首先，到底啥是分布式事務(wù)呢，比如我們?cè)趫?zhí)行一個(gè)業(yè)務(wù)邏輯的時(shí)候有兩步分別操作A數(shù)據(jù)源和B數(shù)據(jù)源，當(dāng)我們?cè)贏數(shù)據(jù)源執(zhí)行數(shù)據(jù)更改后，在B數(shù)據(jù)源執(zhí)行時(shí)出現(xiàn)運(yùn)行時(shí)異常，那么我們必須要讓B數(shù)據(jù)源的操作回滾，并回滾對(duì)A數(shù)據(jù)源的操作；這種情況在支付業(yè)務(wù)時(shí)常常出現(xiàn)；比如買票業(yè)務(wù)在最后支付失敗，那之前的操作必須全部回滾，如果之前的操作分布在多個(gè)數(shù)據(jù)源中，那么這就是典型的分布式事務(wù)回滾；

了解了什么是分布式事務(wù)，那分布式事務(wù)在java的解決方案就是JTA(即Java Transaction API)；springboot官方提供了 Atomikos or Bitronix的解決思路；

其實(shí)，大多數(shù)情況下很多公司是使用消息隊(duì)列的方式實(shí)現(xiàn)分布式事務(wù)。

本篇文章重點(diǎn)講解springboot環(huán)境下，整合 Atomikos +mysql+mybatis+tomcat/jetty；

一、項(xiàng)目依賴

pom.xml中添加atomikos的springboot相關(guān)依賴：

<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-jta-atomikosartifactId>
dependency>

點(diǎn)進(jìn)去會(huì)發(fā)現(xiàn)里面整合好了：transactions-jms、transactions-jta、transactions-jdbc、javax.transaction-api

二、把數(shù)據(jù)源的相關(guān)配置項(xiàng)單獨(dú)提煉到一個(gè)application.yml中：

注意：

1. 這回我們的spring.datasource.type 是com.alibaba.druid.pool.xa.DruidXADataSource；

2. spring.jta.transaction-manager-id的值在你的電腦中是唯一的，這個(gè)詳細(xì)請(qǐng)閱讀官方文檔；

完整的yml文件如下：

spring:
datasource:
type:com.alibaba.druid.pool.xa.DruidXADataSource
druid:

systemDB:
name:systemDB
url:jdbc//localhost:3306/springboot-mybatis?useUnicode=true&characterEncoding=utf-8
username:root
password:root
#下面為連接池的補(bǔ)充設(shè)置，應(yīng)用到上面所有數(shù)據(jù)源中
#初始化大小，最小，最大
initialSize:5
minIdle:5
maxActive:20
#配置獲取連接等待超時(shí)的時(shí)間
maxWait:60000
#配置間隔多久才進(jìn)行一次檢測(cè)，檢測(cè)需要關(guān)閉的空閑連接，單位是毫秒
timeBetweenEvictionRunsMillis:60000
#配置一個(gè)連接在池中最小生存的時(shí)間，單位是毫秒
minEvictableIdleTimeMillis:30
validationQuery:SELECT1
validationQueryTimeout:10000
testWhileIdle:true
testOnBorrow:false
testOnReturn:false
#打開PSCache，并且指定每個(gè)連接上PSCache的大小
poolPreparedStatements:true
maxPoolPreparedStatementPerConnectionSize:20
filters:stat,wall
#通過connectProperties屬性來打開mergeSql功能；慢SQL記錄
connectionProperties:druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
#合并多個(gè)DruidDataSource的監(jiān)控?cái)?shù)據(jù)
useGlobalDataSourceStat:true

businessDB:
name:businessDB

url:jdbc//localhost:3306/springboot-mybatis2?useUnicode=true&characterEncoding=utf-8
username:root
password:root
#下面為連接池的補(bǔ)充設(shè)置，應(yīng)用到上面所有數(shù)據(jù)源中
#初始化大小，最小，最大
initialSize:5
minIdle:5
maxActive:20
#配置獲取連接等待超時(shí)的時(shí)間
maxWait:60000
#配置間隔多久才進(jìn)行一次檢測(cè)，檢測(cè)需要關(guān)閉的空閑連接，單位是毫秒
timeBetweenEvictionRunsMillis:60000
#配置一個(gè)連接在池中最小生存的時(shí)間，單位是毫秒
minEvictableIdleTimeMillis:30
validationQuery:SELECT1
validationQueryTimeout:10000
testWhileIdle:true
testOnBorrow:false
testOnReturn:false
#打開PSCache，并且指定每個(gè)連接上PSCache的大小
poolPreparedStatements:true
maxPoolPreparedStatementPerConnectionSize:20
filters:stat,wall
#通過connectProperties屬性來打開mergeSql功能；慢SQL記錄
connectionProperties:druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
#合并多個(gè)DruidDataSource的監(jiān)控?cái)?shù)據(jù)
useGlobalDataSourceStat:true

