概述
spring boot + mybatis 实现动态多数据源，本文讲解一写两读，更多的配置一样
前提：需要做好mysql的主从同步功能
实现的动态数据源的代码，主要在包conf中
DataSourceConfigurer.java ====> 数据源配置类
DataSourceKey.java ====> 数据源key类
DynamicDataSourceAspect.java ====> AOP切面类
DynamicDataSourceContextHolder.java ====> 切换数据源类
DynamicRoutingDataSource.java ====> 数据源路由类
DataSourceConfigurer.java
package com.example.demo.conf;
import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;
import javax.sql.DataSource;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
/**
* 数据源配置
*/
@Configuration
@MapperScan(basePackages = DataSourceConfigurer.PACKAGE)
public class DataSourceConfigurer {
// 精确到 first 目录，以便跟其他数据源隔离
static final String PACKAGE = "com.example.demo.dao";
static final String MAPPER_LOCATION = "classpath:mapper/*.xml";
@Bean("first")
@Primary
@ConfigurationProperties(prefix = "first.datasource")
public DataSource first() {
return DruidDataSourceBuilder.create().build();
}
@Bean("second")
@ConfigurationProperties(prefix = "second.datasource")
public DataSource second() {
return DruidDataSourceBuilder.create().build();
}
@Bean("third")
@ConfigurationProperties(prefix = "third.datasource")
public DataSource third() {
return DruidDataSourceBuilder.create().build();
}
@Bean("dynamicDataSource")
public DataSource dynamicDataSource() {
DynamicRoutingDataSource dynamicRoutingDataSource = new DynamicRoutingDataSource();
Map<Object, Object> dataSourceMap = new HashMap<>(3);
dataSourceMap.put(DataSourceKey.first.name(), first());
dataSourceMap.put(DataSourceKey.second.name(), second());
dataSourceMap.put(DataSourceKey.third.name(), third());
// 将 first 数据源作为默认指定的数据源
dynamicRoutingDataSource.setDefaultTargetDataSource(first());
// 将 first second third 数据源作为指定的数据源
dynamicRoutingDataSource.setTargetDataSources(dataSourceMap);
// 将数据源的 key 放到数据源上下文的 key 集合中，用于切换时判断数据源是否有效
DynamicDataSourceContextHolder.dataSourceKeys.addAll(dataSourceMap.keySet());
// 将 second third 数据源的 key 放在集合中，用于轮循
DynamicDataSourceContextHolder.slaveDataSourceKeys.addAll(dataSourceMap.keySet());
DynamicDataSourceContextHolder.slaveDataSourceKeys.remove(DataSourceKey.first.name());
return dynamicRoutingDataSource;
}
/**
* 配置 SqlSessionFactoryBean
* @ConfigurationProperties 在这里是为了将 MyBatis 的 mapper 位置和持久层接口的别名设置到
* Bean 的属性中，如果没有使用 *.xml 则可以不用该配置，否则将会产生 invalid bond statement 异常
*/
@Bean
// @ConfigurationProperties(prefix = "mybatis")
public SqlSessionFactoryBean sqlSessionFactoryBean() throws IOException {
// 配置数据源，此处配置为关键配置，如果没有将 dynamicDataSource 作为数据源则不能实现切换
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dynamicDataSource());
sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(DataSourceConfigurer.MAPPER_LOCATION));
return sqlSessionFactoryBean;
}
/**
* 注入 DataSourceTransactionManager 用于事务管理
* @return
*/
@Bean
public PlatformTransactionManager transactionManager() {
return new DataSourceTransactionManager(dynamicDataSource());
}
}
DataSourceKey.java
package com.example.demo.conf;
public enum DataSourceKey {
first, second, third
}
DynamicDataSourceAspect.java
package com.example.demo.conf;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
/**
* 动态数据源切换的切面，切 DAO 层，通过 DAO 层方法名判断使用哪个数据源，实现数据源切换 关于切面的 Order 可以可以不设，
* 因为 @Transactional 是最低的，取决于其他切面的设置，并且在 org.springframework.core.annotation.AnnotationAwareOrderComparator 会重新排序
*/
@Aspect
@Component
public class DynamicDataSourceAspect {
private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceAspect.class);
private final String[] QUERY_PREFIX = {"get", "query", "find", "select", "is"};
@Pointcut("execution(* com.example.demo.service.impl.*.*(..))")
