JPA删除实体 JPA删除实体|JPA

要从数据库中删除一条记录, EntityManager接口提供了remove()方法。 remove()方法使用主键删除特定记录。
JPA实体删除示例 【JPA删除实体】在这里, 我们将删除学生的特定记录。
本示例包含以下步骤：-

在com.srcmini.jpa.student包下创建一个名为StudentEntity.java的实体类, 该实体类包含s_id, s_name和s_age属性。

StudentEntity.java

package com.srcmini.jpa.student; import javax.persistence.*; @Entity@Table(name="student")public class StudentEntity { @Id private int s_id; private String s_name; private int s_age; public StudentEntity(int s_id, String s_name, int s_age) {super(); this.s_id = s_id; this.s_name = s_name; this.s_age = s_age; } public StudentEntity() {super(); } public int getS_id() {return s_id; } public void setS_id(int s_id) {this.s_id = s_id; } public String getS_name() {return s_name; } public void setS_name(String s_name) {this.s_name = s_name; } public int getS_age() {return s_age; } public void setS_age(int s_age) {this.s_age = s_age; } }

现在, 在Persistence.xml文件中映射实体类和其他数据库配置。

Persistence.xml

< persistence> < persistence-unit name="Student_details"> < class> com.srcmini.jpa.student.StudentEntity< /class> < properties> < property name="javax.persistence.jdbc.driver" value="http://www.srcmini.com/com.mysql.jdbc.Driver"/> < property name="javax.persistence.jdbc.url" value="http://www.srcmini.com/jdbc:mysql://localhost:3306/studentdata"/> < property name="javax.persistence.jdbc.user" value="http://www.srcmini.com/root"/> < property name="javax.persistence.jdbc.password" value=""/> < property name="eclipselink.logging.level" value="http://www.srcmini.com/SEVERE"/> < property name="eclipselink.ddl-generation" value="http://www.srcmini.com/create-or-extend-tables"/> < /properties> < /persistence-unit> < /persistence>

Deletion.java

package com.srcmini.jpa.delete; import javax.persistence.*; import com.srcmini.jpa.student.*; public class DeleteStudent { public static void main(String args[]) { EntityManagerFactory emf=Persistence.createEntityManagerFactory("Student_details"); EntityManager em=emf.createEntityManager(); em.getTransaction().begin(); StudentEntity s=em.find(StudentEntity.class, 102); em.remove(s); em.getTransaction().commit(); emf.close(); em.close(); }}

输出：
程序执行后, 将在MySQL工作台下生成Student表, 该表包含Student详细信息。要获取数据, 请在MySQL中从学生查询中运行select *。
删除前