Question

public User getUserOnlyByUserName(String username) {

    LOGGER.info(" into getUserByIdJOIN ServiceImpl in UserDao------>>>>>>");
    Session session = sessionFactory.openSession();

    Criteria criteria = session.createCriteria(User.class);
    criteria.add(Restrictions.eq(USERNAME, username));
    Object obj =  criteria.uniqueResult();

    if(obj==null){
        return null;
    }
        session.close();
LOGGER.info(" out of getUserByIdJOIN ServiceImpl in UserDao------>>>>>>");
        return (User) obj;

}

197在（dbname）

上连接root @ localhost

相同的mysql日志如下所示

197在itaf4上连接root @ localhost 197查询/ *   mysql-connector-java-5.1.42（修订版：   1f61b0b0270d9844b006572ba4e77f19c0f230d4）* / *** SELECT   @@ session.auto_increment_increment AS auto_increment_increment，   @@ character_set_client AS character_set_client，   @@ character_set_connection AS character_set_connection，   @@ character_set_results AS character_set_results，   @@ character_set_server AS character_set_server，@@ init_connect AS   init_connect，@ @ interactive_timeout AS interactive_timeout，@@ license   AS许可证，@@ lower_case_table_names AS lower_case_table_names，   @@ max_allowed_packet AS max_allowed_packet，@@ net_buffer_length AS   net_buffer_length，@@ net_write_timeout AS net_write_timeout，   @@ query_cache_size AS query_cache_size，@@ query_cache_type AS   query_cache_type，@@ sql_mode AS sql_mode，@@ system_time_zone AS   system_time_zone，@@ time_zone AS time_zone，@@ tx_isolation AS   tx_isolation，@@ wait_timeout AS wait_timeout      197查询SET NAMES latin1      197查询SET character_set_results = NULL      197查询SET autocommit = 1      197查询SET sql_mode =＆＃39; STRICT_TRANS_TABLES＆＃39;

197查询选择this_.user_id为user_id1_3_0_，this_.accountNonExpired为accountN2_3_0_，this_.accountNonLocked as   accountN3_3_0_，this_.attempts为attempts4_3_0_，   this_.credentialsNonExpired为credenti5_3_0_，this_.enabled as   enabled6_3_0_，this_.firstname as firstnam7_3_0_，this_.lastAttempt as   lastAtte8_3_0_，this_.lastname为lastname9_3_0_，this_.password为   passwor10_3_0_，this_.roleId as roleId12_3_0_，this_.username as   usernam11_3_0_来自用户this_ where this_.username =＆＃39; demo_admin＆＃39;           197查询显示警告           197退出**

Answer 1

Hibernate不执行这些SQL语句。 MySQL驱动程序为您执行它们。

如果您想知道Hibernate生成什么语句，那么您应该配置datasource-proxy或p6spy as explained in this article。这样，您就可以确定应用程序显式生成了哪些JDBC语句。

在您的情况下，初始化数据库连接时将执行所有这些语句。您可以调试MySQL Connector / J驱动程序并亲自查看。

如果您多次看到这些日志，则表示您不重用连接，即bad for performance and system scalability。配置连接池解决方案后，请确保同时使用FlexyPool，以便了解其下发生的情况。

在使用Hibernate

1 个答案: