spring data jpa 自定义分页插件

实例

 （1）entity代码：

package com.skyline.study.webdemo1.entity;import org.hibernate.annotations.GenericGenerator;import javax.persistence.*;import javax.validation.constraints.NotNull;import java.util.Date;/** * Created by Skyline on 2016/10/10. */@Entity@Table(name="testEntity")public class TestEntity {    @Id//    @GeneratedValue(strategy = GenerationType.AUTO)    @GenericGenerator(name="idGenerator", strategy="uuid") //这个是hibernate的注解/生成32位UUID    @GeneratedValue(generator="idGenerator")    public String id;    @NotNull    public String name;    public String description;    public Date createTime;}

（2）持久层代码：

通用自定义持久层接口：

package com.skyline.study.webdemo1.dao.jpa.base;import org.springframework.data.domain.Page;import javax.persistence.criteria.CriteriaQuery;import java.io.Serializable;/** * 自定义方法 * Created by Skyline on 2017/1/11. */public interface BaseRepositoryCustom<T, ID extends Serializable>{    void say(String s);    Page<T> getPage(Class rootCls, CriteriaQuery<T> criteria, int pageNo, int pageSize);}

通用自定义持久层接口实现：

package com.skyline.study.webdemo1.dao.jpa.base;import com.skyline.study.webdemo1.dao.base.Pagination;import org.springframework.data.domain.Page;import org.springframework.stereotype.Repository;import javax.persistence.EntityManager;import javax.persistence.PersistenceContext;import javax.persistence.TypedQuery;import javax.persistence.criteria.CriteriaBuilder;import javax.persistence.criteria.CriteriaQuery;import javax.persistence.criteria.Root;import java.io.Serializable;import java.util.Collections;import java.util.List;/** * Created by Skyline on 2017/1/11. */@Repositorypublic class BaseRepositoryCustomImpl<T,ID extends Serializable> implements BaseRepositoryCustom<T,ID> {    @PersistenceContext    protected EntityManager em;    @Override    public void say(String s) {        System.out.println(getClass() + " say '" + s + "'");    }    @Override    public Page<T> getPage(Class rootCls, CriteriaQuery<T> criteria, int pageNo, int pageSize) {        //count        CriteriaBuilder builder = em.getCriteriaBuilder();        CriteriaQuery<Long> criteriaC = builder.createQuery(Long.class);        Root root = criteriaC.from(rootCls);        criteriaC.select(builder.count(root));        criteriaC.where(criteria.getRestriction());        List<Long> totals = em.createQuery(criteriaC).getResultList();        Long total = 0L;        for (Long element : totals) {            total += element == null ? 0 : element;        }        //content        TypedQuery<T> query = em.createQuery(criteria);        query.setFirstResult((pageNo - 1) * pageSize);        query.setMaxResults(pageSize);//        List<T> content = query.getResultList();        List<T> content = total > query.getFirstResult() ? query.getResultList() : Collections.<T> emptyList();        Pagination<T> pagination = new Pagination(pageNo, pageSize, total);        pagination.setContent(content);        return pagination;    }}

 备注：getPage（）方法就是自定义的分页接口。

（3）TestEntity的持久层代码：

TestEntity持久层自定义方法接口：定义自定义方法。采用原生的EntityManager自定义方法实现。

package com.skyline.study.webdemo1.dao.jpa;import com.skyline.study.webdemo1.entity.TestEntity;import com.skyline.study.webdemo1.vo.TestEntityPageQuery;import org.springframework.data.domain.Page;import java.util.List;/** * Created by Skyline on 2017/1/11. */public interface TestEntityRepositoryCustom {    void hello();    Page<TestEntity> getPage(TestEntityPageQuery query);    List<TestEntity> getList(TestEntityPageQuery query);}

自定义方法接口实现：

package com.skyline.study.webdemo1.dao.jpa;import com.skyline.study.webdemo1.dao.jpa.base.BaseRepositoryCustomImpl;import com.skyline.study.webdemo1.entity.TestEntity;import com.skyline.study.webdemo1.vo.TestEntityPageQuery;import org.springframework.data.domain.Page;import org.springframework.stereotype.Repository;import javax.persistence.criteria.CriteriaBuilder;import javax.persistence.criteria.CriteriaQuery;import javax.persistence.criteria.Predicate;import javax.persistence.criteria.Root;import java.util.ArrayList;import java.util.List;/** * 自定义方法的实现 * Created by Skyline on 2017/1/11. */@Repositorypublic class TestEntityRepositoryImpl extends BaseRepositoryCustomImpl<TestEntity,String> implements TestEntityRepositoryCustom {    @Override    public void hello() {        System.out.println("entityManger:" + em);        System.out.println("hello!>>>>>>");    }    @Override    public Page<TestEntity> getPage(TestEntityPageQuery pageQuery) {        CriteriaBuilder builder = em.getCriteriaBuilder();        CriteriaQuery<TestEntity> criteria = builder.createQuery(TestEntity.class);        Root<TestEntity> root = criteria.from(TestEntity.class);        criteria.select(root);        List<Predicate> predicates = new ArrayList<>();        if(pageQuery.name != null) {            predicates.add(builder.like(root.get("name"), "%" + pageQuery.name + "%"));        }        if (pageQuery.startTime != null && pageQuery.endTime != null) {            predicates.add(builder.between(root.get("createTime"), pageQuery.startTime, pageQuery.endTime));        }        Predicate[] preArr = new Predicate[predicates.size()];        predicates.toArray(preArr);        criteria.where(preArr);        criteria.orderBy(builder.desc(root.get("createTime")));        Page<TestEntity> page = getPage(TestEntity.class, criteria, pageQuery.pageNo, pageQuery.pageSize);        return page;    }    @Override    public List<TestEntity> getList(TestEntityPageQuery pageQuery) {        CriteriaBuilder builder = em.getCriteriaBuilder();        CriteriaQuery<TestEntity> query = builder.createQuery(TestEntity.class);        Root<TestEntity> root = query.from(TestEntity.class);        query.select(root);        List<Predicate> predicates = new ArrayList<>();        if(pageQuery.name != null) {            predicates.add(builder.like(root.get("name"), "%" + pageQuery.name + "%"));        }        if (pageQuery.startTime != null && pageQuery.endTime != null) {            predicates.add(builder.between(root.get("createTime"), pageQuery.startTime, pageQuery.endTime));        }        query.where(predicates.toArray(new Predicate[]{}));        query.orderBy(builder.desc(root.get("createTime")));        return em.createQuery(query).getResultList();    }}

