覆盖某些存储库的默认方法

2018-06-29 19:14:08

我只是盯着spring-data和spring-data-rest ，我真的想要利用这些工具必须提供的功能。在大多数情况下，基本功能对我的用例来说是完美的，但是在某些情况下，我需要定制相当多的底层功能，并选择性地分配一些存储库来继承我之后的自定义功能。

为了更好地解释这个问题，在spring-data有两个可以从CrudRepository或PagingAndSortingRepository继承功能的接口。我想添加第三个叫let说PesimisticRepository

PesimisticRepository所做的PesimisticRepository就是以不同的方式处理已删除的@Entity的概念。 被删除的实体是其被删除的属性NOT NULL实体。这意味着可以由PesimisticRepository处理的@Entity必须具有已删除的属性。

所有这些都是可能的，几年前我已经实现了这一点。（如果您有兴趣，可以在这里查看）

我目前使用spring-data的尝试如下：

PagingAndSortingRepository的扩展

package com.existanze.xxx.datastore.repositories;

import org.springframework.data.repository.NoRepositoryBean;
import org.springframework.data.repository.PagingAndSortingRepository;

import java.io.Serializable;


@NoRepositoryBean
public interface PesimisticRepository<T,ID extends Serializable> extends PagingAndSortingRepository<T,ID> {
}

为此我提供了一个扩展JPARepository的默认实现

package com.existanze.xxx.datastore.repositories;

import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageImpl;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.data.jpa.repository.support.SimpleJpaRepository;
import org.springframework.transaction.annotation.Transactional;

import javax.persistence.EntityManager;
import javax.persistence.TypedQuery;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import java.io.Serializable;
import java.util.Date;


public class JpaPesimisticRepository<T,ID extends Serializable> extends SimpleJpaRepository<T,ID> implements PesimisticRepository<T,ID> {


    private final EntityManager entityManager;

    public JpaPesimisticRepository(Class<T> domainClass, EntityManager em) {
        super(domainClass, em);
        this.entityManager = em;
    }

    @Override
    @Transactional
    public Page<T> findAll(Specification<T> spec, Pageable pageable) {

        CriteriaBuilder cb = this.entityManager.getCriteriaBuilder();
        CriteriaQuery<T> criteriaQuery = cb.createQuery(getDomainClass());
        Root<T> from = criteriaQuery.from(this.getDomainClass());
        Predicate deleted = cb.equal(from.get("deleted"), cb.nullLiteral(Date.class));
        criteriaQuery.select(from).where(deleted);
        TypedQuery<T> query = this.entityManager.createQuery(criteriaQuery);
        return pageable == null ? new PageImpl<T>(query.getResultList()) : readPage(query, pageable, spec);

    }

}

然后，对于我希望使用悲观方法处理删除的任何bean，我将它定义为这样

package com.existanze.xxx.datastore.repositories;

import com.existanze.xxx.domain.Phone;
import org.springframework.data.rest.core.annotation.RepositoryRestResource;


@RepositoryRestResource
public interface PhoneRepository extends PesimisticRepository<Phone,Integer> {



}

解释为什么我希望重写这些方法而不是提供自定义方法很重要，比如findAllButDeleted 。原因是因为我也希望悲观删除能够缓冲到spring-data-rest 。这样生成的HTTP端点不需要任何形式的定制。

这似乎只适用于findAll方法。但是对于其余的方法，当前的异常被抛出。

$ curl http://localhost:8881/phones/23

<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1"/>
<title>Error 500 </title>
</head>
<body>
<h2>HTTP ERROR: 500</h2>
<p>Problem accessing /phones/23. Reason:
<pre>    org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.dao.InvalidDataAccessApiUsageException: object is not an instance of declaring class; nested exception is java.lang.IllegalArgumentException: object is not an instance of declaring class</pre></p>
<hr /><i><small>Powered by Jetty://</small></i>
</body>
</html>

此外，我已阅读允许您更改所有存储库的默认JpaRepository的文档，但我需要在每个存储库的基础上再次执行此操作。

我希望我足够描述。请在评论部分告诉我是否有需要更好解释的内容。

您可以创建一个自定义存储库，如下所示：

package com.brunocesar.custom.repository.support;

import java.io.Serializable;

import javax.persistence.EntityManager;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.repository.NoRepositoryBean;

import com.brunocesar.custom.entity.CustomAbstractEntity;

@NoRepositoryBean
public interface CustomGenericRepository<E extends CustomAbstractEntity, PK extends Serializable> extends
        JpaRepository<E, PK>, JpaSpecificationExecutor<E> {

    EntityManager getEntityManager();

}

package com.brunocesar.custom.repository.support.impl;

import java.io.Serializable;
import java.util.Calendar;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;

import org.springframework.data.jpa.domain.Specification;
import org.springframework.data.jpa.repository.support.JpaEntityInformation;
import org.springframework.data.jpa.repository.support.SimpleJpaRepository;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.util.Assert;

import com.brunocesar.custom.entity.CustomAbstractEntity;
import com.brunocesar.custom.repository.support.CustomGenericRepository;

