将自定义注释建议应用于 spring 数据 jpa 存储库

Question

我正在研究 mysql 主从复制。我正在使用 spring data jpa(spring boot).

我需要的是所有写操作都到主服务器，只读操作平均分配给多个只读从服务器。

为此我需要：

使用特殊的JDBC驱动程序：com.mysql.jdbc.ReplicationDriver

设置复制：在URL:

spring:
    datasource:
        driverClassName: com.mysql.jdbc.ReplicationDriver
        url: jdbc:mysql:replication://127.0.0.1:3306,127.0.0.1:3307/MyForum?user=root&password=password&autoReconnect=true
        test-on-borrow: true
        validation-query: SELECT 1
    database: MYSQL

需要关闭自动提交。 (*) 需要将连接设置为只读。

为了确保 JDBC 连接设置为只读，我创建了一个注解和一个简单的 AOP 拦截器。

注释

package com.xyz.forum.replication;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target; 

/**
 * Created by Bhupati Patel on 02/11/15.
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface ReadOnlyConnection {
}

拦截器

package com.xyz.forum.replication;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.hibernate.Session;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import javax.persistence.EntityManager;

/**
 * Created by Bhupati Patel on 02/11/15.
 */

@Aspect
@Component
public class ConnectionInterceptor {

    private Logger logger;

    public ConnectionInterceptor() {
        logger = LoggerFactory.getLogger(getClass());
        logger.info("ConnectionInterceptor Started");
    }

    @Autowired
    private EntityManager entityManager;

    @Pointcut("@annotation(com.xyz.forum.replication.ReadOnlyConnection)")
    public void inReadOnlyConnection(){}


    @Around("inReadOnlyConnection()")
    public Object proceed(ProceedingJoinPoint pjp) throws Throwable {
        Session session = entityManager.unwrap(Session.class);
        ConnectionReadOnly readOnlyWork = new ConnectionReadOnly();

        try{
            session.doWork(readOnlyWork);
            return pjp.proceed();
        } finally {
            readOnlyWork.switchBack();
        }
    }

}

以下是我的 spring 数据存储库

package com.xyz.forum.repositories;

import com.xyz.forum.entity.Topic;
import org.springframework.data.repository.Repository;

import java.util.List;

/**
 * Created by Bhupati Patel on 16/04/15.
 */
public interface TopicRepository extends Repository<Topic,Integer>{
    Topic save(Topic topic);
    Topic findByTopicIdAndIsDeletedFalse(Integer topicId);
    List<Topic> findByIsDeletedOrderByTopicOrderAsc(Boolean isDelete);

}

以下是我的经理（服务）class。

package com.xyz.forum.manager;

import com.xyz.forum.domain.entry.impl.TopicEntry;

import com.xyz.forum.domain.exception.impl.AuthException;

import com.xyz.forum.domain.exception.impl.NotFoundException;
import com.xyz.forum.entity.Topic;
import com.xyz.forum.replication.ReadOnlyConnection;
import com.xyz.forum.repositories.TopicRepository;
import com.xyz.forum.utils.converter.TopicConverter;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import java.util.*;

/**
 * Created by Bhupati Patel on 16/04/15.
 */
@Repository
public class TopicManager {
    @Autowired
    TopicRepository topicRepository;

    @Transactional
    public TopicEntry save(TopicEntry topicEntry) {
        Topic topic = TopicConverter.fromEntryToEntity(topicEntry);
        return TopicConverter.fromEntityToEntry(topicRepository.save(topic));
    }

    @ReadOnlyConnection
    public TopicEntry get(Integer id) {
        Topic topicFromDb = topicRepository.findByTopicIdAndIsDeletedFalse(id);
        if(topicFromDb == null) {
            throw new NotFoundException("Invalid Id", "Topic Id [" + id + "] doesn't exist ");
        }
        return TopicConverter.fromEntityToEntry(topicFromDb);
    }
}

在上面的代码中@ReadOnlyConnection注解是在manager或者service层指定的。 上面的代码对我来说工作正常。这是一个微不足道的案例，在服务层我只从从数据库读取并写入主数据库。

话虽如此，我的实际要求是我应该能够在存储库级别本身使用@ReadOnlyConnection，因为我有相当多的业务逻辑，我在其他 classes 中同时执行 read/write 操作服务层 layer.Therefore 我不能将@ReadOnlyConnection 放在服务层。

