Spring Boot 揭秘与实战（二）数据存储篇

文章目录

本文讲解 Spring Boot 基础下，如何整合 JPA 框架，编写数据访问。

环境依赖

修改 POM 文件，添加 spring-boot-starter-data-jpa 依赖。

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

添加 mysql 依赖。

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.35</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.0.14</version>
</dependency>

数据源

使用 Spring Boot 默认配置, 在 src/main/resources/application.properties 中配置数据源信息。

spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/springboot_db
spring.datasource.username=root
spring.datasource.password=root

通过 Java Config 方式配置。

@Configuration
@EnableJpaRepositories("com.lianggzone.springboot.action.data.jpa")
@EntityScan("com.lianggzone.springboot.action.data.jpa.entity")
public class JPAConfig {}

脚本初始化

先初始化需要用到的SQL脚本。

CREATE DATABASE /*!32312 IF NOT EXISTS*/`springboot_db` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `springboot_db`;
DROP TABLE IF EXISTS `t_author`;
CREATE TABLE `t_author` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT COMMENT '用户ID',
`real_name` varchar(32) NOT NULL COMMENT '用户名称',
`nick_name` varchar(32) NOT NULL COMMENT '用户匿名',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

JPA 整合方案一通过继承 JpaRepository 接口

实体对象

创建一个 Author 实体，真实的表名是 t_author，包含 id（自增主键）、 realName、 nickname 字段。

@Entity
@Table(name = "t_author")
public class Author{
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@Column(name="real_name")
private String realName;
@Column(name="nick_name")
private String nickName;
// SET和GET方法
}

DAO相关

数据访问层，通过编写一个继承自 JpaRepository 的接口就能完成数据访问。值得注意的是，这个的 from 对象名，而不是具体的表名。

public interface AuthorRepository extends JpaRepository<Author, Long> {
List<Author> findAll();
@Query("from Author where id = :id")
Author findAuthor(@Param("id") Long id);
}

Service相关

简单的调用 DAO 相关方法。

@Service("jpa.authorService")
public class AuthorService {
@Autowired
private AuthorRepository authorRepository;
public List<Author> findAll() {
return this.authorRepository.findAll();
}
public Author findAuthor(Long id){
return this.authorRepository.findAuthor(id);
}
}

Controller相关

为了展现效果，我们先定义一组简单的　RESTful API 接口进行测试。

@RestController("jpa.authorController")
@RequestMapping(value = "/data/jpa/author")
public class AuthorController {
@Autowired
private AuthorService authorService;
/**
* 查询用户列表
*/
@RequestMapping(method = RequestMethod.GET)
public Map<String, Object> getAuthorList(HttpServletRequest request) {
List<Author> authorList = this.authorService.findAll();
Map<String, Object> param = new HashMap<String, Object>();
param.put("total", authorList.size());
param.put("rows", authorList);
return param;
}
/**
* 查询用户信息
*/
@RequestMapping(value = "/{userId:\\d+}", method = RequestMethod.GET)
public Author getAuthor(@PathVariable Long userId, HttpServletRequest request) {
Author author = this.authorService.findAuthor(userId);
if (author == null) {
throw new RuntimeException("查询错误");
}
return author;
}
}

JPA 整合方案二通过调用 EntityManager 类方法

实体对象

@Entity
@Table(name = "t_author")
public class Author{
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@Column(name="real_name")
private String realName;
@Column(name="nick_name")
private String nickName;
// SET和GET方法
}

DAO相关

数据访问层，通过编写一个调用EntityManager 类方法。值得注意的是，这个的 from 对象名，而不是具体的表名。

public interface AuthorDao {
List<Author> findAll();
Author findAuthor(Long id);
}
@Repository
public class AuthorDaoImpl implements AuthorDao {
@PersistenceContext
private EntityManager entityManager;
@Override
public List<Author> findAll() {
return this.entityManager
.createQuery("select t from Author t", Author.class)
.getResultList();
}
@Override
public Author findAuthor(Long id){
return this.entityManager
.createQuery("select t from Author t where id = ?", Author.class)
.setParameter(1, id)
.getSingleResult();
}
}

Service相关

简单的调用 DAO 相关方法。

@Service("jpa.authorService2")
public class AuthorService2 {
@Autowired
private AuthorDao authorDao;
public List<Author> findAll() {
return this.authorDao.findAll();
}
public Author findAuthor(Long id){
return this.authorDao.findAuthor(id);
}
}

Controller相关

为了展现效果，我们先定义一组简单的　RESTful API 接口进行测试。

@RestController("jpa.authorController2")
@RequestMapping(value = "/data/jpa/author2")
public class AuthorController2 {
@Autowired
private AuthorService2 authorService;
/**
* 查询用户列表
*/
@RequestMapping(method = RequestMethod.GET)
public Map<String, Object> getAuthorList(HttpServletRequest request) {
List<Author> authorList = this.authorService.findAll();
Map<String, Object> param = new HashMap<String, Object>();
param.put("total", authorList.size());
param.put("rows", authorList);
return param;
}
/**
* 查询用户信息
*/
@RequestMapping(value = "/{userId:\\d+}", method = RequestMethod.GET)
public Author getAuthor(@PathVariable Long userId, HttpServletRequest request) {
Author author = this.authorService.findAuthor(userId);
if (author == null) {
throw new RuntimeException("查询错误");
}
return author;
}
}

源代码

相关示例完整代码： springboot-action

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文章标题：Spring Boot 揭秘与实战（二）数据存储篇 - JPA整合
文章链接：http://blog.720ui.com/2017/springboot_02_data_jpa/