hibernate多对多注解配置
上一篇文章主要讲解了Hibernate多对多配置文件的配置方法，接下来继续讲解注解方式配置多对多关系的方法。注解功能已经加入hibernate4之中了，但hibernate3要使用注解配置还需要另外引入jar包。
需要的jar包可见附件：
接下来开始进入正题：
一、第一种直接配置多对多关系，以Role角色-Right权限为例。
import java.util.Date;
import java.util.List;
import javax.persistence.*;
import org.hibernate.annotations.GenericGenerator;
@Entity
@Table(name="SYS_ROLE")
public class Role{
private String role_id;
private String role_name;
private Date cre_time;
private String parent_id;
private String describe;
private int sort;
private List<Right> rights;
@Id
@GeneratedValue(generator = "paymentableGenerator")
@GenericGenerator(name = "paymentableGenerator", strategy = "uuid")
public String getRole_id() {
return role_id;
}
public void setRole_id(String roleId) {
role_id = roleId;
}
@Column(name="role_name")
public String getRole_name() {
return role_name;
}
public void setRole_name(String roleName) {
role_name = roleName;
}
@Column(name="cre_time")
public Date getCre_time() {
return cre_time;
}
public void setCre_time(Date creTime) {
cre_time = creTime;
}
@Column(name="parent_id")
public String getParent_id() {
return parent_id;
}
public void setParent_id(String parentId) {
parent_id = parentId;
}
@Column(name="describe")
public String getDescribe() {
return describe;
}
public void setDescribe(String describe) {
this.describe = describe;
}
@Column(name="sort")
public int getSort() {
return sort;
}
public void setSort(int sort) {
this.sort = sort;
}
//多对多映射
@ManyToMany(targetEntity = Right.class, fetch = FetchType.LAZY)
@JoinTable(name = "ROLE_RIGHT", joinColumns = @JoinColumn(name = "ROLE_ID"), inverseJoinColumns = @JoinColumn(name = "RIGHT_ID"))
public List<Right> getRights() {
return rights;
}
public void setRights(List<Right> rights) {
this.rights = rights;
}
@Override
public String toString() {
return "Role [cre_time=" + cre_time + ", describe=" + describe
+ ", parent_id=" + parent_id + ", role_id=" + role_id
+ ", role_name=" + role_name + ", sort=" + sort + "]";
}
}
import java.util.List;
import javax.persistence.*;
import org.hibernate.annotations.GenericGenerator;
@Entity
@Table(name="SYS_RIGHTS")
public class Right{
private String right_id;
private String right_name;
private String url;
private String parent_id;
private int lev;
private int sort;
private List<Role> roles;
@Id
@GeneratedValue(generator = "paymentableGenerator")
@GenericGenerator(name = "paymentableGenerator", strategy = "uuid")
public String getRight_id() {
return right_id;
}
public void setRight_id(String rightId) {
right_id = rightId;
}
@Column(name="right_name")
public String getRight_name() {
return right_name;
}
public void setRight_name(String rightName) {
right_name = rightName;
}
@Column(name="url")
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
@Column(name="parent_id")
public String getParent_id() {
return parent_id;
}
public void setParent_id(String parentId) {
parent_id = parentId;
}
@Column(name="lev")
public int getLev() {
return lev;
}
public void setLev(int lev) {
this.lev = lev;
}
@Column(name="sort")
public int getSort() {
return sort;
}
public void setSort(int sort) {
this.sort = sort;
}
//多对多映射
@ManyToMany(mappedBy="rights")
public List<Role> getRoles() {
return roles;
}
public void setRoles(List<Role> roles) {
this.roles = roles;
}
@Override
public String toString() {
return "Right [lev=" + lev + ", parent_id=" + parent_id + ", right_id="
+ right_id + ", right_name=" + right_name
+ ", sort=" + sort + ", url=" + url + "]";
}
}
最后，在hibernate-cfg.xml文件中配置对应的Role和Right实体即可。
