poolbean.java

一个ＪＳＰ范例

package com;
import java.io.Serializable;
import java.sql.*;
import java.util.*;
import com.ConnBean;
public class PoolBean implements java.io.Serializable{
  private String driver = null;
  private String url = null;
  private int size = 0;
  private String username = new String("");
  private String password = new String("");
  private Vector pool = null;
  private ConnBean connBean=null;
  public PoolBean()
  {
  	driver="sun.jdbc.odbc.JdbcOdbcDriver";
	url="jdbc:odbc:meeting";
	size=5;
	username="";
	password="";
 }
  public void setDriver(String value){
    if (value!=null) driver=value;
  }
  public String getDriver(){
    return driver;
  }
  public void setURL(String value ){
    if (value!=null) url=value;
  }
  public String getURL(){
    return url;
  }
  public void setSize(int value){
    if (value>1) size=value;
  }
  public int getSize(){
    return size;
  }
  public void setUsername(String value){
     if (value!=null) username=value;
  }
  public String getUserName(){
     return username;
  }
  public void setPassword(String value){
     if (value!=null) password=value;
  }
  public String getPassword(){
     return password;
  }
  public void setConnBean(ConnBean cb)  {
     if (cb!=null) connBean=cb;
  }
  public ConnBean getConnBean() throws Exception{
     Connection con = getConnection();
     ConnBean cb = new ConnBean(con);
     cb.setInuse(true);
     return cb;
  }
  private Connection createConnection() throws Exception
  {
    Connection con = null;
     con = DriverManager.getConnection(url,username,password);
     return con;
  }
  public synchronized void initializePool() throws Exception
  {


    if (driver==null)
      throw new Exception("No Driver Name Specified!");
    if (url==null)
      throw new Exception("No URL Specified!");
    if (size<1)
      throw new Exception("Pool size is less than 1!");
  
    try{
      Class.forName(driver);
      for (int x=0; x<size; x++)
      {
        Connection con = createConnection();
        if (con!=null)
        {
          ConnBean pcon = new ConnBean(con);
          addConnection(pcon);
        }
      }
    }
    catch (Exception e)
    {
      System.err.println(e.getMessage());
      throw new Exception(e.getMessage());
    }
  }
  private void addConnection(ConnBean value)
  {
    if (pool==null) pool=new Vector(size);
    pool.addElement(value);
  }
  public synchronized void releaseConnection(Connection con)
  {
    for (int x=0; x<pool.size(); x++)
    {
      ConnBean pcon =
        (ConnBean)pool.elementAt(x);
      if (pcon.getConnection()==con)
      {
        System.err.println("Releasing Connection " + x);
        pcon.setInuse(false);
        break;
      }
    }
  }
  public synchronized Connection getConnection()
  throws Exception
  {
    ConnBean pcon = null;
    for (int x=0; x<pool.size(); x++)
    {
      pcon = (ConnBean)pool.elementAt(x);
      if (pcon.getInuse()==false)
      {
        pcon.setInuse(true);
        return pcon.getConnection();
      }
    }
    try
      {
      Connection con = createConnection();
      pcon = new ConnBean(con);
      pcon.setInuse(true);
      pool.addElement(pcon);
    }
    catch (Exception e)
    {
      System.err.println(e.getMessage());
      throw new Exception(e.getMessage());
    }
    return pcon.getConnection();
  }
  public synchronized void emptyPool()
  {
    for (int x=0; x<pool.size(); x++)
    {
      System.err.println("Closing JDBC Connection " + x);
      ConnBean pcon =
        (ConnBean)pool.elementAt(x);
      if (pcon.getInuse()==false)
        pcon.close();
      else
      {
        try{
          java.lang.Thread.sleep(20000);
          pcon.close();
        }
        catch (InterruptedException ie){
          System.err.println(ie.getMessage());
        }
      }
    }
  }
  public int getConnectionSize()
  {
  	if (pool==null)
		return 0;
	else
		return pool.size();
  }
}