Hibernate SQLQuery简单实用，做链接查询

工单里面可能有0个告警，一个或多个告警，当工单中没有告警的时候也需要将工单显示出来，所以就需要使用工单和告警的做链接查询，下面是具体实例

表：

CREATE TABLE `alarm` (
  `id` bigint(20) NOT NULL DEFAULT ‘0‘,
  `title` varchar(20) DEFAULT NULL,
  `level` int(11) DEFAULT NULL,
  `customer_id` bigint(20) DEFAULT NULL,
  `work_sheet_id` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `work_sheet_id` (`work_sheet_id`),
  CONSTRAINT `alarm_ibfk_1` FOREIGN KEY (`work_sheet_id`) REFERENCES `alarm` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

CREATE TABLE `worksheet` (
  `id` bigint(20) NOT NULL DEFAULT ‘0‘,
  `serialNo` varchar(20) DEFAULT NULL,
  `seatId` bigint(20) DEFAULT NULL,
  `device_id` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

insert into alarm values(1,‘title‘,‘1‘,‘1‘,‘1‘);
insert into alarm values(2,‘title‘,‘1‘,‘1‘,‘1‘);
insert into alarm values(3,‘title‘,‘1‘,‘1‘,‘1‘);
insert into alarm values(4,‘title‘,‘1‘,‘1‘,‘1‘);
insert into alarm values(5,‘title‘,‘1‘,‘1‘,‘1‘);
insert into alarm values(6,‘title‘,‘1‘,‘1‘,‘1‘);

insert into worksheet values(1,‘serialno‘,1,1);
insert into worksheet values(2,‘serialno‘,1,1);
insert into worksheet values(3,‘serialno‘,1,1);
insert into worksheet values(4,‘serialno‘,1,1);
insert into worksheet values(5,‘serialno‘,1,1);
insert into worksheet values(6,‘serialno‘,1,1);

存放SQL文件的接口

package com.h3c.zgc;

public interface SQL {

    public static final String SELECT_WORKSHEET_LEFT_JOIN_ALARM = "select w.serialNo workSheetSerialNo,a.title title,a.level level,a.id alarmId from worksheet w left join alarm a on w.id=a.work_sheet_id where w.id=?";

}

dao层：将连接查询的数据转换成map对象放入list中

package com.h3c.zgc;

import java.util.List;
import javax.annotation.Resource;

import org.hibernate.SQLQuery;
import org.hibernate.SessionFactory;
import org.hibernate.transform.Transformers;
import org.springframework.orm.hibernate4.support.HibernateDaoSupport;
import org.springframework.stereotype.Repository;

import com.h3c.zgc.alarm.WorkSheet;

@Repository
public class WorkSheetDao extends HibernateDaoSupport {
    @Resource
    private void set(SessionFactory sessionFactory) {
        this.setSessionFactory(sessionFactory);
    }

    public List getWorkSheets(Long worksheetId) {
        SQLQuery sqlQuery = this
                .getSessionFactory()
                .openSession()
                .createSQLQuery(
                        SQL.SELECT_WORKSHEET_LEFT_JOIN_ALARM);
        sqlQuery.setParameter(0, worksheetId);
        sqlQuery.setResultTransformer(Transformers.ALIAS_TO_ENTITY_MAP);
        return sqlQuery.list();
    }

    public WorkSheet getWorkSheet() {
        SQLQuery sqlQuery = this.getSessionFactory().openSession()
                .createSQLQuery("select* from worksheet where id=1")
                .addEntity(WorkSheet.class);
        List<WorkSheet> list = sqlQuery.list();
        return list.get(0);
    }
}

service层：

package com.h3c.zgc;

import java.util.Map;

import javax.annotation.Resource;

import org.springframework.stereotype.Service;

@Service
public class WorkSheetService {
    @Resource
    private WorkSheetDao workSheetDao;
    public Map<String, Object> getWorkSheet(Long worksheetId){
        return  (Map<String, Object>) workSheetDao.getWorkSheets(worksheetId).get(0);
    }
}

controller层

package com.h3c.zgc;

import java.util.Map;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class WorkSheetController {
    @Resource
    private WorkSheetService workSheetService;

    @RequestMapping("getArr")
    public String toGetArr(Long workSheetId,HttpServletRequest request){
        Map<String, Object> o = this.workSheetService.getWorkSheet(workSheetId);
        System.out.println(o.get("alarmId")==null);
        if(o.get("alarmId")==null){
            o.put("alarmId", 0);
        }
        request.setAttribute("obj",o);
        return "test/getWorkSheet";

    }
}

在页面中获取数据

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
${obj[‘workSheetSerialNo‘] } ,${obj[‘alarmId‘] },${obj[‘title‘] },${obj[‘level‘] }
<c:if test="${obj[‘alarmId‘]==0 }">告警不存在</c:if>
</body>
</html>