<mapping class="com.entor.hibernate.manytomany.Role"/> <mapping class="com.entor.hibernate.manytomany.Right"/>
到这里一个多对多配置就完成了。
常用的注解：
1.@Entity 声明实体
2.@Table(name="SYS_ROLE") 声明实体类对应的表名
3.@Column(name="role_name") 声明属性对应的列
4.@Id @GeneratedValue(generator = "paymentableGenerator") @GenericGenerator(name = "paymentableGenerator", strategy = "uuid")
声明主键及生成策略，在这里uid的生成策略
5. @OneToOne(mappedBy="card") 一对一映射
6.@OneToMany(fetch = FetchType.LAZY, mappedBy = "student") 一对多映射
7.@ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "student")
多对一映射
8.@ManyToMany(targetEntity = Right.class, fetch = FetchType.LAZY)
@JoinTable(name = "ROLE_RIGHT", joinColumns = @JoinColumn(name = "ROLE_ID"), inverseJoinColumns = @JoinColumn(name = "RIGHT_ID"))
多对多映射
9.@Transient 表示该属性并非一个到数据库表的字段的映射,ORM框架将忽略该属性
二、第二种情况，就是在中间实体中配置两个多对一关系，以学生Student-成绩Score-课程Course为例。
import java.util.List;
import javax.persistence.*;
import org.hibernate.annotations.GenericGenerator;
@Entity
@Table(name="student")
public class Student {
private String id;
private String name;
private List<Score> scoreList;
@Id
@GeneratedValue(generator = "paymentableGenerator")
@GenericGenerator(name = "paymentableGenerator", strategy = "uuid")
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
@Column(name="name")
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
//学生端一对多，学生的成绩列表，也可以选择不配置
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "student")
public List<Score> getScoreList() {
return scoreList;
}
public void setScoreList(List<Score> scoreList) {
this.scoreList = scoreList;
}
@Override
public String toString() {
return "Student [id=" + id + ", name=" + name + "]";
}
}
import javax.persistence.*;
import org.hibernate.annotations.GenericGenerator;
@Entity
@Table(name="score")
public class Score {
private String id;//主键id
private Student student;//学生id
private Course course;//课程id
private int score;//成绩
@Id
@GeneratedValue(generator = "paymentableGenerator")
@GenericGenerator(name = "paymentableGenerator", strategy = "uuid")
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
//多对一映射
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "student")
public Student getStudent() {
return student;
}
public void setStudent(Student student) {
this.student = student;
}
//多对一映射
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "course")
public Course getCourse() {
return course;
}
public void setCourse(Course course) {
this.course = course;
}
@Column(name="score")
public int getScore() {
return score;
}
public void setScore(int score) {
this.score = score;
}
@Override
public String toString() {
return "Score [course=" + course.getName() + ", score=" + score + ", student="
+ student.getName() + "]";
}
}
import java.util.List;
import javax.persistence.*;
import org.hibernate.annotations.GenericGenerator;
@Entity
@Table(name="course")
public class Course {
private String id;
private String name;
private List<Score> scoreList;
@Id
@GeneratedValue(generator = "paymentableGenerator")
@GenericGenerator(name = "paymentableGenerator", strategy = "uuid")
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
@Column(name="name")
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
//课程端一对多，课程的成绩列表，也可以选择不配置
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "course")
public List<Score> getScoreList() {
return scoreList;
}
public void setScoreList(List<Score> scoreList) {
this.scoreList = scoreList;
}
@Override
public String toString() {
return "Course [id=" + id + ", name=" + name + "]";
}
}
以上就是多对多两种情况的注解配置方法了，注解方式真的是很优秀的配置方法，很直观很简洁一目了然，也不需要另外配置xml文件，直接在实体类文件中注明数据库关系映射的情况即可，开发效率提高很明显，我用过注解配置之后都不想用配置文件来配置了，哈哈~