BBS项目笔记之一:Spring+Hibernate实现Dao层

之前的项目都比较小, 这个是s2sh做的 . Spring和Hibernate整合过好些次了 ,这次看别人写的还是收获挺多的

一:单分出applicationContext-dao.xml 和 hibernate.cfg.xml

spring的配置文件里单分出applicationContext-dao来 ,里边只配置和Dao有关的配置 

web.xml里记得加个配置就行了

<param-value>classpath:applicationContext-*.xml</param-value>

其中包括sessionFactory和事务配置

<!-- 配置sessionFactory --><bean id="sessionFactory"class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"><property name="configLocation"><value>classpath:hibernate.cfg.xml</value></property></bean>

项目里并没有把hibernate的配置文件砍掉,把配置全放在spring配置里

里边除了4个连接属性

还配置了hibernate的映射文件,之前都是用annotation配置的,这次研究一下配置文件

二:mapping映射文件的配置

大致和annotation所反映出来的信息差不多,就是换了中写法,拿文章的映射文件为例

<hibernate-mapping package="com.hrl.model"><class name="Article" table="tb_article"><id name="articleId"><generator class="native" /></id><property name="title" type="string" length="255"/><property name="content" length="2048"/><property name="emitTime" /><property name="lastUpdateTime" /><property name="articleTypeName" length="255" /><many-to-one name="user" column="userId" class="User" cascade="none" fetch="join" /><many-to-one name="articleType" column="articleTypeId" class="ArticleType" cascade="none" fetch="join" /><set name="replies" inverse="true" cascade="all" order-by="replyTime desc"><key column="articleId" /><one-to-many class="Reply" /></set><set name="scans" inverse="true" cascade="all" order-by="scanTime desc"><key column="articleId" /><one-to-many class="Scan" /></set></class></hibernate-mapping>

绝大多数也能看懂:
id是自增 , 然后全部字段都要写上 , 

join还是用来解决1+N

一对多和多对一就比annotation麻烦多了,

set name要写实体中对应的字段

 cascade是级联 这个原来用过, inverse这个查了半天:

第一、概念，指定要不要当自己来维护关系。（其实根本不用去理解）
第二、在one-to-many的时候，设置inverse=“true” 当然是在 one这个地方设置
第三、在many-to-many的时候，随便在哪端先设置inverse=“true”，另一个地方设置inverse=“false”
第四、别问我：“那我不这么设置行不行，换个方法设置下看看”，取消念头，回到第二和第三条。

lazy对应fechType的lazy

三:Dao的实现

还是分为接口和实现两部分

接口中,他用了好多final 保证传输的数据不被更改 挺好

public void updateByQuery(final String queryString,final Object[] parameters);

