Hibernate/MySQL连接超时

Question

我写了一个服务器端应用程序,为网站和多个移动客户端提供支持.我使用Hibernate进行数据访问.我后来发现应用程序在一天后失败了!当我在网上查看时,我发现它是一个众所周知的问题,MySQL在8小时后终止了"陈旧"的连接.为了避免这种情况,我发现了许多建议,比如包括?autoReconnect=true,使用c3P0等.由于autoReconnect正式气馁(特别是在生产环境中),并且因为它在我应用时没有任何效果,我决定去c3p0.不幸的是,c3p0在我的hibernate.cfg.xml文件中引入配置后,应用程序开始NullPointerException在我的代码中抛出一个我调用的地方.dbSession.close() 这意味着HibernateUtil.getSessionFactory()实际返回null.我添加了所需的jar(c3p0-0.9.2-pre2.jar,hibernate-core-3.3.1.GA.jar,hibernate-c3p0-3.3.2.GA.jar,mchange-commons-java-0.2.1 .jar和c3p0-oracle-thin-extras-0.9.2-pre2.jar)即使我不认为所有这些都是必需的.我已经浏览了许多讨论过这个问题的网页,但我仍然无法正确设置它.请帮助我使用"初学者友好"易于实现的逐步程序来设置c3p0Hibernate.我在JDK 1.6,MySQL 5.5上使用Hibernate 3.3.6,我在Netbeans 7.0中开发.

这是我的 hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
  <session-factory>
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/religion_app</property>
    <property name="hibernate.connection.username">*****</property>
    <property name="hibernate.connection.password">*****</property>
    <property name="hibernate.show_sql">true</property>
    <property name="hibernate.current_session_context_class">thread</property>
    <property name="hibernate.query.factory_class">org.hibernate.hql.classic.ClassicQueryTranslatorFactory</property>

    <property name="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
    <property name="connection.autoReconnect">true</property>
    <property name="connection.autoReconnectForPools">true</property>
    <property name="connection.is-connection-validation-required">true</property>

    <!-- configuration pool via c3p0-->
    <property name="c3p0.acquire_increment">1</property> 
    <property name="c3p0.idle_test_period">120</property> <!-- seconds --> 
    <property name="c3p0.max_size">100</property> 
    <property name="c3p0.max_statements">0</property> 
    <property name="c3p0.min_size">10</property> 
    <property name="c3p0.timeout">180</property> <!-- seconds -->
    <property name="c3p0.preferredTestQuery">select 1;</property>

    <!--Mappings go here-->
  </session-factory>
</hibernate-configuration>

这是我在添加c3p0(没有slf4j)后得到的:

    May 23, 2012 2:42:14 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet LoginChurch threw exception
java.lang.NullPointerException
    at com.pacesolutions.religionapp.services.LoginChurch.processRequest(LoginChurch.java:109)
    at com.pacesolutions.religionapp.services.LoginChurch.doPost(LoginChurch.java:138)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:859)
    at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
    at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1555)
    at java.lang.Thread.run(Thread.java:722)

May 23, 2012 2:45:13 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet LoginChurch threw exception
java.lang.ClassNotFoundException: org.slf4j.LoggerFactory
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1516)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1361)
    at org.hibernate.connection.C3P0ConnectionProvider.<clinit>(C3P0ConnectionProvider.java:52)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
    at java.lang.Class.newInstance0(Class.java:372)
    at java.lang.Class.newInstance(Class.java:325)
    at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:73)
    at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:56)
    at org.hibernate.cfg.SettingsFactory.createConnectionProvider(SettingsFactory.java:414)
    at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:62)
    at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:2009)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1292)
    at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:859)
    at com.pacesolutions.religionapp.HibernateUtil.<clinit>(HibernateUtil.java:23)
    at com.pacesolutions.religionapp.services.LoginChurch.processRequest(LoginChurch.java:68)
    at com.pacesolutions.religionapp.services.LoginChurch.doPost(LoginChurch.java:143)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:859)
    at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
    at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1555)
    at java.lang.Thread.run(Thread.java:722)


    note The full stack trace of the root cause is available in the Apache Tomcat/6.0.26 logs.

我的大多数Hibernate配置文件都是由Netbeans生成的.我在地面上有数据库然后我使用Netbeans中的Hibernate向导来生成配置文件,实体类和映射文件.在我介绍c3p0之前它们正常工作(但是它们在8小时后失败).我在我的项目中使用Mecurial并将整个项目恢复到我引入c3p0之前的时间,它再次工作(8小时).甚至手动删除hibernate.cfg.xml中的所有c3p0配置也会使应用程序再次运行.我能做错什么？

Answer 1

C3P0配置所需的jar是c3p0-0.9.2-pre2.jar和mchange-commons-java-0.2.1.jar.另外,您还需要在类路径中放置c3p0.properties.

以下是在使用C3P0和Hibernate时应配置的属性.

的hibernate.cfg.xml

<property name="connection.provider_class">
                org.hibernate.connection.C3P0ConnectionProvider</property>
<property name="hibernate.c3p0.acquire_increment">1</property> 
<property name="hibernate.c3p0.idle_test_period">100</property>
<property name="hibernate.c3p0.max_size">100</property> 
<property name="hibernate.c3p0.max_statements">100</property> 
<property name="hibernate.c3p0.min_size">10</property> 
<property name="hibernate.c3p0.timeout">180</property>

c3p0.properties

• 您可以在每个结帐时验证连接c3p0.testConnectionOnCheckout=true,但这是一项昂贵的操作.

• 否则,您可以定期重试建立连接.

  c3p0.acquireRetryAttempts = 4
  c3p0.acquireRetryDelay = 5000

  这将在每次连续尝试之间以5秒的延迟重试4次.