本文来自 Apache Seata官方文档，欢迎访问官网，查看更多深度文章。
本文来自 Apache Seata官方文档，欢迎访问官网，查看更多深度文章。
Apache Seata透过源码解决SeataAT模式整合Mybatis-Plus失去MP特性的问题
透过源码解决SeataAT模式整合Mybatis-Plus失去MP特性的问题
项目地址：https://gitee.com/itCjb/springboot-dubbo-mybatisplus-seata
本文作者：FUNKYE(陈健斌),杭州某互联网公司主程。
介绍
Mybatis-Plus：MyBatis-Plus（简称 MP）是一个 MyBatis 的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发、提高效率而生。
MP配置：
<bean id="sqlSessionFactory" class="com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean"><property name="dataSource" ref="dataSource"/>
</bean>
Seata：Seata 是一款开源的分布式事务解决方案，致力于提供高性能和简单易用的分布式事务服务。Seata 将为用户提供了 AT、TCC、SAGA 和 XA 事务模式，为用户打造一站式的分布式解决方案。
AT模式机制：
- 一阶段：业务数据和回滚日志记录在同一个本地事务中提交，释放本地锁和连接资源。
- 二阶段：
- 提交异步化，非常快速地完成。
- 回滚通过一阶段的回滚日志进行反向补偿。
分析原因
1.首先我们通过介绍，可以看到，mp是需要注册sqlSessionFactory，注入数据源，而Seata是通过代理数据源来保证事务的正常回滚跟提交。
2.我们来看基于seata的官方demo提供的SeataAutoConfig的代码
package org.test.config;import javax.sql.DataSource; import org.apache.ibatis.session.SqlSessionFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;import com.alibaba.druid.pool.DruidDataSource;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;import io.seata.rm.datasource.DataSourceProxy;
import io.seata.spring.annotation.GlobalTransactionScanner;@Configuration
public class SeataAutoConfig {@Autowired(required = true)private DataSourceProperties dataSourceProperties;private final static Logger logger = LoggerFactory.getLogger(SeataAutoConfig.class);@Bean(name = "dataSource") // 声明其为Bean实例@Primary // 在同样的DataSource中，首先使用被标注的DataSourcepublic DataSource druidDataSource() {DruidDataSource druidDataSource = new DruidDataSource();logger.info("dataSourceProperties.getUrl():{}",dataSourceProperties.getUrl());druidDataSource.setUrl(dataSourceProperties.getUrl());druidDataSource.setUsername(dataSourceProperties.getUsername());druidDataSource.setPassword(dataSourceProperties.getPassword());druidDataSource.setDriverClassName(dataSourceProperties.getDriverClassName());druidDataSource.setInitialSize(0);druidDataSource.setMaxActive(180);druidDataSource.setMaxWait(60000);druidDataSource.setMinIdle(0);druidDataSource.setValidationQuery("Select 1 from DUAL");druidDataSource.setTestOnBorrow(false);druidDataSource.setTestOnReturn(false);druidDataSource.setTestWhileIdle(true);druidDataSource.setTimeBetweenEvictionRunsMillis(60000);druidDataSource.setMinEvictableIdleTimeMillis(25200000);druidDataSource.setRemoveAbandoned(true);druidDataSource.setRemoveAbandonedTimeout(1800);druidDataSource.setLogAbandoned(true);logger.info("装载dataSource........");return druidDataSource;}/*** init datasource proxy* * @Param: druidDataSource datasource bean instance* @Return: DataSourceProxy datasource proxy*/@Beanpublic DataSourceProxy dataSourceProxy(DataSource dataSource) {logger.info("代理dataSource........");return new DataSourceProxy(dataSource);}@Beanpublic SqlSessionFactory sqlSessionFactory(DataSourceProxy dataSourceProxy) throws Exception {MybatisSqlSessionFactoryBean factory = new MybatisSqlSessionFactoryBean();factory.setDataSource(dataSourceProxy);factory.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:/mapper/*.xml"));return factory.getObject();}/*** init global transaction scanner** @Return: GlobalTransactionScanner*/@Beanpublic GlobalTransactionScanner globalTransactionScanner() {logger.info("配置seata........");return new GlobalTransactionScanner("test-service", "test-group");}
}首先看到我们的seata配置数据源的类里,我们配置了一个数据源,然后又配置了一个seata代理datasource的bean,这时候.