实现中:还是继承HibernateDaoSupport用template

Dao的实现类技术含量很高,忍不住copy一份...这个抽象类是供具体的DaoImpl继承的,相当于一个工具类

Serializable... ids是Serializable[] ids的意思 ,里边还定义了QBC的底层操作,这个项目里用QBC做的分页

最后setParameterValue根据传参类型来赋值

public abstract class DefaultDaoImpl extends HibernateDaoSupport implementsIDefaultDao {protected int queryCount = 0;public void setQueryCount(int count) {this.queryCount = count;}    /**     * 保存数据     * @param object     * @return     */public Serializable save(Object object) {return getHibernateTemplate().save(object);}   /**    * 删除数据    * @param clazz    * @param ids    */public void delete(Class clazz, Serializable... ids) {for (Serializable id : ids) {Object obj = getHibernateTemplate().load(clazz, id);getHibernateTemplate().delete(obj);}}   /**    * 修改    */public void update(Object object) {getHibernateTemplate().update(object);}public void saveOrUpdate(Object object) {getHibernateTemplate().saveOrUpdate(object);}    /**     * 得到Criteria的对象，以方便进行QBC查询     * @param clazz     * @return     */public Criteria getCriteria(Class clazz){return this.getHibernateTemplate().getSessionFactory().getCurrentSession().createCriteria(clazz);}public void updateByQuery(final String queryString,final Object[] parameters) {getHibernateTemplate().execute(new HibernateCallback() {public Object doInHibernate(Session session) {Query query = session.createQuery(queryString);if (parameters != null) {for (int i = 0; i < parameters.length; i++) {query.setParameter(i, parameters[i]);}}query.executeUpdate();return null;}});}protected String setEscape(String str) {if (str.indexOf("%") >= 0) {str = str.replaceAll("%", "\\\\%");}if (str.indexOf("_") >= 0) {str = str.replaceAll("_", "\\\\_");}return str;}protected String setEscapeChar() {return " escape '\\'";}public void delete(Class clazz, Serializable id) {getHibernateTemplate().delete(load(clazz, id));}public Integer deleteAll(final Class clazz) {return (Integer) getHibernateTemplate().execute(new HibernateCallback() {public Object doInHibernate(Session session) {Query query = session.createQuery("delete "+ clazz.getName());return new Integer(query.executeUpdate());}});}    /**     * 查询实体的所有对象     */public List findAll(Class clazz) {return getHibernateTemplate().find("from " + clazz.getName());}   /**    * 通过主键，加载对象    */public Object load(Class clazz, Serializable id) {return getHibernateTemplate().load(clazz, id);}public Object get(Class clazz, Serializable id) {return getHibernateTemplate().get(clazz, id);}public List findByNamedQuery(final String queryName) {return getHibernateTemplate().findByNamedQuery(queryName);}public List findByNamedQuery(final String queryName, final Object parameter) {return getHibernateTemplate().findByNamedQuery(queryName, parameter);}public List findByNamedQuery(final String queryName,final Object[] parameters) {return getHibernateTemplate().findByNamedQuery(queryName, parameters);}public List find(final String queryString) {return getHibernateTemplate().find(queryString);}public List find(final String queryString, final Object[] parameters) {return getHibernateTemplate().find(queryString, parameters);}public Integer deleteByQuery(final String queryString,final Object[] parameters) {return (Integer) getHibernateTemplate().execute(new HibernateCallback() {public Object doInHibernate(Session session) {Query query = session.createQuery(queryString);if (parameters != null) {for (int i = 0; i < parameters.length; i++) {query.setParameter(i, parameters[i]);}}return new Integer(query.executeUpdate());}});}public List query(String hql, String firstResult, String maxResults) {Query query = this.getHibernateTemplate().getSessionFactory().getCurrentSession().createQuery(hql);query.setFirstResult(new Integer(firstResult).intValue());query.setMaxResults(new Integer(maxResults).intValue());return query.list();}public Object get(final String queryString, final Object[] parameters) {List list = getHibernateTemplate().find(queryString, parameters);if (list != null && !list.isEmpty()) {return list.get(0);}return null;}/** * Convenience method to set paramers in the query given based on the actual * object type in passed in as the value. You may need to add more * functionaly to this as desired (or not use this at all). *  * @param query *            the Query to set * @param position *            the ordinal position of the current parameter within the query * @param value *            the object to set as the parameter */protected void setParameterValue(Query query, int position, Object value) {if (null == value) {return;} else if (value instanceof Boolean) {query.setBoolean(position, ((Boolean) value).booleanValue());} else if (value instanceof String) {query.setString(position, (String) value);} else if (value instanceof Integer) {query.setInteger(position, ((Integer) value).intValue());} else if (value instanceof Long) {query.setLong(position, ((Long) value).longValue());} else if (value instanceof Float) {query.setFloat(position, ((Float) value).floatValue());} else if (value instanceof Double) {query.setDouble(position, ((Double) value).doubleValue());} else if (value instanceof BigDecimal) {query.setBigDecimal(position, (BigDecimal) value);} else if (value instanceof Byte) {query.setByte(position, ((Byte) value).byteValue());} else if (value instanceof Calendar) {query.setCalendar(position, (Calendar) value);} else if (value instanceof Character) {query.setCharacter(position, ((Character) value).charValue());} else if (value instanceof Timestamp) {query.setTimestamp(position, (Timestamp) value);} else if (value instanceof Date) {query.setDate(position, (Date) value);} else if (value instanceof Short) {query.setShort(position, ((Short) value).shortValue());}}/** * Convenience method to set paramers in the query given based on the actual * object type in passed in as the value. You may need to add more * functionaly to this as desired (or not use this at all). *  * @param query *            the Query to set * @param key *            the key name * @param value *            the object to set as the parameter */protected void setParameterValue(Query query, String key, Object value) {if (null == key || null == value) {return;} else if (value instanceof Boolean) {query.setBoolean(key, ((Boolean) value).booleanValue());} else if (value instanceof String) {query.setString(key, (String) value);} else if (value instanceof Integer) {query.setInteger(key, ((Integer) value).intValue());} else if (value instanceof Long) {query.setLong(key, ((Long) value).longValue());} else if (value instanceof Float) {query.setFloat(key, ((Float) value).floatValue());} else if (value instanceof Double) {query.setDouble(key, ((Double) value).doubleValue());} else if (value instanceof BigDecimal) {query.setBigDecimal(key, (BigDecimal) value);} else if (value instanceof Byte) {query.setByte(key, ((Byte) value).byteValue());} else if (value instanceof Calendar) {query.setCalendar(key, (Calendar) value);} else if (value instanceof Character) {query.setCharacter(key, ((Character) value).charValue());} else if (value instanceof Timestamp) {query.setTimestamp(key, (Timestamp) value);} else if (value instanceof Date) {query.setDate(key, (Date) value);} else if (value instanceof Short) {query.setShort(key, ((Short) value).shortValue());}}}