1、連接池模型

　　本文討論的連接池包括一個連接池類（DBConnectionPool）和一個連接池管理類（DBConnetionPoolManager）和一個配置文件操作類(ParseDSConfig)。連接池類是對某一數據庫所有連接的“緩沖池”，主要實現以下功能：①從連接池獲取或創建可用連接；②使用完畢之后，把連接返還給連接池；③在系統關閉前，斷開所有連接并釋放連接占用的系統資源；④還能夠處理無效連接（原來登記為可用的連接，由于某種原因不再可用，如超時，通訊問題），并能夠限制連接池中的連接總數不低于某個預定值和不超過某個預定值。(5)當多數據庫時,且數據庫是動態增加的話,將會加到配置文件中。

　　連接池管理類是連接池類的外覆類（wrapper）,符合單例模式，即系統中只能有一個連接池管理類的實例。其主要用于對多個連接池對象的管理，具有以下功能：①裝載并注冊特定數據庫的JDBC驅動程序；②根據屬性文件給定的信息，創建連接池對象；③為方便管理多個連接池對象，為每一個連接池對象取一個名字，實現連接池名字與其實例之間的映射；④跟蹤客戶使用連接情況，以便需要是關閉連接釋放資源。連接池管理類的引入主要是為了方便對多個連接池的使用和管理，如系統需要連接不同的數據庫，或連接相同的數據庫但由于安全性問題，需要不同的用戶使用不同的名稱和密碼。
???????? 2、連接池實現(經過本人改版,可以適用多數據庫類型的應用以及一種數據庫類型多個數據庫且數據? 庫的數量可以動態增加的應用程序)
???????? 1),DBConnectionPool.java?? 數據庫連接池類
???????? 2),DBConnectionManager?.java?? 數據庫管理類
???????? 3),DSConfigBean?.java??????????????? 單個數據庫連接信息Bean
???????? 4),ParseDSConfig.java??????????????? 操作多(這個'多'包括不同的數據庫和同一種數據庫有多個數據庫)
??????????????????????????????????????????????????????????? 數據 配置文件xml
???????? 5),ds.config.xml?????????????????????????? 數據庫配置文件xml
???????? 原代碼如下:?
??????? DBConnectionPool.java??
??????? ----------------------------------------------------------
????? /**
?*?數據庫連接池類
?*/
package com.chunkyo.db;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Timer;

/**
?* @author chenyanlin
?*
?*/
public class DBConnectionPool implements TimerListener {

?private Connection con=null;
?private int inUsed=0;??? //使用的連接數
?private ArrayList freeConnections = new ArrayList();//容器，空閑連接
?private int minConn;???? //最小連接數
?private int maxConn;???? //最大連接
?private String name;???? //連接池名字
?private String password; //密碼
?private String url;????? //數據庫連接地址
?private String driver;?? //驅動
?private String user;???? //用戶名
?public Timer timer;????? //定時
?/**
? *
? */
?public DBConnectionPool() {
??// TODO Auto-generated constructor stub
?}
?/**
? * 創建連接池
? * @param driver
? * @param name
? * @param URL
? * @param user
? * @param password
? * @param maxConn
? */
?public DBConnectionPool(String name, String driver,String URL, String user, String password, int maxConn)
?{
??this.name=name;
??this.driver=driver;
??this.url=URL;
??this.user=user;
??this.password=password;
??this.maxConn=maxConn;
?}
?/**
? * 用完，釋放連接
? * @param con
? */
?public synchronized void freeConnection(Connection con)
?{
??this.freeConnections.add(con);//添加到空閑連接的末尾
??this.inUsed--;
?}
?/**
? * timeout? 根據timeout得到連接
? * @param timeout
? * @return
? */
?public synchronized Connection getConnection(long timeout)
?{
??Connection con=null;
??if(this.freeConnections.size()>0)
??{
???con=(Connection)this.freeConnections.get(0);
???if(con==null)con=getConnection(timeout); //繼續獲得連接
??}
??else
??{
???con=newConnection(); //新建連接
??}
??if(this.maxConn==0||this.maxConn<this.inUsed)
??{
???con=null;//達到最大連接數，暫時不能獲得連接了。
??}
??if(con!=null)
??{
???this.inUsed++;
??}
??return con;
?}
?/**
? *
? * 從連接池里得到連接
? * @return
? */
?public synchronized Connection getConnection()
?{
??Connection con=null;
??if(this.freeConnections.size()>0)
??{
???con=(Connection)this.freeConnections.get(0);
???this.freeConnections.remove(0);//如果連接分配出去了，就從空閑連接里刪除
???if(con==null)con=getConnection(); //繼續獲得連接
??}
??else
??{
???con=newConnection(); //新建連接
??}
??if(this.maxConn==0||this.maxConn<this.inUsed)
??{
???con=null;//等待 超過最大連接時
??}
??if(con!=null)
??{
???this.inUsed++;
???System.out.println("得到　"+this.name+"　的連接，現有"+inUsed+"個連接在使用!");
??}
??return con;
?}
?/**
? *釋放全部連接
? *
? */
?public synchronized void release()
?{
??Iterator allConns=this.freeConnections.iterator();
??while(allConns.hasNext())
??{
???Connection con=(Connection)allConns.next();
???try
???{
????con.close();
???}
???catch(SQLException e)
???{
????e.printStackTrace();
???}
???
??}
??this.freeConnections.clear();
???
?}
?/**
? * 創建新連接
? * @return
? */
?private Connection newConnection()
?{
??try {
???Class.forName(driver);
???con=DriverManager.getConnection(url, user, password);
??} catch (ClassNotFoundException e) {
???// TODO Auto-generated catch block
???e.printStackTrace();
???System.out.println("sorry can't find db driver!");
??} catch (SQLException e1) {
???// TODO Auto-generated catch block
???e1.printStackTrace();
???System.out.println("sorry can't create Connection!");
??}
??return con;
??
?}
?/**
? * 定時處理函數
? */
?public synchronized void TimerEvent()
?{
???? //暫時還沒有實現以后會加上的
?}

