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使用原生SQL查询必须注意:程序必须选出所有的数据列才可被转换成持久化实体。
假设实体在映射时有一个<many-to-one../>的关联指向另外一个实体,则SQL查询中必须返回该<many-to-one../>映射的外键列,否则将导致抛出"column not found"异常。最简单的做法是,在SQL字符串中使用星(*)来表示返回所有列。
在原生SQL语句中一样支持使用参数,这些参数即可使用问号参数(?),也可使用名字参数。
示例1:名字参数
public void entityQuery(){ Seesion session=HibernateUtil.currentSession(); Transaction tx=session.beginTransaction(); String sqlString="Select * From strudent Where year =:year"; List l=session.createSQLQuery(sqlString) .addEntity(Strudent.class) .setParameter("year",2015) .list(); tx.commit(); HibernateUtil.closeSession(); }
示例2:问号(?)参数
public void listInstalledOrUn() { try { StringBuilder mysql = new StringBuilder(); mysql.append("SELECT t.*,c.*,p.* FROM (SELECT * FROM vrv_paw_reportlog WHERE TYPE IN(1001,1002) GROUP BY pcInfoId ORDER BY TIME DESC) "
+"t INNER JOIN vrv_paw_cloudaccount c ON t.cloudAccountId=c.id INNER JOIN vrv_paw_pcinfo p ON t.pcInfoId=p.id WHERE 1=1 "); List<Object> getParamList = new ArrayList<Object>(); createSQLWhereCondition(mysql, getParamList); GridData<ReportLog> gridData = reportLogService.getPageView(mysql.toString(), getParamList, getPageNum(), getPageSize()); print(ActionUtil.jsonObj(gridData)); } catch (Exception e) { log.info("获取列表失败"); e.printStackTrace(); } } private void createSQLWhereCondition(StringBuilder mysql, List<Object> getParamList) { if (StringUtils.isNotBlank(userName)) { mysql.append(" AND c.name LIKE ? "); getParamList.add("%" + userName + "%"); } if (StringUtils.isNotBlank(ip)) { mysql.append(" AND p.ip LIKE ? "); getParamList.add("%" + ip + "%"); } if (StringUtils.isNotBlank(mac)) { mysql.append(" AND p.mac LIKE ? "); getParamList.add("%" + mac + "%"); } if (StringUtils.isNotBlank(version)) { mysql.append(" AND VERSION LIKE ? "); getParamList.add("%" + version + "%"); } if (StringUtils.isNotBlank(type)) { mysql.append(" AND TYPE=?"); getParamList.add(type); } if (StringUtils.isNotBlank(startTime)) { mysql.append("AND TIME >=?"); getParamList.add(startTime); } if (StringUtils.isNotBlank(endTime)) { mysql.append("AND TIME <=?"); getParamList.add(endTime); } }
方法getPageView:
@SuppressWarnings("unchecked")
@Override
public GridData<ReportLog> getPageView(String sql, List<Object> getParamList, int pageNum, int pageSize) {
List<Object> paramList = getParamList;
// 一、查询总记录数
// a, 生成查询recordCount的Query对象,并设置参数
Query countQuery = this.getSession().createSQLQuery(sql).addEntity(ReportLog.class);
for (int i = 0; i < paramList.size(); i++) {
countQuery.setParameter(i, paramList.get(i));
}
// b, 查询出总记录数
int recordCount = countQuery.list().size();
// 计算总页数
int maxPageNum = (recordCount + pageSize - 1) / pageSize;
if (pageNum > maxPageNum)
pageNum = maxPageNum;
List<ReportLog> recordlist = null;
if (recordCount > 0) {
// ===============
// 二、查询指定页的数据列表
// a, 生成查询recordList的Query对象,并设置参数
countQuery.setFirstResult((pageNum - 1) * pageSize);
countQuery.setMaxResults(pageSize);
// b, 查询出当前页的数据列表
recordlist = countQuery.list();
}
return new GridData<ReportLog>(recordCount, recordlist);
}
package com.vrv.paw.bean; import java.io.Serializable; import java.util.List; /** * JavaBean:代表UI的一个网格*/ public class GridData<T> implements Serializable { private static final long serialVersionUID = 1L; /** 总行数 **/ private int total; /** 行数据 **/ private List<T> rows; public GridData() { } public GridData(int total, List<T> rows) { this.total = total; this.rows = rows; } public int getTotal() { return total; } public void setTotal(int total) { this.total = total; } public List<T> getRows() { return rows; } public void setRows(List<T> rows) { this.rows = rows; } }
不仅如此,如果在SQL语句中显示使用了多表连接,则SQL语句可以选出多个数据表的数据。Hibernate还支持将查询结果转换成多个实体。如果要将查询结果转换成多个实体,则SQL字符串中应为不同数据表指定不同别名,并调用addEntity(String alias,Class entityClass)方法将不同数据表转换程不同实体。
public void multiEntityQuery(){ Session session=HibernateUtil.currentSession(); Transaction tx=session.beginTransaction(); String sql="Select s.*,e.*,c.* From student s,enrolment e,course c Where s.id=e.id And e.code=c.code "; List l=session.createSQLQuery(sql) .addEntity("s",Student.class) .addEntity("e",Enrolment.class) .addEntity("c",Course.class) .list(); tx.commit(); HibernateUtil.closeSession(); }
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原文地址:http://www.cnblogs.com/liaojie970/p/5132572.html