Spring Data JPA 全局DAO的扩展

前几天看了springside4的mini-web代码发现确实有不少新的东东，咱这次单说说Spring Data JPA吧。

引用springside4的 wiki关于对Spring Data JPA的简介

Spring Data JPA在JPA上又做了一层封装，只要编写接口就够了，不用写一行实现代码，CRUD方法啦，分页啦，自动将findByLoginName()的方法定义翻译成适当的QL啦都由它包了：

public interface UserDao extends PagingAndSortingRepository<User, Long> {
User findByLoginName(String loginName);
}
使用上很简单，快速浏览一下下面的资料就够了。

只有一个坑爹的地方，如果要为UserDao扩展方法(而不是接口)，要新增一个UserDaoCustom接口，这时候，实现类的名字必须是UserDaoImpl，而不是UserDaoCustomImpl。

另外，除了智能地翻译连Less,Not,And,Or都支持的方法名，它当然也可以直接用@Query在方法上标注复杂的查询语句。

资料
•官方文档

•使用 Spring Data JPA 简化 JPA 开发 IBM DW上的中文版教程.

 如果看完上面的资料 也许你对Spring Data JPA有了初步的认识，动动手你就知道他的强大，但是对DAO的扩展上有点麻烦，上面红字部分是对单个dao进行扩展的方法。下面我们来说一下对全局DAO的扩展，创建你自己的CustomRepository。

 

首先咱们要建一个自己的扩展接口类MyRepository

 

import java.io.Serializable;

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

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

String  sharedCustomMethod();
}

import java.io.Serializable;

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

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

String  sharedCustomMethod();
}

 

其中sharedCustomMethod是全局的共享自定义方法。

 

然后在建一个实现类MyCustomRepository

import java.io.Serializable;

import javax.persistence.EntityManager;

import org.springframework.data.jpa.repository.support.JpaEntityInformation;
import org.springframework.data.jpa.repository.support.SimpleJpaRepository;
import org.springframework.data.repository.NoRepositoryBean;

@NoRepositoryBean
public class MyCustomRepository<T, ID extends Serializable>
extends SimpleJpaRepository<T, ID> implements MyRepository<T, ID> {


private final EntityManager entityManager;

public MyCustomRepository(Class<T> domainClass, EntityManager em) {
        super(domainClass, em);
        // TODO Auto-generated constructor stub

        entityManager=em;
    }

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


public String sharedCustomMethod() {
    return "hello sharedCustomMethod";
  // implementation goes here
}
}

import java.io.Serializable;

import javax.persistence.EntityManager;

import org.springframework.data.jpa.repository.support.JpaEntityInformation;
import org.springframework.data.jpa.repository.support.SimpleJpaRepository;
import org.springframework.data.repository.NoRepositoryBean;

@NoRepositoryBean
public class MyCustomRepository<T, ID extends Serializable> 
extends SimpleJpaRepository<T, ID> implements MyRepository<T, ID> {

	
private final EntityManager entityManager;
	
public MyCustomRepository(Class<T> domainClass, EntityManager em) {
		super(domainClass, em);
		// TODO Auto-generated constructor stub
		
		entityManager=em;
	}

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


public String sharedCustomMethod() {
	return "hello sharedCustomMethod";
  // implementation goes here
} 
}

 

 注意 @NoRepositoryBean一定要有的，还有全局的扩展实现类不要用Imp作为后缀名，不然会报异常的（目前还没搞清楚报异常的具体原因，个人猜测可能是和局部的扩展有冲突吧）。

 

然后在定义MyRepositoryFactory

import java.io.Serializable;

import static org.mockito.Mockito.*;

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.repository.core.RepositoryMetadata;


public class MyRepositoryFactory extends JpaRepositoryFactory {

    public MyRepositoryFactory(EntityManager entityManager) {
        super(entityManager);
        // TODO Auto-generated constructor stub
    }
    @Override
    @SuppressWarnings("unchecked")
    protected JpaRepository<?, ?> getTargetRepository(RepositoryMetadata metadata, EntityManager em) {

        JpaEntityInformation<Object, Serializable> entityMetadata = mock(JpaEntityInformation.class);
        when(entityMetadata.getJavaType()).thenReturn((Class<Object>) metadata.getDomainType());
        return new MyCustomRepository<Object, Serializable>(entityMetadata, em);
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * org.springframework.data.repository.support.RepositoryFactorySupport#
     * getRepositoryBaseClass()
     */
    @Override
    protected Class<?> getRepositoryBaseClass(RepositoryMetadata metadata) {

        return MyCustomRepository.class;
    }
}

import java.io.Serializable;

import static org.mockito.Mockito.*;

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.repository.core.RepositoryMetadata;


public class MyRepositoryFactory extends JpaRepositoryFactory {

	public MyRepositoryFactory(EntityManager entityManager) {
		super(entityManager);
		// TODO Auto-generated constructor stub
	}
	@Override
	@SuppressWarnings("unchecked")
	protected JpaRepository<?, ?> getTargetRepository(RepositoryMetadata metadata, EntityManager em) {

		JpaEntityInformation<Object, Serializable> entityMetadata = mock(JpaEntityInformation.class);
		when(entityMetadata.getJavaType()).thenReturn((Class<Object>) metadata.getDomainType());
		return new MyCustomRepository<Object, Serializable>(entityMetadata, em);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.springframework.data.repository.support.RepositoryFactorySupport#
	 * getRepositoryBaseClass()
	 */
	@Override
	protected Class<?> getRepositoryBaseClass(RepositoryMetadata metadata) {

		return MyCustomRepository.class;
	}
}

 

接着在建一个MyRepositoryFactoryBean

import java.io.Serializable;

import javax.persistence.EntityManager;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean;
import org.springframework.data.repository.core.support.RepositoryFactorySupport;

public class MyRepositoryFactoryBean<T extends JpaRepository<Object, Serializable>> extends JpaRepositoryFactoryBean<T, Object, Serializable> {


    @Override
    protected RepositoryFactorySupport createRepositoryFactory(EntityManager em) {

        return new MyRepositoryFactory(em);
    }
}

import java.io.Serializable;

import javax.persistence.EntityManager;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean;
import org.springframework.data.repository.core.support.RepositoryFactorySupport;

public class MyRepositoryFactoryBean<T extends JpaRepository<Object, Serializable>> extends JpaRepositoryFactoryBean<T, Object, Serializable> {

	
	@Override
	protected RepositoryFactorySupport createRepositoryFactory(EntityManager em) {

		return new MyRepositoryFactory(em);
	}
}

 
最后在配置文件里需要定义

<jpa:repositories base-package="org.springside.examples.miniweb"  transaction-manager-ref="transactionManager" 

 factory-class="org.springside.examples.miniweb.dao.account.MyRepositoryFactoryBean"

entity-manager-factory-ref="entityManagerFactory"/>

 其实这里还有个repository-impl-postfix=" "个人理解他是来定义局部扩展库的实现类的后缀的默认是Imp。

 

 呵呵 这样你就可以使用全局的自定义扩展库了。

 

public interface UserDao extends MyRepository<User, Long> ,JpaSpecificationExecutor<User>{

}

public interface UserDao extends MyRepository<User, Long> ,JpaSpecificationExecutor<User>{

}