如何解決休眠中的太多連接錯誤

Question

我在我的web應用程序中使用struts2 + hibernate3。它工作正常。有時顯示無法打開連接。用於連接休眠的Follwoing連接語句動作類。

protected SessionFactory getSessionFactory() { 
    try { 

     Configuration cfg = new Configuration(); 
     cfg.configure("hibernate.cfg.xml"); 
     SessionFactory factory = cfg.buildSessionFactory(); 
     return factory; 

    } catch (Exception e) { 
     log.error("sessionFactory", e); 
     throw new IllegalStateException(
       "Could not locate SessionFactory"); 
    } 
} 
    public List viewAllPromotion() { 
     System.out.println("finding student instance"); 
     try { 
      Session session = sessionFactory.openSession(); 
      System.out.println("View All Student"); 
      session.beginTransaction(); 
      List results = session.createQuery("from Student").list(); 
      System.out.println("List got Rsults:"+results.size()); 

      session.close(); 
      return results; 


     } catch (RuntimeException re) { 
      log.error("find by example failed", re); 
      throw re; 
     } 
    } 

Hibernate配置文件：

<session-factory> 
    <property name="hibernate.bytecode.use_reflection_optimizer">false</property> 
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> 
    <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/marksheet</property> 
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> 
    <property name="hibernate.connection.username">root</property> 
    <property name="hibernate.connection.password">admin</property> 
    <property name="hibernate.search.autoregister_listeners">false</property> 
    <property name="hibernate.session_factory_name">MySessionFactory</property> 
    <property name="current_session_context_class">thread</property> 
    <property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property> 
    <property name="hibernate.connection.pool_size">10</property> 

    <property name="show_sql">true</property> 
    <mapping resource="com/rewardz/model/student.hbm.xml" /> 
    <mapping resource="com/rewardz/model/course.hbm.xml" />    
    <mapping resource="com/rewardz/model/subject.hbm.xml" /> 
    <mapping resource="com/rewardz/model/staff.hbm.xml" /> 
    <mapping resource="com/rewardz/model/Role.hbm.xml" /> 
    <mapping resource="com/rewardz/model/Privilege.hbm.xml" /> 
    <mapping resource="com/rewardz/model/Logtab.hbm.xml" /> 
</session-factory> 

我收到以下錯誤消息，當我做更多的交易。

HTTP Status 500 - type Exception report 

    message 

     descriptionThe server encountered an internal error() that prevented it from fulfilling this request. 

    exception 

     org.hibernate.exception.JDBCConnectionException: Cannot open connection 

注意異常的完整堆棧跟蹤和其根源是在GlassFish Server開源版3.1.1日誌可用。

任何人都可以幫我解決這個問題嗎？提前致謝。

Answer 1

您應該發佈堆棧跟蹤。我猜它告訴你更多關於什麼是錯的。

此外，請嘗試使用連接池，如c3p0或bonecp。你可能會遇到奇怪的連接問題，當不使用這些庫之一，例如連接超時打開後超時等。