备注：hibernate jpa 默认查找 持久层接口名 + 'Impl' 这个类作为自定义方法的实现，如TestEntityRepositoryImpl中的方法作为TestEntityRepository 接口中自定义方法的实现。

最终TestEntity持久层接口：

package com.skyline.study.webdemo1.dao.jpa;import com.skyline.study.webdemo1.dao.jpa.base.BaseRepositoryCustom;import com.skyline.study.webdemo1.entity.TestEntity;import org.springframework.data.jpa.repository.JpaRepository;import org.springframework.data.jpa.repository.JpaSpecificationExecutor;/** * Created by Skyline on 2017/1/10. */public interface TestEntityRepository extends JpaRepository<TestEntity,String>, JpaSpecificationExecutor<TestEntity>, BaseRepositoryCustom<TestEntity,String>,TestEntityRepositoryCustom {    TestEntity findByName(String name);}

备注：

hibernate jpa会自动为Repository接口的子接口生成代理类。默认是SimpleJpaRepository。继承JpaSpecificationExecutor类是为了让hibernate jpa自带的分页方法支持条件查询。

jpa依据规范化的方法名称或者通过注解如@Query指定的sql自动生成对应的实现方法。

（4）Service层代码：

TestEntityService代码：

package com.skyline.study.webdemo1.service;import com.skyline.study.webdemo1.entity.TestEntity;import com.skyline.study.webdemo1.vo.TestEntityPageQuery;import org.springframework.data.domain.Page;import java.util.List;/** * Created by Skyline on 2016/10/14. */public interface TestEntityService {    void save(TestEntity testEntity);    void delete(String id);    TestEntity getByName(String name);    Page<TestEntity> getPage(TestEntityPageQuery pageQuery);    Page<TestEntity> getPageCustom(TestEntityPageQuery pageQuery);    List<TestEntity> getList(TestEntityPageQuery pageQuery);    List<TestEntity> getAll();}

TestEntityServiceImpl

package com.skyline.study.webdemo1.service;import com.skyline.study.webdemo1.dao.jpa.TestEntityRepository;import com.skyline.study.webdemo1.entity.TestEntity;import com.skyline.study.webdemo1.vo.TestEntityPageQuery;import org.springframework.data.domain.Page;import org.springframework.data.domain.PageRequest;import org.springframework.data.jpa.domain.Specification;import org.springframework.stereotype.Service;import javax.annotation.Resource;import javax.persistence.criteria.CriteriaBuilder;import javax.persistence.criteria.CriteriaQuery;import javax.persistence.criteria.Predicate;import javax.persistence.criteria.Root;import java.util.ArrayList;import java.util.List;/** * Created by Skyline on 2016/10/14. */@Servicepublic class TestEntityServiceImpl implements TestEntityService {    @Resource    private TestEntityRepository testEntityRepository;    @Override    public void save(TestEntity testEntity) {        testEntityRepository.save(testEntity);    }    @Override    public void delete(String id) {        testEntityRepository.delete(id);    }    @Override    public TestEntity getByName(String name) {        return testEntityRepository.findByName(name);    }    /**     * 采用hibernate jpa 自带的分页方法     * @param pageQuery     * @return     */    @Override    public Page<TestEntity> getPage(TestEntityPageQuery pageQuery) {        PageRequest pageRequest = new PageRequest(pageQuery.pageNo - 1, pageQuery.pageSize);        Specification spe = new Specification<TestEntity>() {            @Override            public Predicate toPredicate(Root<TestEntity> root, CriteriaQuery<?> query, CriteriaBuilder cb) {                List<Predicate> list = new ArrayList<>();                if(pageQuery.name != null) {                    list.add(cb.like(root.get("name"), "%" + pageQuery.name + "%"));                }                if (pageQuery.startTime != null && pageQuery.endTime != null) {                    list.add(cb.between(root.get("createTime"), pageQuery.startTime, pageQuery.endTime));                }                query.orderBy(cb.desc(root.get("createTime")));                Predicate[] predicates = new Predicate[list.size()];                predicates = list.toArray(predicates);                return cb.and(predicates);            }        };        return testEntityRepository.findAll(spe, pageRequest);    }    /**     * 采用自定义分页方法     * @param pageQuery     * @return     */    @Override    public Page<TestEntity> getPageCustom(TestEntityPageQuery pageQuery) {        return testEntityRepository.getPage(pageQuery);    }    @Override    public List<TestEntity> getList(TestEntityPageQuery pageQuery) {        return testEntityRepository.getList(pageQuery);    }    @Override    public List<TestEntity> getAll() {        return testEntityRepository.findAll();    }}