Java 无法使用JSP/DAO/Servlet更新表_Java_Jsp_Servlets_Dao

Java 无法使用JSP/DAO/Servlet更新表

java jsp servlets

Java 无法使用JSP/DAO/Servlet更新表,java,jsp,servlets,dao,Java,Jsp,Servlets,Dao,您好，我正在尝试创建一个页面来更新数据库表中的一行，我正在使用DAO/Servlet和JSP页面 DAO代码： public static AnimalUpdateBean updateAnimal(AnimalUpdateBean bean) { //preparing some objects for connection PreparedStatement up = null; Statement stmt = null;

您好，我正在尝试创建一个页面来更新数据库表中的一行，我正在使用DAO/Servlet和JSP页面

DAO代码：

public static AnimalUpdateBean updateAnimal(AnimalUpdateBean bean) {

          //preparing some objects for connection 
        PreparedStatement up = null;   
        Statement stmt = null;    

          String id = bean.getAnimalId();
          String aname = bean.getAnimalName();
          String dob = bean.getAnimalDob();  
          String gender = bean.getAnimalGender();  
          String breedid = bean.getAnimalBreed();  
          String remark = bean.getAnimalRemark();
          try 
           { 
            //connect to DB 
              currentCon = dbConnection.getConnection();

              up = currentCon.prepareStatement("update animal set aname = '"+aname+"' , gender = '"+gender+"', specie_id = '"
                      +breedid+"' , remark = '"+remark+"' where animal_id = '"+id+"'");

              up.executeUpdate();

              if (up.executeUpdate()>=1){
                  stmt=currentCon.createStatement();
                  rs = stmt.executeQuery("select aname , dob, gender, specie_id , remark from animal where animal_id = '"+id+"'");
              }


          System.out.println("done");
       }


       catch (Exception ex) 
       {
          System.out.println("Log In failed: An Exception has occurred! " + ex);
       } 

       //some exception handling
       finally 
       {
          if (rs != null)   {try {rs.close();} catch (Exception e) {} rs = null;}

          if (stmt != null) {try {stmt.close();} catch (Exception e) {}stmt = null;}

          if (currentCon != null) {try {currentCon.close();} catch (Exception e) {}currentCon = null;}
       }

    return bean;

       }    
   }

UpdateAnimal.jsp代码：

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> 
<%@ page import="java.util.ArrayList" %>
<%@page import="content.*"%>
<%@page import="java.sql.*"%>
<%@page import="java.util.*"%>
<%@ page session="true"%>
<%@page import="java.io.*"%>
<%@page import="java.net.*"%>
<%@page import="javax.servlet.*"%>
<%@ page language="java" 
         contentType="text/html; charset=windows-1256"
         pageEncoding="windows-1256" %>


<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1256">
<title>Update Animal</title>
<link rel="stylesheet"
      href="./css/styles.css"
      type="text/css"/>
</head>
<body>
<table class="title">
  <tr><th>Zoo keeper</th></tr>
</table>


<h1>Update Animal</h1>

<form action="Relay" >
<fieldset>
Animal new name: <input type= "text" name = "aname"><br>
Animal new DOB: <input type= "text" name = "dob"><br>

<br>
Animal new gender: 
<select name="gender" id="gender">
<option value="male">Male</option>
<option value="female">Female</option>
</select>
<br>

Animal new Breed: <input type= "text" name = "breedid" ><br>
Animal new remarks: <textarea name = "remark" rows="4" cols="20">

</textarea> <br /> <br/>


<input type="submit" value="submit">
<input type="hidden" name="animal_id" value="<%= request.getParameter("animal_id") %>">
<input type="hidden" name="command" value="UpdateAnimalServlet" > 

</fieldset>
</form>
</body></html>

负责启动更新的servlet是UpdateAnimalServlet：

package content;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class LoginServlet
 */
public class UpdateAnimalServlet extends HttpServlet {


public void doGet(HttpServletRequest request, HttpServletResponse response) 
                       throws ServletException, java.io.IOException {

try
{       

     AnimalUpdateBean animal = new AnimalUpdateBean();
     animal.setAnimalId(request.getParameter("animal_id"));
     animal.setAnimalName(request.getParameter("aname"));
 //    animal.setAnimalDob(request.getParameter("dob"));
     animal.setAnimalGender(request.getParameter("gender"));
     animal.setAnimalBreed(request.getParameter("breedid"));
     animal.setAnimalRemark(request.getParameter("remark"));
     String test = request.getParameter("animal_id");
     System.out.println(test);
     System.out.println(animal);

     animal = DAO.updateAnimal(animal);


          response.sendRedirect("/oosd/member.jsp"); 


} 


catch (Throwable theException)      
{
     System.out.println(theException); 
}
       }
    }

我正在使用一个调用AnimalUpdateServlet执行的中继servlet：

package content;

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

/**
 * Servlet implementation class LoginServlet
 */
public class Relay extends HttpServlet {


public void doGet(HttpServletRequest request, HttpServletResponse response) 
                       throws ServletException, java.io.IOException {

    try
    {       



        String command = request.getParameter("command");  
        if (command.equals("LoginServlet")){ 
            RequestDispatcher rd =request.getRequestDispatcher("/"+command);
            rd.forward(request, response);
            //for testing 
            System.out.println("Request forwarded to " + command + " servlet"); 
        } else if (command.equals("UpdateAnimalServlet")){ 
            RequestDispatcher rd =request.getRequestDispatcher("/"+command);
            rd.forward(request, response);
            //for testing 
            System.out.println("Request forwarded to " + command + " servlet"); 
        } 

        else 
            System.out.println("=> command='" + command + "'");  
            String url = "/oosd/" + command;     
            String encodedUrl = response.encodeRedirectURL(url);   
            System.out.println("   url=" + url);    
            System.out.println("   encodedUrl=" + encodedUrl);  
            response.sendRedirect(encodedUrl);



    } 


    catch (Throwable theException)      
    {
         System.out.println(theException); 
    }
           }
        }


and last thing is the web.xml page:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:javaee="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

  <servlet>
    <servlet-name>LoginServlet</servlet-name>
    <servlet-class>content.LoginServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>UpdateAnimalServlet</servlet-name>
    <servlet-class>content.UpdateAnimalServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>SelectAnimalServlet</servlet-name>
    <servlet-class>content.SelectAnimalServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>Relay</servlet-name>
    <servlet-class>content.Relay</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>SelectAnimalServlet</servlet-name>
    <url-pattern>/SelectAnimalServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>UpdateAnimalServlet</servlet-name>
    <url-pattern>/UpdateAnimalServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/LoginServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>Relay</servlet-name>
    <url-pattern>/Relay</url-pattern>
  </servlet-mapping>
</web-app>

知道我的错误在哪里吗？

因为specie_id是一个数字，这就是抛出的异常所声明的“条件表达式中的数据类型不匹配”。由于此异常，sendRedirect错误正在发生，因为SQLException数据已写入响应。您的查询应该类似于

  "update animal set aname = '"+aname+"' , gender = '"+gender+"', specie_id = "
                  +Integer.parseInt(breedid)+" , remark = '"+remark+"' where animal_id = '"+id+"'"

如果animal_id也是一个数字，则需要执行相同的操作。

当您已经将数据写入响应（如转发，或直接写入JSP编写器）然后尝试重定向时，会发生

发送重定向

错误

SQL错误可能是因为您在SQL中使用了字符串ID（用单引号括起来），而DB中的ID很可能定义为整数

另外，在更新动物后，您可以执行查询，但对结果不做任何处理。

主题外，但如果您没有编写任何scriptlet代码（您不是，也不应该是），则JSP中不需要任何这些导入指令。您能提供动物表的模式吗？您到底想要什么？因为访问生成的shcema是sorta HUGECA，所以您可以在调试器中检查在db上执行的更新查询是什么？尝试通过sqldeveloper/SQL+或任何其他GUI工具执行该查询，如果该工具不起作用，请使用该工具修复查询和相应的代码。我删除了值周围的单个QOUTS，现在得到的java.SQL.SQLException:[Microsoft][ODBC Microsoft Access Driver]参数太少。预期为2。您必须仅删除DBi中数字字段的单引号。我删除了值周围的单引号，现在我得到的java.sql.SQLException:[Microsoft][ODBC Microsoft Access Driver]参数太少。预期为2。它现在已更新。我只需要删除java.lang.IllegalStateException:在提交响应后无法调用sendRedirect（）error@user1031152代码太多了，我无法通过。有东西正在写入响应，或者是通过转发（比如JSP）或者是直接写入输出流。一旦发生这种情况，就不能发送重定向。

package content;

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

/**
 * Servlet implementation class LoginServlet
 */
public class Relay extends HttpServlet {


public void doGet(HttpServletRequest request, HttpServletResponse response) 
                       throws ServletException, java.io.IOException {

    try
    {       



        String command = request.getParameter("command");  
        if (command.equals("LoginServlet")){ 
            RequestDispatcher rd =request.getRequestDispatcher("/"+command);
            rd.forward(request, response);
            //for testing 
            System.out.println("Request forwarded to " + command + " servlet"); 
        } else if (command.equals("UpdateAnimalServlet")){ 
            RequestDispatcher rd =request.getRequestDispatcher("/"+command);
            rd.forward(request, response);
            //for testing 
            System.out.println("Request forwarded to " + command + " servlet"); 
        } 

        else 
            System.out.println("=> command='" + command + "'");  
            String url = "/oosd/" + command;     
            String encodedUrl = response.encodeRedirectURL(url);   
            System.out.println("   url=" + url);    
            System.out.println("   encodedUrl=" + encodedUrl);  
            response.sendRedirect(encodedUrl);



    } 


    catch (Throwable theException)      
    {
         System.out.println(theException); 
    }
           }
        }


and last thing is the web.xml page:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:javaee="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

  <servlet>
    <servlet-name>LoginServlet</servlet-name>
    <servlet-class>content.LoginServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>UpdateAnimalServlet</servlet-name>
    <servlet-class>content.UpdateAnimalServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>SelectAnimalServlet</servlet-name>
    <servlet-class>content.SelectAnimalServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>Relay</servlet-name>
    <servlet-class>content.Relay</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>SelectAnimalServlet</servlet-name>
    <url-pattern>/SelectAnimalServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>UpdateAnimalServlet</servlet-name>
    <url-pattern>/UpdateAnimalServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/LoginServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>Relay</servlet-name>
    <url-pattern>/Relay</url-pattern>
  </servlet-mapping>
</web-app>

package content;


import java.sql.*;


public class dbConnection {

   static Connection con;
   static String url;

   public static Connection getConnection()
   {

      try
      {
         String url = "jdbc:odbc:oosd"; 
         // assuming "DataSource" is your DataSource name

         Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");

         try
         {              
            con = DriverManager.getConnection(url,"",""); 

         // assuming your SQL Server's  username is "username"               
         // and password is "password"

         }

         catch (SQLException ex)
         {
            ex.printStackTrace();
         }
      }

      catch(ClassNotFoundException e)
      {
         System.out.println(e);
      }

   return con;
}
}

  "update animal set aname = '"+aname+"' , gender = '"+gender+"', specie_id = "
                  +Integer.parseInt(breedid)+" , remark = '"+remark+"' where animal_id = '"+id+"'"