Eclipselink Jpa 之 映射类型（多对一）

技术：Eclipselink Jpa + Lombok +mysql8.0.13 package com.atsico.pojo;

import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import lombok.experimental.Accessors;

import javax.persistence.*;

@Entity @Data @NoArgsConstructor @AllArgsConstructor @Accessors(chain = true) public class Course {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int c_id;
private String c_name;

@ManyToOne
private Stu stu;

}

package com.atsico.pojo;

import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import lombok.experimental.Accessors;

import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import ;

@Entity @Data @NoArgsConstructor @AllArgsConstructor @Accessors(chain = true) public class Stu {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int s_id;
private String s_name;

}

<properties>
        <!-- 连接数据库的基本信息 -->
        <property name="javax.persistence.jdbc.driver"
                  value="com.mysql.cj.jdbc.Driver"/>
        <property name="javax.persistence.jdbc.url"
                  value="jdbc:mysql://localhost:3306/jpadb?useSSL=false&amp;serverTimezone=Asia/Shanghai"/>
        <property name="javax.persistence.jdbc.user" value="root"/>
        <property name="javax.persistence.jdbc.password"
                  value="root"/>
        <property name="eclipselink.logging.level" value="all"/>
        <property name="eclipselink.ddl-generation"
                  value="create-or-extend-tables"/>
        <property name="eclipselink.show_sql" value="true"/>
    </properties>
</persistence-unit>

package com.atsico.service;

import com.atsico.pojo.Course; import com.atsico.pojo.LibraryPojo; import com.atsico.pojo.Stu; import com.atsico.pojo.StudentPojo; import org.junit.Test;

import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.EntityTransaction; import javax.persistence.Persistence; import java.util.LinkedList;

public class Jpa_Mapping_Test {

@Test
public void test_many2one() {
    EntityManagerFactory emf =
            Persistence.createEntityManagerFactory("myPersistUnit");
    EntityManager em = emf.createEntityManager();
    EntityTransaction ts = em.getTransaction();
    ts.begin();
    /******************************************主体部分********************************************/
    Stu stu = new Stu();
    stu.setS_id(1);
    stu.setS_name("Tom");

    em.persist(stu);

    Course c1 = new Course();
    c1.setC_id(101);
    c1.setC_name("Math");
    c1.setStu(stu);

    Course c2 = new Course();
    c2.setC_id(102);
    c2.setC_name("English");
    c2.setStu(stu);

    em.persist(c1);
    em.persist(c2);

    /******************************************主体部分********************************************/
    ts.commit();
    em.close();
    emf.close();

}

}

运行正常