以下是我的错误的地方(全部代码在附件里)
我引用的的方法原体是
public ResultSet executeQuery(String sql) throws Exception
{ try
{
Class.forName(driverClass);
conn=DriverManager.getConnection(url,username,password);
Statement stmt=conn.createStatement();
rs=stmt.executeQuery(sql);
}
catch(SQLException ex)
{
System.err.println("sql_data.executeQuery:"+ex.getMessage());
}
return rs;
}
具体实现的核心是
<%
Sql mysql=new Sql();
ResultSet rs=mysql.executeQuery("select sno from student");
while(rs.next()){
//out.println(""+rs.getInt(1)+""); } %>
出错信息如下
org.apache.jasper.JasperException: An exception occurred processing JSP page /MyJsp.jsp at line 27 24: <%
25: Sql mysql=new Sql();
26: mysql.executeQuery("select sno from student");
27: while(rs.next()){
28: //out.println(""+rs.getInt(1)+"");
29:
30: } %> 本人菜鸟,望各位大虾赐教!!
我引用的的方法原体是
public ResultSet executeQuery(String sql) throws Exception
{ try
{
Class.forName(driverClass);
conn=DriverManager.getConnection(url,username,password);
Statement stmt=conn.createStatement();
rs=stmt.executeQuery(sql);
}
catch(SQLException ex)
{
System.err.println("sql_data.executeQuery:"+ex.getMessage());
}
return rs;
}
具体实现的核心是
<%
Sql mysql=new Sql();
ResultSet rs=mysql.executeQuery("select sno from student");
while(rs.next()){
//out.println(""+rs.getInt(1)+""); } %>
出错信息如下
org.apache.jasper.JasperException: An exception occurred processing JSP page /MyJsp.jsp at line 27 24: <%
25: Sql mysql=new Sql();
26: mysql.executeQuery("select sno from student");
27: while(rs.next()){
28: //out.println(""+rs.getInt(1)+"");
29:
30: } %> 本人菜鸟,望各位大虾赐教!!
如果没有用户名和密码那么得不到connection,你的rs就没办法得到结果集了。
package com.fox;
import java.sql.*;public class Sql{
String driverClass="com.mysql.jdbc.Driver";
String url="jdbc:mysql://localhost:3306/student_course";
String username = "root";
String password = "";
Connection conn=null;
ResultSet rs=null; public Sql()
{
try{
Class.forName(driverClass);
}
catch(java.lang.ClassNotFoundException e)
{
System.err.println("sql_data():"+e.getMessage());
}
} public void executeInsert(String sql)
{
try
{
conn=DriverManager.getConnection(url,username,password);
Statement stmt=conn.createStatement();
stmt.execute(sql);
}
catch(SQLException ex)
{
System.err.println("sql_data.executeUpdate:"+ex.getMessage());
}
} public void executeupdate(String sql)
{
try
{
conn=DriverManager.getConnection(url,username,password);
Statement stmt=conn.createStatement();
stmt.executeUpdate(sql);
}
catch(SQLException ex)
{
System.err.println("sql_data.executeUpdate:"+ex.getMessage());
}
} public ResultSet executeQuery(String sql) throws Exception
{ try
{
Class.forName(driverClass);
conn=DriverManager.getConnection(url,username,password);
Statement stmt=conn.createStatement();
rs=stmt.executeQuery(sql);
}
catch(SQLException ex)
{
System.err.println("sql_data.executeQuery:"+ex.getMessage());
}
return rs;
} public void executeDelete(String sql)
{
try
{
conn=DriverManager.getConnection(url,username,password);
Statement stmt=conn.createStatement();
stmt.executeUpdate(sql);
}
catch(SQLException ex)
{
System.err.println("sql_data.executeDelete:"+ex.getMessage());
}
}
}