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jsp使用连接池连接数据库的问题


  各位高手麻烦帮我看下面这三个文件(一个jsp,两个.java),我在ie输入地址时,提示如下错误(代码应该没有错,不知是不是设置的问题),望高手指教,不胜感激:
  
  d:/program files/apache group/tomcat 4.1/work/standalone/localhost/_/shopping/index_jsp.java:44: package mybean does not exist
  mybean.dbconnmanager connmanager = null;
  ^
  an error occurred at line: 2 in the jsp file: /shopping/index.jsp
  
  generated servlet error:
  d:/program files/apache group/tomcat 4.1/work/standalone/localhost/_/shopping/index_jsp.java:46: package mybean does not exist
  connmanager = (mybean.dbconnmanager) pagecontext.getattribute("connmanager", pagecontext.application_scope);
  ^
  an error occurred at line: 2 in the jsp file: /shopping/index.jsp
  
  generated servlet error:
  d:/program files/apache group/tomcat 4.1/work/standalone/localhost/_/shopping/index_jsp.java:49: package mybean does not exist
  connmanager = (mybean.dbconnmanager) java.beans.beans.instantiate(this.getclass().getclassloader(), "mybean.dbconnmanager");
  ^
  //下面这两个是连接池,下面两个文件都放在一个mybean的包里.
  
  package mybean;
  import java.sql.*;
  import java.util.*;
  
  public class dbconnpool {
  //正在使用连接的数量
  private int using;
  //目前可用的连接数,即空闲连接
  private vector connections=new vector();
  //最大连接数
  private int maxconn;
  //连接池名
  private string poolname;
  //数据库标识
  private string dbid;
  //驱动程序名
  private string drivername;
  //数据库帐号
  private string username;
  //数据库密码
  private string passwd;
  
  public dbconnpool(string poolname,string dbid,string drivername,
  string username,string passwd,int maxconn){
  this.poolname=poolname;
  this.drivername=drivername;
  this.dbid =dbid;
  this.username =username;
  this.passwd=passwd;
  this.maxconn=maxconn;
  }
  
  /*将空闲连接返回给连接池*/
  public synchronized void returnconnection(connection conn){
  //将指定连接加到向量末尾
  connections.addelement(conn);
  //连接用户减一
  using--;
  }
  
  /*从连接池得到一个连接*/
  public synchronized connection getconnection(){
  connection conn = null; //connection是一个类,
  //connections是一个向量,用于存储连接对象,它所存储是的所有空闲状态的可用连接
  if (connections.size() > 0) {
  
  //获取连接列表的第一个连接
  conn = (connection) connections.elementat(0);
  connections.removeelementat(0);//获得一个连接,并将此连接从队列中删除.
  
  //如果此连接已关闭,刚继续获取,
  try {
  if (conn.isclosed())
  conn = getconnection();
  }
  catch (exception e) {
  e.printstacktrace();
  }
  }
  //如果实际使用的连接数小于最大连接数即有可用连接),就新增加一个连接
  else if (maxconn == 0 || using < maxconn){
  //如此时无可用连接(maxconn == 0)且连接数又未达到上限(using < maxconn)),就创建一个新连接
  conn=newconnection();
  }
  //如果连接数已达到上限就返回空指针
  if (conn!=null){
  using++;
  }
  return conn;
  }
  
  /*创建新的连接*/
  public connection newconnection(){
  connection conn=null;
  try{
  //加载驱动
  class.forname(drivername);
  conn=drivermanager.getconnection(dbid,username,passwd);
  }catch(exception e){
  e.printstacktrace();
  return null;
  }
  return conn;
  }
  