public void daoAspect() {
}
@Before("daoAspect()")
public void switchDataSource(JoinPoint point) {
logger.info("--------------------------------------------------");
logger.info(" Class Name ----> "+ point.getTarget().getClass().getName());
logger.info(" Method Name ----> "+ point.getSignature().getName());
logger.info("--------------------------------------------------");
Boolean isQueryMethod = isQueryMethod(point.getSignature().getName());
logger.info("--------------------------------------------------");
logger.info(" Var ----> true 从数据源, false 主数据源 ----> "+ isQueryMethod);
logger.info("--------------------------------------------------");
if (isQueryMethod) {
DynamicDataSourceContextHolder.useSlaveDataSource();
logger.debug("Switch DataSource to [{}] in Method [{}]", DynamicDataSourceContextHolder.getDataSourceKey(), point.getSignature());
}
if (!isQueryMethod) {
logger.info("分割线====================================================================================================分割线");
}
}
@After("daoAspect())")
public void restoreDataSource(JoinPoint point) {
DynamicDataSourceContextHolder.clearDataSourceKey();
logger.debug("Restore DataSource to [{}] in Method [{}]", DynamicDataSourceContextHolder.getDataSourceKey(), point.getSignature());
}
private Boolean isQueryMethod(String methodName) {
for (String prefix : QUERY_PREFIX) {
if (methodName.startsWith(prefix)) {
return true;
}
}
return false;
}
}
DynamicDataSourceContextHolder.java
package com.example.demo.conf;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* 该类为数据源上下文配置，用于切换数据源
*/
public class DynamicDataSourceContextHolder {
private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceContextHolder.class);
// 用于在切换数据源时保证不会被其他线程修改
private static Lock lock = new ReentrantLock();
// 用于轮循的计数器
private static int counter = 0;
// 为每个线程维护变量，以避免影响其他线程
private static final ThreadLocal<String> CONTEXT_HOLDER = ThreadLocal.withInitial(DataSourceKey.first::name);
// 所有数据源key
public static List<Object> dataSourceKeys = new ArrayList<>();
// 从数据源key
public static List<Object> slaveDataSourceKeys = new ArrayList<>();
public static void setDataSourceKey(String key) {
CONTEXT_HOLDER.set(key);
}
public static void useMasterDataSource() {
CONTEXT_HOLDER.set(DataSourceKey.first.name());
}
public static String getDataSourceKey() {
return CONTEXT_HOLDER.get();
}
public static void clearDataSourceKey() {
CONTEXT_HOLDER.remove();
}
public static boolean containDataSourceKey(String key) {
return dataSourceKeys.contains(key);
}
/**
* 当使用只读数据源时通过轮循方式选择要使用的数据源
*/
public static void useSlaveDataSource() {
lock.lock();
try {
int datasourceKeyIndex = counter % slaveDataSourceKeys.size();
CONTEXT_HOLDER.set(String.valueOf(slaveDataSourceKeys.get(datasourceKeyIndex)));
counter++;
} catch (Exception e) {
logger.error("Switch slave datasource failed, error message is {}", e.getMessage());
useMasterDataSource();
e.printStackTrace();
} finally {
logger.info("--------------------------------------------------");
logger.info(" Var ----> CONTEXT_HOLDER.get() ----> "+ CONTEXT_HOLDER.get());
logger.info("--------------------------------------------------");
logger.info("分割线====================================================================================================分割线");
lock.unlock();
}
}
}
DynamicRoutingDataSource.java
package com.example.demo.conf;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
public class DynamicRoutingDataSource extends AbstractRoutingDataSource {
private final Logger logger = LoggerFactory.getLogger(getClass());
@Override
protected Object determineCurrentLookupKey() {
logger.debug("Current DataSource is [{}]", DynamicDataSourceContextHolder.getDataSourceKey());
return DynamicDataSourceContextHolder.getDataSourceKey();
}
}
测试结果
- 查询
这个getDetail方法被打倒了third数据库上
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] Class Name ----> com.example.demo.service.impl.UserServiceImpl
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] Method Name ----> getDetail
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] Var ----> true 从数据源, false 主数据源 ----> true
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceContextHolder] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceContextHolder] Var ----> CONTEXT_HOLDER.get() ----> third
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceContextHolder] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceContextHolder] 分割线====================================================================================================分割线
- 插入
这个register方法被打到了主数据源上
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] Class Name ----> com.example.demo.service.impl.UserServiceImpl
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] Method Name ----> register
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] Var ----> true 从数据源, false 主数据源 ----> false
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] 分割线====================================================================================================分割线
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