Hibernate 左外連接查詢

AdvertScreen對象和Advert對象 ：首先對這兩個對象配置映射關係，這裏採用的是註解配置。

@Entity
@Table(name = "app_ad_setting_cp",catalog="app_data")
public class AdvertScreen implements Serializable{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    @Column(name = "app_id")
    private String appId;//使用32位UUID，這個設置屬於的APP的id
    @Column(name = "name")
    private String name;
    @Column(name = "install_limit")
    private int installLimit = -1;//廣告安裝量限制

    @OneToOne(cascade=CascadeType.ALL,fetch=FetchType.EAGER)
    @JoinColumn(name ="app_id",referencedColumnName="uuid",insertable=false,updatable=false)
    private Advert advert;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getAppId() {
        return appId;
    }
    public void setAppId(String appId) {
        this.appId = appId;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getInstallLimit() {
        return installLimit;
    }
    public void setInstallLimit(int installLimit) {
        this.installLimit = installLimit;
    }
    public Advert getAdvert() {
        return advert;
    }
    public void setAdvert(Advert advert) {
        this.advert = advert;
    }

}
    ***************************************************************************

    @Entity
@Table(name = "app_ad_setting",catalog="app_data")
public class Advert implements Serializable{
    private static final long serialVersionUID = 4888493675123264544L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    @Column(name = "uuid")
    private String uuid;
    @Column(name = "ad_cp_enable")
    private int aDCpEnable;

    @OneToOne(cascade=CascadeType.ALL,fetch=FetchType.EAGER)//一對一多向配置
    @JoinColumn(name ="uuid",referencedColumnName="app_id",insertable=false,updatable=false)
    public AdvertScreen advertScreen;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUuid() {
        return uuid;
    }

    public void setUuid(String uuid) {
        this.uuid = uuid;
    }

    public int getaDCpEnable() {
        return aDCpEnable;
    }

    public void setaDCpEnable(int aDCpEnable) {
        this.aDCpEnable = aDCpEnable;
    }


}

***********************************************************************


//以AdvertScreen爲主表  左外連接查詢  
//注意：這裏連接的就是AdvertScreen類中的advert屬性了
//如果後面要加條件，就用with
    @Test
    public void testScreenAdvertService(){
        String hql="select ac from AdvertScreen ac left join ac.advert ";
        AdvertScreenService service=(AdvertScreenService) cxt.getBean("advertScreenService");
        //AdvertService advertService=(AdvertService) cxt.getBean("advertService");
        List<AdvertScreen> advertScreens=new ArrayList<AdvertScreen>();
        advertScreens=service.findAll(hql);

        for(AdvertScreen as:advertScreens){
            System.out.println(as);
            System.out.println(as.getAdvert());
        }

    }