選項??

????????final?boolean?tflag?=?true?;//如為true?為使用連接池??否則直接創建一個新連接。??

????????//??

????????while(flag){??

??????????

????????????con?=?tflag???pool.getConnection():newConnection();//;??

????????????if(con?==?null)?continue;??

????????????try??

????????????{?????

????????????????Statement?stm?=?con.createStatement();??

????????????????ResultSet?rev?=?stm.executeQuery("select?*?from?user");??

????????????????while(false?&&?rev!=null?&&?rev.next())??

????????????????{??

????????????????????System.out.println(rev.getString("id"));??

????????????????}??

????????????????stm.close();??

????????????}??

????????????catch(Exception?e)??

????????????{??

????????????????e.printStackTrace();??

??????????????????

????????????}??

????????//??if(Math.abs(Math.random())%10<4)??

????????????if(tflag)//使用完之后要釋放，否則會出大問題??

????????????????pool.freeConnection(con);??

????????????try{??

????????????????if(!tflag)??

????????????????????con.close();//釋放連接?當不用pool時??

????????????}??

????????????catch(Exception?exx)??

????????????{??

????????????????exx.printStackTrace();??

????????????}??

????????????/*?

????????????try{?

????????????????sleep(100);?///間隔時間?

????????????}?

????????????catch(Exception?ee)?

????????????{?

????????????????ee.printStackTrace();?

????????????}?

????????????*/??

????????//??System.out.println("threadId:"+id+"??cnt:"+cnt);??

???????????//System.out.println("con_Cnt:"+((Pool)pool).getConCount());??

????????????if(--cnt<0)??

????????????????break;??

????????}??

????????System.out.println("used?time:"+(Calendar.getInstance().getTimeInMillis()-t0));??

????}??

????public?Connection?newConnection()??

????{??

????????try??

????????{??

????????????Class.forName("com.mysql.jdbc.Driver");??

????????????int?cnt?=?0;??

????????????Connection?c?=?null;??

????????????do??

????????????{??

????????????????c?=?DriverManager.getConnection(dbname,user,psw);??

????????????????cnt++;??

????????????}while(null?==?c?&&?cnt<15);??

????????????if(null?==?c)??

????????????????return?null;??

????????????else??

????????????????return?c;//創建一個新的connection??

????????}??

????????catch(Exception?e)??

????????{??

????????????e.printStackTrace();??

????????????return?null;??

????????}??

????}??

????public?static?void?main(String?argv[])??

????{??

????????Pool?pool?=?null;??

????????boolean?who?=?true;??

????????pool?=?who???new?VectorPool()?:?new?ListPool();??

????????boolean?flag?=?pool.start(20,30,100,"jdbc:mysql://localhost/finance","root","");??

????????int?cnt?=?100;??

????????while(cnt-->0)??

????????{??

????????????testPool?p?=?new?testPool(pool,flag,"jdbc:mysql://localhost/finance","root","");??

????????????p.start();??

????????}?????

????

????}??

??????

}??

/*?

?*測試結果表明，當100*100時，Pool要略優于ListPool（差異不大，如下）?

?*?

Pool:?

used?time:4967?

used?time:4997?

used?time:5017?

used?time:5218?

used?time:5558?

used?time:4937?

used?time:4977?

used?time:5107?

used?time:5378?

used?time:5368?

used?time:5408?

2:?

used?time:5779?

used?time:6049?

used?time:6269?

used?time:6269?

used?time:6209?

used?time:6009?

ListPool?

used?time:5788?

used?time:6148?

used?time:5589?

used?time:5819?

used?time:5619?

used?time:6089?

used?time:5558?

used?time:6029?

used?time:5629?

2?

used?time:5158?

used?time:5188?

used?time:5808?

used?time:5117?

used?time:5648?

used?time:5718?

used?time:5668?

used?time:5868?

used?time:5908?

used?time:5948?

used?time:5958?

used?time:5828?

used?time:5969?

used?time:5979?

used?time:6329?

used?time:6089?

?*/??

?

轉載于:https://www.cnblogs.com/jiushini/archive/2012/06/05/2535595.html

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