然后我们如果直接启动mp整合seata的项目会发现,分页之类的插件会直接失效,连扫描mapper都得从代码上写,这是为什么呢?
通过阅读以上代码,是因为我们另外的配置了一个sqlSessionFactory,导致mp的sqlSessionFactory失效了,这时候我们发现了问题的所在了，即使我们不配置sqlSessionFactoryl，也会因为mp所使用的数据源不是被seata代理过后的数据源，导致分布式事务失效.但是如何解决这个问题呢?
这时候我们需要去阅读mp的源码,找到他的启动类,一看便知
/** Copyright (c) 2011-2020, baomidou (jobob@qq.com).* <p>* Licensed under the Apache License, Version 2.0 (the "License"); you may not* use this file except in compliance with the License. You may obtain a copy of* the License at* <p>* https://www.apache.org/licenses/LICENSE-2.0* <p>* Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the* License for the specific language governing permissions and limitations under* the License.*/
package com.baomidou.mybatisplus.autoconfigure;import com.baomidou.mybatisplus.core.MybatisConfiguration;
import com.baomidou.mybatisplus.core.config.GlobalConfig;
import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import com.baomidou.mybatisplus.core.incrementer.IKeyGenerator;
import com.baomidou.mybatisplus.core.injector.ISqlInjector;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.mapping.DatabaseIdProvider;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.scripting.LanguageDriver;
import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.type.TypeHandler;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.mapper.MapperFactoryBean;
import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeanWrapperImpl;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.boot.autoconfigure.AutoConfigurationPackages;
import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnSingleCandidate;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.util.Assert;
import org.springframework.util.CollectionUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;import javax.sql.DataSource;
import java.util.List;
import java.util.Optional;
import java.util.stream.Stream;/*** {@link EnableAutoConfiguration Auto-Configuration} for Mybatis. Contributes a* {@link SqlSessionFactory} and a {@link SqlSessionTemplate}.* <p>* If {@link org.mybatis.spring.annotation.MapperScan} is used, or a* configuration file is specified as a property, those will be considered,* otherwise this auto-configuration will attempt to register mappers based on* the interface definitions in or under the root auto-configuration package.* </p>* <p> copy from {@link org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration}</p>** @author Eddú Meléndez* @author Josh Long* @author Kazuki Shimizu* @author Eduardo Macarrón*/
@Configuration
@ConditionalOnClass({SqlSessionFactory.class, SqlSessionFactoryBean.class})
@ConditionalOnSingleCandidate(DataSource.class)
@EnableConfigurationProperties(MybatisPlusProperties.class)
@AutoConfigureAfter(DataSourceAutoConfiguration.class)
public class MybatisPlusAutoConfiguration implements InitializingBean {private static final Logger logger = LoggerFactory.getLogger(MybatisPlusAutoConfiguration.class);private final MybatisPlusProperties properties;private final Interceptor[] interceptors;private final TypeHandler[] typeHandlers;private final LanguageDriver[] languageDrivers;private final ResourceLoader resourceLoader;private final DatabaseIdProvider databaseIdProvider;private final List<ConfigurationCustomizer> configurationCustomizers;private final List<MybatisPlusPropertiesCustomizer> mybatisPlusPropertiesCustomizers;private final ApplicationContext applicationContext;public MybatisPlusAutoConfiguration(MybatisPlusProperties properties,ObjectProvider<Interceptor[]> interceptorsProvider,ObjectProvider<TypeHandler[]> typeHandlersProvider,ObjectProvider<LanguageDriver[]> languageDriversProvider,ResourceLoader