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javax.el.E​​LException：讀取Person類型的[name]時出錯

[英]javax.el.ELException: Error reading [name] on type Person

 原文  2017-10-15 14:32:52  1   1    java/ spring/ jsp/ spring-mvc

問題描述

我使用hibenate和spring mvc編寫了一個程序，但是當我執行編輯功能時會拋出錯誤。 

Type Exception Report

Message An exception occurred processing JSP page [/WEB-INF/views/person.jsp] at line [24]

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception

org.apache.jasper.JasperException: An exception occurred processing JSP page [/WEB-INF/views/person.jsp] at line [24]

21: 
22: <form:form action="${addAction}" commandName="person">
23:     <table>
24:         <c:if test="${!empty person.name}">
25:             <tr>
26:                 <td>
27:                     <form:label path="id">


Stacktrace:
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:584)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:481)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168)
    org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
    org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1257)
    org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1037)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:980)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

Root Cause

javax.el.ELException: Error reading [name] on type [com.baotrung.entity.Person_$$_jvsta7c_0]
    javax.el.BeanELResolver.getValue(BeanELResolver.java:98)
    org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:110)
    org.apache.el.parser.AstValue.getValue(AstValue.java:169)
    org.apache.el.parser.AstEmpty.getValue(AstEmpty.java:46)
    org.apache.el.parser.AstNot.getValue(AstNot.java:43)
    org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:184)
    org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:944)
    org.apache.jsp.WEB_002dINF.views.person_jsp._jspx_meth_c_005fif_005f0(person_jsp.java:325)
    org.apache.jsp.WEB_002dINF.views.person_jsp._jspx_meth_form_005fform_005f0(person_jsp.java:247)
    org.apache.jsp.WEB_002dINF.views.person_jsp._jspService(person_jsp.java:170)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168)
    org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
    org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1257)
    org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1037)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:980)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

Root Cause

org.hibernate.LazyInitializationException: could not initialize proxy - no Session
    org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:147)
    org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:260)
    org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:68)
    com.baotrung.entity.Person_$$_jvsta7c_0.getName(Person_$$_jvsta7c_0.java)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    javax.el.BeanELResolver.getValue(BeanELResolver.java:94)
    org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:110)
    org.apache.el.parser.AstValue.getValue(AstValue.java:169)
    org.apache.el.parser.AstEmpty.getValue(AstEmpty.java:46)
    org.apache.el.parser.AstNot.getValue(AstNot.java:43)
    org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:184)
    org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:944)
    org.apache.jsp.WEB_002dINF.views.person_jsp._jspx_meth_c_005fif_005f0(person_jsp.java:325)
    org.apache.jsp.WEB_002dINF.views.person_jsp._jspx_meth_form_005fform_005f0(person_jsp.java:247)
    org.apache.jsp.WEB_002dINF.views.person_jsp._jspService(person_jsp.java:170)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168)
    org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
    org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1257)
    org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1037)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:980)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

人物實體 

package com.baotrung.entity;

import javax.persistence.*;

@Entity
@Table(name = "PERSON")
public class Person {
    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String name;
    private String country;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

    @Override
    public String toString() {
        return "Person{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", country='" + country + '\'' +
                '}';
    }
}

控制器類 

package com.baotrung.controller;

import com.baotrung.entity.Person;
import com.baotrung.services.PersonService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class PersonController {

    private PersonService personService;

    @Autowired(required = true)

    public void setPersonService(PersonService personService) {
        this.personService = personService;
    }

    @RequestMapping(value ="/persons",method = RequestMethod.GET)
    public String listPersons(Model model){
        model.addAttribute("person",new Person());
        model.addAttribute("listPersons",this.personService.listPerson());
        return "person";
    }

    @RequestMapping(value ="/person/add",method = RequestMethod.POST)
    public String addPerson(@ModelAttribute("person")Person p){
        if(p.getId()==0){
            this.personService.addPerson(p);
        }else{
            this.personService.updatePerson(p);
        }
        return "redirect:/persons";
    }
    @RequestMapping("/edit/{id}")
    public String editPerson(@PathVariable("id")int id,Model model){
        model.addAttribute("person",this.personService.getPersonById(id));
        model.addAttribute("listPersons",this.personService.listPerson());
        return "person";
    }
    @RequestMapping("/remove/{id}")
    public String removePerson(@PathVariable("id")int id){
        this.personService.removePerson(id);
        return "redirect:/persons";
    }

}

人道 

package com.baotrung.dao;

import com.baotrung.entity.Person;
import org.hibernate.Session;
import org.hibernate.SessionFactory;


import java.util.List;



public class PersonDAOImpl implements PersonDAO {
    private SessionFactory sessionFactory;

    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }

    @Override
    public void addPerson(Person p) {
        Session session = this.sessionFactory.getCurrentSession();
        session.persist(p);

    }

    @Override
    public void updatePerson(Person p) {
        Session session = this.sessionFactory.getCurrentSession();
        session.update(p);

    }
    @SuppressWarnings("unchecked")
    @Override
    public List<Person> listPerson() {
        Session session = this.sessionFactory.getCurrentSession();
        List<Person> personList = session.createQuery("from Person").list();
        return personList;
    }

