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最新评论
-
lt26w:
理解成门面模式应该比较容易明白吧
FacadePattern-Java代码实例讲解 -
lt26w:
看下面的例子比较明白.
FacadePattern-Java代码实例讲解 -
javaloverkehui:
这也叫文档,别逗我行吗,也就自己看看。
HtmlCleaner API -
SE_XiaoFeng:
至少也应该写个注释吧。
HtmlCleaner API -
jfzshandong:
...
org.springframework.web.filter.CharacterEncodingFilter 配置
一直都很疑惑在spring框架中getSession与getHibernateTemplate的区别。相同的地方不用说大家都是调用数据库返回结果的。但为什么要这样有二个不同的兄弟呢。认真学习了一下(其实还是很粗略的)
从使用上看
getHibernateTemplate必须继承或实例HibernateDaoSupport当然包括sessionFactory
- @SuppressWarnings ( "unchecked" )
- public T get(String id) {
- T ret = (T) getHibernateTemplate().get(type, id);
- if (ret == null ) {
- throw new ObjectRetrievalFailureException(type,
- "can't get object with id " + id);
- }
- return ret;
- }
- public IResponseDataNPage findPageByCriteria(
- final DetachedCriteria detachedCriteria, final Order order,
- final int pageSize, final int startIndex) {
- return (IResponseDataNPage) getHibernateTemplate().execute(
- new HibernateCallback() {
- public Object doInHibernate(Session session)
- throws HibernateException {
- Criteria criteria = detachedCriteria
- .getExecutableCriteria(session);
- int totalCount = ((Integer) criteria.setProjection(
- Projections.rowCount()).uniqueResult())
- .intValue();
- criteria.setProjection( null );
- if (order != null )
- criteria.addOrder(order);
- if (pageSize> 0 && startIndex>= 0 )
- {
- criteria.setFirstResult(startIndex).setMaxResults(
- pageSize);
- }
- List items = getHibernateTemplate().findByCriteria(
- detachedCriteria);
- // IResponseDataNPage ps = new IResponseDataNPage(items,
- // totalCount, pageSize, startIndex);
- IResponseDataNPage dataNPage = buildResponseDataNPage(
- null , items, totalCount);
- return dataNPage;
- }
- }, true );
- }
- }
@SuppressWarnings("unchecked") public T get(String id) { T ret = (T) getHibernateTemplate().get(type, id); if (ret == null) { throw new ObjectRetrievalFailureException(type, "can't get object with id " + id); } return ret; } public IResponseDataNPage findPageByCriteria( final DetachedCriteria detachedCriteria, final Order order, final int pageSize, final int startIndex) { return (IResponseDataNPage) getHibernateTemplate().execute( new HibernateCallback() { public Object doInHibernate(Session session) throws HibernateException { Criteria criteria = detachedCriteria .getExecutableCriteria(session); int totalCount = ((Integer) criteria.setProjection( Projections.rowCount()).uniqueResult()) .intValue(); criteria.setProjection(null); if (order != null) criteria.addOrder(order); if(pageSize>0 && startIndex>=0) { criteria.setFirstResult(startIndex).setMaxResults( pageSize); } List items = getHibernateTemplate().findByCriteria( detachedCriteria); // IResponseDataNPage ps = new IResponseDataNPage(items, // totalCount, pageSize, startIndex); IResponseDataNPage dataNPage = buildResponseDataNPage( null, items, totalCount); return dataNPage; } }, true); } }
getSession只有sessionFactory
- public T get( final PK id) {
- return (T) getSession().load(entityClass, id);
- }
- public Page<T> find(Page<T> page, String hql, Object... values) {
- Assert.notNull(page);
- Query q = createQuery(hql, values);
- if (page.isFirstSetted()) {
