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实现按条件查询
第一步:
定义接口:
public interface ICommonDao<T> {
List<T> findCollectionByConditionNoPage(String codition,Object[] params, Map<String, String> orderby);
}
第二步:
实现接口的类:
Class entityClass = TUtils.getTClass(this.getClass()); public class TUtils { /**泛型转换,目的获取子类传递父类的真实类型。也就是T所相应的类型*/ public static Class getTClass(Class entity) { ParameterizedType type = (ParameterizedType)entity.getGenericSuperclass(); Class entityClass = (Class) type.getActualTypeArguments()[0]; return entityClass; } }
/**指定查询条件查询相应的结果,返回List(不分页)*/ /** * FROM ElecText o WHERE 1=1 #Dao层 AND o.textName LIKE ‘%张%‘ #Service层 AND o.textRemark LIKE ‘%张%‘ #Service层 ORDER BY o.textDate ASC,o.textName DESC #Service层 */ public List<T> findCollectionByConditionNoPage(String condition, final Object[] params, Map<String, String> orderby) { //定义hql语句 String hql = "FROM "+entityClass.getSimpleName()+" o WHERE 1=1"; //定义排序语句 String orderbyHql = this.orderbyHql(orderby); //定义终于的语句 final String finalHql = hql + condition + orderbyHql; //运行语句一 //List<T> list = this.getHibernateTemplate().find(finalHql, params); //运行语句二 // SessionFactory sf = this.getHibernateTemplate().getSessionFactory(); // Session s = sf.getCurrentSession(); // Query query = s.createQuery(finalHql); // List<T> list = query.list(); //运行语句三 List<T> list = this.getHibernateTemplate().execute(new HibernateCallback() { public Object doInHibernate(Session session) throws HibernateException, SQLException { Query query = session.createQuery(finalHql); if(params!=null && params.length>0){ for(int i=0;i<params.length;i++){ query.setParameter(i, params[i]); } } return query.list(); } }); return list; } /**组织排序的语句*/ /*ORDER BY o.textDate ASC,o.textName DESC*/ private String orderbyHql(Map<String, String> orderby) { StringBuffer buffer = new StringBuffer(""); if(orderby!=null && orderby.size()>0){ buffer.append(" order by "); for(Map.Entry<String, String> map:orderby.entrySet()){ buffer.append(map.getKey()+" "+map.getValue()+","); } //删除最后一个逗号 buffer.deleteCharAt(buffer.length()-1); } return buffer.toString(); }
以下是依据不同的业务来编写不同的代码。
第三步:
service接口:
public interface IElecTextService { public static final String SERVICE_NAME = "com.itheima.elec.service.impl.ElecTextServiceImpl"; List<ElecText> findCollectionByConditionNoPage(ElecText elecText); }
第四步:
service实现
/**指定查询条件查询相应的结果,返回List*/ /** * FROM ElecText o WHERE 1=1 #Dao层 AND o.textName LIKE ‘%张%‘ #Service层 AND o.textRemark LIKE ‘%张%‘ #Service层 ORDER BY o.textDate ASC,o.textName DESC #Service层 */ public List<ElecText> findCollectionByConditionNoPage(ElecText elecText) { //查询条件 String condition = ""; List<Object> paramsList = new ArrayList<Object>(); //推断是否加入查询条件 if(StringUtils.isNotBlank(elecText.getTextName())){ condition += " and o.textName like ?"; paramsList.add("%"+elecText.getTextName()+"%"); } if(StringUtils.isNotBlank(elecText.getTextRemark())){ condition += " and o.textRemark like ?"; paramsList.add("%"+elecText.getTextRemark()+"%"); } Object [] params = paramsList.toArray(); //排序语句(hql语句和sql语句的排序是有顺序的 Map<String, String> orderby = new LinkedHashMap<String, String>(); orderby.put("o.textDate", "asc"); orderby.put("o.textName", "desc"); //查询 List<ElecText> list = elecTextDao.findCollectionByConditionNoPage(condition,params,orderby); return list; }
第五步:
/**模拟Action,调用Service,指定查询条件查询相应的结果。返回List*/ @Test public void findCollectionByConditionNoPage(){ ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml"); IElecTextService elecTextService = (IElecTextService) ac.getBean(IElecTextService.SERVICE_NAME); ElecText elecText = new ElecText(); // elecText.setTextName("张"); // elecText.setTextRemark("张"); List<ElecText> list = elecTextService.findCollectionByConditionNoPage(elecText); if(list!=null && list.size()>0){ for(ElecText elecText2:list){ System.out.println(elecText2.getTextName()+" "+elecText2.getTextDate()+" "+elecText2.getTextRemark()); } } }
真正的action:
package com.itheima.elec.web.action; import java.util.List; import javax.annotation.Resource; import org.springframework.context.annotation.Scope; import org.springframework.stereotype.Controller; import com.itheima.elec.domain.ElecSystemDDL; import com.itheima.elec.service.IElecSystemDDLService; @SuppressWarnings("serial") @Controller("elecSystemDDLAction") @Scope(value=http://www.mamicode.com/"prototype")>
总结:依据什么样的条件查询,是在service层完毕的,把全部的条件组织好后,给dao层,dao层再拼接SQL或者hql语句,进行真正的查询。web层的action仅仅是传递參数,进行简单的调用service层的方法。
实现按条件查询
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