java多对一单项关联

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实质是多的一方加外键：user为多的一方。
package hibernate002test.copy;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Groups {

 private int id;
 private String name;
 @Id
 @GeneratedValue
public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}

}
package hibernate002test.copy;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToOne;

@Entity
public class User {

private int userid;
private String username;
private Groups groups;
@ManyToOne
public Groups getGroups() {
    return groups;
}
public void setGroups(Groups groups) {
    this.groups = groups;
}
@Id
@GeneratedValue
public int getUserid() {
    return userid;
}
public void setUserid(int userid) {
    this.userid = userid;
}
public String getUsername() {
    return username;
}
public void setUsername(String username) {
    this.username = username;
}

}
测试类
package datatest;

import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
/**
* 在一对一双向关联时要使用例如：@OneToOne(mappedBy=”wife”)
* @author Lenovo
*
*/
public class Test {

@org.junit.Test
public void test() {
   new SchemaExport(new AnnotationConfiguration().configure()).create(false,true);
}

}