?/**
? * @param args
? */
?public static void main(String[] args) {
??// TODO Auto-generated method stub

?}
?/**
? * @return the driver
? */
?public String getDriver() {
??return driver;
?}
?/**
? * @param driver the driver to set
? */
?public void setDriver(String driver) {
??this.driver = driver;
?}
?/**
? * @return the maxConn
? */
?public int getMaxConn() {
??return maxConn;
?}
?/**
? * @param maxConn the maxConn to set
? */
?public void setMaxConn(int maxConn) {
??this.maxConn = maxConn;
?}
?/**
? * @return the minConn
? */
?public int getMinConn() {
??return minConn;
?}
?/**
? * @param minConn the minConn to set
? */
?public void setMinConn(int minConn) {
??this.minConn = minConn;
?}
?/**
? * @return the name
? */
?public String getName() {
??return name;
?}
?/**
? * @param name the name to set
? */
?public void setName(String name) {
??this.name = name;
?}
?/**
? * @return the password
? */
?public String getPassword() {
??return password;
?}
?/**
? * @param password the password to set
? */
?public void setPassword(String password) {
??this.password = password;
?}
?/**
? * @return the url
? */
?public String getUrl() {
??return url;
?}
?/**
? * @param url the url to set
? */
?public void setUrl(String url) {
??this.url = url;
?}
?/**
? * @return the user
? */
?public String getUser() {
??return user;
?}
?/**
? * @param user the user to set
? */
?public void setUser(String user) {
??this.user = user;
?}

}

-------------------------------------------
?DBConnectionManager?.java
------------------------------------------
/**
?*?數據庫連接池管理類
?*/
package com.chunkyo.db;

import java.sql.Connection;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Properties;
import java.util.Vector;

import com.chunkyo.db.ParseDSConfig;
import com.chunkyo.db.DSConfigBean;
import com.chunkyo.db.DBConnectionPool;

