一个在Spring里使用quartz完成时序调度工作的例子
Spring提供了支持时序调度的整合类。现在， Spring支持内置于1.3版本以来的JDK中的Timer和Quartz Scheduler(http://www.quartzscheduler.org)。 两个时序调度器通过FactoryBean建立，保持着可选的对Timers或者Triggers的引用。更进一步的, 对于Quartz Scheduler和Timer两者存在一个方便的类允许你调用目标对象(类似于通常的MethodInvokingFactoryBeans)上的某个方法。
Hibernate optimistic locking exception
HibernateOptimisticLockingFailureException,The error occurs because at least 2 transactions are working on the same record(s). If a record is read by 2 transactions, and if the record is saved by one transaction first, and then by the second one, an optimistic locking exception is thrown in the second transaction, because the assumption that nobody else was going to modify the record, doesn't hold. (Optimistic locking = You are optimistic about the facts that nobody else is going to need the same record)
Are you using multithreading in batch mode? Probably multiple transactions are modifying the same record at the same moment.
There are different solutions:
1) make sure (by design) that records that are going to be updated, are touched by only a single transaction at any given moment
2) instead of optimistic locking, use pessimistic locking (problem: reduces scalability, and added complexity in application)
3) retry the transaction: make sure that no non-transactional state is kept between retries.
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使用Jmeter进行需登录的Web页面性能压力测试
使用Jmeter进行需登录的Web页面性能压力测试，首先必须解决登录的问题。要登录，应该模拟登录过程，即传递用户名和密码请求登录处理URL进行登录，然后让Jmeter维护会话Session，在同一个会话Session里，继续请求目标测试页面，进行测试。在Jmeter里有两种机制可以维护Session会话，一是新建HTTP URL Re-writing Modifier，一个是新建HTTP Cookie 管理器。在HTTP URL Re-writing Modifier需要指定session参数名称，有的是jsessionid、JSESSIONID，有的是其他名字，所以我觉得还是HTTP Cookie Manager好，它会自动地维护一个会话Session。
在Hibernate里使用Oracle的强制索引查询提示hints
在Hibernate Hql里使用数据库某些特殊的功能，例如使用Oracle的查询提示(hints)(如强制Oracle使用某个索引)，使用用户自定义的数据库函数等，Hibernate的官方文档里已经有提到这个，不能使用Hql做数据库查询提示，而是使用三种Hibernate查询方法HQL,Criteria Queries,Native SQL里的Native SQL 本地SQL。