SpringDataJpa2

* @NoRepositoryBean
*   防止底层去找SimpleJpaRepository的实现类   我们需要找我们自己的实现类
* */

public interface <T,ID extends Serializable> extends JpaRepository<T, ID>,
JpaSpecificationExecutor<T> {

    //根据BaseQuery拿到分页对象
    Page findPageByQuery(BaseQuery baseQuery);

    //根据BaseQuery拿到对应的数据  不分页
    List<T> findByQuery(BaseQuery baseQuery);

    //根据jpql与对应的参数拿到数据
    List findByJpql(String jpql,Object...value);

}

* Serializable  序列化  用来网络传输
* extends SimpleJpaRepository  不会覆写SpringDataJpa本身的方法
* implements BaseRepository  实现自身的方法
*
*
* */
public class BaseRepositoryImpl<T,ID extends Serializable> extends SimpleJpaRepository<T,ID> implements <T,ID> {
    //让Spring把entityManager注入进来
    private EntityManager entityManager;
    
    //继承了SimpleJpaRepository中没有无参构造 必须覆写里面的有参构造
    public BaseRepositoryImpl(Class<T> domainClass, EntityManager em) {
        super(domainClass, em);
        this.entityManager = em;
    }
    //分页查询方法
    @Override
    public Page findPageByQuery(BaseQuery baseQuery) {
        //排序
        Sort sort = baseQuery.createSort();
        //条件
        Specification specs = baseQuery.createSpecifications();
        //分页
        Pageable pageable = new PageRequest(baseQuery.getCurrentPage(), baseQuery.getPageSize(), sort);
        //查询
        Page page = super.findAll(specs, pageable);
        return page;
    }

    @Override
    public List<T> findByQuery(BaseQuery baseQuery) {
        Sort sort = baseQuery.createSort();
        Specification spec = baseQuery.createSpecifications();
        //条件加排序查询
        List<T> list = super.findAll(spec, sort);
        return list;
    }

    @Override
    public List findByJpql(String jpql, Object... value) {
        Query query = entityManager.createQuery(jpql);
        for (int i = 0; i < value.length; i++) {
            query.setParameter(i+1, value[i]);
        }
        return query.getResultList();
    }
}

/**
 * BaseRepositoryFactoryBean --FactoryBean
 * JpaRepositoryFactoryBean --提供的FactoryBean
 *      写一个类去继承 JpaRepositoryFactoryBean  --Spring就会自动调用createRepositoryFactory
 *
 */
public class BaseRepositoryFactoryBean<T extends Repository<S, ID>, S, ID extends Serializable>
        extends JpaRepositoryFactoryBean<T,S,ID> {

    @Override
    protected RepositoryFactorySupport createRepositoryFactory(EntityManager entityManager) {
          return new MyRepositoryFactory<T,ID>(entityManager); //注：这里创建是我们的自定义类
    }

    //继承JpaRepositoryFactory后，把返回的对象修改成我们自己的实现
    private static  class MyRepositoryFactory<T,ID extends Serializable>   extends JpaRepositoryFactory {
        private final EntityManager entityManager;
        /**
         * Creates a new {@link JpaRepositoryFactory}.
         *
         * @param entityManager must not be {@literal null}
         */
        public MyRepositoryFactory(EntityManager entityManager) {
            super(entityManager);
            this.entityManager = entityManager;
        }
	   //这里返回最后的功能对象
        @Override
        protected Object getTargetRepository(RepositoryInformation information) {
            return new BaseRepositoryImpl<T,ID>((Class<T>)information.getDomainType(),entityManager);
        }
        //这里返回最后的功能对象 --最终Spring调用方法返回的对象 -->得到对最终的对象
        //factoryBean 默认调用getObject -- 现在调用getTargetRepository
        @Override
        protected Class<?> getRepositoryBaseClass(RepositoryMetadata metadata) {
            return BaseRepositoryImpl.class;
        }
    }
}

public interface IBaseService<T,ID extends Serializable> {
    //增加  修改
    void save(T t);
    //删除
    void del(ID id);
    //查询单个
    T findOne(ID id);
    //查询全部
    List<T> findAll();
    //分页排序查询
    Page findPageByQuery(BaseQuery baseQuery);
    //排序查询
    List<T> findByQuery(BaseQuery baseQuery);
    //jpql语句查询
    List jpqlByQuery(String jpql,Object...value);
}

@Transactional(propagation = Propagation.SUPPORTS,readOnly = true)
public class BaseServiceImpl<T,ID extends Serializable> implements IBaseService<T, ID> {

    @Autowired
    private BaseRepository<T,ID> baseRepository;

    @Override
    @Transactional
    public void save(T t) {
        baseRepository.save(t);
    }

    @Override
    @Transactional
    public void del(ID id) {
        baseRepository.delete(id);
    }

    @Override
    @Transactional
    public T findOne(ID id) {
        return baseRepository.findOne(id);
    }

    @Override
    public List<T> findAll() {
        return baseRepository.findAll();
    }

    @Override
    public Page findPageByQuery(BaseQuery baseQuery) {
        return baseRepository.findPageByQuery(baseQuery);
    }

    @Override
    public List<T> findByQuery(BaseQuery baseQuery) {
        return baseRepository.findByQuery(baseQuery);
    }

    @Override
    public List jpqlByQuery(String jpql, Object... value) {
        return baseRepository.findByJpql(jpql, value);
    }
}

public class UIPage {
    //总条数
    private Long total;
    //每页显示数据
    private List rows;

    public UIPage() {}

    public UIPage(Page page) {
        this.total = page.getTotalElements();
        this.rows = page.getContent();
    }
   	//下面有get/set方法
}

@RequestMapping("/page")
@ResponseBody
public UIPage page(EmployeeQuery employeeQuery){
    Page page = employeeService.findPageByQuery(employeeQuery);
    UIPage uiPage = new UIPage(page);
    return uiPage;
}

//因为前台传入的参数是page和rows
public void setPage(Integer page){
    System.out.println(page);
    this.currentPage = page;
}
public void setRows(Integer rows){
    this.pageSize = rows;
}

@ManyToOne
@JoinColumn(name = "department_id")
@JsonIgnoreProperties(value={"hibernateLazyInitializer","handler","fieldHandler"})
private Department department;

public class CustomMapper extends ObjectMapper {
    public CustomMapper(){
        this.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        // 设置 SerializationFeature.FAIL_ON_EMPTY_BEANS 为 false 对null的bean 不做序列化
        this.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
    }
}

@Controller
@RequestMapping("/util")
public class UtilController {
    @Autowired
    private IDepartmentService departmentService;

    @RequestMapping("/departmentList")
    @ResponseBody
    public List<Department> departmentList(){
        List<Department> list = departmentService.findAll();
        return list;
    }
}

public Specification createSpecifications() {
    Specification<Employee> specification = Specifications.<Employee>and()
        .like(StringUtils.isNotBlank(this.username), "username", "%" + this.username + "%")
        .like(StringUtils.isNotBlank(this.email), "email", "%" + this.email + "%")
        .eq(this.departmentId != null,"department.id",this.departmentId)
        .build();
    return specification;
}