hibernate多对多关系-注解配置

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~