resourceLoader,ObjectProvider<DatabaseIdProvider> databaseIdProvider,ObjectProvider<List<ConfigurationCustomizer>> configurationCustomizersProvider,ObjectProvider<List<MybatisPlusPropertiesCustomizer>> mybatisPlusPropertiesCustomizerProvider,ApplicationContext applicationContext) {this.properties = properties;this.interceptors = interceptorsProvider.getIfAvailable();this.typeHandlers = typeHandlersProvider.getIfAvailable();this.languageDrivers = languageDriversProvider.getIfAvailable();this.resourceLoader = resourceLoader;this.databaseIdProvider = databaseIdProvider.getIfAvailable();this.configurationCustomizers = configurationCustomizersProvider.getIfAvailable();this.mybatisPlusPropertiesCustomizers = mybatisPlusPropertiesCustomizerProvider.getIfAvailable();this.applicationContext = applicationContext;}@Overridepublic void afterPropertiesSet() {if (!CollectionUtils.isEmpty(mybatisPlusPropertiesCustomizers)) {mybatisPlusPropertiesCustomizers.forEach(i -> i.customize(properties));}checkConfigFileExists();}private void checkConfigFileExists() {if (this.properties.isCheckConfigLocation() && StringUtils.hasText(this.properties.getConfigLocation())) {Resource resource = this.resourceLoader.getResource(this.properties.getConfigLocation());Assert.state(resource.exists(),"Cannot find config location: " + resource + " (please add config file or check your Mybatis configuration)");}}@SuppressWarnings("SpringJavaInjectionPointsAutowiringInspection")@Bean@ConditionalOnMissingBeanpublic SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {// TODO 使用 MybatisSqlSessionFactoryBean 而不是 SqlSessionFactoryBeanMybatisSqlSessionFactoryBean factory = new MybatisSqlSessionFactoryBean();factory.setDataSource(dataSource);factory.setVfs(SpringBootVFS.class);if (StringUtils.hasText(this.properties.getConfigLocation())) {factory.setConfigLocation(this.resourceLoader.getResource(this.properties.getConfigLocation()));}applyConfiguration(factory);if (this.properties.getConfigurationProperties() != null) {factory.setConfigurationProperties(this.properties.getConfigurationProperties());}if (!ObjectUtils.isEmpty(this.interceptors)) {factory.setPlugins(this.interceptors);}if (this.databaseIdProvider != null) {factory.setDatabaseIdProvider(this.databaseIdProvider);}if (StringUtils.hasLength(this.properties.getTypeAliasesPackage())) {factory.setTypeAliasesPackage(this.properties.getTypeAliasesPackage());}if (this.properties.getTypeAliasesSuperType() != null) {factory.setTypeAliasesSuperType(this.properties.getTypeAliasesSuperType());}if (StringUtils.hasLength(this.properties.getTypeHandlersPackage())) {factory.setTypeHandlersPackage(this.properties.getTypeHandlersPackage());}if (!ObjectUtils.isEmpty(this.typeHandlers)) {factory.setTypeHandlers(this.typeHandlers);}if (!ObjectUtils.isEmpty(this.properties.resolveMapperLocations())) {factory.setMapperLocations(this.properties.resolveMapperLocations());}// TODO 对源码做了一定的修改(因为源码适配了老旧的mybatis版本,但我们不需要适配)Class<? extends LanguageDriver> defaultLanguageDriver = this.properties.getDefaultScriptingLanguageDriver();if (!ObjectUtils.isEmpty(this.languageDrivers)) {factory.setScriptingLanguageDrivers(this.languageDrivers);}Optional.ofNullable(defaultLanguageDriver).ifPresent(factory::setDefaultScriptingLanguageDriver);// TODO 自定义枚举包if (StringUtils.hasLength(this.properties.getTypeEnumsPackage())) {factory.setTypeEnumsPackage(this.properties.getTypeEnumsPackage());}// TODO 此处必为非 NULLGlobalConfig globalConfig = this.properties.getGlobalConfig();// TODO 注入填充器if (this.applicationContext.getBeanNamesForType(MetaObjectHandler.class,false, false).length > 0) {MetaObjectHandler metaObjectHandler = this.applicationContext.getBean(MetaObjectHandler.class);globalConfig.setMetaObjectHandler(metaObjectHandler);}// TODO 注入主键生成器if (this.applicationContext.getBeanNamesForType(IKeyGenerator.class, false,false).length > 0) {IKeyGenerator keyGenerator = this.applicationContext.getBean(IKeyGenerator.class);globalConfig.getDbConfig().setKeyGenerator(keyGenerator);}// TODO 注入sql注入器if (this.applicationContext.getBeanNamesForType(ISqlInjector.class, false,false).length > 0) {ISqlInjector iSqlInjector = this.applicationContext.getBean(ISqlInjector.class);globalConfig.setSqlInjector(iSqlInjector);}// TODO 设置 GlobalConfig 到 MybatisSqlSessionFactoryBeanfactory.setGlobalConfig(globalConfig);return factory.getObject();}// TODO 入参使用 MybatisSqlSessionFactoryBeanprivate void applyConfiguration(MybatisSqlSessionFactoryBean factory) {// TODO 使用 MybatisConfigurationMybatisConfiguration configuration = this.properties.getConfiguration();if (configuration == null && !StringUtils.hasText(this.properties.getConfigLocation())) {configuration = new MybatisConfiguration();}if (configuration != null && !CollectionUtils.isEmpty(this.configurationCustomizers)) {for (ConfigurationCustomizer customizer : this.configurationCustomizers) {customizer.customize(configuration);}}factory.setConfiguration(configuration);}@Bean@ConditionalOnMissingBeanpublic SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {ExecutorType executorType = this.properties.getExecutorType();if (executorType != null) {return new SqlSessionTemplate(sqlSessionFactory, executorType);} else {return new SqlSessionTemplate(sqlSessionFactory);}}/*** This will just scan the same base package as Spring Boot does. If you want more power, you can explicitly use* {@link org.mybatis.spring.annotation.MapperScan} but this will get typed mappers working correctly, out-of-the-box,* similar to using Spring Data JPA repositories.*/public static class AutoConfiguredMapperScannerRegistrar implements BeanFactoryAware, ImportBeanDefinitionRegistrar {private BeanFactory beanFactory;@Overridepublic void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {if (!AutoConfigurationPackages.has(this.beanFactory)) {logger.debug("Could not determine auto-configuration package, automatic mapper scanning disabled.");return;}logger.debug("Searching for mappers annotated with @Mapper");List<String> packages = AutoConfigurationPackages.get(this.beanFactory);if (logger.isDebugEnabled()) {packages.forEach(pkg -> logger.debug("Using auto-configuration base package '{}'", pkg));}BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(MapperScannerConfigurer.class);builder.addPropertyValue("processPropertyPlaceHolders", true);builder.addPropertyValue("annotationClass", Mapper.class);builder.addPropertyValue("basePackage", StringUtils.collectionToCommaDelimitedString(packages));BeanWrapper beanWrapper = new BeanWrapperImpl(MapperScannerConfigurer.class);Stream.of(beanWrapper.getPropertyDescriptors())// Need to mybatis-spring 2.0.2+.filter(x -> x.getName().equals("lazyInitialization")).findAny().ifPresent(x -> builder.addPropertyValue("lazyInitialization", "${mybatis.lazy-initialization:false}"));registry.registerBeanDefinition(MapperScannerConfigurer.class.getName(), builder.getBeanDefinition());}@Overridepublic void setBeanFactory(BeanFactory beanFactory) {this.beanFactory = beanFactory;}}/*** If mapper registering configuration or mapper scanning configuration not present, this configuration allow to scan* mappers based on the same component-scanning path as Spring Boot itself.*/@Configuration@Import(AutoConfiguredMapperScannerRegistrar.class)@ConditionalOnMissingBean({MapperFactoryBean.class, MapperScannerConfigurer.class})public static class MapperScannerRegistrarNotFoundConfiguration implements InitializingBean {@Overridepublic void afterPropertiesSet() {logger.debug("Not found configuration for registering mapper bean using @MapperScan, MapperFactoryBean and MapperScannerConfigurer.");}}
}看到mp启动类里的sqlSessionFactory方法了吗,他也是一样的注入一个数据源,这时候大家应该都知道解决方法了吧?
