Hibernate 多对多映射package com.entity.manytomany;import java.util.List;import javax.persistence.Entity;import javax.persistence.JoinColumn;import javax.persistence.JoinTable;import javax.persistence.ManyToMany;import com.entity.BaseEntity;@Entitypublic class Student extends BaseEntity{PRivate String name;@ManyToMany//学生是不稳定的一方 所以由学生来维护@JoinTable(name="student_course",joinColumns=@JoinColumn(name="s_id"),inverseJoinColumns=@JoinColumn(name="c_id"))//关联表的表名//关联当前表的主键//关联对方表的主键 （）内的name即关联表内的字段名 可以自己自由设计private List<Course> courses;public String getName() {return name;}public void setName(String name) {this.name = name;}public List<Course> getCourses() {return courses;}public void setCourses(List<Course> courses) {this.courses = courses;}}
student.java
package com.entity.manytomany;import java.util.List;import javax.persistence.Entity;import javax.persistence.ManyToMany;import com.entity.BaseEntity;@Entitypublic class Course extends BaseEntity{private String name;@ManyToMany(mappedBy ="courses")//被学生类的courses对象维护private List<Student> students;public String getName() {return name;}public void setName(String name) {this.name = name;}public List<Student> getStudents() {return students;}public void setStudents(List<Student> students) {this.students = students;}}
Course.java
package com;import java.util.ArrayList;import java.util.List;import org.hibernate.session;import org.hibernate.Transaction;import org.junit.After;import org.junit.Before;import org.junit.Test;import com.entity.manytomany.Course;import com.entity.manytomany.Student;public class TestManyToMany {private Session s;private Transaction tran;@Beforepublic void before(){s=HibernateUtils.getSession();tran=s.beginTransaction();}public void manytomany(){Course c1=new Course();Course c2=new Course();Course c3=new Course();Student stu1=new Student();Student stu2=new Student();Student stu3=new Student();stu1.setName("zhangsan");stu2.setName("lisi");stu3.setName("wangwu");c1.setName("java");c2.setName("Oracle");c3.setName("html");//新建对象List<Course> courses =new ArrayList<Course>();//建立了一个课程集合List<Course> courses1 =new ArrayList<Course>();courses1.add(c2);courses1.add(c3);courses.add(c1);courses.add(c2);courses.add(c3);//向集合中插入要选的课程stu1.setCourses(courses);stu2.setCourses(courses);stu3.setCourses(courses1);//建立关联 将课程集合set到学生的课程属性中 即学生选择了集合中所有的课程s.save(c1);s.save(c2);s.save(c3);s.save(stu1);s.save(stu2);s.save(stu3);}@Testpublic void manytomanyquery(){Course c=(Course)s.get(Course.class, 1);for(Student s:c.getStudents()){System.out.println(c.getName()+"-------选这门课的学生"+s.getName());}Course c1=(Course)s.get(Course.class, 2);for(Student s:c1.getStudents()){System.out.println(c1.getName()+"-------选这门课的学生"+s.getName());}Course c2=(Course)s.get(Course.class, 3);for(Student s:c2.getStudents()){System.out.println(c1.getName()+"-------选这门课的学生"+s.getName());}}@Afterpublic void after(){tran.commit();s.close();}}
testmanytomany.java