/**
?* @author chenyanlin
?*
?*/
public class DBConnectionManager {

?static private DBConnectionManager instance;//唯一數據庫連接池管理實例類
?static private int clients;???????????????? //客戶連接數
?private Vector drivers? = new Vector();//驅動信息
?private Hashtable pools=new Hashtable();//連接池
?
?/**
? * 實例化管理類
? */
?public DBConnectionManager() {
??// TODO Auto-generated constructor stub
??this.init();
?}
?/**
? * 得到唯一實例管理類
? * @return
? */
?static synchronized public DBConnectionManager getInstance()
?{
??if(instance==null)
??{
???instance=new DBConnectionManager();
??}
??return instance;
??
?}
?/**
? * 釋放連接
? * @param name
? * @param con
? */
?public void freeConnection(String name, Connection con)
?{
??DBConnectionPool pool=(DBConnectionPool)pools.get(name);//根據關鍵名字得到連接池
??if(pool!=null)
??pool.freeConnection(con);//釋放連接
?}
?/**
? * 得到一個連接根據連接池的名字name
? * @param name
? * @return
? */
?public Connection getConnection(String name)
?{
??DBConnectionPool pool=null;
??Connection con=null;
??pool=(DBConnectionPool)pools.get(name);//從名字中獲取連接池
??con=pool.getConnection();//從選定的連接池中獲得連接
??if(con!=null)
??System.out.println("得到連接。。。");
??return con;
?}
?/**
? * 得到一個連接，根據連接池的名字和等待時間
? * @param name
? * @param time
? * @return
? */
?public Connection getConnection(String name, long timeout)
?{
??DBConnectionPool pool=null;
??Connection con=null;
??pool=(DBConnectionPool)pools.get(name);//從名字中獲取連接池
??con=pool.getConnection(timeout);//從選定的連接池中獲得連接
??System.out.println("得到連接。。。");
??return con;
?}
?/**
? * 釋放所有連接
? */
?public synchronized void release()
?{
??Enumeration allpools=pools.elements();
??while(allpools.hasMoreElements())
??{
???DBConnectionPool pool=(DBConnectionPool)allpools.nextElement();
???if(pool!=null)pool.release();
??}
??pools.clear();
?}

?/**
? * 創建連接池
? * @param props
? */
?private void createPools(DSConfigBean dsb)
?{
??DBConnectionPool dbpool=new DBConnectionPool();
??dbpool.setName(dsb.getName());
??dbpool.setDriver(dsb.getDriver());
??dbpool.setUrl(dsb.getUrl());
??dbpool.setUser(dsb.getUsername());
??dbpool.setPassword(dsb.getPassword());
??dbpool.setMaxConn(dsb.getMaxconn());
??System.out.println("ioio:"+dsb.getMaxconn());
??pools.put(dsb.getName(), dbpool);
?}
?/**
? * 初始化連接池的參數
? */
?private void init()
?{
??//加載驅動程序
??this.loadDrivers();
??//創建連接池
??Iterator alldriver=drivers.iterator();
??while(alldriver.hasNext())
??{
???this.createPools((DSConfigBean)alldriver.next());
???System.out.println("創建連接池。。。");
???
??}
??System.out.println("創建連接池完畢。。。");
?}

?/**
? * 加載驅動程序
? * @param props
? */
?private void loadDrivers()
?{
??ParseDSConfig pd=new ParseDSConfig();
?//讀取數據庫配置文件
??drivers=pd.readConfigInfo("ds.config.xml");
??System.out.println("加載驅動程序。。。");
?}
?/**
? * @param args
? */
?public static void main(String[] args) {
??// TODO Auto-generated method stub

?}

}
----------------------------------------
DSConfigBean.java
----------------------------------------
/**
?*?配置文件Bean類
?*/
package com.chunkyo.db;

/**
?* @author chenyanlin
?*
?*/
public class DSConfigBean {

?private String type???? =""; //數據庫類型
?private String name???? =""; //連接池名字
?private String driver?? =""; //數據庫驅動
?private String url????? =""; //數據庫url
?private String username =""; //用戶名
?private String password =""; //密碼
?private int maxconn? =0; //最大連接數
?/**
? *
? */
?public DSConfigBean() {
??// TODO Auto-generated constructor stub
?}

?/**
? * @param args
? */
?public static void main(String[] args) {
??// TODO Auto-generated method stub

?}

?/**
? * @return the driver
? */
?public String getDriver() {
??return driver;
?}

?/**
? * @param driver the driver to set
? */
?public void setDriver(String driver) {
??this.driver = driver;
?}

?/**
? * @return the maxconn
? */
?public int getMaxconn() {
??return maxconn;
?}

?/**
? * @param maxconn the maxconn to set
? */
?public void setMaxconn(int maxconn) {
??this.maxconn = maxconn;
?}

?/**
? * @return the name
? */
?public String getName() {
??return name;
?}

?/**
? * @param name the name to set
? */
?public void setName(String name) {
??this.name = name;
?}

?/**
? * @return the password
? */
?public String getPassword() {
??return password;
?}

?/**
? * @param password the password to set
? */
?public void setPassword(String password) {
??this.password = password;
?}

?/**
? * @return the type
? */
?public String getType() {
??return type;
?}

?/**
? * @param type the type to set
? */
?public void setType(String type) {
??this.type = type;
?}

?/**
? * @return the url
? */
?public String getUrl() {
??return url;
?}

?/**
? * @param url the url to set
? */
?public void setUrl(String url) {
??this.url = url;
?}