    @Override
    public Person getPersonById(int id) {
        Session session = this.sessionFactory.getCurrentSession();
        Person p = (Person) session.load(Person.class,new Integer(id));
        return p;
    }

    @Override
    public void removePerson(int id) {
        Session session = this.sessionFactory.getCurrentSession();
        Person p = (Person)session.load(Person.class,new Integer(id));
        if(null!=p){
            session.delete(p);
        }
    }
}

人事服務 

package com.baotrung.services;

import com.baotrung.dao.PersonDAO;
import com.baotrung.entity.Person;
import org.springframework.transaction.annotation.Transactional;


import java.util.List;

public class PersonServiceImpl implements PersonService {
    private PersonDAO personDAO;

    public void setPersonDAO(PersonDAO personDAO) {
        this.personDAO = personDAO;
    }

    @Override
    @Transactional
    public void addPerson(Person p) {
        this.personDAO.addPerson(p);
    }


    @Override
    @Transactional
    public void updatePerson(Person p) {
        this.personDAO.updatePerson(p);
    }

    @Override
    @Transactional
    public List<Person> listPerson() {
        return this.personDAO.listPerson();
    }

    @Override
    @Transactional
    public Person getPersonById(int id) {
        return this.personDAO.getPersonById(id);
    }

    @Override
    @Transactional
    public void removePerson(int id) {
        this.personDAO.removePerson(id);
    }
}

Jsp頁面：Person.jsp 

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="http://www.springframework.org/tags" prefix="spring" %>
<%@ taglib uri="http://www.springframework.org/tags/form" prefix="form" %>
<%@ page session="false" %>
<html>
<head>
    <title>Person Page</title>
    <style type="text/css">
        .tg  {border-collapse:collapse;border-spacing:0;border-color:#ccc;}
        .tg td{font-family:Arial, sans-serif;font-size:14px;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:#ccc;color:#333;background-color:#fff;}
        .tg th{font-family:Arial, sans-serif;font-size:14px;font-weight:normal;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:#ccc;color:#333;background-color:#f0f0f0;}
        .tg .tg-4eph{background-color:#f9f9f9}
    </style>
</head>
<body>
<h1>
    Add a Person
</h1>
<c:url var="addAction" value="/person/add" ></c:url>

<form:form action="${addAction}" commandName="person">
    <table>
        <c:if test="${!empty person.name}">
            <tr>
                <td>
                    <form:label path="id">
                        <spring:message text="ID"/>
                    </form:label>
                </td>
                <td>
                    <form:input path="id" readonly="true" size="8"  disabled="true" />
                    <form:hidden path="id" />
                </td>
            </tr>
        </c:if>
        <tr>
            <td>
                <form:label path="name">
                    <spring:message text="Name"/>
                </form:label>
            </td>
            <td>
                <form:input path="name" />
            </td>
        </tr>
        <tr>
            <td>
                <form:label path="country">
                    <spring:message text="Country"/>
                </form:label>
            </td>
            <td>
                <form:input path="country" />
            </td>
        </tr>
        <tr>
            <td colspan="2">
                <c:if test="${!empty person.name}">
                    <input type="submit"
                           value="<spring:message text="Edit Person"/>" />
                </c:if>
                <c:if test="${empty person.name}">
                    <input type="submit"
                           value="<spring:message text="Add Person"/>" />
                </c:if>
            </td>
        </tr>
    </table>
</form:form>
<br>
<h3>Persons List</h3>
<c:if test="${!empty listPersons}">
    <table class="tg">
        <tr>
            <th width="80">Person ID</th>
            <th width="120">Person Name</th>
            <th width="120">Person Country</th>
            <th width="60">Edit</th>
            <th width="60">Delete</th>
        </tr>
        <c:forEach items="${listPersons}" var="person">
            <tr>
                <td>${person.id}</td>
                <td>${person.name}</td>
                <td>${person.country}</td>
                <td><a href="<c:url value='/edit/${person.id}' />" >Edit</a></td>
                <td><a href="<c:url value='/remove/${person.id}' />" >Delete</a></td>
            </tr>
        </c:forEach>
    </table>
</c:if>
</body>
</html>

我不明白為什么春天找不到財產person.name。 我已經親自設置了setter和getter。 請幫我。 謝謝

1 個解決方案

解決方案1
 0 已采納  2017-10-15 15:24:03

該異常不是在您的Person類（看起來不錯）上發生的，而是在為您的類創建的Hibernate的proxy對象中，請注意奇怪的類名Person_$$_jvsta7c_0 。

發生這種情況的原因是，當您調用edit操作時，將調用方法getPersonById來調用 

Person p = (Person) session.load(Person.class,new Integer(id));

session.load()創建一個未初始化其值的proxy對象。

有關session.load()和session.get()一些信息（ 源 ）

session.load()

  • 它將始終返回“代理”（休眠術語），而無需訪問數據庫。 在Hibernate中，proxy是具有給定標識符值的對象，其屬性尚未初始化，它看起來像一個臨時的偽對象。
  • 如果未找到任何行，則將引發ObjectNotFoundException。

session.get()

  • 它總是命中數據庫並返回真實對象，該對象代表數據庫行，而不是代理。
  • 如果未找到行，則返回null。

簡而言之，嘗試將session.load()更改為session.get()

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