环境tomcat 5.0和sql server 2000程序运行一段时间后报错？？？

Question

index.jsp页面里出现了空指针，好好的查一查哪个地方没有检查

Answer 1

看看这段代码有没有问题：
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DBQuery
{    Connection conn;
    ResultSet rs;
    Statement stmt;
    private DBConnectionManager connMgr;    public DBQuery()
    {
        conn = null;
        rs = null;
        stmt = null;
        try
        {
            //connMgr = DBConnectionManager.getInstance();
            connMgr = DBConnectionManager.getInstance();
        }
        catch(Exception exception)
        {
            System.err.println("data begin err: " + exception.getMessage());
        }
    }    public void cls()
    {
        try
        {
            stmt.close();
        }
        catch(SQLException sqlexception)
        {
            System.err.println(sqlexception.getMessage());
        }
    }    public ResultSet executeQuery(String s)
    {
        rs = null;
        try
        {
            conn = connMgr.getConnection("sqlserver");
            stmt = conn.createStatement();
            rs = stmt.executeQuery(s);
        }
        catch(SQLException sqlexception)
        {
            System.err.println("data query connect err:" + sqlexception.getMessage());
            System.out.println(s);
        }            return rs;
     
    }    public void executeUpdate(String s)
    {
        try
        {
            conn = connMgr.getConnection("sqlserver");
            stmt = conn.createStatement();
            stmt.executeUpdate(s);
        }
        catch(SQLException sqlexception)
        {
            System.err.println("data update connect err:" + sqlexception.getMessage());
            System.out.println(s);
        }
        finally
        {
            connMgr.freeConnection("sqlserver", conn);
        }
    }    public ResultSet getResult()
    {
        return rs;
    }    public void setSql(String s)
    {
        rs = executeQuery(s);
    }
}

Answer 2

    public ResultSet executeQuery(String s)
    {
        rs = null;
        try
        {
            conn = connMgr.getConnection("sqlserver");
            stmt = conn.createStatement();
            rs = stmt.executeQuery(s);
        }
        catch(SQLException sqlexception)
        {
            System.err.println("data query connect err:" + sqlexception.getMessage());
            System.out.println(s);
        }            return rs;
     
    }
连接没关闭.

Answer 3

会不会是session过期导致空指针的啊，看这种问题应该不是tomcat和sql的问题

Answer 4

你这个bean看不出问题，不过写的比较乱。

Answer 5

wzs(兔子)说的有道理：是session过期导致空指针的啊，看这种问题应该不是tomcat和sql的问题