Spring Data Jpa初体验(内含demo)

<!-- spring-data-jpa -->
<dependency>
  <groupId>org.springframework.data</groupId>
  <artifactId>spring-data-jpa</artifactId>
</dependency>

<dependency>
  <groupId>org.hibernate</groupId>
  <artifactId>hibernate-core</artifactId>
  <version>5.3.7.Final</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-annotations -->
<dependency>
  <groupId>org.hibernate</groupId>
  <artifactId>hibernate-annotations</artifactId>
  <version>3.5.6-Final</version>
</dependency>

<dependency>
  <groupId>com.zaxxer</groupId>
  <artifactId>HikariCP</artifactId>
  <version>3.2.0</version>
</dependency>

server:
  port: 9999

spring:
  profiles:
    active: local
  datasource:
    type: com.zaxxer.hikari.HikariDataSource
    hikari:
      minimum-idle: 0
      initial-size: 5
      maximum-pool-size: 15
      auto-commit: true
      pool-name: NezhaHikariCP
      test-connection-on-checkout: true

  jpa:
    database: MYSQL
    database-platform: org.hibernate.dialect.MySQL5InnoDBDialect

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://127.0.0.1/test?characterEncoding=utf8&useSSL=false
    username: root
    password: root
  jpa:
    show-sql: true

mysql> desc student;
+------------+-------------+------+-----+---------------------+-----------------------------+
| Field      | Type        | Null | Key | Default             | Extra                       |
+------------+-------------+------+-----+---------------------+-----------------------------+
| id         | int(10)     | NO   |     | NULL                |                             |
| name       | varchar(45) | NO   | PRI | NULL                |                             |
| class_num  | int(12)     | YES  |     | NULL                |                             |
| age        | int(3)      | YES  |     | 18                  |                             |
| created_at | timestamp   | NO   |     | CURRENT_TIMESTAMP   |                             |
| updated_at | timestamp   | NO   |     | 2018-01-01 00:00:00 | on update CURRENT_TIMESTAMP |
+------------+-------------+------+-----+---------------------+-----------------------------+
6 rows in set (0.01 sec)

CREATE TABLE `student` (
 `id` int(10) NOT NULL AUTO_INCREMENT COMMENT 'id',
 `name` varchar(45) NOT NULL COMMENT '姓名',
 `class_num` int(12) DEFAULT NULL COMMENT '班级',
 `age` int(3) DEFAULT '18' COMMENT '年龄',
 `created_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
 `updated_at` timestamp NOT NULL DEFAULT '2018-01-01 00:00:00' ON UPDATE CURRENT_TIMESTAMP COMMENT '修改时间',
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8

package com.huyan.demo.model;

import java.util.Date;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

/**
 * created by huyanshi on 2018/12/21
 */
@AllArgsConstructor
@Builder
@Data
@NoArgsConstructor
@Entity
@Table(name = "student")
public class Student {

  @Id
  private int id;

  private String name;

  private int classNum;

  private  int age;

  @Temporal(TemporalType.TIMESTAMP)
  private Date createdAt;

  @Temporal(TemporalType.TIMESTAMP)
  private Date updatedAt;
}

package com.huyan.demo.dao;

import com.huyan.demo.model.Student;
import java.util.List;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

/**
 * created by huyanshi on 2018/12/21
 */
@Repository
public interface StudentDao extends JpaRepository<Student,String> {

  List<Student> findAll();
}

@Repository
public interface StudentDao extends JpaRepository<Student, Integer> {

  //查询所有
  List<Student> findAll();
  //查询年龄大于传入值得
  List<Student> findByAgeAfter(int age);
  //查询年龄和班级等于入参的
  List<Student> findByAgeAndClassNum(int age, int classNum);
  //查询年龄为入参的学生,且结果按照创建时间排序
  List<Student> findByAgeOrderByCreatedAt(int age);
  //根据主键更新实体的名字年龄及班级
  @Modifying(clearAutomatically = true)
  @Transactional
  @Query(value = "UPDATE Student SET name = :name, classNum = :classNum, "
      + "age = :age WHERE id = :id ")
  int updateNameAndAgeAndClassNumById(@Param("name") String name, @Param("age") int age,
      @Param("classNum") int classNum, @Param("id") int id);

}