JPA是java Persistence API简称,中文名:java持久层API,JPA是JCP组织发布的J2EE标准之一

1.创建DataSource连接池对象

 1 <dependency>
 2             <groupId>org.springframework.boot</groupId>
 3             <artifactId>spring-boot-starter-jdbc</artifactId>
 4         </dependency>
 5         <!-- 数据库驱动 -->
 6         <dependency>
 7             <groupId>com.oracle</groupId>
 8             <artifactId>ojdbc6</artifactId>
 9             <version>11.2.0.3</version>
10         </dependency>

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2.在pom.xml中定义spring-boot-starter-data-jpa

1 <!-- 定义spring-boot-starter-data-jpa -->
2           <dependency>
3               <groupId>org.springframework.boot</groupId>
4               <artifactId>spring-boot-starter-data-jpa</artifactId>
5           </dependency>

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3.根据数据库表定义实体类

 1 package cn.xdl.entity;
 2 
 3 import java.io.Serializable;
 4 
 5 import javax.persistence.Column;
 6 import javax.persistence.Entity;
 7 import javax.persistence.Id;
 8 import javax.persistence.Table;
 9 
10 @Entity
11 @Table(name="EMP")  //通常和@Entity配合使用,只能标注在实体的class定义处,表示实体对应的数据库表的信息
12 public class Emp implements Serializable{
13     /**
14      * 
15      */
16     private static final long serialVersionUID = 1L;
17     @Id  //定义了映射到数据库表的主键的属性,一个实体只能有一个属性被映射为主键置于getXxxx()前
18     @Column(name="EMPNO")  //name表示表的名称默认地,表名和实体名称一致,只有在不一致的情况下才需要指定表名
19     private Integer empno;
20     @Column(name="ENAME")
21     private String ename;
22     @Column(name="JOB")
23     private String job;
24     @Column(name="MGR")
25     private int mgr;
26     public Integer getEmpno() {
27         return empno;
28     }
29     public void setEmpno(Integer empno) {
30         this.empno = empno;
31     }
32     public String getEname() {
33         return ename;
34     }
35     public void setEname(String ename) {
36         this.ename = ename;
37     }
38     public String getJob() {
39         return job;
40     }
41     public void setJob(String job) {
42         this.job = job;
43     }
44     public int getMgr() {
45         return mgr;
46     }
47     public void setMgr(int mgr) {
48         this.mgr = mgr;
49     }
50     @Override
51     public String toString() {
52         return "Emp [empno=" + empno + ", ename=" + ename + ", job=" + job + ", mgr=" + mgr + "]";
53     }
54 }

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4.定义Dao接口,继承JPA功能接口

 1 package cn.xdl.jpa;
 2 
 3 import org.springframework.data.jpa.repository.JpaRepository;
 4 
 5 import cn.xdl.entity.Emp;
 6 //JpaRepository:JPA资源库
 7 /**
 8  * 1.所有继承该接口的都被spring所管理，改接口作为标识接口，功能就是用来控制domain模型的
 9  * 2.Spring Data可以让我们只定义接口，只要遵循spring data的规范,无需写实现类。 
10  *
11  */
12 public interface EmpDao extends JpaRepository<Emp, Integer>{
13 
14 }

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5.获取Dao接口对象操作数据库

 1 @SpringBootApplication
 2 public class MyBootApplication {
 3     public static void main(String[] args) throws SQLException {
 4         ApplicationContext ioc = SpringApplication.run(MyBootApplication.class, args);
 5         // 自动配置创建DataSource，id名为dataSource
 6         DataSource ds = ioc.getBean("dataSource", DataSource.class);
 7         System.out.println(ds);
 8         System.out.println("=================");
 9         System.out.println("=================");
10         System.out.println("=================");
11         EmpDao empDao = ioc.getBean("empDao", EmpDao.class);
12         /**
13          * 遍历
14          */
15         List<Emp> empdatas = empDao.findAll();
16         for (Emp emp : empdatas) {
17             System.out.println(emp);
18         }
19     }
20 }

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