十万火急啊，菜鸟问一个很简单的JSP问题，请懂的人帮看一下

<%@ page contentType="text/html;charset=gb2312" language="java" import="java.sql.*" errorPage=""%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=gb2312">
<title>通过JAVABEAN访问数据库</title>
</head>
<body>
<jsp:useBean id="t" class="com.prodb.Test1" scope="page"/>
<%
  ResultSet rs=t.getRs("Test");
  while(rs.next())
     {out.print(rs.getInt(1)+"");
     out.print(rs.getString(2)+"<br>");
     }
     t.close();
     
 %>
     </body>
     </html>这是原代码
下面的是JAVABEAN的代码package com.prodb;
import java.sql.*;
import javax.naming.*;
import javax.sql.DataSource;
public class Test1{
                  private Statement stmt;
          private ResultSet rs;
          private static Connection con;
          public static synchronized Connection getCon()throws Exception{
          Context ctx;
          DataSource ds;
             try{
                 ctx=new InitialContext();
                 ds=(DataSource)ctx.lookup("java:comp/env/jdbc/Project");
                 return ds.getConnection();
                }catch(SQLException e){
                                       throw e;
                          }catch(NamingException e)
                             {
                  throw e;
                             }
             } public Statement getStmt(){ 
                       try{
                       con=getCon();
                       stmt=con.createStatement();
                      }catch(Exception e){
                                          System.out.println("getStmt");
                                  System.out.println("e.getMessage()");
      
                                 }
                        return stmt;     
     
                      }
public Statement getStmtread(){
     
     
                           try{
                           con=getCon();
                           stmt=con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
                          }catch(Exception e){
                                              System.out.println("getStmtread");
                                              System.out.println("e.getMessage()");
                                         }
                            return stmt;
                          }
public ResultSet getRs(String sql){
    
                               try{
                                   stmt=this.getStmtread();
                               rs=stmt.executeQuery("select * from "+sql);
                               return rs;
                                  }catch(Exception e){
                                                  System.out.println("getRS");
                                          System.out.println("e.getMessage()");
                                         }                            return null;                               }
public void close(){
     
                 try{                  if(rs!=null)rs.close();                 }catch(Exception e){}              try{
    
                 if(stmt!=null)stmt.close();                     }catch(Exception e){}              try{
                 if(con!=null)con.close();
    } catch(Exception e){}
    {
                       System.out.println("close");
               System.out.println("e.getMessage()");
            }
     
                } }运行时显示如下错误：type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: Exception in JSP: /Test3.jsp:118: <jsp:useBean id="t" class="com.prodb.Test1" scope="page"/>
9: <%
10:   ResultSet rs=t.getRs("Test");
11:   while(rs.next())
12:      {out.print(rs.getInt(1)+"");
13:      out.print(rs.getString(2)+"<br>");
14:      }
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:504)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause java.lang.NullPointerException
org.apache.jsp.Test3_jsp._jspService(org.apache.jsp.Test3_jsp:62)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.15 logs.

解决方案 »

  1.   

    public ResultSet getRs(String sql){
        
                                   try{
                                       stmt=this.getStmtread();
                                   rs=stmt.executeQuery("select * from "+sql);
                                   return rs;
                                      }catch(Exception e){
                                                      System.out.println("getRS");
                                              System.out.println("e.getMessage()");
                                             }                            return null;                               }
    两个return…………
    还有，貌似stmt,rs,con之类的，最好在各自的方法里声明，不要通用
      

  2.   

    两个return没错啊，可能你没看清楚吧，第二个return是出错才返回的啊