Java 如何在调用servlet之前静态初始化HibernateUtil?
我想要一个Javaservlet通过doGet方法中的hibernate访问数据库,我创建了HibernateUtil类以在静态上下文中调用buildSessionFactory 测试时,我得到一个错误“tomcat未能启动”,显然是(?),因为doGet方法中的openSession在HibernateUtil类中的buildSessionFactory调用之前被调用 如何确保在servlet中的doGet方法之前静态初始化HibernateUtil类 下面是课堂:Java 如何在调用servlet之前静态初始化HibernateUtil?,java,hibernate,tomcat,Java,Hibernate,Tomcat,我想要一个Javaservlet通过doGet方法中的hibernate访问数据库,我创建了HibernateUtil类以在静态上下文中调用buildSessionFactory 测试时,我得到一个错误“tomcat未能启动”,显然是(?),因为doGet方法中的openSession在HibernateUtil类中的buildSessionFactory调用之前被调用 如何确保在servlet中的doGet方法之前静态初始化HibernateUtil类 下面是课堂: import org.hi
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateUtil {
private static final SessionFactory sessionFactory = buildSessionFactory();
private static SessionFactory buildSessionFactory() {
try {
// Create the SessionFactory from hibernate.cfg.xml
return new Configuration()
.configure()
.buildSessionFactory();
} catch (Throwable ex) {
System.err.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
}
我从doGet()方法调用如下:
Session session = null;
try {
session = HibernateUtil.getSessionFactory().openSession();
// ...
}
堆栈跟踪如下所示:
INFO: Starting service Catalina
Feb 10, 2014 12:58:21 PM org.apache.catalina.core.StandardEngine startInternal
INFO: Starting Servlet Engine: Apache Tomcat/7.0.42
Feb 10, 2014 12:58:21 PM org.apache.catalina.core.ContainerBase startInternal
SEVERE: A child container failed during start
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/dbwebtest]]
at java.util.concurrent.FutureTask$Sync.innerGet(Unknown Source)
at java.util.concurrent.FutureTask.get(Unknown Source)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:800)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/dbwebtest]]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
... 7 more
Caused by: java.lang.NoClassDefFoundError: org/hibernate/HibernateException
at java.lang.Class.getDeclaredFields0(Native Method)
at java.lang.Class.privateGetDeclaredFields(Unknown Source)
at java.lang.Class.getDeclaredFields(Unknown Source)
at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:106)
at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:263)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:142)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:67)
at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:405)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:881)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:376)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5322)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
... 7 more
Caused by: java.lang.ClassNotFoundException: org.hibernate.HibernateException
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1714)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559)
... 21 more
您应该使用Servlet过滤器来创建SessionFactory和打开/关闭会话。Hibernate将其称为视图中的开放会话模式,实现如下所述:看起来Hibernate jar文件(或其依赖项之一)不在webapp的类路径中,即在WEB-INF/lib中: java.lang.NoClassDefFoundError:org/hibernate/hibernateeException
你对错误的解释是错误的。显示异常的完整堆栈跟踪。看起来hibernate jar文件(或其依赖项之一)不在webapp的类路径中,即在WEB-INF/lib:
java.lang.NoClassDefFoundError:org/hibernate/HibernateException
中确实如此;如果你把这个作为答复,我可以接受。