获取多表中的数据 博客分类： Hibernate Hibernate

往往在页面上展示数据的时候往往不是来自同一张数据表中，这就需要进行多表查询，我一般操作有两种方式：但这两种方式都需要建立一个VO，就是需要将查询出来的数据用一个临时VO接受。
第一种做法：通过构造
1.先建立VO，vo的属性就是页面上显示的数据（如果页面上的数据来自一个表，就不需要这个操作了，因为一般都会给每个表建立一个对应的PO，数据直接从PO中获取接）

public class ErBaseStationVo {
	private String id;//基站信息objectid
	private String stationId;//基站编号
	private String stationName;//基站名称
	private String planLong;//滚动规划精度
	private String planLat;//滚动规划纬度
	private String isImport;//是否已导入
	public ErBaseStationVo(String id, String stationId, String stationName,
			String planLong, String planLat,String isImport) {
		super();
		this.id = id;
		this.stationId = stationId;
		this.stationName = stationName;
		this.planLong = planLong;
		this.planLat = planLat;
		this.isImport=isImport;
	}
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getStationId() {
		return stationId;
	}
	public void setStationId(String stationId) {
		this.stationId = stationId;
	}
	public String getStationName() {
		return stationName;
	}
	public void setStationName(String stationName) {
		this.stationName = stationName;
	}
	public String getPlanLong() {
		return planLong;
	}
	public void setPlanLong(String planLong) {
		this.planLong = planLong;
	}
	public String getPlanLat() {
		return planLat;
	}
	public void setPlanLat(String planLat) {
		this.planLat = planLat;
	}
	public String getIsImport() {
		return isImport;
	}
	public void setIsImport(String isImport) {
		this.isImport = isImport;
	}
	
}

2.通过sql语句查出每条记录，通过Object类型的List集合接受数据，这个List中的元素都是Object类型的，将其进行转换，通过构造函数，将获得的数据存到我们之前定义好的List中，代码如下:

public List<ErBaseStationVo> getAllStationVoInfoByProjectId(String projectId,String empId) {
		String sql="select e.objectId,e.gstaId,e.gstaPlanName,e.gstaDesLongit,e.gstaDesLatit,e.gisImport  from ErBaseinfo e where e.projectId='"+projectId+"' "
				+ " and e.ldesignInsId='"+empId+"'";
		List list=basedao.find(sql);
		List<ErBaseStationVo> returnlist=new ArrayList<ErBaseStationVo>();
		for (Object object : list) {
			Object[] o=(Object[]) object;
			returnlist.add(new ErBaseStationVo((String)o[0], (String)o[1], (String)o[2], (String)o[3], (String)o[4],(String)o[5]));
		}
		return returnlist;
	}

第二种做法：通过Transformers函数

1.依然是建立我们的VO，这个VO有一个空构造函数

public class StationForDesignerVO {
	private String objectId;
	private String stationName;//基站规划名称
	private String gbelongBanner;//旗县
	private String gnetStandard;//网络制式
	private String gsight;//场景
	private String gstaBuildState;//物理站建设状态
	
	public StationForDesignerVO(){
		
	}
	
	public StationForDesignerVO(String objectId, String stationName,
			String gbelongBanner, String gnetStandard, String gsight,
			String gstaBuildState) {
		super();
		this.objectId = objectId;
		this.stationName = stationName;
		this.gbelongBanner = gbelongBanner;
		this.gnetStandard = gnetStandard;
		this.gsight = gsight;
		this.gstaBuildState = gstaBuildState;
	}
	public String getObjectId() {
		return objectId;
	}
	public void setObjectId(String objectId) {
		this.objectId = objectId;
	}
	public String getStationName() {
		return stationName;
	}
	public void setStationName(String stationName) {
		this.stationName = stationName;
	}
	public String getGbelongBanner() {
		return gbelongBanner;
	}
	public void setGbelongBanner(String gbelongBanner) {
		this.gbelongBanner = gbelongBanner;
	}
	public String getGnetStandard() {
		return gnetStandard;
	}
	public void setGnetStandard(String gnetStandard) {
		this.gnetStandard = gnetStandard;
	}
	public String getGsight() {
		return gsight;
	}
	public void setGsight(String gsight) {
		this.gsight = gsight;
	}
	public String getGstaBuildState() {
		return gstaBuildState;
	}
	public void setGstaBuildState(String gstaBuildState) {
		this.gstaBuildState = gstaBuildState;
	}
	
}

2.通过sql语句查询数据，与上一种不同的是，需要将每个字段重命名即as，之后的每个字段与建立的VO中的属性名一致即可，用Hibernate的转换函数即可实现内容的存储，比第一种方便的多

public List<StationForDesignerVO> getStationInfo(String projectId) {
		// TODO Auto-generated method stub
		String hql="select e.objectId as objectId,e.gstaPlanName as stationName,e.gbelongBanner as gbelongBanner,"
				+ " e.gnetStandard as gnetStandard,e.gsight as gsight,e.gstaBuildState as gstaBuildState  from ErBaseinfo e "
				+ " where e.projectId='"+projectId+"' and e.ldesignInsId='未分配'";
		Session session=basedao.sessionFactory.openSession();
		Query query=session.createQuery(hql);
		query.setResultTransformer(Transformers.aliasToBean(StationForDesignerVO.class));
		List<StationForDesignerVO> list=query.list();
		return list;
	}