javax.el.PropertyNotFoundException：プロパティ 'id'が型model.Groceryに見つかりません

Question

データベース内のデータを更新、編集、削除、挿入できるページを作成しています。挿入ページは正常に動作し、データは正常に挿入されますが、「追加」ボタンをクリックすると、AllGroceryページにリダイレクトされませんが、Eclipse.Panによってこのエラーが発生します。問題がどこにあるか把握できません。誰も私を助けますか？データベース：GroceryStore、表：grocerys（ID、名前、価格）

DataAccess.java

package dao; 
import java.sql.PreparedStatement; 
import java.sql.ResultSet; 
import java.sql.SQLException; 
import java.util.LinkedList; 
import java.util.List; 

import com.sun.istack.internal.logging.Logger; 

import db.DBUtils; 
import model.Grocery; 

public class DataAccess { 

    public void addNew(Grocery g) throws ClassNotFoundException, SQLException{ 
     try { 
     PreparedStatement ps = DBUtils.getPreparedStatement("insert into grocerys values(?,?,?)"); 
     ps.setInt(1, g.getID()); 
     ps.setString(2, g.getName()); 
     ps.setDouble(3, g.getPrice()); 

     ps.executeUpdate(); 

     } catch(ClassNotFoundException | SQLException ex){ 

     } 
    } 

    public static List<Grocery> getAll(){ 
     List<Grocery> gs = new LinkedList<>(); 

     try { 
      ResultSet rs = DBUtils.getPreparedStatement("select * from grocerys").executeQuery(); 

      while (rs.next()){ 
       Grocery g = new Grocery(); 
       g.setID(rs.getInt(1)); 
       g.setName(rs.getString(2)); 
       g.setPrice(rs.getDouble(3)); 

       gs.add(g); 
      } 

     } catch (ClassNotFoundException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } catch (SQLException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 

     return gs; 
    } 
} 

DBUtils.java

package db; 

import java.sql.DriverManager; 
import java.sql.PreparedStatement; 
import java.sql.Connection; 
import java.sql.SQLException; 

public class DBUtils { 

    public static PreparedStatement getPreparedStatement(String sql) throws ClassNotFoundException, SQLException{ 

     PreparedStatement ps = null; 

     Class.forName("com.mysql.jdbc.Driver"); 

     String url = "jdbc:mysql://localhost:3306/GroceryStore"; 
     String user = "root"; 
     String pass = "adil"; 

     Connection conn = DriverManager.getConnection(url,user,pass); 

     ps = conn.prepareStatement(sql); 


     return ps; 

    } 

    public static void main(String[] args)throws ClassNotFoundException, SQLException { 

     getPreparedStatement("select * from grocerys"); 

    } 

} 

Grocery.java

package model; 

public class Grocery { 

    private int id; 
    private String name; 
    private Double price; 

    public void setID(int id_){ 
     id = id_; 
    } 

    public void setName(String name_){ 
     name = name_; 
    } 

    public void setPrice(Double price_){ 
     price = price_; 
    } 

    public int getID(){ 
     return id; 
    } 

    public String getName(){ 
     return name; 
    } 

    public Double getPrice(){ 
     return price; 
    } 

} 

AllGrocery。 java

package servlet; 

import java.io.IOException; 

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

import dao.DataAccess; 

/** 
* Servlet implementation class AllGrocery 
*/ 
@WebServlet("/AllGrocery") 
public class AllGrocery extends HttpServlet { 
    private static final long serialVersionUID = 1L; 

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

    /** 
    * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) 
    */ 
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 

     request.setAttribute("AllGrocery", DataAccess.getAll()); 

     RequestDispatcher rd = request.getRequestDispatcher("AllGrocery.jsp"); 

     rd.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 
    } 

} 


     public Double getPrice(){ 
      return price; 
     } 

    } 

AddNew.html

<!DOCTYPE html> 
<html> 
<head> 
<meta charset="ISO-8859-1"> 
<title>Add Grocery</title> 
</head> 
<body> 

<h1>Add New Grocery</h1> 
<form action = "ManagerAddNew.jsp" method = "post"> 
<table> 

<tr> 
<th>ID</th> 
<td><input type = "number" name = "id" style = "width : 200px;"/></td> 
</tr> 

<tr> 
<th>NAME</th> 
<td><input type = "text" name = "name" style = "width : 200px;"/></td> 
</tr> 


<tr> 
<th>PRICE</th> 
<td><input type = "number" name = "price" style = "width : 200px;"/></td> 
</tr> 


