chars — Mon, 02 Jul 2007 09:46:00 GMT

package chars.pool;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

import COM.ibm.db2.jdbc.app.DB2Driver;

/**
* JDK version used : jdk1.4.2_07

* Description : 一个数据库�q�接池的实现

* Comments Name : CharsConnectionPool

* author �Q�chars

* date �Q?007-06-11

* Version : 1.00

*/
public class CharsConnectionPool
{
   //---------------�q�接数据库所需要的元素---------------
private String driver;

private String url;

private String userName;

private String password;

//----------------------------------------------
private List connections = null;//�q�接池的容器

private int intiateCount = 10;// 初始化连接数

private int maxCount = 100;// �q�接池可以��生的最大连接数

private int rateCount = 10;// �q�接不够时一�ơ可以申��L��q�接�?br>
public static int ACTIVE_ACOUNT = 0;//记录目前的活动连接数

public String getDriver()
{
    return driver;
}

public void setDriver(String driver)
{
     this.driver = driver;
}

public int getIntiateCount()
{
     return intiateCount;
}

public void setIntiateCount(int intiateCount)
{
     this.intiateCount = intiateCount;
}

public int getMaxCount()
{
     return maxCount;
}

public void setMaxCount(int maxCount)
{
     this.maxCount = maxCount;
}

public String getPassword()
{
     return password;
}

public void setPassword(String password)
{
    this.password = password;
}

public int getRateCount()
{
     return rateCount;
}

public void setRateCount(int rateCount)
{
     this.rateCount = rateCount;
}

public String getUrl()
{
     return url;
}

public void setUrl(String url)
{
     this.url = url;
}

public String getUserName()
{
     return userName;
}

public void setUserName(String userName)
{
     this.userName = userName;
}
    /**
     * �q�接池构造函�?br>     * @param driver
     * @param url
     * @param userName
     * @param password
     * @param connections
     */
public CharsConnectionPool(String driver, String url, String userName, String password)
{
    super();
    this.driver = driver;
    this.url = url;
    this.userName = userName;
    this.password = password;
}

public CharsConnectionPool(Properties p)
{
    super();
    this.driver = p.getProperty("driver");
    this.url = p.getProperty("url");
    this.userName = p.getProperty("userName");
    this.password = p.getProperty("password");
}

/**
* 初始化连接池
*
*/
public void initiatePools()throws Exception
{
     if (connections != null)return;//如果�q�接池已�l�徏立则不再�ơ进行初始化

     connections = new ArrayList();
     initParamters();//�Ҏ��数据库支持的最大连接数配置该连接池的相兛_��?
    for (int i = 0; i < intiateCount; i++){
     connections.add(newCharsConnection());
  }
}
/**
* 销毁连接池
* @throws Exception
*/
public void destoryPools()throws Exception
{
     if (connections == null) return ;
    for(int i=0; i     CharsPoolConnection conn = (CharsPoolConnection)connections.get(i);

     if(conn.isBusy()) Thread.sleep(5000);//如果该连接正在��用则再给5�U�时�?br>    closeConnection(conn.getConnection());
     connections.remove(conn);
  }
  connections = null;
}
    /**
     * 从连接池获取�q�接
     *
     */
public Connection getConnection()throws SQLException
{
        Connection conn = null;
        try{

        conn = getFreeConnection();
        if(conn == null) {
           Thread.sleep(3000);//暂停3�U�钟再试着获取�q�接
           conn = getFreeConnection();
        }
        if(conn == null) {//此时如果�q�不能获得连接则表示,�q�接池中的连接已�l�用�?br>          throw new SQLException("�q�接池连接连接��用枯�?��L��后再�?!");
        }
        }catch(Exception e)
        {
        e.printStackTrace();
        }
        return conn;
}
    /**
     * 归还�q�接到连接池(当连接用完时)
     * @param conn
     */
public void rebackConnection(Connection conn)
{
           for(int i = 0;i < connections.size();i++){
            CharsPoolConnection charsCon = (CharsPoolConnection)connections.get(i);
            if(charsCon.getConnection() == conn){
             charsCon.setBusy(false);
             conn = null;//外部引用为空.
             ACTIVE_ACOUNT --;
             break;
            }
           }
}

