Java MySQLIntegrityConstraintViolationException
我在hibernate bt中实现了一对多关系，但我得到了一个复制密钥的错误，所以有点困惑该怎么做 如果有人能纠正我的错误，这将是一个grt的帮助，它实际上只是好几天我进入冬眠 这是我的大学课Java MySQLIntegrityConstraintViolationException,java,hibernate,Java,Hibernate,我在hibernate bt中实现了一对多关系，但我得到了一个复制密钥的错误，所以有点困惑该怎么做 如果有人能纠正我的错误，这将是一个grt的帮助，它实际上只是好几天我进入冬眠 这是我的大学课 package com.hibernate.arjun3; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; @Entity public cla
package com.hibernate.arjun3;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
public class College {
private String name;
@Id
@GeneratedValue
private int college_id;
private String location;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getCollege_id() {
return college_id;
}
public void setCollege_id(int college_id) {
this.college_id = college_id;
}
public String getLocation() {
return location;
}
public void setLocation(String location) {
this.location = location;
}
package com.hibernate.arjun3;
import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.CascadeType;
import javax.persistence.ElementCollection;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinTable;
import javax.persistence.OneToMany;
import javax.persistence.JoinColumn;
@Entity
public class Students {
private String firstname;
private String lastname;
@Id
@GeneratedValue
private int college_id;
@ElementCollection
@OneToMany(cascade = CascadeType.ALL)
@JoinTable(name="College_Students" , joinColumns=@JoinColumn(name="College_Id"))
private Collection<College> college = new ArrayList<College>();
public Collection<College> getCollege() {
return college;
}
public void setCollege(Collection<College> college) {
this.college = college;
}
public String getFirstname() {
return firstname;
}
public void setFirstname(String firstname) {
this.firstname = firstname;
}
public String getLastname() {
return lastname;
}
public void setLastname(String lastname) {
this.lastname = lastname;
}
public int getCollege_id() {
return college_id;
}
public void setCollege_id(int college_id) {
this.college_id = college_id;
}
谢谢你你的映射毫无意义 首先，我觉得有点奇怪，一个学生有很多学院，而不是相反：一个学院有很多学生。让我们忽略这一点，看看技术问题
package com.hibernate.arjun3;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
public class Main1 {
public static void main(String args[]) {
College colg = new College();
colg.setName("Vivekanand");
colg.setLocation("Chembur");
Students students = new Students();
students.setFirstname("Arjun");
students.setLastname("Narahari");
Students students2 = new Students();
students2.setFirstname("Sagar");
students2.setLastname("Abhyankar");
students.getCollege().add(colg);
students2.getCollege().add(colg);
SessionFactory factory = new AnnotationConfiguration().configure().buildSessionFactory();
Session session = factory.openSession();
session.beginTransaction();
session.save(students);
session.save(students2);
session.getTransaction().commit();
session.close();
factory.close();
}
@ElementCollection
@OneToMany(cascade = CascadeType.ALL)
@Entity
public class Students {
@Id
@GeneratedValue
private int college_id;
@JoinTable(name="College_Students" , joinColumns=@JoinColumn(name="College_Id"))
private Collection<College> college = new ArrayList<College>();
students.getCollege().add(colg);
students2.getCollege().add(colg);