关于Hibernate读取select count(*)的返回值到底是Long还是Integer的疑惑

我select count(uid) 后返回的是一个list
int count_user = (Integer)DaoFactory.getDemomiap2DaoInstance().Getsql(hqlcount).get(0);
来得到的没报错

hibernate不太熟悉但是看错误是类型转换的问题

Long 是基本类型
Integer是 int的封装型
是不是在这里出现了问题?最好是都改成封装型的 Hibernate 读取数据的时候是通过 class文件反射的
"但是，有几个网友却是正好相反，他们直接运行报 java.lang.ClassCastException: java.lang.Integer 改成Integer却正常了。
希望大家使用Hibernate比较熟悉的人，确认一下，大家随意使用 count(*) 然后读取看看，到底是Integer,还是 Long "

这个应该是配置映射的时候你们之间有差别

跟hibernate版本有关,3之后都是long

测试代码：         public void countAllSubject() {
    this.session = this.sessionFactory.getSessionFactory().openSession();
    this.session.beginTransaction();
    System.out.println(session.createQuery("select count(*) from User").iterate().next().getClass());

}
public static void main(String args[]) {
BaseDAO b=new BaseDAO();
b.countAllSubject();
}显示结果15:07:51,046  INFO Environment:479 - Hibernate 3.1.3
15:07:51,062  INFO Environment:509 - hibernate.properties not found
15:07:51,062  INFO Environment:525 - using CGLIB reflection optimizer
15:07:51,078  INFO Environment:555 - using JDK 1.4 java.sql.Timestamp handling
15:07:51,140  INFO Configuration:1308 - configuring from resource: /hibernate.cfg.xml
15:07:51,140  INFO Configuration:1285 - Configuration resource: /hibernate.cfg.xml
15:07:51,390  INFO Configuration:469 - Reading mappings from resource: pojo/hbm/authority.hbm.xml
15:07:51,500  INFO HbmBinder:309 - Mapping class: pojo.Authority -> authority
15:07:51,515  INFO Configuration:469 - Reading mappings from resource: pojo/hbm/character.hbm.xml
15:07:51,546  INFO HbmBinder:309 - Mapping class: pojo.Character -> characters
15:07:51,546  INFO Configuration:469 - Reading mappings from resource: pojo/hbm/characterAuthority.hbm.xml
15:07:51,578  INFO HbmBinder:309 - Mapping class: pojo.CharacterAuthority -> characterAuthority
15:07:51,593  INFO Configuration:469 - Reading mappings from resource: pojo/hbm/user.hbm.xml
15:07:51,609  INFO HbmBinder:309 - Mapping class: pojo.User -> user
15:07:51,609  INFO Configuration:469 - Reading mappings from resource: pojo/hbm/userCharacter.hbm.xml
15:07:51,625  INFO HbmBinder:309 - Mapping class: pojo.UserCharacter -> usercharacter
15:07:51,640  INFO Configuration:1419 - Configured SessionFactory: null
15:07:51,843  WARN RootClass:210 - composite-id class does not override equals(): pojo.UserCharacter
15:07:51,843  WARN RootClass:215 - composite-id class does not override hashCode(): pojo.UserCharacter
15:07:51,859  WARN RootClass:210 - composite-id class does not override equals(): pojo.CharacterAuthority
15:07:51,859  WARN RootClass:215 - composite-id class does not override hashCode(): pojo.CharacterAuthority
15:07:51,875  INFO DriverManagerConnectionProvider:41 - Using Hibernate built-in connection pool (not for production use!)
15:07:51,875  INFO DriverManagerConnectionProvider:42 - Hibernate connection pool size: 20
15:07:51,875  INFO DriverManagerConnectionProvider:45 - autocommit mode: false
15:07:51,875  INFO DriverManagerConnectionProvider:80 - using driver: com.mysql.jdbc.Driver at URL: jdbc:mysql://127.0.0.1:3306/test
15:07:51,875  INFO DriverManagerConnectionProvider:86 - connection properties: {user=root, password=****}
15:07:52,156  INFO SettingsFactory:77 - RDBMS: MySQL, version: 5.0.22-community-nt
15:07:52,156  INFO SettingsFactory:78 - JDBC driver: MySQL-AB JDBC Driver, version: mysql-connector-java-5.0.8 ( Revision: ${svn.Revision} )
15:07:52,171  INFO Dialect:103 - Using dialect: org.hibernate.dialect.MySQLDialect
15:07:52,171  INFO TransactionFactoryFactory:31 - Using default transaction strategy (direct JDBC transactions)
15:07:52,171  INFO TransactionManagerLookupFactory:33 - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended)
15:07:52,171  INFO SettingsFactory:125 - Automatic flush during beforeCompletion(): disabled
15:07:52,171  INFO SettingsFactory:129 - Automatic session close at end of transaction: disabled
15:07:52,171  INFO SettingsFactory:136 - JDBC batch size: 15
15:07:52,171  INFO SettingsFactory:139 - JDBC batch updates for versioned data: disabled
15:07:52,171  INFO SettingsFactory:144 - Scrollable result sets: enabled
15:07:52,171  INFO SettingsFactory:152 - JDBC3 getGeneratedKeys(): enabled
15:07:52,171  INFO SettingsFactory:160 - Connection release mode: auto
15:07:52,187  INFO SettingsFactory:184 - Maximum outer join fetch depth: 2
15:07:52,187  INFO SettingsFactory:187 - Default batch fetch size: 1
15:07:52,187  INFO SettingsFactory:191 - Generate SQL with comments: disabled
15:07:52,187  INFO SettingsFactory:195 - Order SQL updates by primary key: disabled
15:07:52,187  INFO SettingsFactory:338 - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory
15:07:52,187  INFO ASTQueryTranslatorFactory:24 - Using ASTQueryTranslatorFactory
15:07:52,187  INFO SettingsFactory:203 - Query language substitutions: {}
15:07:52,187  INFO SettingsFactory:209 - Second-level cache: enabled
15:07:52,187  INFO SettingsFactory:213 - Query cache: disabled
15:07:52,187  INFO SettingsFactory:325 - Cache provider: org.hibernate.cache.EhCacheProvider
15:07:52,187  INFO SettingsFactory:228 - Optimize cache for minimal puts: disabled
15:07:52,187  INFO SettingsFactory:237 - Structured second-level cache entries: disabled
15:07:52,187  INFO SettingsFactory:257 - Echoing all SQL to stdout
15:07:52,203  INFO SettingsFactory:264 - Statistics: disabled
15:07:52,203  INFO SettingsFactory:268 - Deleted entity synthetic identifier rollback: disabled
15:07:52,203  INFO SettingsFactory:283 - Default entity-mode: pojo
15:07:52,234  INFO SessionFactoryImpl:154 - building session factory
15:07:52,250  WARN Configurator:126 - No configuration found. Configuring ehcache from ehcache-failsafe.xml found in the classpath: jar:file:/F:/Program%20Files/MyEclipse%206.0/myeclipse/eclipse/plugins/com.genuitec.org.hibernate.eclipse_6.0.0.zmyeclipse60020070820/myeclipse-data/3.0/lib/ehcache-1.1.jar!/ehcache-failsafe.xml
15:07:52,500  INFO SessionFactoryObjectFactory:82 - Not binding factory to JNDI, no JNDI name configured
Hibernate: select count(*) as col_0_0_ from user user0_
class java.lang.Integer

