解决Hibernate使用HQL查询出现is not mapped问题

环境：Hibernate 5.1.0.Final，IntelliJ IDEA 2016.2.2

首先检查实体Bean配置一切正常，检查映射配置文件和hibernate.cfg.xml配置文件也是正常的。
通过搜索都说是HQL查询根据的是实体名而不是表名查找的，那个我也是对的，实在想不通会出现is not mapped问题。异常信息如下：

Exception in thread "main" org.hibernate.hql.internal.ast.QuerySyntaxException: UsersEntity is not mapped [FROM UsersEntity ]
    at org.hibernate.hql.internal.ast.QuerySyntaxException.generateQueryException(QuerySyntaxException.java:79)
    at org.hibernate.QueryException.wrapWithQueryString(QueryException.java:103)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:218)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:142)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:115)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:76)
    at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:150)
    at org.hibernate.internal.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:302)
    at org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:240)
    at org.hibernate.internal.SessionImpl.createQuery(SessionImpl.java:1907)
    at TestHibernate.main(TestHibernate.java:18)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: UsersEntity is not mapped
    at org.hibernate.hql.internal.ast.util.SessionFactoryHelper.requireClassPersister(SessionFactoryHelper.java:171)
    at org.hibernate.hql.internal.ast.tree.FromElementFactory.addFromElement(FromElementFactory.java:91)
    at org.hibernate.hql.internal.ast.tree.FromClause.addFromElement(FromClause.java:79)
    at org.hibernate.hql.internal.ast.HqlSqlWalker.createFromElement(HqlSqlWalker.java:321)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3704)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:3593)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:718)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:574)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:311)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:259)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:262)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:190)
    ... 13 more

最后仔细排查才发现是被IDE给坑了。。

我是通过IDEA自动生成的Session工厂类和映射配置文件，问题就出在IDE自动生成的那个获取Session的工厂类上。以下是IDE自动生成类的完整内容：

public class Main {
    private static final SessionFactory ourSessionFactory;
    private static final ServiceRegistry serviceRegistry;

    static {
        try {
            Configuration configuration = new Configuration();
            configuration.configure();

            serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
            ourSessionFactory = configuration.buildSessionFactory(serviceRegistry);
        } catch (Throwable ex) {
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static Session getSession() throws HibernateException {
        return ourSessionFactory.openSession();
    }

    /*
    public static void main(final String[] args) throws Exception {
        final Session session = getSession();
        try {
            System.out.println("querying all the managed entities...");
            final Map metadataMap = session.getSessionFactory().getAllClassMetadata();
            for (Object key : metadataMap.keySet()) {
                final ClassMetadata classMetadata = (ClassMetadata) metadataMap.get(key);
                final String entityName = classMetadata.getEntityName();
                final Query query = session.createQuery("from " + entityName);
                System.out.println("executing: " + query.getQueryString());
                for (Object o : query.list()) {
                    System.out.println("  " + o);
                }
            }
        } finally {
            session.close();
        }
    } */
}

我只是简单的将main方法注释掉了，其实问题就是出在serviceRegistry上面的，只要移除掉这个就好了。
修改后为：

public class Main {
    private static final SessionFactory ourSessionFactory;

    static {
        try {
            Configuration configuration = new Configuration();
            configuration.configure();

            ourSessionFactory = configuration.buildSessionFactory();
        } catch (Throwable ex) {
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static Session getSession() throws HibernateException {
        return ourSessionFactory.openSession();
    }
}

因为才刚开始学，具体的原因还没有进行分析，以后有时间再慢慢查找资料阅读源码分析吧。