org.hibernate.hql.ast.QuerySyntaxException: is not mapped

org.hibernate.hql.ast.QuerySyntaxException: User is not mapped [select u from User u where u.userName=:userName and u.password=:password]

    at org.hibernate.hql.ast.util.SessionFactoryHelper.requireClassPersister(SessionFactoryHelper.java:158)

    at org.hibernate.hql.ast.tree.FromElementFactory.addFromElement(FromElementFactory.java:87)

    at org.hibernate.hql.ast.tree.FromClause.addFromElement(FromClause.java:70)

    at org.hibernate.hql.ast.HqlSqlWalker.createFromElement(HqlSqlWalker.java:257)

    at org.hibernate.hql.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3056)

    at org.hibernate.hql.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:2945)

    at org.hibernate.hql.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:688)

    at org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:544)

    at org.hibernate.hql.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:281)

    at org.hibernate.hql.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:229)

    at org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:228)

    at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:160)

    at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:111)

    at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:77)

    at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:56)

    at org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:72)

    at org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:133)

    at org.hibernate.impl.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:112)

    at org.hibernate.impl.SessionImpl.createQuery(SessionImpl.java:1623)

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

    at java.lang.reflect.Method.invoke(Method.java:597)

    at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:301)

    at $Proxy0.createQuery(Unknown Source)

    at org.kf.dao.impl.UserDaoImpl.userLogin(UserDaoImpl.java:40)

    at org.kf.biz.UserBiz.userLogin(UserBiz.java:19)

    at test.Test.main(Test.java:13)

上面的异常的抛出主要有几个方面：

1、最容易想到的，就是你的from是实体类而不是表名，这个应该大家都知道，注意大小写

2、你的hibernate配置文件中没有加入相应的映射文件<mapping resource=" " />

3、如果上面两方面都对了，那就是你hql语句有错了，好好检查一下，仔细点，不行就重新写一遍，有可能是空格。