hibernate关联关系注解（一对多、多对一、一对一）

一对多、多对一、一对一的注解实现

casecade={CasecadeType.REFRESH}的含义是只是查询级联，它还有其他3个类型：

CascadeType.MERGE级联更新

CascadeType.PERSIST级联保存

CascadeType.REMOVE级联删除

optional=false定义关联类不一定要存在

@JoinColumn 关联的对象的字段

@ManyToOne多对一   @OneToMany一对多 @OneToOne一对一

需要注意的是一对一关联关系，hibernate会建立唯一约束，用错的话，后果很严重奥。

event对象

@Entity@Table(name = "event")public class EventEntity implements Serializable{/** *  */private static final long serialVersionUID = 1L;@Id@GeneratedValue(strategy = GenerationType.IDENTITY)@Column(name = "eventId", nullable = true)private long eventId;               //事件idprivate String eventNote;           //事件内容private String eventTitle;          //事件标题private String createTime;          //创建时间@ManyToOne(cascade = {CascadeType.REFRESH}, optional = false)@JoinColumn(name="userId")private UserEntity user;@OneToOne(optional = false, cascade = CascadeType.REFRESH)@JoinColumn(name = "eventTitleImage")private EventImageEntity eventTitleImage;  //事件封面照片private String eventAddress;       //事件地址private String eventType;          //事件类型private String lon;                //经度private String lat;                //纬度private String eventstate;         //事件状态@OneToMany(cascade = {CascadeType.REFRESH})@JoinColumn(name = "eventId")        private List<EventImageEntity> eventImageList;public long getEventId() {return eventId;}public void setEventId(long eventId) {this.eventId = eventId;}public String getEventNote() {return eventNote;}public void setEventNote(String eventNote) {this.eventNote = eventNote;}public String getEventTitle() {return eventTitle;}public void setEventTitle(String eventTitle) {this.eventTitle = eventTitle;} public String getCreateTime() {return createTime;}public void setCreateTime(String createTime) {this.createTime = createTime;}public UserEntity getUser() {return user;}public void setUser(UserEntity user) {this.user = user;}public EventImageEntity getEventTitleImage() {return eventTitleImage;}public void setEventTitleImage(EventImageEntity eventTitleImage) {this.eventTitleImage = eventTitleImage;}public String getEventAddress() {return eventAddress;}public void setEventAddress(String eventAddress) {this.eventAddress = eventAddress;}public String getEventType() {return eventType;}public void setEventType(String eventType) {this.eventType = eventType;}public String getLon() {return lon;}public void setLon(String lon) {this.lon = lon;}public String getLat() {return lat;}public void setLat(String lat) {this.lat = lat;}public String getEventstate() {return eventstate;}public void setEventstate(String eventstate) {this.eventstate = eventstate;}public List<EventImageEntity> getEventImageList() {return eventImageList;}public void setEventImageList(List<EventImageEntity> eventImageList) {this.eventImageList = eventImageList;}}

user对象

@Entity@Table(name = "user")public class UserEntity implements Serializable {/** *  */private static final long serialVersionUID = 1L;@Id@GeneratedValue(strategy = GenerationType.IDENTITY)@Column(name = "userId")private long userId;private String username;   //用户名称   private String phone;      //用户电话private String password;   //密码@OneToOne(optional = false, cascade = CascadeType.REFRESH)@JoinColumn(name = "userimage")private ImageEntity userImage;  //用户头像private String isRole;          //是否有权限private String createTime;      //创建时间private String sign;            //签名private String sex;             //性别private String age;             //年纪private String birthday;        //生日private String numberId;        //用户ID标示private String emotional;//情感状态private String updateTime;      //修改时间private String userstate;       //用户状态（1正常 2禁用 3删除）@ManyToOne(cascade={CascadeType.REFRESH},optional = false)@JoinColumn(name="userLevel")        private Exp exp;                //等级private long exping;            //当前经验值public long getUserId() {return userId;}public void setUserId(long userId) {this.userId = userId;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPhone() {return phone;}public void setPhone(String phone) {this.phone = phone;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public ImageEntity getUserImage() {return userImage;}public void setUserImage(ImageEntity userImage) {this.userImage = userImage;}public String getIsRole() {return isRole;}public void setIsRole(String isRole) {this.isRole = isRole;}public String getCreateTime() {return createTime;}public void setCreateTime(String createTime) {this.createTime = createTime;}public String getSign() {return sign;}public void setSign(String sign) {this.sign = sign;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public String getAge() {return age;}public void setAge(String age) {this.age = age;}public String getBirthday() {return birthday;}public void setBirthday(String birthday) {this.birthday = birthday;}public String getNumberId() {return numberId;}public void setNumberId(String numberId) {this.numberId = numberId;}public String getEmotional() {return emotional;}public void setEmotional(String emotional) {this.emotional = emotional;}public String getUpdateTime() {return updateTime;}public void setUpdateTime(String updateTime) {this.updateTime = updateTime;}public String getUserstate() {return userstate;}public void setUserstate(String userstate) {this.userstate = userstate;}public Exp getExp() {return exp;}public void setExp(Exp exp) {this.exp = exp;}public long getExping() {return exping;}public void setExping(long exping) {this.exping = exping;}}

image对象

@Entity@Table(name = "image")public class ImageEntity implements Serializable{/** *  */private static final long serialVersionUID = 1L;@Id@GeneratedValue(strategy = GenerationType.IDENTITY)@Column(name = "imageId")private long imageId;private String url;public long getImageId() {return imageId;}public void setImageId(long imageId) {this.imageId = imageId;}public String getUrl() {return url;}public void setUrl(String url) {this.url = url;}}

exp对象

@Entity@Table(name = "exp")public class Exp {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)@Column(name = "expId")    private long expId;    private long grade;     //等级    private long expnumber; //经验值    private String expname; //显示名称public long getExtId() {return expId;}public void setExtId(long expId) {this.expId = expId;}public long getGrade() {return grade;}public void setGrade(long grade) {this.grade = grade;}public long getExpnumber() {return expnumber;}public void setExpnumber(long expnumber) {this.expnumber = expnumber;}public String getExpname() {return expname;}public void setExpname(String expname) {this.expname = expname;}    }

eventImage对象

@Entity@Table(name = "eventimage")public class EventImageEntity implements Serializable{/** *  */private static final long serialVersionUID = 1L;@Id@GeneratedValue(strategy = GenerationType.IDENTITY)@Column(name = "eventImageId")private long eventImageId;private long eventId;@OneToOne(optional = false, cascade = CascadeType.REFRESH)@JoinColumn(name = "imageId")private ImageEntity image;public long getEventImageId() {return eventImageId;}public void setEventImageId(long eventImageId) {this.eventImageId = eventImageId;}public long getEventId() {return eventId;}public void setEventId(long eventId) {this.eventId = eventId;}public ImageEntity getImage() {return image;}public void setImage(ImageEntity image) {this.image = image;}}