// ---------------------------------------------------------------------------------------------------
    /**
     * 加蝲驱动�E�序,配置实际上可以用的最大连接数
     */
private void initParamters() throws Exception
{
   int realMaxCount = -1;
   Connection con = null;
   try
  {
    Driver driver1 = new DB2Driver();
      DriverManager.registerDriver(driver1);
     con = DriverManager.getConnection(this.url, this.userName, this.password);
      DatabaseMetaData dmd = con.getMetaData();
      realMaxCount = dmd.getMaxConnections();

    if(realMaxCount == 0){//如果�q�回的��gؓ0,则表�C�最大的�q�接��C��受限�?br>      realMaxCount = 1000;//那么默认赋一个较大的值给�?br>   }
  }
  finally{
     if(con == null) con.close();
  }

  if(realMaxCount < intiateCount) {//如果数据库允许的最大活动连接数��于初始化的�q�接�?br>   intiateCount = maxCount;     //则实际上初始化的�q�接数应该等于数据库允许的最大活动连接数�?br>    maxCount = realMaxCount;
  }
  else if(intiateCount < realMaxCount && maxCount >= realMaxCount){//如果数据库最大的�z�d��q�接数大于初始化�q�接��C��是小于该�q�接池允许的最大连接数
    maxCount = realMaxCount;                                     //则该池的最大连接数�{�于数据库允许的最大活动连接数
  }
}
/**
* 获取可以用的�q�接,如果没有查找到则�Ҏ��条�g在池中加入新的连�?br> * @return
* @throws SQLException
*/
private Connection getFreeConnection()throws SQLException
{
     Connection conn = null;
     conn = findFreeConnection();//首先到连接池中找�I�闲的连�?br>     if(conn == null){//如果没有扑ֈ�,则试着产生新的�q�接攑օ�池中
   for(int i = 1; connections.size() < maxCount && i <= rateCount;i++){//是否再能在连接池中增加连接取决与maxCount
     connections.add(newCharsConnection());
    }
    conn = findFreeConnection();//再次在连接池中找
  }
return conn;
}
/**
* 在池中查扑֏�以��用的�q�接
* @return
*/
private Connection findFreeConnection()throws SQLException
{
     CharsPoolConnection charsConn = null;
     Connection conn = null;
     for(int i = 0; i < connections.size();i++){
     charsConn = (CharsPoolConnection)connections.get(i);
     if(charsConn.isBusy())continue;
     else {
         if(!isAvalidConnection(charsConn.getConnection())) {
          charsConn.setConnection(newConnection());
          }
      conn = charsConn.getConnection();//得到可以用的�q�接
      charsConn.setBusy(true);//表明��Z��用状�?br>      ACTIVE_ACOUNT++;
      break;
      }
    }
    return conn;
}

/**
* 判断池中的连接是否因为其他原因变得不可以�?br> * @param conn
* @return
*/
private boolean isAvalidConnection(Connection conn)
{
   try
    {
         conn.setAutoCommit(true);//模拟动作,如果能够能够操作则说明该�q�接可用
     }catch(SQLException e)
    {
       closeConnection(conn);
       return false;
    }
    return true;
}

/**
* 判断一个连接是否还可以�?如果不可以用则创��Z��个新的连接代替它
* @param conn
* @return
*/
private CharsPoolConnection newCharsConnection()throws SQLException
{

     CharsPoolConnection charsCon = new CharsPoolConnection();
     charsCon.setConnection(newConnection());
     charsCon.setBusy(false);

     return charsCon;
}
/**
* 获取一个新的数据库�q�接
* @return
* @throws SQLException
*/
private Connection newConnection()throws SQLException
{
      return DriverManager.getConnection(this.url,this.userName,this.password);
}
/**
* 关闭数据库连�?br> * @param conn
*/
private void closeConnection(Connection conn)
{
  try
  {
       conn.close();
  }catch(SQLException se)
  {
      System.out.println("关闭�q�接发生异常...");
  }
}
}

��装�q�接池的�q�接:
package chars.pool;

public class CharsPoolConnection
{
    private boolean isBusy;

    private java.sql.Connection connection;

   public java.sql.Connection getConnection()
{
       return connection;
}

public void setConnection(java.sql.Connection connection)
{
     this.connection = connection;
}

public boolean isBusy()
{
      return isBusy;
}

public void setBusy(boolean isBusy)
{
      this.isBusy = isBusy;
}
}

调用的方式大致可以这�?
    CharsConnectionPool pool = new CharsConnectionPool(env);
    pool.initiatePools();
    Connection conn= pool.getConnection(); //获取�q�接
    //do something with your code;
    pool .rebackConnection(conn); 归还�q�接到连接池

chars 2007-07-02 17:46 发表评论

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