关于SessionFactory

public static void main(String args[]){

        SessionFactory sf = new Configuration()   
            .setProperty("hibernate.connection.driver_class", "com.mysql.jdbc.Driver")   
            .setProperty("hibernate.dialect", "org.hibernate.dialect.MySQLDialect")   
            .setProperty("hibernate.connection.url", "jdbc:mysql://localhost/huayi?useUnicode=true&characterEncoding=latin1")   
            .setProperty("hibernate.connection.username", "root")   
            .setProperty("hibernate.connection.password", "root")   
//          .setProperty("hibernate.hbm2ddl.auto", "create")   
//          validate               加载hibernate时，验证创建数据库表结构   
//          create                  每次加载hibernate，重新创建数据库表结构，这就是导致数据库表数据丢失的原因。   
//          create-drop        加载hibernate时创建，退出是删除表结构   
//          update                 加载hibernate自动更新数据库结构   
//            .addAnnotatedClass(Order.class)   
//            .addAnnotatedClass(Item.class)   
            .buildSessionFactory();   
           
        Session session = sf.openSession();   
        session.beginTransaction();   
        List result = session.createQuery("from PlcAmsNetID").list();   

          session.getTransaction().commit();   
                   System.out.println("done...");   
    }   

提示
Exception in thread "main" org.hibernate.hql.ast.QuerySyntaxException: PlcAmsNetID is not mapped [from PlcAmsNetID]
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:255)
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 com.corona.web.action.SaveTrouble1Action.main(SaveTrouble1Action.java:394)



但是hibernate.cfg.xml中有
<mapping resource="com/corona/servive/entity/PlcAmsNetID.hbm.xml" />






请问为什么，如何解决
[解决办法]
你没指明类。

new Configuration()需要再加一句
.addClass(PlcAmsNetID.class)

[解决办法]
你在创建Configuration的时候，并没有加载hibernate.cfg.xml,你要修改一下，new Configuration().comfigure()这个方法，建议楼主先一步一步的来。这样基本上不会出什么问题。
[解决办法]
SessionFactory sf = new Configuration().configure() 默认加载类路径下的hibernate配置文件，别setProperty()和addClass()了。把这些属性值和mapping文件加入hibernate.cfg.xml文件中去。