#jta相關(guān)參數(shù)配置
jta:
log-dir:classpath:tx-logs
transaction-manager-id:txManager

三、在DruidConfig.java中實(shí)現(xiàn)多個(gè)數(shù)據(jù)源的注冊(cè)；分布式事務(wù)管理器的注冊(cè)；druid的注冊(cè)；

packagecom.zjt.config;

importcom.alibaba.druid.filter.stat.StatFilter;
importcom.alibaba.druid.support.http.StatViewServlet;
importcom.alibaba.druid.support.http.WebStatFilter;
importcom.alibaba.druid.wall.WallConfig;
importcom.alibaba.druid.wall.WallFilter;
importcom.atomikos.icatch.jta.UserTransactionImp;
importcom.atomikos.icatch.jta.UserTransactionManager;
importorg.springframework.beans.factory.annotation.Autowired;
importorg.springframework.boot.jta.atomikos.AtomikosDataSourceBean;
importorg.springframework.boot.web.servlet.FilterRegistrationBean;
importorg.springframework.boot.web.servlet.ServletRegistrationBean;
importorg.springframework.context.annotation.Bean;
importorg.springframework.context.annotation.Configuration;
importorg.springframework.context.annotation.Primary;
importorg.springframework.core.env.Environment;
importorg.springframework.transaction.jta.JtaTransactionManager;

importjavax.sql.DataSource;
importjavax.transaction.UserTransaction;
importjava.util.Properties;

/**
*Druid配置
*
*
*/
@Configuration
publicclassDruidConfig{
@Bean(name="systemDataSource")
@Primary
@Autowired
publicDataSourcesystemDataSource(Environmentenv){
AtomikosDataSourceBeands=newAtomikosDataSourceBean();
Propertiesprop=build(env,"spring.datasource.druid.systemDB.");
ds.setXaDataSourceClassName("com.alibaba.druid.pool.xa.DruidXADataSource");
ds.setUniqueResourceName("systemDB");
ds.setPoolSize(5);
ds.setXaProperties(prop);
returnds;

}

@Autowired
@Bean(name="businessDataSource")
publicAtomikosDataSourceBeanbusinessDataSource(Environmentenv){

AtomikosDataSourceBeands=newAtomikosDataSourceBean();
Propertiesprop=build(env,"spring.datasource.druid.businessDB.");
ds.setXaDataSourceClassName("com.alibaba.druid.pool.xa.DruidXADataSource");
ds.setUniqueResourceName("businessDB");
ds.setPoolSize(5);
ds.setXaProperties(prop);

returnds;
}


/**
*注入事物管理器
*@return
*/
@Bean(name="xatx")
publicJtaTransactionManagerregTransactionManager(){
UserTransactionManageruserTransactionManager=newUserTransactionManager();
UserTransactionuserTransaction=newUserTransactionImp();
returnnewJtaTransactionManager(userTransaction,userTransactionManager);
}


privatePropertiesbuild(Environmentenv,Stringprefix){

Propertiesprop=newProperties();
prop.put("url",env.getProperty(prefix+"url"));
prop.put("username",env.getProperty(prefix+"username"));
prop.put("password",env.getProperty(prefix+"password"));
prop.put("driverClassName",env.getProperty(prefix+"driverClassName",""));
prop.put("initialSize",env.getProperty(prefix+"initialSize",Integer.class));
prop.put("maxActive",env.getProperty(prefix+"maxActive",Integer.class));
prop.put("minIdle",env.getProperty(prefix+"minIdle",Integer.class));
prop.put("maxWait",env.getProperty(prefix+"maxWait",Integer.class));
prop.put("poolPreparedStatements",env.getProperty(prefix+"poolPreparedStatements",Boolean.class));

prop.put("maxPoolPreparedStatementPerConnectionSize",
env.getProperty(prefix+"maxPoolPreparedStatementPerConnectionSize",Integer.class));