<tr> 
<th></th> 
<td><input type = "submit" name = "submit" value = "ADD"/></td> 
</tr> 

</table> 
</form> 

</body> 
</html> 

AllGrocery.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" 
    pageEncoding="ISO-8859-1"%> 

    <%@ taglib prefix = "c" uri = "http://java.sun.com/jsp/jstl/core" %> 

<!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=ISO-8859-1"> 
<title>Grocerys Available</title> 
</head> 
<body> 

<div syle = "width : 1200px; margin-left:auto;margin-right:auto;"> 

<table cellpadding = "10"> 

<tr> 

<th>ID</th> 
<th>Name</th> 
<th>Price</th> 

</tr> 

<c:forEach items = "${AllGrocery}" var = "p"> 

<tr> 
<td>${p.id}</td> 
<td>${p.name}</td> 
<td>${p.price}</td> 
<td> 

<a href = "edit?id = ${p.id}">Edit</a> 
<a href = "delete?id = ${p.id}">Delete</a> 

</td> 
</tr> 


</c:forEach> 

</table> 

</div> 

</body> 
</html> 

ManagerAddNew.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" 
    pageEncoding="ISO-8859-1"%> 

    <%@ page import = "model.Grocery" %> 
    <%@ page import = "dao.DataAccess" %> 

<!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=ISO-8859-1"> 
<title>Insert title here</title> 
</head> 
<body> 

<% 

String name = request.getParameter("name"); 
int id = Integer.parseInt(request.getParameter("id")); 
Double price = Double.parseDouble(request.getParameter("price")); 

Grocery g = new Grocery(); 
g.setID(id); 
g.setName(name); 
g.setPrice(price); 

DataAccess da = new DataAccess(); 

da.addNew(g); 

response.sendRedirect("/SimpleServletProject/AllGrocery"); 

%> 

</body> 
</html> 

エラー：

org.apache.jasper.JasperException: An exception occurred processing JSP page /AllGrocery.jsp at line 29 

26: <c:forEach items = "${AllGrocery}" var = "p"> 
27: 
28: <tr> 
29: <td>${p.id}</td> 
30: <td>${p.name}</td> 
31: <td>${p.price}</td> 
32: <td> 


Stacktrace: 
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:575) 
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477) 
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) 
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:731) 
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 
    servlet.AllGrocery.doGet(AllGrocery.java:38) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:624) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:731) 
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 


root cause 

javax.el.PropertyNotFoundException: Property 'id' not found on type model.Grocery 
    javax.el.BeanELResolver$BeanProperties.get(BeanELResolver.java:290) 
    javax.el.BeanELResolver$BeanProperties.access$300(BeanELResolver.java:243) 
    javax.el.BeanELResolver.property(BeanELResolver.java:377) 
    javax.el.BeanELResolver.getValue(BeanELResolver.java:97) 
    org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:104) 
    org.apache.el.parser.AstValue.getValue(AstValue.java:184) 
    org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:184) 
    org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:950) 
    org.apache.jsp.AllGrocery_jsp._jspx_meth_c_005fout_005f0(AllGrocery_jsp.java:215) 
    org.apache.jsp.AllGrocery_jsp._jspx_meth_c_005fforEach_005f0(AllGrocery_jsp.java:163) 
    org.apache.jsp.AllGrocery_jsp._jspService(AllGrocery_jsp.java:113) 
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:731) 
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:439) 
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) 
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:731) 
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 
    servlet.AllGrocery.doGet(AllGrocery.java:38) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:624) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:731) 
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 

Answer 1

に変更する必要があります。 idのgetterメソッド名はgetId（）に変更する必要があり、getID（）ではありません。あなたがcamelCaseを使うときに変数の最初の文字を変数全体ではなく大文字に変更するだけなので、getId（）でなければなりません。

Answer 2

あなたのJava Bean Groceryは、Bean標準に準拠していません。 JavaBeans Conventions

IDEを使用している場合は、いつでも右クリックしてGenerate Getters and Settersをクリックすることができます。ほとんどのIDEは、生成するための機能を提供します。

コードの追加提案はほとんどありません。

<c:forEach items = "${AllGrocery}" var = "p"> 

あなたは例外が表示された場合、食料品のオブジェクトのプロパティIDを見つけることができない

<c:forEach items = "${requestScope.AllGrocery}" var = "p"> 

と

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 

      request.setAttribute("AllGrocery", DataAccess.getAll()); 

      RequestDispatcher rd = getServletContext().getRequestDispatcher("/AllGrocery.jsp"); 

      rd.forward(request, response); 
    }