hibernate使用中常見的問題

classes根目錄下放置了hibernate.properties及hibernate.cfg.xml文件。
classes\test目錄下放置了Admin.hbm.xml文件。
工程中引用了hibernate3.jar、dom4j-1.5.2.jar及oracel數(shù)據(jù)庫驅(qū)動程序classes12.jar、nls_charset12.jar、ocrs12.jar、hibernate3的lib下所有的包及其它要使用的包。

（1）hibernate警告 Could not obtain connection metadata
運行時報錯如下：
2005-12-1 13:29:19 org.hibernate.connection.DriverManagerConnectionProvider configure
信息: using driver: oracle.jdbc.driver.OracleDriver at URL: jdbc:oracle:thin:@localhost:1521:icts
2005-12-1 13:29:19 org.hibernate.connection.DriverManagerConnectionProvider configure
信息: connection properties: {user=system, password=****}
2005-12-1 13:29:19 org.hibernate.cfg.SettingsFactory buildSettings
警告: Could not obtain connection metadata
java.sql.SQLException: Io 異常: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=150999297)(ERR=12505)(ERROR_STACK=(ERROR=(CODE=12505)(EMFI=4))))
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:180)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:222)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:335)
at oracle.jdbc.driver.OracleConnection.<init>(OracleConnection.java:361)
at oracle.jdbc.driver.OracleDriver.getConnectionInstance(OracleDriver.java:442)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:321)
at java.sql.DriverManager.getConnection(DriverManager.java:525)
at java.sql.DriverManager.getConnection(DriverManager.java:140)
at org.hibernate.connection.DriverManagerConnectionProvider.getConnection(DriverManagerConnectionProvider.java:110)
at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:118)
at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:1505)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1053)
at test.Test.insertAdmin(Test.java:31)
at test.Test.myTest(Test.java:54)
at test.Test.main(Test.java:59)
2005-12-1 13:29:19 org.hibernate.cfg.SettingsFactory buildSettings
信息: JDBC batch size: 15
......

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連接數(shù)據(jù)庫有問題。檢查用戶名稱與密碼及數(shù)據(jù)庫全局名稱。

（2）報錯：CUSTOMER is not mapped
錯在這里：List list = session.createQuery("from CUSTOMER").list();
注意這里from后面對應(yīng)的是類名，而不是數(shù)據(jù)庫表名。
因為Customer類和表CUSTOMERS做了映射，在sql的檢索中不是從數(shù)據(jù)庫中取，而是從類中，這也是ORM的思想。
（3）報錯：Could not bind factory to JNDI
此錯誤是配置文件的問題，如果hibernate配置文件有session_factory_name這個變量，<session-factory name="foo"> 會試圖將一個SessionFactory實例以foo為名bind到j(luò)ndi上，而有的application container不支持jndi綁定。把這個變量去掉即可。