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服务器之家 - 编程语言 - Java教程 - Spring boot实现数据库读写分离的方法

Spring boot实现数据库读写分离的方法

2020-07-29 14:16Srggggg Java教程

本篇文章主要介绍了Spring boot实现数据库读写分离的方法,小编觉得挺不错的,现在分享给大家,也给大家做个参考。一起跟随小编过来看看吧

背景

数据库配置主从之后,如何在代码层面实现读写分离?

用户自定义设置数据库路由

Spring boot提供了AbstractRoutingDataSource根据用户定义的规则选择当前的数据库,这样我们可以在执行查询之前,设置读取从库,在执行完成后,恢复到主库。

实现可动态路由的数据源,在每次数据库查询操作前执行

ReadWriteSplitRoutingDataSource.java

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import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
 
/**
 * @author songrgg
 * @since 1.0
 */
public class ReadWriteSplitRoutingDataSource extends AbstractRoutingDataSource {
  @Override
  protected Object determineCurrentLookupKey() {
    return DbContextHolder.getDbType();
  }
}

线程私有路由配置,用于ReadWriteSplitRoutingDataSource动态读取配置

DbContextHolder.java

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/**
 * @author songrgg
 * @since 1.0
 */
public class DbContextHolder {
  public enum DbType {
    MASTER,
    SLAVE
  }
 
  private static final ThreadLocal<DbType> contextHolder = new ThreadLocal<>();
 
  public static void setDbType(DbType dbType) {
    if(dbType == null){
      throw new NullPointerException();
    }
    contextHolder.set(dbType);
  }
 
  public static DbType getDbType() {
    return contextHolder.get() == null ? DbType.MASTER : contextHolder.get();
  }
 
  public static void clearDbType() {
    contextHolder.remove();
  }
}

AOP优化代码

利用AOP将设置数据库的操作从代码中抽离,这里的粒度控制在方法级别,所以利用注解的形式标注这个方法涉及的数据库事务只读,走从库。

只读注解,用于标注方法的数据库操作只走从库。

ReadOnlyConnection.java

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package com.wallstreetcn.hatano.config;
 
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
 
/**
 * Indicates the database operations is bound to the slave database.
 * AOP interceptor will set the database to the slave with this interface.
 * @author songrgg
 * @since 1.0
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface ReadOnlyConnection {
}

ReadOnlyConnectionInterceptor.java

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import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.Ordered;
import org.springframework.stereotype.Component;
 
/**
 * Intercept the database operations, bind database to read-only database as this annotation
 * is applied.
 * @author songrgg
 * @since 1.0
 */
@Aspect
@Component
public class ReadOnlyConnectionInterceptor implements Ordered {
 
  private static final Logger logger = LoggerFactory.getLogger(ReadOnlyConnectionInterceptor.class);
 
  @Around("@annotation(readOnlyConnection)")
  public Object proceed(ProceedingJoinPoint proceedingJoinPoint, ReadOnlyConnection readOnlyConnection) throws Throwable {
    try {
      logger.info("set database connection to read only");
      DbContextHolder.setDbType(DbContextHolder.DbType.SLAVE);
      Object result = proceedingJoinPoint.proceed();
      return result;
    } finally {
      DbContextHolder.clearDbType();
      logger.info("restore database connection");
    }
  }
 
  @Override
  public int getOrder() {
    return 0;
  }
}

UserService.java

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@ReadOnlyConnection
public List<User> getUsers(Integer page, Integer limit) {
  return repository.findAll(new PageRequest(page, limit));
}

配置Druid数据库连接池

build.gradle

compile("com.alibaba:druid:1.0.18")

groovy依赖注入

配置dataSource为可路由数据源

context.groovy

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import com.alibaba.druid.pool.DruidDataSource
import DbContextHolder
import ReadWriteSplitRoutingDataSource
 
** SOME INITIALIZED CODE LOAD PROPERTIES **
def dataSourceMaster = new DruidDataSource()
dataSourceMaster.url = properties.get('datasource.master.url')
println("master set to " + dataSourceMaster.url)
dataSourceMaster.username = properties.get('datasource.master.username')
dataSourceMaster.password = properties.get('datasource.master.password')
 
def dataSourceSlave = new DruidDataSource()
dataSourceSlave.url = properties.get('datasource.slave.url')
println("slave set to " + dataSourceSlave.url)
dataSourceSlave.username = properties.get('datasource.slave.username')
dataSourceSlave.password = properties.get('datasource.slave.password')
beans {
  dataSource(ReadWriteSplitRoutingDataSource) { bean ->
    targetDataSources = [
        (DbContextHolder.DbType.MASTER): dataSourceMaster,
        (DbContextHolder.DbType.SLAVE): dataSourceSlave
    ]
  }
}

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。

原文链接:http://www.cnblogs.com/pier2/p/spring-boot-read-write-split.html

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