高手请进，帮忙看一下连接池的异常

Question

严重: Servlet.service() for servlet [LoginServlet] in context with path [/chart] threw exception [org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper cannot be cast to org.apache.tomcat.dbcp.dbcp.BasicDataSource] with root cause
javax.servlet.ServletException: org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper cannot be cast to org.apache.tomcat.dbcp.dbcp.BasicDataSource连接可以取得，但是执行SQL和关闭资源就报错误

Answer 1

帮我看一下怎样转为连接池,多谢
public class LoginFactory {
    Connection connection;
    CallableStatement callableStatement;
    ResultSet resultSet;    public UserBean loginControl(String uid,String pwd) throws Exception{
        UserBean userBean = new UserBean();
        connection = ConnectionPoolInit.getConnection();
        System.out.println(connection);        callableStatement = connection.prepareCall("{call usp_web_login (?,?)}");
        callableStatement.setString(1,uid);
        callableStatement.setString(2, pwd);
        resultSet = callableStatement.executeQuery();        while (resultSet.next()){
            userBean.setUserId(uid);
            userBean.setUserName(resultSet.getString("username"));
            userBean.setLogInfo(resultSet.getString("loginfo"));
        }
        ConnectionPoolInit.close(resultSet,callableStatement,connection);
        return userBean;
    }
}

Answer 2

看不出你connection内部获得的细节Tomcat uses the Apache Commons DBCP package (see http://jakarta.apache.org/commons/dbcp/) for database connection pooling. When you lookup a DataSource object using JNDI, like this:Context context = new InitialContext();
DataSource ds = (DataSource)context.lookup("java:comp/env/jdbc/ari");the object that you get is an instance of class org.apache.commons.dbcp.BasicDataSource. When you call getConnection on this object, you get an instance of class org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper (which obviously implements java.sql.Connection, and wraps the OracleConnection object).https://forums.oracle.com/forums/thread.jspa?threadID=279238可能如果从BasicDataSource中获得的PoolGuardConnectionWrapper实例的connection的话就不会报这种类型转换错误了

Answer 3

这是连接池的实现，谢谢，帮我看一下
public final class ConnectionPoolInit {
    private static BasicDataSource basicDataSource = null;    private ConnectionPoolInit(){}    public static void createDataSource() throws Exception{
        Properties properties = new Properties();
        InputStream inputStream = ConnectionPoolInit.class.
            getClassLoader().getResourceAsStream("dbcpconfig.properties");
        properties.load(inputStream);
        basicDataSource = (BasicDataSource)BasicDataSourceFactory.createDataSource(properties);
    }    public static DataSource getDataSource(){
        return basicDataSource;
    }    public static synchronized Connection getConnection() throws Exception{
        return basicDataSource.getConnection();
    }    public static void close(ResultSet resultSet,Statement statement,Connection connection) throws Exception{
        try{
            if (resultSet != null) {
                resultSet.close();
            }
        } catch (Exception e){
            throw new Exception(e.getMessage());
        } finally {
            try{
                if (statement != null) {
                    statement.close();
                }
            } catch (Exception e) {
                throw new Exception(e.getMessage());
            } finally {
                try{
                    if (connection != null) {
                        ((BasicDataSource)connection).close();
                    }
                } catch (Exception e) {
                    throw new Exception(e.getMessage());
                }
            }
        }
    }
}

Answer 4

看了org.apache.tomcat.dbcp.dbcp源码，感觉这两者之间没有直接关联，正常情况应该是不会类型转换的
PoolGuardConnectionWrapper
BasicDataSourcepublic class BasicDataSource implements  DataSource private class PoolGuardConnectionWrapper extends
                    DelegatingConnection没有异常发生的具体行号位置吗？

Answer 5

数据驱动用的JTDS第三方sql server驱动driverClassName=net.sourceforge.jtds.jdbc.Driver，tomcat7.0，sqlserver2000，jdk1.7。用微软官方的驱动提示同样的错误

Answer 6

cannot be cast to org.apache.tomcat.dbcp.dbcp.BasicDataSource
这句说的很清楚，你BasicDataSourceFactory.createDataSource(properties)无法强制类型转换为BasicDataSource类型。;

Answer 7

问题已经解决，原来是apache的实现有问题，现在换了c3p0就好了，郁闷被折磨了好几天。推荐c3p0希望兄弟们不要走弯路了