  /*关闭所有连接*/
  public synchronized void closeconn(){
  enumeration allconnections=connections.elements();
  while (allconnections.hasmoreelements()){
  connection conn=(connection) allconnections.nextelement();
  try{
  conn.close();
  }catch(sqlexception e){
  e.printstacktrace();
  }
  }
  connections.removeallelements();
  }
  }
  
  package mybean;
  import java.sql.*;
  import java.util.*;
  
  public class dbconnmanager {
  //连接池名列表
  private vector poolnames =new vector();
  //驱动程序名列表
  private vector drivernames=new vector();
  //数据库标识列表
  private vector dbids=new vector();
  //用户名列表
  private vector usernames=new vector();
  //用户密码列表
  private vector passwds=new vector();
  //最大连接数列表
  private vector maxconns=new vector();
  //连接池队列
  private hashtable connpools=new hashtable();
  
  public dbconnmanager() {
  //添加access数据库的连接信息
  poolnames.addelement("access");
  drivernames.addelement("sun.jdbc.odbc.jdbcodbcdriver");
  dbids.addelement("jdbc:odbc:shopping");
  usernames.addelement("");
  passwds.addelement("");
  maxconns.addelement("5");
  
  //添加sql server2000数据库的连接信息
  poolnames.addelement("sqlserver2000");
  drivernames.addelement("com.microsoft.jdbc.sqlserver.sqlserverdriver");
  dbids.addelement("jdbc:microsoft:sqlserver://localhost:1433;databsername=shopping");
  usernames.addelement("");
  passwds.addelement("");
  maxconns.addelement("5");
  
  //连接mysql数据库信息
  poolnames.addelement("mysql");
  drivernames.addelement("org.gjt.mm.mysql.driver");
  dbids.addelement("jdbc:mysql://localhost/shopping");
  usernames.addelement("");
  passwds.addelement("");
  maxconns.addelement("5");
  
  //连接oracle8i/9i数据库
  poolnames.addelement("oracle");
  drivernames.addelement("oracle.jdbc.driver.oracledriver");
  dbids.addelement("jdbc:oracle:thin:@localhost:1521:shopping");
  usernames.addelement("");
  passwds.addelement("");
  maxconns.addelement("5");
  
  //创建连接池
  createpools();
  }
  
  /*将连接返回给由指定的连接池*/
  public void returnconnection(string name,connection conn){
  dbconnpool pool=(dbconnpool) connpools.get(name);
  if (pool!=null)
  {
  pool.returnconnection(conn);
  }
  }
  
  /*得到一个指定连接池中的连接*/
  public connection getconnection(string name){
  dbconnpool pool=(dbconnpool) connpools.get(name);
  if (pool!=null)
  {
  return pool.getconnection();
  }
  return null;
  }
  
  /*关闭所有连接*/
  public synchronized void closeconns(){
  enumeration allpools=connpools.elements();
  while (allpools.hasmoreelements()){
  dbconnpool pool=(dbconnpool) allpools.nextelement();
  pool.closeconn();
  }
  }
  
  /*创建连接池*/
  private void createpools(){
  for (int i=0;i<poolnames.size();i++)
  {
  string poolname=poolnames.elementat(i).tostring();
  string drivername=drivernames.elementat(i).tostring();
  string dbid=dbids.elementat(i).tostring();
  string username=usernames.elementat(i).tostring();
  string passwd=passwds.elementat(i).tostring();
  int maxconn=0;
  try{
  maxconn=integer.parseint(maxconns.elementat(i).tostring());
  }catch (numberformatexception e){
  e.printstacktrace();
  }
  dbconnpool pool=new dbconnpool(poolname,drivername,dbid,username,
  passwd,maxconn);
  connpools.put(poolname,pool);
  }
  }
  }
  
  下面这个是主页面.jsp文件
  
  <%@ page contenttype="text/html; charset=gbk" %>
  <%@ page import ="java.sql.*" %>
  <jsp:usebean id="connmanager" scope="application" class="mybean.dbconnmanager" />
  <html>
  <head>
  <title>
  购物商城首页
  </title>
  </head>
  <body bgcolor="#b0c4de">
  <center><h1>欢迎访问本购物商城</h1></c

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