//import ShoppingCart;
import dbSql;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.lang.Float;
import java.sql.*;

public class AddToCart extends HttpServlet{

  
   public void doGet(HttpServletRequest request,HttpServletResponse response)
   {
  
      try{
          String id=request.getParameter("productid");
         dbSql dbc = new dbSql();
 String sql = "select * from product where productid="+id;
 ResultSet products = dbc.executeQuery(sql);
 if(products.next())
 {
  String desc=products.getString("disc");
  float price=products.getFloat("price");
  String name=products.getString("productname");
 
  int quantity=1;
  products.close();
                dbc.closeStmt();
                dbc.closeConn();
              
  String[] item={id,name,desc,Float.toString(price),Integer.toString(quantity)};


      
          HttpSession session=request.getSession(true);
      
         Vector cart=(Vector)session.getAttribute("cart");
         if(cart==null)
         {
            cart=new Vector();
         
         }
         cart.addElement(item);
         
         session.setAttribute("cart",cart);
         getServletConfig().getServletContext().getRequestDispatcher("/listshoppingcart.jsp").forward(request,response);
     
    
      }
     else{
      products.close();
                dbc.closeStmt();
                dbc.closeConn();
         
     getServletConfig().getServletContext().getRequestDispatcher("/login.jsp").forward(request,response);

     }
      
        
           
      }
       catch(SQLException se) { 
      System.err.println("aq.executeQuery: " + se.getMessage());
    }  
     }  
}


编译时就出现下面的错误：

E:javaworkmyjspweb-infclasses>javac AddToCart.java
AddToCart.java:46: unreported exception javax.servlet.ServletException; must be
caught or declared to be thrown
         getServletConfig().getServletContext().getRequestDispatcher("/listshop
ingcart.jsp").forward(request,response);
                         ^
AddToCart.java:55: unreported exception javax.servlet.ServletException; must be
caught or declared to be thrown
     getServletConfig().getServletContext().getRequestDispatcher("/login.jsp").
orward(request,response);
                     ^

只要将catch(SQLException  se)改成catch(Exception  se)就可以了！ 
至少编译可以通过，但你的程序的具体运行可以再自己调试一下！