我已经开始学习Hibernate并且出现了这样的错误：
exception
javax.servlet.ServletException: Servlet execution threw an exception
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause
java.lang.ExceptionInInitializerError
logic.HibernateUtil.<clinit>(HibernateUtil.java:16)
logic.DefaultTableDAO.getItems(DefaultTableDAO.java:38)
servlet.TestServlet.doGet(TestServlet.java:36)
javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause
org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:267)
org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:231)
org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210)
org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:51)
org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94)
org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:240)
org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210)
org.hibernate.boot.model.process.spi.MetadataBuildingProcess.handleTypes(MetadataBuildingProcess.java:352)
org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:111)
org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83)
org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418)
org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87)
org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:691)
org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:726)
logic.HibernateUtil.<clinit>(HibernateUtil.java:14)
logic.DefaultTableDAO.getItems(DefaultTableDAO.java:38)
servlet.TestServlet.doGet(TestServlet.java:36)
javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause
org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set
org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.determineDialect(DialectFactoryImpl.java:100)
org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:54)
org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:137)
org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35)
org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:88)
org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:257)
org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:231)
org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210)
org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:51)
org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94)
org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:240)
org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210)
org.hibernate.boot.model.process.spi.MetadataBuildingProcess.handleTypes(MetadataBuildingProcess.java:352)
org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:111)
org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83)
org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418)
org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87)
org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:691)
org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:726)
logic.HibernateUtil.<clinit>(HibernateUtil.java:14)
logic.DefaultTableDAO.getItems(DefaultTableDAO.java:38)
servlet.TestServlet.doGet(TestServlet.java:36)
javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
我使用Tomcate 8.5.6，Java 8，Hibernate和postgresql 9.5.2。 JDBC驱动程序9.4-1201
的hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<hibernate-configuration>
<session-factory>
<property name="connection.url">jdbc:postgresql://localhost:5432/postgres?charSet=LATIN1</property>
<property name="connection.driver_class">org.postgresql.Driver</property>
<property name="connection.username">postgres</property>
<property name="connection.password">java1235</property>
<property name="connection.pool_size">1</property>
<property name="dialect">org.hibernate.dialect.PostgreSQL9Dialect</property>
<property name="cache.provider_class">org.hibernate.cache.internal.NoCachingRegionFactory</property>
<property name="show_sql">true</property>
</session-factory>
</hibernate-configuration>
HibernateUtil.java
public class HibernateUtil {
private static SessionFactory sessionFactory;
static {
try {
sessionFactory = new Configuration().buildSessionFactory();
} catch (Throwable e){
throw new ExceptionInInitializerError(e);
}
}
private HibernateUtil(){}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
}
调用Hibernate的类
package servlet;
import logic.DefaultTable;
import logic.DefaultTableDAO;
import logic.Factory;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
public class TestServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("UTF-8");
List<Integer> list = new ArrayList<>();
list.add(1);
list.add(1);
list.add(1);
list.add(1);
list.add(1);
Factory factory = Factory.getInstance();
DefaultTableDAO table = factory.getItemDao();
List<DefaultTable> items = null;
try {
items = table.getItems();
} catch (SQLException e) {
e.printStackTrace();
}
req.setAttribute("listItem", list);
req.setAttribute("str", items.get(0).getPartName());
req.getRequestDispatcher("/WEB-INF/my_page.jsp").forward(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.getWriter().write("NOOOOOOOOOOOOOOOOOO");
}
}
记录Tomcate
05-Nov-2016 15:44:39.412 INFO [main] org.apache.catalina.startup.Catalina.start Server startup in 846 ms
05-Nov-2016 15:44:46.519 INFO [http-nio-80-exec-1] org.hibernate.Version.logVersion HHH000412: Hibernate Core {5.2.4.Final}
05-Nov-2016 15:44:46.522 INFO [http-nio-80-exec-1] org.hibernate.cfg.Environment.<clinit> HHH000206: hibernate.properties not found
05-Nov-2016 15:44:46.524 INFO [http-nio-80-exec-1] org.hibernate.cfg.Environment.buildBytecodeProvider HHH000021: Bytecode provider name : javassist
05-Nov-2016 15:44:46.567 INFO [http-nio-80-exec-1] org.hibernate.annotations.common.reflection.java.JavaReflectionManager.<clinit> HCANN000001: Hibernate Commons Annotations {5.0.1.Final}
05-Nov-2016 15:44:46.730 WARN [http-nio-80-exec-1] org.hibernate.engine.jdbc.connections.internal.ConnectionProviderInitiator.initiateService HHH000181: No appropriate connection provider encountered, assuming application will be supplying connections
05-Nov-2016 15:44:46.733 WARN [http-nio-80-exec-1] org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService HHH000342: Could not obtain connection to query metadata : The application must supply JDBC connections
org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
05-Nov-2016 15:46:49.454 INFO [ContainerBackgroundProcessor[StandardEngine[Catalina]]] org.apache.catalina.core.StandardContext.reload Reloading Context with name [] has started
05-Nov-2016 15:46:49.986 INFO [ContainerBackgroundProcessor[StandardEngine[Catalina]]] org.apache.catalina.core.StandardContext.reload Reloading Context with name [] is completed
org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
答案 0 :(得分：0)
当前错误是因为您没有正确配置displayLevel，您可以在hibernate.dialect文件中将其设置如下：
hibernate.cfg.xml另外，请确保使用正确的属性名称设置其他属性：
<property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
您可以参考here