java hibernate 4 org.hibernate.HibernateException：找不到方言类：org.hibernate.dialect.MYSQLDialect [英] java hibernate 4 org.hibernate.HibernateException: Dialect class not found: org.hibernate.dialect.MYSQLDialect

问题描述

我在Eclipse中创建了一个动态Web项目，我'已经将它转换成MAVEN项目，将mysql-connector-java和hibernate-core依赖项添加到pom.xml中。
我已经添加了一个servlet，并且在doGet方法中，我尝试初始化sessionfactory来创建表。我正在使用tomcat。

在向servlet发出请求时，我收到以下异常：

  org.hibernate.HibernateException：找不到方言类：org.hibernate.dialect.MYSQLDialect 
 org.hibernate.service.jdbc.dialect.internal.DialectFactoryImpl.constructDialect （DialectFactoryImpl.java:77）
 org.hibernate.service.jdbc.dialect.internal.DialectFactoryImpl.buildDialect（DialectFactoryImpl.java:65）
 org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure （JdbcServicesImpl.java:146）
 org.hibernate.service.internal.StandardServiceRegistryImpl.configureService（StandardServiceRegistryImpl.java:76）
 org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService（AbstractServiceRegistryImpl.java:160 ）
 org.hibernate.service.internal.AbstractServiceRegistryImpl.getService（AbstractServiceRegistryImpl.java:132）
 org.hibernate.cfg.Configuration.buildTypeRegistrations（Configuration.java:1818）
 org.hibernate.cfg.Configuration.buildSessionFactory（Configuration.java:1776）
 hu.adamsan.testhibernate.TestHibernate.doGet（TestHibernate.java:74）
  

pom.xml：

 依赖项> 
< dependency> 
< groupId> mysql< / groupId> 
< artifactId> mysql-connector-java< / artifactId> 
< version> 5.1.26< / version> 
< /依赖关系> 
< dependency> 
< groupId> org.hibernate< / groupId> 
< artifactId> hibernate-core< / artifactId> 
< version> 4.2.6.Final< / version> 
< /依赖关系> 
< /依赖关系> 
  

我试着去研究Maven Dependencies，org.hibernate.dialect.MySQLDialect.class是在那里，位置：getServletContext（）。getRealPath（。） - > E：\eclips_jee\workspace.metadata.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\ TestHibernateWeb\\
，在WEB-INF\lib目录中有hibernate-core-4.2.6.Final.jar，当我用7zip打开它时，可以在org / hibernate / dialect / MySQL5Dialect.class。

我错过了什么？我真的不知道。

doGet方法：

  PrintWriter w = response.getWriter（）; 
 w.println（测试休眠< br />）; 
 w.println（getServletContext（）。getRealPath（。）+< br />）; 
 
配置配置; 
 ServiceRegistry注册表; 
 SessionFactory工厂; 
 config = new Configuration（）。addAnnotatedClass（Modell.class）; 
属性props = getProperties（）; 
 props.setProperty（Environment.HBM2DDL_AUTO，create）; 
 config.setProperties（道具）; 
 registry = new ServiceRegistryBuilder（）。applySettings（props）.buildServiceRegistry（）; 
 factory = config.buildSessionFactory（registry）; 
 factory.close（）; 
  

解决方案

答案在问题中。您在jar文件中发现了 MySQLDialect 和 MySQL5Dialect ，但是您的配置文件尝试使用 MYSQLDialect 。 Java是区分大小写的。

I'm learning Java EE and Hibernate, and I've run into the following problem:

I've created a Dynamic Web Project in Eclipse, I've converted it into a MAVEN project, added the mysql-connector-java and the hibernate-core dependencies to the pom.xml. I've added a servlet, and in the doGet method, I've tried to initialize the sessionfactory to create the tables. I'm using tomcat.

When I'm making a request to the servlet I'm getting the following exception:

org.hibernate.HibernateException: Dialect class not found:   org.hibernate.dialect.MYSQLDialect
 org.hibernate.service.jdbc.dialect.internal.DialectFactoryImpl.constructDialect(DialectFactoryImpl.java:77)
org.hibernate.service.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:65)
org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:146)
org.hibernate.service.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:76)
org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:160)
org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:132)
org.hibernate.cfg.Configuration.buildTypeRegistrations(Configuration.java:1818)
org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1776)
hu.adamsan.testhibernate.TestHibernate.doGet(TestHibernate.java:74)

pom.xml:

dependencies>
    <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.26</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>4.2.6.Final</version>
        </dependency>
</dependencies>

I've tried to look into the Maven Dependencies, org.hibernate.dialect.MySQLDialect.class is in there, in the location: getServletContext().getRealPath(".") ->E:\eclips_jee\workspace.metadata.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\TestHibernateWeb\ , in the WEB-INF\lib directory, there is hibernate-core-4.2.6.Final.jar, when I opened it with 7zip, I could find inside the org/hibernate/dialect/MySQL5Dialect.class.

What am I missing? I really have no idea.

doGet method:

    PrintWriter w = response.getWriter();
    w.println("Testing hibernate<br/>");
    w.println(getServletContext().getRealPath(".")+"<br/>");

    Configuration config;
    ServiceRegistry registry;
    SessionFactory factory;     
    config = new Configuration().addAnnotatedClass(Modell.class);       
    Properties props = getProperties();     
    props.setProperty(Environment.HBM2DDL_AUTO, "create");      
    config.setProperties(props);        
    registry = new ServiceRegistryBuilder().applySettings(props).buildServiceRegistry();        
    factory = config.buildSessionFactory(registry);     
    factory.close();

解决方案

The answer is in the question. You've found MySQLDialect and MySQL5Dialect in your jar files, but your configuration file tries to use MYSQLDialect. Java is case-sensitive.

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