- q.setFirstResult(page.getFirst());
- }
- if (page.isPageSizeSetted()) {
- q.setMaxResults(page.getPageSize());
- }
- page.setResult(q.list());
- return page;
- }
public T get(final PK id) { return (T) getSession().load(entityClass, id); } public Page<T> find(Page<T> page, String hql, Object... values) { Assert.notNull(page); Query q = createQuery(hql, values); if (page.isFirstSetted()) { q.setFirstResult(page.getFirst()); } if (page.isPageSizeSetted()) { q.setMaxResults(page.getPageSize()); } page.setResult(q.list()); return page; }
从上面可以看出getSession能实现与getHibernateTemplate完全一样的代码。
但getSession要自己实现一堆的功能。如createQuery等等。
但深入比较发现一下不同处:
getSession() 获得的是原始的sessionFactory,每次你必须自己维护session如结束后你必须关闭session。如果是hibernate中进行数据库操作,你获得是原始的hibernate style和excepttion。
而hibernate template是spring包装过的,它会帮你管理session,并且它会将hibernate exceptions转换成其他的分类后的错误。这点getSession是肯定不行了。例如你用orcle和mysql返回的错误在 getSession中就是不一样的,而在hibernate template中就是一样的。
但我在实际使用中发现,对于基本的操作Hibernate template处理的的确比getSession要好,但到了复杂查询的时候如分页时需要调用 getHibernateTemplate().execute(HibernateCallBack).要产生很多innerClass,调试非常不 便。而getSession就相当简单多了。
总之:dao layer的设计五花八门,只能根据需要自己选择了。晕 java 的多态?还是变态?
发表评论
-
java.lang.ClassCastException: java.lang.Integer
2010-01-09 12:55 1357java.lang.ClassCastException: j ... -
Error:org.springframework.web.context.ContextLoaderListener
2010-01-06 21:17 8664Error con ... -
Error configuring application listener of class org.springframework.web.context.
2010-01-06 21:11 20096急!!tomcat启动报错:Error configuring ... -
Cannot find bean org.apache.struts.taglib.html.BEAN
2009-12-29 14:29 1271Cannot find bean org.apache.str ... -
attempt to create delete event with null entity
2009-12-29 11:07 4648attempt to create delete event ... -
懒加载异常org.hibernate.LazyInitializationException: could not initialize proxy - no
2009-12-28 20:44 20177错误页面提示 could n ... -
getHibernateTemplate.load() 和get()之间的区别
2009-12-28 20:16 18441. getHibernateTemplate.load() ... -
使用Hibernate持久层 --- 2 出现的问题与解决方法总结
2009-12-28 15:04 1178使用Hibernate持久层 --- 2 出现的问题与解决方法 ... -
java.lang.NullPointerException DAO
2009-12-28 15:02 1814~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ... -
JSTL1.1中要用的jar--standard.jar jstl.jar
2009-12-09 00:35 4040gg -
Jsessionid
2009-12-07 16:22 1253(1) 这是一个 ... -
spring有三种启动方式,
2009-12-07 15:21 2428spring有三种启动方式,使用 ... -
ContextLoaderListener VS. ContextLoaderServlet
2009-12-07 15:20 3525一旦ContextLoaderServlet或Cont ... -
ERRORcheck whether you have multiple ContextLoader* definitions in your web.xml!
2009-12-07 15:17 6222ERROR:check whether you have mu ... -
从tomcat 迁移到 WebSphere 经验总结(修改)
2009-12-07 15:08 2411从tomcat 迁移到 WebSphere ... -
CGlib & asm
2009-12-07 15:01 2687缺少包出现的错误信息:cglib-2.1.3.jar CGL ... -
Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTup
2009-12-07 14:57 5418Unable to instantiate default t ... -
asm.jar的冲突问题
2009-12-07 14:53 1456No configuration found. Confi ... -
异常:ERROR [org.hibernate.proxy.BasicLazyInitializer] - CGLIB Enhancement failed..
2009-12-07 14:25 1765用MyEclipse6.0写了一个spri ... -
ssh 整合时报错java.lang.reflect.InvocationTargetException... 但是能运行起[
2009-12-07 14:17 11795内容太长(多次发): [Tomcat]2007-09-0 ...
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