在JPA中, 我们可以轻松地通过实体将数据插入数据库。 EntityManager提供了persist()方法来插入记录。
JPA实体插入示例
在这里, 我们将插入学生的记录。
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, 该实体类包含属性s_id, s_name, s_age。
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>
<
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>
- 在com.srcmini.jpa.persist包下创建一个名为PersistStudent.java的持久性类, 以将实体对象与数据持久化。
package com.srcmini.jpa.persist;
import com.srcmini.jpa.student.*;
import javax.persistence.*;
public class PersistStudent { public static void main(String args[]) {EntityManagerFactory emf=Persistence.createEntityManagerFactory("Student_details");
EntityManager em=emf.createEntityManager();
em.getTransaction().begin();
StudentEntity s1=new StudentEntity();
s1.setS_id(101);
s1.setS_name("Gaurav");
s1.setS_age(24);
StudentEntity s2=new StudentEntity();
s2.setS_id(102);
s2.setS_name("Ronit");
s2.setS_age(22);
StudentEntity s3=new StudentEntity();
s3.setS_id(103);
s3.setS_name("Rahul");
s3.setS_age(26);
em.persist(s1);
em.persist(s2);
em.persist(s3);
em.getTransaction().commit();
emf.close();
em.close();
}}输出：
【JPA插入实体】程序执行后, 将在MySQL工作台下生成Student表, 该表包含学生详细信息, 要获取数据, 请在MySQL中从Student查询中运行select *。
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