没错,就是把被代理过的数据源给放到mp的sqlSessionFactory中.
很简单,我们需要稍微改动一下我们的seata配置类就行了
package org.test.config;import javax.sql.DataSource;import org.mybatis.spring.annotation.MapperScan;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;import com.alibaba.druid.pool.DruidDataSource;import io.seata.rm.datasource.DataSourceProxy;
import io.seata.spring.annotation.GlobalTransactionScanner;@Configuration
@MapperScan("com.baomidou.springboot.mapper*")
public class SeataAutoConfig {@Autowired(required = true)private DataSourceProperties dataSourceProperties;private final static Logger logger = LoggerFactory.getLogger(SeataAutoConfig.class);private DataSourceProxy dataSourceProxy;@Bean(name = "dataSource") // 声明其为Bean实例@Primary // 在同样的DataSource中，首先使用被标注的DataSourcepublic DataSource druidDataSource() {DruidDataSource druidDataSource = new DruidDataSource();logger.info("dataSourceProperties.getUrl():{}", dataSourceProperties.getUrl());druidDataSource.setUrl(dataSourceProperties.getUrl());druidDataSource.setUsername(dataSourceProperties.getUsername());druidDataSource.setPassword(dataSourceProperties.getPassword());druidDataSource.setDriverClassName(dataSourceProperties.getDriverClassName());druidDataSource.setInitialSize(0);druidDataSource.setMaxActive(180);druidDataSource.setMaxWait(60000);druidDataSource.setMinIdle(0);druidDataSource.setValidationQuery("Select 1 from DUAL");druidDataSource.setTestOnBorrow(false);druidDataSource.setTestOnReturn(false);druidDataSource.setTestWhileIdle(true);druidDataSource.setTimeBetweenEvictionRunsMillis(60000);druidDataSource.setMinEvictableIdleTimeMillis(25200000);druidDataSource.setRemoveAbandoned(true);druidDataSource.setRemoveAbandonedTimeout(1800);druidDataSource.setLogAbandoned(true);logger.info("装载dataSource........");dataSourceProxy = new DataSourceProxy(druidDataSource);return dataSourceProxy;}/*** init datasource proxy* * @Param: druidDataSource datasource bean instance* @Return: DataSourceProxy datasource proxy*/@Beanpublic DataSourceProxy dataSourceProxy() {logger.info("代理dataSource........");return dataSourceProxy;}/*** init global transaction scanner** @Return: GlobalTransactionScanner*/@Beanpublic GlobalTransactionScanner globalTransactionScanner() {logger.info("配置seata........");return new GlobalTransactionScanner("test-service", "test-group");}
}看代码,我们去掉了自己配置的sqlSessionFactory,直接让DataSource bean返回的是一个被代理过的bean,并且我们加入了@Primary,导致mp优先使用我们配置的数据源,这样就解决了mp因为seata代理了数据源跟创建了新的sqlSessionFactory,导致mp的插件,组件失效的bug了!
总结
踩到坑不可怕，主要又耐心的顺着每个组件实现的原理，再去思考，查找对应冲突的代码块，你一定能找到个兼容二者的方法。
