Servlet字符串异常

我为一个在线表单创建了一个Servlet，每次我尝试提交在线表单时，它都会给我以下异常：java.lang.NumberFormatException：对于输入字符串：“”。问题是我的jsp文件中没有任何字符串变量。还有一件事：当我尝试填写在线表单中的所有字段时，信息会发送到数据库，但是当我只用其中的一些尝试时，它会再次给我这种异常。这是我的代码：Servlet字符串异常

import java.io.IOException; 
import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.ResultSet; 
import java.sql.Statement; 
import java.util.ArrayList; 

import javax.servlet.RequestDispatcher; 
import javax.servlet.ServletContext; 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 

import database.databases; 

/** 
* Servlet implementation class feildsSERVLET 
*/ 
public class feildsSERVLET extends HttpServlet 
{ 
    private static final long serialVersionUID = 1L; 

    /** 
    * @see HttpServlet#HttpServlet() 
    */ 
    public feildsSERVLET() 
    { 
     super(); 
     // TODO Auto-generated constructor stub 
    } 

    /** 
    * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse 
    *  response) 
    */ 
    protected void doGet(HttpServletRequest request, HttpServletResponse response) 
     throws ServletException, IOException 
    { 
     try 
     { 
     Class.forName("com.mysql.jdbc.Driver"); 
     Connection connection = DriverManager.getConnection(
       "jdbc:mysql://localhost:3306/WhizzoChocolate", "root", ""); 
     try 
     { 
      /* 
      * int customerID = Integer.parseInt(request 
      * .getParameter("customerID")); 
      */ 
      int frog = Integer.parseInt(request.getParameter("frog")); 

      int redspring = Integer.parseInt(request.getParameter("redspring")); 
      int bluespring = Integer.parseInt(request 
        .getParameter("bluespring")); 
      int silverspring = Integer.parseInt(request 
        .getParameter("silverspring")); 

      int ramsquare = Integer.parseInt(request.getParameter("ramsquare")); 
      int ramoval = Integer.parseInt(request.getParameter("ramoval")); 
      int ramhex = Integer.parseInt(request.getParameter("ramhex")); 
      int rambutt = Integer.parseInt(request.getParameter("rambutt")); 

      int product_id = Integer.parseInt(request 
        .getParameter("product_id")); 
      Statement statement = connection.createStatement(); 

      int upd = statement 
        .executeUpdate("INSERT INTO `product`(`product_id`, `RWA`, `BWA`,`SWA`, `OSA`,`SSA`,`HSA`,`BSA`)" 
         + "VALUES" + "(" + product_id 
         + frog 

         + ", " 

         + redspring 

         + ", " 

         + bluespring 

         + ", " 

         + silverspring 

         + ", " 

         + ramoval 

         + ", " 

         + ramsquare 

         + ", " 

         + ramhex 

         + ", " + rambutt + ")"); 

      request.setAttribute("product_id", product_id); 
      request.setAttribute("frog", frog); 

      request.setAttribute("redspring", redspring); 
      request.setAttribute("bluespring", bluespring); 
      request.setAttribute("silverspring", silverspring); 

      request.setAttribute("ramsquare", ramsquare); 
      request.setAttribute("ramoval", ramoval); 
      request.setAttribute("ramhex", ramhex); 
      request.setAttribute("rambutt", rambutt); 

     } 
     finally 
     { 
      connection.close(); 

     } 
     } 
     catch (Exception e) 
     { 
     throw new ServletException(e); 
     } 

     ServletContext context = getServletContext(); 
     RequestDispatcher dispatcher = context 
      .getRequestDispatcher("/feildsjsp.jsp"); 
     dispatcher.forward(request, response); 
    } 

    /** 
    * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse 
    *  response) 
    */ 
    protected void doPost(HttpServletRequest request, 
     HttpServletResponse response) throws ServletException, IOException 
    { 
     // TODO Auto-generated method stub 
    } 

}

来源

2011-12-10 user1087920

每当你有'用request.getParameter（“XXX”）'你有一个字符串。 –

我猜想，这个问题是从类似这些线路中的一个来此一：

int redspring = Integer.parseInt(request.getParameter("redspring"));

如果request.getParameter("redspring")值是一个空字符串，它会给你这个例外。

来源

2011-12-10 21:13:26

根据documantation：

第一个参数是空值或零长度的字符串：

NumberFormatException类型的异常，如果发生任何的以下情况被抛出。

可能当你不把所有的参数，你解析空字符串

来源

2011-12-10 21:17:04

Servlet字符串异常

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