学步园

Student.java

package com.aspn.hibernate;</p> <p>import java.util.HashSet;<br /> import java.util.Set;</p> <p>import javax.persistence.Entity;<br /> import javax.persistence.GeneratedValue;<br /> import javax.persistence.Id;<br /> import javax.persistence.JoinColumn;<br /> import javax.persistence.JoinTable;<br /> import javax.persistence.ManyToMany;</p> <p>@Entity<br /> public class Student {<br /> private int id;<br /> private String name;<br /> private Set<Course> courses = new HashSet<Course>();</p> <p> @ManyToMany<br /> @JoinTable(name="score",<br /> joinColumns=@JoinColumn(name="student_id", referencedColumnName="id"),<br /> inverseJoinColumns=@JoinColumn(name="course_id", referencedColumnName="id")<br /> )<br /> public Set<Course> getCourses() {<br /> return courses;<br /> }<br /> public void setCourses(Set<Course> courses) {<br /> this.courses = courses;<br /> }<br /> @Id<br /> @GeneratedValue<br /> public int getId() {<br /> return id;<br /> }<br /> public void setId(int id) {<br /> this.id = id;<br /> }<br /> public String getName() {<br /> return name;<br /> }<br /> public void setName(String name) {<br /> this.name = name;<br /> }</p> <p>}<br />

Course.java

package com.aspn.hibernate;</p> <p>import javax.persistence.Entity;<br /> import javax.persistence.GeneratedValue;<br /> import javax.persistence.Id;</p> <p>@Entity<br /> public class Course {<br /> private int id;<br /> private String name;<br /> @Id<br /> @GeneratedValue<br /> public int getId() {<br /> return id;<br /> }<br /> public void setId(int id) {<br /> this.id = id;<br /> }<br /> public String getName() {<br /> return name;<br /> }<br /> public void setName(String name) {<br /> this.name = name;<br /> }</p> <p>}<br />

Score.java

package com.aspn.hibernate;</p> <p>import javax.persistence.Entity;<br /> import javax.persistence.GeneratedValue;<br /> import javax.persistence.Id;<br /> import javax.persistence.JoinColumn;<br /> import javax.persistence.ManyToOne;<br /> import javax.persistence.Table;</p> <p>@Entity<br /> @Table(name="score")<br /> public class Score {<br /> private int id;<br /> private int score;<br /> private Student student;<br /> private Course course;<br /> @Id<br /> @GeneratedValue<br /> public int getId() {<br /> return id;<br /> }<br /> public void setId(int id) {<br /> this.id = id;<br /> }<br /> public int getScore() {<br /> return score;<br /> }<br /> public void setScore(int score) {<br /> this.score = score;<br /> }<br /> @ManyToOne<br /> @JoinColumn(name="student_id")<br /> public Student getStudent() {<br /> return student;<br /> }<br /> public void setStudent(Student student) {<br /> this.student = student;<br /> }</p> <p> @ManyToOne<br /> @JoinColumn(name="course_id")<br /> public Course getCourse() {<br /> return course;<br /> }<br /> public void setCourse(Course course) {<br /> this.course = course;<br /> }</p> <p>}<br />

 Student表里面用了

@ManyToMany
 @JoinTable(name="score",
  joinColumns=@JoinColumn(name="student_id", referencedColumnName="id"),
  inverseJoinColumns=@JoinColumn(name="course_id", referencedColumnName="id")
  )
 public Set<Course> getCourses() {
  return courses;
 }

这里JoinTable是自己创建一个临时表，可是已经有了score的表，所以那里面累加字段，

Student->course   inverseJoinColumns 的意思是 过 Student->score->course 应该是这样的过程。。。务必记住他