实现按条件查询

第一步： 定义接口本文来源gaodai#ma#com搞*代#码9网#： public interface ICommonDaoT { ListT findCollectionByConditionNoPage(String codition,Object[] params, MapString, String orderby); } 第二步： 实现接口的类： Class entityClass = TUtils.getTClass(this.getClass());public cl

第一步：

定义接口：

public interface ICommonDao {

List findCollectionByConditionNoPage(String codition,Object[] params, Map 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所对应的类型*/	public static Class getTClass(Class entity) {		ParameterizedType type = (ParameterizedType)entity.getGenericSuperclass();		Class entityClass = (Class) type.getActualTypeArguments()[0];		return entityClass;	}} 

/**指定查询条件查询对应的结果，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 findCollectionByConditionNoPage(String condition,			final Object[] params, Map 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);		//定义最终的语句		final String finalHql = hql + condition + orderbyHql;		//执行语句一		//List list = this.getHibernateTemplate().find(finalHql, params);		//执行语句二//		SessionFactory sf = this.getHibernateTemplate().getSessionFactory();//		Session s = sf.getCurrentSession();//		Query query = s.createQuery(finalHql);//		List list = query.list();		//执行语句三		List 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 orderby) {		StringBuffer buffer = new StringBuffer("");		if(orderby!=null && orderby.size()>0){			buffer.append(" order by ");			for(Map.Entry 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();	}

下面是根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 findCollectionByConditionNoPage(ElecText elecText);}

第四步：

service实现

/**指定查询条件查询对应的结果，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 findCollectionByConditionNoPage(ElecText elecText) {		//查询条件		String condition = "";		List paramsList = new ArrayList();		//判断是否添加查询条件		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 orderby = new LinkedHashMap();		orderby.put("o.textDate", "asc");		orderby.put("o.textName", "desc");		//查询		List list = elecTextDao.findCollectionByConditionNoPage(condition,params,orderby);		return list;	}

第五步：

/**模拟Action，调用Service，指定查询条件查询对应的结果，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 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="prototype")public class ElecSystemDDLAction extends BaseAction{		ElecSystemDDL  elecSystemDDL = this.getModel();		@Resource(name=IElecSystemDDLService.SERVICE_NAME)	private IElecSystemDDLService elecSystemDDLService;	public String home(){		List list = elecSystemDDLService.findKeywordWithDistinct();		request.setAttribute("list", list);		return "home";	}			public String edit(){		//获取数据类型		String keyword = elecSystemDDL.getKeyword();		//1：使用数据类型作为查询条件，查询数据字典表，返回List		List list = elecSystemDDLService.findSystemDDLListByKeyword(keyword);		request.setAttribute("systemList", list);		return "edit";	}	}

总结：根据什么样的条件查询，是在service层完成的，把所有的条件组织好后，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只是传递参数，进行简单的调用service层的方法。

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