如何从spring-data mongodb扩展SimpleMongoRepository？

我正在尝试创建一个可以由所有DAO扩展的BaseDAO接口.该项目使用mongodb的spring-data.问题是,如果我让所有单独的DAO扩展MongoRepository而不是编写实现类,那么一切正常.但是如果我尝试使用泛型将MongoRepository添加到BaseDAO接口,则该应用程序不再起作用,因为实例化SimpleMongoRepository所需的参数为null.这是我到目前为止的代码：

BaseDAO.java

import com.test.mongodb.BaseEntity;
import org.springframework.data.mongodb.repository.MongoRepository;
import org.springframework.data.repository.NoRepositoryBean;

import java.io.Serializable;

@NoRepositoryBean
public interface BaseDAO<T extends BaseEntity, ID extends Serializable> extends         MongoRepository<T, ID> {
    public T getTestObject(ID id);
}

BaseDAOImpl.java

import com.test.mongodb.BaseEntity;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.repository.query.EntityInformationCreator;
import org.springframework.data.mongodb.repository.query.MongoEntityInformation;
import org.springframework.data.mongodb.repository.support.SimpleMongoRepository;
import org.springframework.data.repository.NoRepositoryBean;

import java.io.Serializable;

@NoRepositoryBean
public class BaseDAOImpl<T extends BaseEntity, ID extends Serializable> extends     SimpleMongoRepository<T,
        ID> implements BaseDAO<T, ID> {

    @Autowired
    private static MongoTemplate mongoTemplate;

    @Autowired
    private static EntityInformationCreator entityInformationCreator;

    public BaseDAOImpl(Class<T> type){
        super((MongoEntityInformation<T, ID>)     entityInformationCreator.getEntityInformation(type), mongoTemplate);
    }

    @Override
    public T getTestObject(ID id){
        return findOne(id);
    }
}

UserDAO.java

import com.test.mongodb.User;
import org.springframework.stereotype.Repository;

@Repository
public interface UserDAO extends BaseDAO<User, String> {}

UserDAOImpl.java

import com.test.mongodb.User;
import org.springframework.stereotype.Repository;

@Repository
public class UserDAOImpl extends BaseDAOImpl<User, String> implements UserDAO {

    public UserDAOImpl(){
        super(User.class);
    }
}

applicationContext.xml中

    <?xml version="1.0" encoding="UTF-8"?><beans xmlns:xsi="http://www./2001/XMLSchema-instance"
       xmlns="http://www./schema/beans"
       xmlns:mongo="http://www./schema/data/mongo"
       xsi:schemaLocation="http://www./schema/beans http://www./schema/beans/spring-beans-3.2.xsd
    http://www./schema/data/mongo http://www./schema/data/mongo/spring-mongo-1.1.xsd">

    <!-- MongoFactoryBean instance -->
    <mongo:mongo host="localhost" port="27017" />

    <mongo:db-factory dbname="bank" mongo-ref="mongo" />

    <!-- MongoTemplate instance -->
    <bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate">
        <constructor-arg name="mongoDbFactory" ref="mongoDbFactory" />
    </bean>

    <bean id="mappingContext" class="org.springframework.data.mongodb.core.mapping.MongoMappingContext" />

    <bean id="entityInformationCreator" class="org.springframework.data.mongodb.repository.support.DefaultEntityInformationCreator">
        <constructor-arg name="mappingContext" ref="mappingContext" />
    </bean>
    <mongo:repositories base-package="com.test.mongodb.repo"/>
</beans>

App.java

public class App {

    public static void main(String[] args) {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

        UserRepository userRepository = context.getBean("userRepository", UserRepository.class);

        User user = new User("Test User");

        userRepository.save(user);

        String id = user.getId();
        System.out.println(id);

        System.out.println(userRepository.getTestObject(user.getId()));
    }
}

因此,当我运行它时,我在BaseDAOImpl中得到一个NPE,因为mongoTemplate和entityInformationCreator都是null.如何加载它们？我还查看了Spring MongoDB参考文档,但它主要是说要遵循其他类型的存储库的文档.我在那里和网上其他地方唯一能找到的就是创建一个工厂bean.所以我也试过了：

