問題Spring + Hibernate的應用：org.hibernate.HibernateException：無會話發現當前線程

Question

我學習如何Spring框架與Hibernate整合創建我的DAO對象

我有執行從讀操作的一些問題CRUD操作集。

我有這個類實現我的DAO對象：

package org.andrea.myexample.HibernateOnSpring.dao; 

import org.andrea.myexample.HibernateOnSpring.entity.Person; 
import org.hibernate.Session; 
import org.hibernate.SessionFactory; 
import org.springframework.transaction.annotation.Transactional; 

public class PersonDAOImpl implements PersonDAO{ 

private SessionFactory sessionFactory; 

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

// Metodo che inserisce un nuovo record nella tabella person 
@Transactional(readOnly=false) 
public void addPerson(Person p) { 
    Session session = sessionFactory.openSession(); 
    session.save(p); 
    session.close();   
} 

/* Metodo che recupera un record, rappresentante uno studente, avente uno 
* specifico id dalla tabella. 
* 
* @param L'id dello studente 
* @see org.andrea.myexample.myJdbcSpringExample.StudentDAO#getStudent(java.lang.Integer) 
*/ 
public Person getById(int id){ 
    Session session = sessionFactory.openSession(); 
    return (Person) sessionFactory.getCurrentSession().get(Person.class, id); 
} 

} 

而且我有一個用於廣告tesing類主要有以下幾個等級：

package org.andrea.myexample.HibernateOnSpring; 

import org.andrea.myexample.HibernateOnSpring.dao.PersonDAO; 
import org.andrea.myexample.HibernateOnSpring.dao.PersonDAOImpl; 
import org.andrea.myexample.HibernateOnSpring.entity.Person; 
import org.springframework.beans.factory.annotation.Autowired; 
import org.springframework.context.ApplicationContext; 
import org.springframework.context.support.ClassPathXmlApplicationContext; 

public class App { 

public static void main(String[] args){ 

    ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml"); 
    System.out.println("Contesto recuperato: " + context); 

    Person persona1 = new Person(); 

    persona1.setFirstname("Pippo"); 
    persona1.setLastname("Blabla"); 
    //persona1.setPid(1); 

    System.out.println("Creato persona1: " + persona1); 

    PersonDAO dao = (PersonDAO) context.getBean("personDAOImpl"); 

    System.out.println("Creato dao object: " + dao); 

    dao.addPerson(persona1); 

    System.out.println("persona1 salvata nel database"); 

    Person personaEstratta = dao.getById(persona1.getPid()); 

    System.out.println("Persona con id: " + personaEstratta.getPid() + " estratta dal DB"); 
    System.out.println("Dati persona estratta:"); 
    System.out.println("Nome: " + personaEstratta.getFirstname()); 
    System.out.println("Cognome: " + personaEstratta.getLastname()); 

} 
} 

這種測試類第一插入新記錄在我的數據庫表中，並確定...這工作良好（新行已正確插入表中）

嘗試提取具有特定ID的行。在這裏，我遇到了一些問題，因爲試圖獲取對象時拋出以下異常：

Contesto recuperato: org.springframework.context.support.ClassPathXmlApplicationContext@11ba3c1f: startup date [Sat Feb 23 19:07:42 CET 2013]; root of context hierarchy 
Creato persona1: org.andrea.myexample.HibernateOnSpring.entity.Person@777dcf23 
Creato dao object: org.andrea.myexample.HibernateOnSpring.dao.PersonDAOImpl@3f12ccc4 
persona1 salvata nel database 
** 
Exception in thread "main" org.hibernate.HibernateException: No Session found for current thread 
    at org.springframework.orm.hibernate4.SpringSessionContext.currentSession(SpringSessionContext.java:97) 
    at org.hibernate.internal.SessionFactoryImpl.getCurrentSession(SessionFactoryImpl.java:978) 
    at org.andrea.myexample.HibernateOnSpring.dao.PersonDAOImpl.getById(PersonDAOImpl.java:31) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:601) 
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317) 
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:198) 
    at sun.proxy.$Proxy11.getById(Unknown Source) 
    at org.andrea.myexample.HibernateOnSpring.App.main(App.java:33)** 

問題是什麼？我的策略是讓對象正確嗎？

TNX

安德烈

Answer 1

你的問題是在這裏：

public Person getById(int id){ 
    Session session = sessionFactory.openSession(); 
    return (Person) sessionFactory.getCurrentSession().get(Person.class, id); 
} 

getCurrentSession()返回綁定到當前情境會話的方法。你不能在你的設置中使用這種方法，你需要使用openSession()和你的addPerson方法一樣。所以，你需要做的：

public Person getById(int id){ 
    Session session = sessionFactory.openSession(); 
    try { 
     return (Person) session.get(Person.class, id); 
    } finally { 
     session.close(); 
    }  
}