jpa入门案例

persistence.xml

<?xml version="1.0" encoding="UTF-8"?>

<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0">

  <!-- persistence-unit

       name指定持久化单元的名字

       transaction-type指定事务类型为本地事务

  -->

  <persistence-unit name="jpaDemo" transaction-type="RESOURCE_LOCAL">

      <properties>

         <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect"/>

         <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>

         <property name="hibernate.connection.username" value="root"/>

         <property name="hibernate.connection.password" value="root"/>

         <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/mysql?useUnicode=true&amp;characterEncoding=UTF-8"/>

         <property name="hibernate.hbm2ddl.auto" value="update"/>

         <property name="hibernate.show_sql" value="true"/>

      </properties>

  </persistence-unit>

</persistence>

Person.java

package com.morris.entity;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

@Entity

public class Person {

    @Id

    @GeneratedValue

    private Integer id;

    private String name;

    private Integer age;

    public Integer getId() {

       return id;

    }

    public void setId(Integer id) {

       this.id = id;

    }

    public String getName() {

       return name;

    }

    public void setName(String name) {

       this.name = name;

    }

    public Integer getAge() {

       return age;

    }

    public void setAge(Integer age) {

       this.age = age;

    }

    public Person( String name, Integer age) {

       super();

       this.name = name;

       this.age = age;

    }

    public Person() {

       super();

       // TODO Auto-generated constructor stub

    }

    @Override

    public String toString() {

       return "Person [id=" + id + ", name=" + name + ", age=" + age + "]";

    }

}

TestPerson.java

package com.morris.entity;

import javax.persistence.EntityManager;

import javax.persistence.EntityManagerFactory;

import javax.persistence.Persistence;

import org.junit.Test;

public class TestPerson {

    @Test

    public void save() {

       //实体管理工厂类 jpaDemo为配置文件中持久化单元名

       EntityManagerFactory factory = Persistence.createEntityManagerFactory("jpaDemo");

       //尸体管理器

       EntityManager manager = factory.createEntityManager();

       //开始事务

       manager.getTransaction().begin();

       //持久化person对象

       manager.persist(new Person("morris", 22));

       //提交事务

       manager.getTransaction().commit();

       //关闭资源

       manager.close();

       factory.close();

    }

}

后台打印sql语句：

Hibernate: insert into Person (age, name) values (?, ?)