@Transactional(readOnly = true)
public class CustomGenericRepositoryImpl<E extends CustomAbstractEntity, PK extends Serializable> extends
        SimpleJpaRepository<E, PK> implements CustomGenericRepository<E, PK> {

    private final EntityManager entityManager;
    private final JpaEntityInformation<E, ?> entityInformation;

    public CustomGenericRepositoryImpl(final JpaEntityInformation<E, ?> entityInformation,
            final EntityManager entityManager) {
        super(entityInformation, entityManager);
        this.entityManager = entityManager;
        this.entityInformation = entityInformation;
    }

    @Override
    @Transactional
    public void delete(final E entity) {
        Assert.notNull(entity, "Entity object must not be null!");
        entity.setChangeDate(Calendar.getInstance().getTime());
        entity.setDeleted(true);
    }

    @Override
    public List<E> findAll() {
        return super.findAll(this.isRemoved());
    }

    @Override
    public E findOne(final PK pk) {
        return this.findOne(this.isRemovedByID(pk));
    }

    private Specification<E> isRemoved() {
        return new Specification<E>() {

            @Override
            public Predicate toPredicate(final Root<E> root, final CriteriaQuery<?> query, final CriteriaBuilder cb) {
                return cb.isFalse(root.<Boolean> get("deleted"));
            }

        };
    }

    private Specification<E> isRemovedByID(final PK pk) {
        return new Specification<E>() {

            @Override
            public Predicate toPredicate(Root<E> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
                final Predicate id = cb.equal(root.get("id"), pk);
                final Predicate hidden = cb.isFalse(root.<Boolean> get("deleted"));
                return cb.and(id, hidden);
            }

        };
    }

    @Override
    public EntityManager getEntityManager() {
        return this.entityManager;
    }

    protected JpaEntityInformation<E, ?> getEntityInformation() {
        return this.entityInformation;
    }

}

您还需要一个自定义工厂bean来设置您的自定义存储库。看起来像这样：

package com.brunocesar.custom.repository.support.factory;

import java.io.Serializable;

import javax.persistence.EntityManager;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.support.JpaEntityInformation;
import org.springframework.data.jpa.repository.support.JpaRepositoryFactory;
import org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean;
import org.springframework.data.jpa.repository.support.SimpleJpaRepository;
import org.springframework.data.repository.core.RepositoryMetadata;
import org.springframework.data.repository.core.support.RepositoryFactorySupport;

import com.brunocesar.custom.repository.support.impl.CustomGenericRepositoryImpl;

public class CustomGenericRepositoryFactoryBean<T extends JpaRepository<S, ID>, S, ID extends Serializable> extends
        JpaRepositoryFactoryBean<T, S, ID> {

    @Override
    protected RepositoryFactorySupport createRepositoryFactory(final EntityManager entityManager) {
        return new RepositoryFactory(entityManager);
    }

    private static class RepositoryFactory extends JpaRepositoryFactory {

        public RepositoryFactory(final EntityManager entityManager) {
            super(entityManager);
        }

        @Override
        @SuppressWarnings({"unchecked", "rawtypes"})
        protected <T, ID extends Serializable> SimpleJpaRepository<?, ?> getTargetRepository(
                final RepositoryMetadata metadata, final EntityManager entityManager) {
            final JpaEntityInformation<?, Serializable> entityInformation = this.getEntityInformation(metadata
                    .getDomainType());
            return new CustomGenericRepositoryImpl(entityInformation, entityManager);
        }

        @Override
        protected Class<?> getRepositoryBaseClass(final RepositoryMetadata metadata) {
            return CustomGenericRepositoryImpl.class;
        }

    }

}

最后，应用程序上下文配置。

通用储存库配置如下所示：

<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
        p:dataSource-ref="dataSource" p:jpaProperties-ref="jpaProperties" p:jpaVendorAdapter-ref="jpaVendorAdapter"/>

<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager" p:entityManagerFactory-ref="entityManagerFactory" />

<jpa:repositories base-package="com.brunocesar.repository"
    transaction-manager-ref="transactionManager" entity-manager-factory-ref="entityManagerFactory" />

和自定义一样（可以使用或不使用分离的EMF和事务管理器）：

<bean id="entityManagerFactoryCustom" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
    p:dataSource-ref="dataSource" p:jpaProperties-ref="jpaProperties" p:jpaVendorAdapter-ref="jpaVendorAdapter"/>

<bean id="transactionManagerCustom" class="org.springframework.orm.jpa.JpaTransactionManager" p:entityManagerFactory-ref="entityManagerFactoryCustom" />

<jpa:repositories base-package="com.brunocesar.custom.repository,com.brunocesar.custom.repository.support"
    factory-class="com.brunocesar.custom.repository.support.factory.CustomGenericRepositoryFactoryBean"
    transaction-manager-ref="transactionManagerCustom" entity-manager-factory-ref="entityManagerFactoryCustom" />

例1，使用JpaRepository：

package com.brunocesar.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import com.brunocesar.entity.CommonEntity;

@Repository
public interface CommonRepository extends JpaRepository<CommonEntity, Long> {

}

示例2，使用自定义存储库：

package com.brunocesar.custom.repository;

import org.springframework.stereotype.Repository;

import com.brunocesar.custom.entity.CustomEntity;
import com.brunocesar.custom.repository.support.CustomGenericRepository;

@Repository
public interface CustomRepository extends CustomGenericRepository<CustomEntity, Long> {

}

这是我通常做的一部分。如果你需要，我可以创建一个基本的应用程序作为例子。

链接地址: http://www.djcxy.com/p/83175.html

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