准备工作
pom.xml引入依赖
...
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
...
application.yml 中加入
...
spring:
application:
name: demo-article #指定服务名
datasource:
driverClassName: com.mysql.jdbc.Driver
url: jdbc:mysql://192.168.1.2:3306/demo-article?characterEncoding=UTF8
username: root
password: 123456
jpa:
database: MySQL
show-sql: true
...
使用Specification接口实现（一）
...
@Service
@Transactional
public class ArticleService {
@Autowired
private ArticleDao articleDao;
@Autowired
private IdWorker idWorker;
...
public Page<Label> pageQuery(Article article, int page, int size){
//封装了一个分页对象，在springdatajpa中想要实现分页，直接传一个分页对象即可
Pageable pageable = PageRequest.of(page-1, size);
return articleDao.findAll(new Specification<Article>(){
@Override
public Predicate toPredicate(Root<Article> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
List<Predicate> list = new ArrayList<>();
if(hasText(article.getName())){
Predicate predicate = cb.like(root.get("name").as(String.class), "%" + article.getName() + "%");
list.add(predicate);
}
if(hasText(article.getState())){
Predicate predicate = cb.equal(root.get("state").as(String.class), article.getState());
list.add(predicate);
}
Predicate[] parr = new Predicate[list.size()];
//把集合中的属性复制到数组中
parr = list.toArray(parr);
return cb.and(parr);
}
}, pageable);
}
...
}
通过Dao方法名方式实现（二）
...
public interface ArticleDao extends JpaRepository<Article,String>,JpaSpecificationExecutor<Article>{
...
List<Article> findTop6ByStateOrderByCreatetimeDesc(String state);
List<Recruit> findTop6ByStateNotOrderByCreatetimeDesc(String state);
...
}
通过原生sql方式实现（三）
...
public interface ArticleDao extends JpaRepository<Article,String>,JpaSpecificationExecutor<Article>{
...
@Query(value = "SELECT * FROM tb_article WHERE id IN (SELECT articleid FROM tb_pa WHERE articleid=?) ORDER BY replytime DESC", nativeQuery = true)
public Page<Problem> selectArticlesPage(String articleid, Pageable pageable);
@Modifying
@Query(value = "UPDATE tb_article SET state = 1 WHERE id = ?", nativeQuery = true)
public void examine(String id);
...
}
个人感悟
以上三中均可以对数据库进行操作，这表明JPA实现方式还是比较全面。但在实际的开发过程中，个人认为还是通过原生sql的方式比较好，sql语句在navicat premium 或者 SQLyog 运行通过后拷贝过来，修改参数值为？。
