JPA插入实体

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。

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="com.mysql.jdbc.Driver"/>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/studentdata"/>
<property name="javax.persistence.jdbc.user" value="root"/>
<property name="javax.persistence.jdbc.password" value=""/>
<property name="eclipselink.logging.level" value="SEVERE"/>
<property name="eclipselink.ddl-generation" value="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。

PersistStudent.java

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：

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 *。