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;@NoRepositoryBeanpublic 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;@NoRepositoryBeanpublic 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;@Repositorypublic interface UserDAO extends BaseDAO<User, String> {}

UserDAOImpl.java

import com.test.mongodb.User;import org.springframework.stereotype.Repository;@Repositorypublic 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.w3.org/2001/XMLSchema-instance"       xmlns="http://www.springframework.org/schema/beans"       xmlns:mongo="http://www.springframework.org/schema/data/mongo"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd    http://www.springframework.org/schema/data/mongo http://www.springframework.org/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;@NoRepositoryBeanpublic 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)

@Configurationpublic 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：

@Repositorypublic 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.icode9.com/content-2-281701.html