Springboot集成SpringData JPA

序

StringData JPA 是微服务框架下一款ORM框架，在微服务体系架构下，数据持久化框架，主要为SpringData JPA及Mybatis两种，这两者的具体比较，本文不做阐述，本文只简单阐述SpringData JPA的使用方法。

简介

SpringData JPA的Repository接口介绍，本文主要介绍CrudRepository、PagingAndSortingRepository、JpaSpecificationExecutor。

示例

pom.xml

<!--Springboot-web-->
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!--SpringData-JPA-->
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<!--mysql启动-->
<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
	<scope>runtime</scope>
</dependency>
<!--测试驱动-->
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-test</artifactId>
	<scope>test</scope>
</dependency>

　entity：

/*
* 数据实体，表名test_emp
*/
@Entity
@Table(name="test_emp")
public class Emp implements Serializable{
	private static final long serialVersionUID = 1L;
	@Id
	@GeneratedValue(strategy=GenerationType.AUTO)
	private Integer id;
	@Column
	private Integer age;
	@Column
	private String name;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	@Override
	public String toString() {
		return "Emp [id=" + id + ", age=" + age + ", name=" + name + "]";
	}	
}

CrudRepository实现：

public interface EmpCrudRepository extends CrudRepository<Emp, Integer> {
        /*
        *Query高级查询
        */
	@Query("select e from Emp e")
	public List<Emp> queryAllTest();
}

PagingAndSortingRepository实现：

public interface EmpPagingAndSortingRepository extends PagingAndSortingRepository<Emp, Integer> {

}

EmpJpaSpecificationExecutor实现：

public interface EmpJpaSpecificationExecutor extends JpaSpecificationExecutor<Emp>,Repository<Emp, Integer>{

}

　CurdRepository测试：

@SpringBootTest
@RunWith(SpringRunner.class)
public class EmpCurdRepositoryTest {

	@Autowired
	private EmpCrudRepository empCrudRepository;
	
	@Test
	public void testAdd() {
		Emp emp = new Emp();
		emp.setAge(22);
		emp.setId(1);
		emp.setName("test1");
		empCrudRepository.save(emp);
	}
	
	@Test
	public void testAddAll() {
		List<Emp> emps = new ArrayList<>();
		for (int i = 0; i < 10; i++) {
			Emp emp = new Emp();
			emp.setAge(i+20);
			emp.setName("test"+i);
			emps.add(emp);
		}
		empCrudRepository.saveAll(emps);
	}
	
	/**
	 * Query注解使用
	 */
	@Test
	public void testQueryAll() {
		List<Emp> emps = empCrudRepository.queryAllTest();
		for(Emp emp:emps) {
			System.out.println(emp);
		}
	}
}

　　PagingAndSortingRepository测试：

@SpringBootTest
@RunWith(SpringRunner.class)
public class EmpPagingAndSortingRepositoryTest {

	@Autowired
	private EmpPagingAndSortingRepository empPagingAndSortingRepository;
	@Test
	public void query() {
		Pageable pageable = PageRequest.of(0, 10, Direction.DESC, "id");
		Iterable<Emp> emps = empPagingAndSortingRepository.findAll(pageable);
		for(Emp emp:emps) {
			System.out.println(emp);
		}
	}
	
	@Test
	public void queryAll() {
		Pageable pageable = PageRequest.of(0, 7, Direction.DESC, "id");
		Page<Emp> result = empPagingAndSortingRepository.findAll(pageable); //查询结果是pageable对象
	//	Iterable<Emp> emps = empPagingAndSortingRepository.findAll(pageable);  //查询结果直接是emp对象
		System.out.println(result.getContent());
		System.out.println(result.getNumber());
		System.out.println(result.getNumberOfElements());
		System.out.println(result.getTotalElements());
		System.out.println(result.getTotalPages());
		for(Emp emp:result.getContent()) {
			System.out.println(emp);
		}
	}
}

　　JpaSpecificationExecutor测试：

@RunWith(SpringRunner.class)
@SpringBootTest
public class EmpJpaSpecificationExecutorTest {

	@Autowired
	private EmpJpaSpecificationExecutor empJpaSpecificationExecutor;
	
	@Test
	public void test() {
		Specification<Emp> spec = new Specification<Emp>() {
			@Override
                        //多种复杂条件组合查询，属于JPA高级
			public Predicate toPredicate(Root<Emp> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
				List<Predicate> predicates = new ArrayList<>();
				Predicate p1 = cb.gt(root.get("age"), 25);
				Predicate p2 = cb.lt(root.get("age"), 28);
				Predicate p3 = cb.and(p1,p2);
				predicates.add(p3);		
				return query.where(predicates.toArray(new Predicate[predicates.size()])).getRestriction();
			}
		};
		
		Pageable pageable = PageRequest.of(0, 5, Direction.ASC, "id");
		
		Page<Emp> emps = empJpaSpecificationExecutor.findAll(spec, pageable);
		for (Emp emp: emps.getContent()) {
			System.out.println(emp);
		}
		
	}
}