这个应该是跟数据库有关的
DB2是返回java.lang.Long
MySQL返回java.math.BigInteger
其它数据库不知道

select count（*）
返回的是Long类型的，
我用mysql时是这样的。

补充一下，我的数据库用的 MySQL我想count(*) 这个应该没有关系吧，呵呵！！

本帖最后由 java2000_net 于 2008-07-25 16:24:54 编辑

。
我的jar包还没下好呢
呵呵

是的我觉得Long本来就要比integer 明智
integer的最大值才21亿多
而long有 9223372036854775807我是在想他为什么要把Integer变为Long
这个有原因吗？

我用Integer 接收没有报错

推荐一个方法,
  @Override
  public int countAllSubject() {
    Session session = HibernateUtil.getSessionFactory().getCurrentSession();
    session.beginTransaction();
    Number number=((Number) session.createQuery(
        "select count(*) from Post where idParent=0").iterate().next());
    return number.intValue();

  }因为无论是Long还是Integer,还是BigInteger,它们都是Number的子类,所以用Number去cast这个结果是肯定不会错的,然后,最好定义在Number里面这些方法可以统一的返回需要的类型; byte byteValue()
          以 byte 形式返回指定的数值。
abstract  double doubleValue()
          以 double 形式返回指定的数值。
abstract  float floatValue()
          以 float 形式返回指定的数值。
abstract  int intValue()
          以 int 形式返回指定的数值。
abstract  long longValue()
          以 long 形式返回指定的数值。
short shortValue()
          以 short 形式返回指定的数值。
=====================================================
java.lang
类 Number
java.lang.Object
  java.lang.Number
所有已实现的接口：
Serializable
直接已知子类：
AtomicInteger, AtomicLong, BigDecimal, BigInteger, Byte, Double, Float, Integer, Long, Short

你可以返回值.class 看看到底什么类型。

直接弄成Number，然后自己拿出来想怎么转就怎么转(int,long).

hibernate配置了什么就是什么！！

但是我用的是hibernate3.0，对于这个错误还是java.math.BigInteger cannot be cast to java.lang.Long？？？

调试易

关于Hibernate读取select count(*)的返回值到底是Long还是Integer的疑惑

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