MongoRepoFactoryBean.java

import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.repository.MongoRepository;
import org.springframework.data.mongodb.repository.support.MongoRepositoryFactory;
import org.springframework.data.mongodb.repository.support.MongoRepositoryFactoryBean;
import org.springframework.data.repository.NoRepositoryBean;
import org.springframework.data.repository.core.support.RepositoryFactorySupport;

import java.io.Serializable;

@NoRepositoryBean
public class MongoRepoFactoryBean<T extends MongoRepository<?,?>, ID extends
    Serializable> extends MongoRepositoryFactoryBean {

    protected RepositoryFactorySupport createRepositoryFactory(Class<T> clazz, MongoTemplate mongoTemplate) {
        return new MongoRepoFactory(clazz, mongoTemplate);
    }

    private static class MongoRepoFactory extends MongoRepositoryFactory {
        private Class clazz;
        private MongoTemplate mongoTemplate;

        public MongoRepoFactory(Class clazz, MongoTemplate mongoTemplate) {
            super(mongoTemplate);
            this.mongoTemplate = mongoTemplate;
            this.clazz = clazz;
        }

        public Object getTargetRepository() {
            return new BaseDAOImpl(clazz);
        }

        public Class<?> getRepositoryBaseClass() {
            return BaseDAOImpl.class;
        }
    }
}

并使用以下命令更改了applicationContext.xml：

<mongo:repositories base-package="com.test.mongodb.repo"
                    factory-class="com.test.mongodb.repo.MongoRepoFactoryBean"/>

但这也不起作用.我也尝试使用JavaConfig,但是在使用注释进行配置时我不知道如何设置工厂类.我究竟做错了什么？ SimpleMongoRepository没有默认构造函数.注入静态字段有问题吗？

解决方法:

参考文档已过时,未反映spring-data-mongodb 1.1.1.RELEASE的更改.

我和你有同样的问题,这就是我解决它的方法.

请注意,我使用的是MongoConfig类和应用程序上下文XML,但您确实不需要两者,我只是决定这样做来举例说明它们的用法.

MongoConfig类:(你也可以通过spring app context XML来做到这一点)

@Configuration
public class MongoConfig extends AbstractMongoConfiguration {
    @Override
    protected String getDatabaseName() {
        return "myDb";
    }

    @Override
    @Bean
    public Mongo mongo() throws Exception {
        return new Mongo("localhost");
    }
}

Spring App Context XML：

<!-- You can also expose the bean as a method in the MongoConfig class -->
<bean id="mongoRepositoryFactory" class="org.springframework.data.mongodb.repository.support.MongoRepositoryFactory">
    <!-- mongoTemplate comes from AbstractMongoConfiguration -->
    <constructor-arg ref="mongoTemplate" />
</bean>

<context:annotation-config />
<context:component-scan base-package="com.example.domain" />
<mongo:repositories base-package="com.example.domain.repository" mongo-template-ref="mongoTemplate" />

我的repository / dao类：

@Repository
public class MyBeanDao extends SimpleMongoRepository<MyBean, String> {

    public MyBeanDao(MongoEntityInformation<MyBean, String> metadata, MongoOperations mongoOperations) {
        super(metadata, mongoOperations);
    }

    @Autowired
    public MyBeanDao(MongoRepositoryFactory factory, MongoOperations mongoOperations) {
        this(factory.<MyBean, String>getEntityInformation(MyBean.class), mongoOperations);
    }

    ... // more stuff
}

我知道这真的很丑,只适用于Java 6,但由于getEntityInformation()的返回类型是完全无界限的,所以它或者ID类型是Serializable而不是你的实际ID类型,并且每次你都进行显式转换需要它.

我希望有一个更清洁的方式,但我已经看了很长一段时间通过API甚至源代码,并没有想出一个更好的方法来做到这一点,而没有提出你自己的一些弹簧数据的实现-mongodb课程.

希望能帮助到你.

来源：https://www./content-2-281701.html