Hibernate笔记7--JPA CRUD

1.环境搭建,注意包结构的问题,src下建立名为META-INF的文件夹,放persistence.xml,位置放错,读不到会报错.

    <?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_2_0.xsd"
         version="2.0">

         <!--配置持久化单元  -->
         <persistence-unit name="unit" transaction-type="RESOURCE_LOCAL">
             <!--配置jpa持久化类提供者  -->
             <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
             <!--配置数据库 Hibernate基本信息  -->
             <properties>
                 <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
                 <property name="hibernate.connection.url" value="jdbc:mysql:///day581"/>
                 <property name="hibernate.connection.username" value="root"/>
                 <property name="hibernate.connection.password" value="root"/>
                 <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
                 <property name="hibernate.hbm2ddl.auto" value="update"/>
                 <property name="hibernate.show_sql" value="true"/>
                 <property name="hibernate.format_sql" value="true"/>
                 <property name="hibernate.connection.isolation" value="4"/>
                     <!-- c3p0连接池 -->
                 <property name="hibernate.connection.provider_class" value="org.hibernate.connection.C3P0ConnectionProvider"/>
             </properties>
         </persistence-unit>
     </persistence>

2.实体类编写

package huguangqin.com.cnblogs.entity;
 import java.io.Serializable;
 import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
 import javax.persistence.Table;

@Entity
 @Table(name = "cst_customer")
 public class Customer implements Serializable {
     private static final long serialVersionUID = 1L;

    @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     @Column(name = "cust_id")
     private Long custId;

    @Column(name = "cust_name")
     private String custName;

    @Column(name = "cust_source")
     private String custSource;

    @Column(name = "cust_industry")
     private String custIndustry;

    @Column(name = "cust_level")
     private String custLevel;

    @Column(name = "cust_address")
     private String custAddress;

    @Column(name = "cust_phone")
     private String custPhone;

    public Long getCustId() {
         return custId;
     }

    public void setCustId(Long custId) {
         this.custId = custId;
     }

    public String getCustName() {
         return custName;
     }

    public void setCustName(String custName) {
         this.custName = custName;
     }

    public String getCustSource() {
         return custSource;
     }

    public void setCustSource(String custSource) {
         this.custSource = custSource;
     }

    public String getCustIndustry() {
         return custIndustry;
     }

    public void setCustIndustry(String custIndustry) {
         this.custIndustry = custIndustry;
     }

    public String getCustLevel() {
         return custLevel;
     }

    public void setCustLevel(String custLevel) {
         this.custLevel = custLevel;
     }

    public String getCustAddress() {
         return custAddress;
     }

    public void setCustAddress(String custAddress) {
         this.custAddress = custAddress;
     }

    public String getCustPhone() {
         return custPhone;
     }

    public void setCustPhone(String custPhone) {
         this.custPhone = custPhone;
     }

    // toString
     @Override
     public String toString() {
         return "Customer [custId=" + custId + ", custName=" + custName + ", custSource=" + custSource
                 + ", custIndustry=" + custIndustry + ", custLevel=" + custLevel + ", custAddress=" + custAddress
                 + ", custPhone=" + custPhone + "]";
     }

}

3.工具类-JPAUtil,用于启动创建一次EntityManagerFactory,并获取EntityManager
   

 package huguangqin.com.cnblogs.util;
     import javax.persistence.EntityManager;
     import javax.persistence.EntityManagerFactory;
     import javax.persistence.Persistence;

    public class JPAUtil {
         private static EntityManagerFactory factory;

        static {
             factory = Persistence.createEntityManagerFactory("unit");
         }

        public static EntityManager getEntityManager() {
             return factory.createEntityManager();
         }
     }

4.测试代码

package huguangqin.com.cnblogs.demo;

import javax.persistence.EntityManager;
 import javax.persistence.EntityTransaction;

import org.junit.Test;

import huguangqin.com.cnblogs.entity.Customer;
 import huguangqin.com.cnblogs.util.JPAUtil;

/**
  * 保存一个数据到客户表中:persist
  */
 public class JPATest1 {
     @Test
     public void addTest() {
         // 获取EntityManager
         EntityManager em = JPAUtil.getEntityManager();
         // 得到事务对象
        EntityTransaction et = em.getTransaction();
         // 开启事务
        et.begin();
         // CRUD
         Customer cust = new Customer();
         cust.setCustName("阿里");
         // 持久化
        em.persist(cust);
         // 提交事务
        et.commit();
         // 关闭资源
        em.close();
     }

    /**
      * 根据id查询:find
      */
     @Test
     public void findTest() {
         // 获取EntityManager
         EntityManager em = JPAUtil.getEntityManager();
         // 得到事务对象
        EntityTransaction et = em.getTransaction();
         // 开启事务
        et.begin();
         // 根据ID查询
        Customer customer = em.find(Customer.class, 1L);
         System.out.println(customer);

        // 提交事务
        et.commit();
         // 关闭资源
        em.close();
     }

    /**
      * 延迟加载测试(getReference),用到的时候才发送sql
      */
    @Test
     public void delayTest() {
         // 获取EntityManager
         EntityManager em = JPAUtil.getEntityManager();
         // 获取事务对象
        EntityTransaction et = em.getTransaction();
        // 开启事务
        et.begin();
         // 延迟加载
        Customer cust = em.getReference(Customer.class, 1L);
         System.out.println(cust);
         // 提交事务
        et.commit();
         // 关闭资源
        em.close();
     }

    /**
      * 修改:查询-修改(setter)
      */
     @Test
     public void updateTest() {
         // 获取EntityManager
         EntityManager em = JPAUtil.getEntityManager();
         // 获取事务对象
        EntityTransaction et = em.getTransaction();
         // 开启事务
        et.begin();
         // 修改
        Customer cust = em.find(Customer.class, 1L);
         cust.setCustName("Tecent");

        // 提交事务
        et.commit();
         // 关闭资源
        em.close();
     }

    /**
      *删除 remove
      */
     @Test
     public void delTest() {
         // 获取EntityManager
         EntityManager em = JPAUtil.getEntityManager();
         // 获取事务对象
        EntityTransaction et = em.getTransaction();
         // 开启事务
        et.begin();
         // 删除
        Customer cust = em.find(Customer.class, 1L);
         em.remove(cust);
         // 提交事务
        et.commit();
         // 关闭资源
        em.close();
     }
 }