JSP使用连接池连接数据库的问题

新客网 XKER.COM 2006-09-14 来源：收藏本文

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;

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