?/**
? * @return the username
? */
?public String getUsername() {
??return username;
?}

?/**
? * @param username the username to set
? */
?public void setUsername(String username) {
??this.username = username;
?}

}
-----------------------------------------------------
ParseDSConfig.java
-----------------------------------------------------
/**
?*?操作配置文件類 讀? 寫 修改 刪除等操作
?*/
package com.chunkyo.db;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.Vector;
import java.util.Iterator;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.Format;
import org.jdom.output.XMLOutputter;

/**
?* @author chenyanlin
?*
?*/
public class ParseDSConfig {

?/**
? * 構造函數
? */
?public ParseDSConfig() {
??// TODO Auto-generated constructor stub
?}
?/**
? * 讀取xml配置文件
? * @param path
? * @return
? */
?public Vector readConfigInfo(String path)
?{
??String rpath=this.getClass().getResource("").getPath().substring(1)+path;
??Vector dsConfig=null;
??FileInputStream fi = null;
??try
??{
???fi=new FileInputStream(rpath);//讀取路徑文件
???dsConfig=new Vector();
???SAXBuilder sb=new SAXBuilder();
???Document doc=sb.build(fi);
???Element root=doc.getRootElement();
???List pools=root.getChildren();
???Element pool=null;
???Iterator allPool=pools.iterator();
???while(allPool.hasNext())
???{
????pool=(Element)allPool.next();
????DSConfigBean dscBean=new DSConfigBean();
????dscBean.setType(pool.getChild("type").getText());
????dscBean.setName(pool.getChild("name").getText());
????System.out.println(dscBean.getName());
????dscBean.setDriver(pool.getChild("driver").getText());
????dscBean.setUrl(pool.getChild("url").getText());
????dscBean.setUsername(pool.getChild("username").getText());
????dscBean.setPassword(pool.getChild("password").getText());
????dscBean.setMaxconn(Integer.parseInt(pool.getChild("maxconn").getText()));
????dsConfig.add(dscBean);
???}
???
??} catch (FileNotFoundException e) {
???// TODO Auto-generated catch block
???e.printStackTrace();
??} catch (JDOMException e) {
???// TODO Auto-generated catch block
???e.printStackTrace();
??} catch (IOException e) {
???// TODO Auto-generated catch block
???e.printStackTrace();
??}
??
??finally
??{
???try {
????fi.close();
???} catch (IOException e) {
????// TODO Auto-generated catch block
????e.printStackTrace();
???}
??}
??
??return dsConfig;
?}

/**
?*修改配置文件 沒時間寫 過段時間再貼上去 其實一樣的
?*/
?public void modifyConfigInfo(String path,DSConfigBean dsb) throws Exception
?{
??String rpath=this.getClass().getResource("").getPath().substring(1)+path;
??FileInputStream fi=null; //讀出
??FileOutputStream fo=null; //寫入
??
?}
/**
?*增加配置文件
?*
?*/
?public void addConfigInfo(String path,DSConfigBean dsb)
?{
??String rpath=this.getClass().getResource("").getPath().substring(1)+path;
??FileInputStream fi=null;
??FileOutputStream fo=null;
??try
??{
???fi=new FileInputStream(rpath);//讀取xml流
???
???SAXBuilder sb=new SAXBuilder();
???
???Document doc=sb.build(fi); //得到xml
???Element root=doc.getRootElement();
???List pools=root.getChildren();//得到xml子樹
???
???Element newpool=new Element("pool"); //創建新連接池
???
???Element pooltype=new Element("type"); //設置連接池類型
???pooltype.setText(dsb.getType());
???newpool.addContent(pooltype);
???
???Element poolname=new Element("name");//設置連接池名字
???poolname.setText(dsb.getName());
???newpool.addContent(poolname);
???
???Element pooldriver=new Element("driver"); //設置連接池驅動
???pooldriver.addContent(dsb.getDriver());
???newpool.addContent(pooldriver);
???
???Element poolurl=new Element("url");//設置連接池url
???poolurl.setText(dsb.getUrl());
???newpool.addContent(poolurl);
???
???Element poolusername=new Element("username");//設置連接池用戶名
???poolusername.setText(dsb.getUsername());
???newpool.addContent(poolusername);
???
???Element poolpassword=new Element("password");//設置連接池密碼
???poolpassword.setText(dsb.getPassword());
???newpool.addContent(poolpassword);
???
???Element poolmaxconn=new Element("maxconn");//設置連接池最大連接
???poolmaxconn.setText(String.valueOf(dsb.getMaxconn()));
???newpool.addContent(poolmaxconn);
???pools.add(newpool);//將child添加到root
???Format format = Format.getPrettyFormat();
????? format.setIndent("");
????? format.setEncoding("utf-8");
????? XMLOutputter outp = new XMLOutputter(format);
????? fo = new FileOutputStream(rpath);
????? outp.output(doc, fo);
??} catch (FileNotFoundException e) {
???// TODO Auto-generated catch block
???e.printStackTrace();
??} catch (JDOMException e) {
???// TODO Auto-generated catch block
???e.printStackTrace();
??} catch (IOException e) {
???// TODO Auto-generated catch block
???e.printStackTrace();
??}
??finally
??{
???
??}
?}
?/**
? *刪除配置文件
? */
?public void delConfigInfo(String path,String name)
?{
??String rpath=this.getClass().getResource("").getPath().substring(1)+path;
??FileInputStream fi = null;
??FileOutputStream fo=null;
??try
??{
???fi=new FileInputStream(rpath);//讀取路徑文件
???SAXBuilder sb=new SAXBuilder();
???Document doc=sb.build(fi);
???Element root=doc.getRootElement();
???List pools=root.getChildren();
???Element pool=null;
???Iterator allPool=pools.iterator();
???while(allPool.hasNext())
???{
????pool=(Element)allPool.next();
????if(pool.getChild("name").getText().equals(name))
????{
?????pools.remove(pool);
?????break;
????}
???}
???Format format = Format.getPrettyFormat();
????? format.setIndent("");
????? format.setEncoding("utf-8");
????? XMLOutputter outp = new XMLOutputter(format);
????? fo = new FileOutputStream(rpath);
????? outp.output(doc, fo);

