HIBERNATE读书笔记

HIBERNATE读书笔记 

HIBERNAT的查询语言HQL： 当查询多个属性时，HIBERNATE默认返回的是一个数组来保存结果集，但是可以灵活改变为List，Map，和自定义的JAVA Bean。 １．默认情况，返回数组 String sql = "select id , title from Event" ;        Query q  =  session.createQuery(sql);        List<Object[]> list = q.list() ;        for(Object[] o : list)        {            Integer id = (Integer)o[0];            String title = (String)o[1];            System.out.println(id);            System.out.println(title);        }   ２．返回一个List String sql = "select new List(id , title) from Event" ;        Query q  =  session.createQuery(sql);        List<Object[]> list = q.list() ;        for(Object[] o : list)        {            Integer id = (Integer)o[0];            String title = (String)o[1];            System.out.println(id);            System.out.println(title);        }   ３．返回一个Map String sql = "select new Map(id , title) from Event";        Query q = session.createQuery(sql);        List<Map> list = q.list();        for (Map o : list)        {            Set<Map.Entry> s = o.entrySet();            System.out.println(s+"set");            for(Map.Entry entry : s)            {               System.out.println(entry);               System.out.println(entry.getKey());               System.out.println(entry.getValue());            }        } ４．返回自定义的JAVA Bean 注意：自定义JAVA Bean 必须提供一个PUBLIC的构造函数，引用是必须包含完整的包点类名 String sql = "select new cn.coolbi.lcj.EventProxy(id , title) from Event";        Query q = session.createQuery(sql);        List<EventProxy> list = q.list();        for (EventProxy o : list)        {            int date = o.getId() ;            String title = o.getTitle() ;                       System.out.println(date);            System.out.println(title);                   } EventProxy代理类 package cn.coolbi.lcj;   public class EventProxy {     private int id ;         private String title ;         public EventProxy(int id ,String title)     {        this.id = id ;        this.title = title ;     }       public int getId()     {        return id;     }       public void setId(int id)     {        this.id = id;     }       public String getTitle()     {        return title;     }       public void setTitle(String title)     {        this.title = title;     } }

 

 

Where条件查询时有四种方式设置条件的值，详细见上图： １）通过set Properties();方法设置一下JAVABean时注意“：”后面没有空格 String sql = "select new cn.coolbi.lcj.EventProxy(id , title) from Event where id =:id and title =:title";        Query q = session.createQuery(sql);               //一个Event的代理类        EventProxy up = new EventProxy(18,"hello");        q.setProperties(up);                      List<EventProxy> list = q.list();        for (EventProxy o : list)        {            int date = o.getId() ;            String title = o.getTitle() ;                       System.out.println(date);            System.out.println(title);                   }

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