Java Hibernate对象不刷新

Question

我正在Hibernate上工作。我正在测试一个简单的Java，在两个单独的会话中加载2本书的实体。我加载了第一本书对象，让主线程睡眠5秒，在此期间，我在数据库中更改了书的名称。之后，第二次会话将再次加载该书。但这本书的名字还是一样的。当它预计也会改变。

请帮忙。我编写了一个servlet程序，但具有相同的问题，更新后的数据不会在db更改后显示。

这里是我的代码：

import java.util.Date; 
import java.util.HashSet; 
import java.util.Iterator; 
import java.util.List; 
import java.util.Set; 

import org.hibernate.CacheMode; 
import org.hibernate.Hibernate; 
import org.hibernate.Query; 
import org.hibernate.Session; 
import org.hibernate.SessionFactory; 
import org.hibernate.Transaction; 
import org.hibernate.cfg.Configuration; 

import org.hibernate.stat.Statistics; 

/** 
* @author Guruzu 
* 
*/ 
public class Launch_3_5 { 

    private static SessionFactory sessionFactory; 

    public static Session getSession() { 
     if (sessionFactory == null) { 
      sessionFactory = new Configuration().configure() 
        .buildSessionFactory(); 
     } 
     Session hibernateSession = sessionFactory.openSession(); 
     return hibernateSession; 
    } 

    public static SessionFactory getSessionFactory() { 
     if (sessionFactory == null) { 
      sessionFactory = new Configuration().configure() 
        .buildSessionFactory(); 
     } 
     return sessionFactory; 
    } 

    public static void main(String[] args) { 
     Session session1 = getSessionFactory().openSession(); 

     try { 

      Transaction tx = session1.beginTransaction(); 

      Book book1 = (Book) session1.get(Book.class, (long) 1); 

      System.out.println("Book: " + book1.getName()); 


     // session1.flush(); 
     } finally { 

      session1.close(); 
     } 

     try { 
      Thread.sleep(5000); 
     } catch (InterruptedException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
     Session session2 = getSessionFactory().openSession(); 

     try { 

      Book book2 = (Book) session2.get(Book.class, (long) 1); 
      System.out.println("Book: " + book2.getName()); 

     } finally { 

      session2.close(); 
     } 

    } 
} 

Book6_1.hbm.xml

<?xml version="1.0" encoding="UTF-8"?> 
<!DOCTYPE hibernate-mapping PUBLIC 
"-//Hibernate/Hibernate Mapping DTD 3.0//EN" 
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> 
<hibernate-mapping> 
    <class name="Book" table="Book6_1"> 

     <id name="book_id" type="long" column="BOOK_ID"> 
      <generator class="increment"> 
      </generator> 
     </id> 
     <property name="isbn" type="string"> 
      <column name="ISBN" length="50" not-null="true" unique="true" /> 
     </property> 
     <property name="name" type="string"> 
      <column name="BOOK_NAME" length="100" not-null="true" /> 
     </property> 
     <property name="publishDate" type="date" column="PUBLISH_DATE" /> 
     <property name="price" type="int" column="PRICE" /> 


    </class> 
</hibernate-mapping> 

的hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?> 
<!DOCTYPE hibernate-configuration PUBLIC 
"-//Hibernate/Hibernate Configuration DTD//EN" 
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> 

<hibernate-configuration> 
    <session-factory> 
     <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> 
     <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernatetutorial</property> 
     <property name="hibernate.connection.username">root</property> 
     <property name="hibernate.connection.password">root</property> 
     <property name="hibernate.connection.pool_size">10</property> 
     <property name="show_sql">true</property> 
     <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> 

     <mapping resource="Book_6_1.hbm.xml" /> 

    </session-factory> 
</hibernate-configuration> 

Answer 1

你的第二届会议的击球second-level cache。如果你不想这样做，你可以完全在你的配置文件（use_second_level_cache = false）或映射文件（从hbm.xml中删除'cache'元素）中关闭缓存。

或者你可以改变你的查询使用经常去数据库CacheMode.REFRESH

Session session2 = getSessionFactory().openSession(); 
    session2.setCacheMode(CacheMode.REFRESH); 
    try { 
     Book book2 = (Book) session2.get(Book.class, (long) 1); 
    } finally { 
     session2.close(); 
    }