我应该可以用这样的东西

public interface TopicRepository extends Repository<Topic,Integer>{
    Topic save(Topic topic);
    @ReadOnlyConnection
    Topic findByTopicIdAndIsDeletedFalse(Integer topicId);
    @ReadOnlyConnection
    List<Topic> findByIsDeletedOrderByTopicOrderAsc(Boolean isDelete);

}

喜欢spring的@Transactional 或@Modifying 或@Query 注释。以下是我所指的示例。

    public interface AnswerRepository extends Repository<Answer,Integer> {
    @Transactional
    Answer save(Answer answer);

    @Transactional
    @Modifying
    @Query("update Answer ans set ans.isDeleted = 1, ans.deletedBy = :deletedBy, ans.deletedOn = :deletedOn " +
            "where ans.questionId = :questionId and ans.isDeleted = 0")
    void softDeleteBulkAnswers(@Param("deletedBy") String deletedBy, @Param("deletedOn") Date deletedOn,
                               @Param("questionId") Integer questionId);
}

我是 aspectj 和 aop 世界的新手，我在 ConnectionInterceptor 中尝试了很多切入点正则表达式，但其中 none 有效。我已经尝试了很长时间，但还没有成功。

如何完成要求的任务。

Answer 1

我无法找到在方法级别使用我的自定义注释 @ReadOnlyConnection（如@Transactional）的解决方法，但一个小问题确实对我有用。

我正在粘贴下面的代码片段。

@Aspect
@Component
@EnableAspectJAutoProxy
public class ConnectionInterceptor {

    private Logger logger;
    private static final String JPA_PREFIX = "findBy";
    private static final String CUSTOM_PREFIX = "read";

    public ConnectionInterceptor() {
        logger = LoggerFactory.getLogger(getClass());
        logger.info("ConnectionInterceptor Started");
    }

    @Autowired
    private EntityManager entityManager;

    @Pointcut("this(org.springframework.data.repository.Repository)")
    public void inRepositoryLayer() {}

    @Around("inRepositoryLayer()")
    public Object proceed(ProceedingJoinPoint pjp) throws Throwable {
        String methodName = pjp.getSignature().getName();
        if (StringUtils.startsWith(methodName, JPA_PREFIX) || StringUtils.startsWith(methodName, CUSTOM_PREFIX)) {
            System.out.println("I'm there!" );
            Session session = entityManager.unwrap(Session.class);
            ConnectionReadOnly readOnlyWork = new ConnectionReadOnly();

            try{
                session.doWork(readOnlyWork);
                return pjp.proceed();
            } finally {
                readOnlyWork.switchBack();
            }
        }
        return pjp.proceed();
    }
}

所以在上面的代码中我使用了如下的切入点

@Pointcut("this(org.springframework.data.repository.Repository)")
public void inRepositoryLayer() {}

它的作用是

any join point (method execution only in Spring AOP) where the proxy implements the Repository interface

你可以看看 http://docs.spring.io/spring/docs/current/spring-framework-reference/html/aop.html

现在我所有的存储库读取查询方法都以前缀 "findByXXX"（默认 spring-data-jpa 可读方法）或 "readXXX"（带有 @Query 注释的自定义读取方法）开头) 在我的 around 方法执行中与上述切入点匹配。根据我的要求，我将 JDBC Connection readOnly 设置为 true。

Session session = entityManager.unwrap(Session.class);
ConnectionReadOnly readOnlyWork = new ConnectionReadOnly();

我的 ConnectionReadOnly 如下所示

package com.xyz.forum.replication;

import org.hibernate.jdbc.Work;

import java.sql.Connection;
import java.sql.SQLException;

/**
 * Created by Bhupati Patel on 04/11/15.
 */
public class ConnectionReadOnly implements Work {

    private Connection connection;
    private boolean autoCommit;
    private boolean readOnly;

    @Override
    public void execute(Connection connection) throws SQLException {
        this.connection = connection;
        this.autoCommit = connection.getAutoCommit();
        this.readOnly = connection.isReadOnly();
        connection.setAutoCommit(false);
        connection.setReadOnly(true);
    }

    //method to restore the connection state before intercepted
    public void switchBack() throws SQLException{
        connection.setAutoCommit(autoCommit);
        connection.setReadOnly(readOnly);
    }
}

以上设置符合我的要求。

Answer 2

@Pointcut && @Around 似乎应该以如下方式声明：

@Pointcut(value = "execution(public * *(..))")
public void anyPublicMethod() {
}

@Around("@annotation(readOnlyConnection)")

将自定义注释建议应用于 spring 数据 jpa 存储库

Applying custom annotation advice to spring data jpa repository

spring

aspectj

spring-aop

spring-data-jpa

spring-aspects