???
??} catch (FileNotFoundException e) {
???// TODO Auto-generated catch block
???e.printStackTrace();
??} catch (JDOMException e) {
???// TODO Auto-generated catch block
???e.printStackTrace();
??} catch (IOException e) {
???// TODO Auto-generated catch block
???e.printStackTrace();
??}
??
??finally
??{
???try {
????fi.close();
???} catch (IOException e) {
????// TODO Auto-generated catch block
????e.printStackTrace();
???}
??}
?}
?/**
? * @param args
? * @throws Exception
? */
?public static void main(String[] args) throws Exception {
??// TODO Auto-generated method stub

??ParseDSConfig pd=new ParseDSConfig();
??String path="ds.config.xml";
??pd.readConfigInfo(path);
??//pd.delConfigInfo(path, "tj012006");
??DSConfigBean dsb=new DSConfigBean();
??dsb.setType("oracle");
??dsb.setName("yyy004");
??dsb.setDriver("org.oracle.jdbc");
??dsb.setUrl("jdbc:oracle://localhost");
??dsb.setUsername("sa");
??dsb.setPassword("");
??dsb.setMaxconn(1000);
??pd.addConfigInfo(path, dsb);
??pd.delConfigInfo(path, "yyy001");
?}

}

--------------------------------------
ds.config.xml?? 配置文件
--------------------------------------


<ds-config>
<pool>
<type>mysql</type>
<name>user</name>
<driver>com.mysql.jdbc.driver</driver>
<url>jdbc:mysql://localhost:3306/user</url>
<username>sa</username>
<password>123456</password>
<maxconn>100</maxconn>
</pool>
<pool>
<type>mysql</type>
<name>user2</name>
<driver>com.mysql.jdbc.driver</driver>
<url>jdbc:mysql://localhost:3306/user2</url>
<username>sa</username>
<password>1234</password>
<maxconn>10</maxconn>
</pool>
<pool>
<type>sql2000</type>
<name>books</name>
<driver>com.microsoft.sqlserver.driver</driver>
<url>jdbc:sqlserver://localhost:1433/books:databasename=books</url>
<username>sa</username>
<password></password>
<maxconn>100</maxconn>
</pool>
</ds-config>


3. 連接池的使用
? 1。Connection的獲得和釋放
? DBConnectionManager?? connectionMan=DBConnectionManager?.getInstance();//得到唯一實例
?? //得到連接
?? String name="mysql";//從上下文得到你要訪問的數據庫的名字
?? Connection? con=connectionMan.getConnection(name);
? //使用
? 。。。。。。。
? // 使用完畢
?connectionMan.freeConnection(name,con);//釋放，但并未斷開連接
?2。數據庫連接的動態增加和連接池的動態增加
????? 1。調用xml操作增加類

??????2。重新實例華連接池管理池類