Question

在插入之前，我需要帮助将数据检入数据库。

问题：

我已经使用通用方法将值插入到数据库中。但是我需要将这个条件包含到我的servlet代码中，即如果数据已经存在于数据库中，那么该数据不应该插入到数据库中剩下的数据应该插入到数据库中。这样做时不应该向用户发出警报。

这是我的代码。

products.jsp

<%@page import="java.util.List"%>
    <%@page import="web.Products"%>
    <%@page import="java.util.ArrayList"%>
    <%@page contentType="text/html" pageEncoding="UTF-8"%>
    <!DOCTYPE html>
    <html>
     <form method="post" action="Save_Products">   
<b>          
            Brand Name:<font color="green">
            <% String brand_name=(String)session.getAttribute("brand_name");
       out.print(brand_name);%> 
        <c:set var="brand_name" value="brand_name" scope="session"  />
       </font></b>         
            <table>            
                <tr>                
                    <th> Products</th> 
                    <th> Description </th>
                </tr>
                <tr>
               <td> <b><%
      List<Products> pdts = (List<Products>) request.getAttribute("list");
      if(pdts!=null){
        for(Products prod: pdts){
           out.println("<input type=\"checkbox\" name=\"prod\" value=\""  + prod.getProductname() + "\">"  + prod.getProductname()+"<br>");
            } %> </b></td>   

            <td><%for(Products prod: pdts){
            out.println("<input type=\"text\" name=\"desc\" style=\"width:50px; height:22px\"/><br/>"); 
        } 

      }  
            %> </td>  

        </tr>
        <br/>
        <br/>
        <tr><td align="center">  <input type="submit" value="Save" name="save"/> </td></tr> 
            </table>
    </form>
    </body>
    </html>

Servlet代码

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.sql.*;
import javax.servlet.RequestDispatcher;
import javax.servlet.http.HttpSession;


public class Save_Products extends HttpServlet {
 static final String dbURL = "jdbc:mysql://localhost:3306/pdt";
     static final String dbUser = "root";
     static final String dbPass = "root";
    @Override
     public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
         response.setContentType("text/html;charset=UTF-8");    
        PrintWriter out = response.getWriter();
            ResultSet rs=null;
            Connection connection = null;  
            try{
      HttpSession session = request.getSession();
    String brand_name =(String) session.getAttribute("brand_name");
String [] prod_list = request.getParameterValues("prod");
String [] desc_list = request.getParameterValues("desc");
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection (dbURL,dbUser,dbPass);

String sql="insert into pdt_list(brand_name,product_name,desc)values(?,?,?)";
PreparedStatement prep = connection.prepareStatement(sql); 
int num_values = Math.min(prod_list.size(), desc_list.size());

int count_updated = 0;
for(int i = 0; i < num_values; i++){
    prep.setString(1, brand_name);
    prep.setString(2, prod_list[i]);
    prep.setString(3,desc_list[i]);
    count_updated += prep.executeUpdate();
}
if(count_updated>0)
{    
   out.print("Products Saved Successfully...");
 RequestDispatcher rd=request.getRequestDispatcher("Save_Success.jsp");    
            rd.forward(request,response);    
}
else{
    RequestDispatcher rd=request.getRequestDispatcher("Save_Failure.jsp");    
            rd.forward(request,response);   
}

prep.close();
       }
     catch(Exception E){
//Any Exceptions will be caught here
System.out.println("The error is"+E.getMessage());

    }  

        finally {
            try {
                connection.close();
            } 
        catch (Exception ex) {
                System.out.println("The error is"+ex.getMessage());
            }
                }

}

}

插入前将数据检入数据库

0 个答案: