java servlet getparameter返回null

Question

I have a page that uses a servlet 我有一个使用servlet的页面

<!DOCTYPE html>
<!--
To change this license header, choose License Headers in Project Properties.
To change this template file, choose Tools | Templates
and open the template in the editor.
-->

<html>
    <head>
        <title>Estoque Online - Registro</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/materialize/0.97.1/css/materialize.min.css">
        <script src="https://cdnjs.cloudflare.com/ajax/libs/materialize/0.97.1/js/materialize.min.js"></script>
    </head>
    <body>
        <div>
            <FORM ACTION="ValidaRegistro" method="post">
            <label>
                <font size="6"> 
                Cadastro de Usuários
                </font>
            </label><br>
            <label for="Nome">
                <font size ="4">
                Nome
                </font>
            </label>
            <input autocomplete="on" type="Text" name="inNome" id="Nome"> 
            <label for="Email">
                <font size="4">
                Email
                </font>
            </label>
            <input autocomplete="on" type="Text" name="inEmail" id="Email"> 
            <label for="Senha">
                <font size="4">
                Senha
                </font>
            </label>
            <input  type="password" name="inSenha" id="Senha">    
            <label for="Tipo">
                <font size="4">
                Tipo
                </font>
            </label>
            <input  type="Text" name="inTipo" id="Tipo">  
            <input type="submit" id="Submeter" value="Submeter" class="btn waves-effect waves-light col s12">
            </FORM>
        </div>
    </body>
</html>

This is the page 这是页面

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

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 javax.swing.JOptionPane;
import java.sql.*;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.annotation.WebServlet;

/**
 *
 * @author Rafael
 */
/**
 *
 * @author Rafael
 */

public class ValidaRegistro extends HttpServlet {


    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        try (PrintWriter out = response.getWriter()) {
            /* TODO output your page here. You may use following sample code. */
            out.println("<!DOCTYPE html>");
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet ValidaRegistro</title>");            
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet ValidaRegistro at " + request.getContextPath() + "</h1>");
            out.println("</body>");
            out.println("</html>");
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String Nome = (String)request.getParameter("Nome");
        String Email =(String)request.getParameter("Email");
        String Senha =(String)request.getParameter("Senha");
        int Tipo = Integer.parseInt(request.getParameter("Tipo"));
        DAO.main(null); 

        try {
            Inserir(Nome,Email,Senha,Tipo);
        } catch (SQLException ex) {
            Logger.getLogger(ValidaRegistro.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

    public void Inserir(String Nome,String Email,String Senha,int Tipo) throws SQLException{
      DAO.Inserir(Nome,Email,Senha,Tipo);
    }
}

And this is the servlet, but in doPost Method request.getParameters always return null and i don't know why. 这是servlet，但是在doPost方法中request.getParameters总是返回null，我不知道为什么。 I tried to change to request.getAtributes but the result is the same. 我尝试将其更改为request.getAtributes，但结果相同。

Please help me. 请帮我。

Answer 1

Hi can you try the below 嗨，你可以尝试以下

    String Nome = (String)request.getParameter("inNome");
    String Email =(String)request.getParameter("inEmail");
    String Senha =(String)request.getParameter("inSenha");
    int Tipo = Integer.parseInt(request.getParameter("inTipo"));

Answer 2

Form parameters are identified by name, not by ID. 表单参数是通过名称而不是ID标识的。 You should use the same value for both name and ID and in the getParameter() method. 您应在name和ID以及getParameter()方法中使用相同的值。

java servlet getparameter返回null

问题描述

2 个解决方案

解决方案1
1 2016-03-06 01:17:59

解决方案2
0 2016-03-06 01:46:16

java servlet getparameter返回null

问题描述

2 个解决方案

解决方案1 1 2016-03-06 01:17:59

解决方案2 0 2016-03-06 01:46:16

解决方案1
1 2016-03-06 01:17:59

解决方案2
0 2016-03-06 01:46:16