prop.put("maxPoolPreparedStatementPerConnectionSize",
env.getProperty(prefix+"maxPoolPreparedStatementPerConnectionSize",Integer.class));
prop.put("validationQuery",env.getProperty(prefix+"validationQuery"));
prop.put("validationQueryTimeout",env.getProperty(prefix+"validationQueryTimeout",Integer.class));
prop.put("testOnBorrow",env.getProperty(prefix+"testOnBorrow",Boolean.class));
prop.put("testOnReturn",env.getProperty(prefix+"testOnReturn",Boolean.class));
prop.put("testWhileIdle",env.getProperty(prefix+"testWhileIdle",Boolean.class));
prop.put("timeBetweenEvictionRunsMillis",
env.getProperty(prefix+"timeBetweenEvictionRunsMillis",Integer.class));
prop.put("minEvictableIdleTimeMillis",env.getProperty(prefix+"minEvictableIdleTimeMillis",Integer.class));
prop.put("filters",env.getProperty(prefix+"filters"));

returnprop;
}

@Bean
publicServletRegistrationBeandruidServlet(){
ServletRegistrationBeanservletRegistrationBean=newServletRegistrationBean(newStatViewServlet(),"/druid/*");

//控制臺(tái)管理用戶，加入下面2行進(jìn)入druid后臺(tái)就需要登錄
//servletRegistrationBean.addInitParameter("loginUsername","admin");
//servletRegistrationBean.addInitParameter("loginPassword","admin");
returnservletRegistrationBean;
}

@Bean
publicFilterRegistrationBeanfilterRegistrationBean(){
FilterRegistrationBeanfilterRegistrationBean=newFilterRegistrationBean();
filterRegistrationBean.setFilter(newWebStatFilter());
filterRegistrationBean.addUrlPatterns("/*");
filterRegistrationBean.addInitParameter("exclusions","*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
filterRegistrationBean.addInitParameter("profileEnable","true");
returnfilterRegistrationBean;
}

@Bean
publicStatFilterstatFilter(){
StatFilterstatFilter=newStatFilter();
statFilter.setLogSlowSql(true);//slowSqlMillis用來配置SQL慢的標(biāo)準(zhǔn)，執(zhí)行時(shí)間超過slowSqlMillis的就是慢。
statFilter.setMergeSql(true);//SQL合并配置
statFilter.setSlowSqlMillis(1000);//slowSqlMillis的缺省值為3000，也就是3秒。
returnstatFilter;
}

@Bean
publicWallFilterwallFilter(){
WallFilterwallFilter=newWallFilter();
//允許執(zhí)行多條SQL
WallConfigconfig=newWallConfig();
config.setMultiStatementAllow(true);
wallFilter.setConfig(config);
returnwallFilter;
}

}

四、分別配置每個(gè)數(shù)據(jù)源對(duì)應(yīng)的sqlSessionFactory，以及MapperScan掃描的包：

MybatisDatasourceConfig.java

packagecom.zjt.config;

importcom.zjt.util.MyMapper;
importorg.apache.ibatis.session.SqlSessionFactory;
importorg.mybatis.spring.SqlSessionFactoryBean;
importorg.mybatis.spring.SqlSessionTemplate;
importorg.mybatis.spring.annotation.MapperScan;
importorg.springframework.beans.factory.annotation.Autowired;
importorg.springframework.beans.factory.annotation.Qualifier;
importorg.springframework.context.annotation.Bean;
importorg.springframework.context.annotation.Configuration;
importorg.springframework.core.io.support.PathMatchingResourcePatternResolver;
importorg.springframework.core.io.support.ResourcePatternResolver;

importjavax.sql.DataSource;

/**
*
*@description
*/
@Configuration
//精確到mapper目錄，以便跟其他數(shù)據(jù)源隔離
@MapperScan(basePackages="com.zjt.mapper",markerInterface=MyMapper.class,sqlSessionFactoryRef="sqlSessionFactory")
publicclassMybatisDatasourceConfig{

@Autowired
@Qualifier("systemDataSource")
privateDataSourceds;

@Bean
publicSqlSessionFactorysqlSessionFactory()throwsException{
SqlSessionFactoryBeanfactoryBean=newSqlSessionFactoryBean();
factoryBean.setDataSource(ds);
//指定mapperxml目錄
ResourcePatternResolverresolver=newPathMatchingResourcePatternResolver();
factoryBean.setMapperLocations(resolver.getResources("classpath:mapper/*.xml"));
returnfactoryBean.getObject();

}

@Bean
publicSqlSessionTemplatesqlSessionTemplate()throwsException{
SqlSessionTemplatetemplate=newSqlSessionTemplate(sqlSessionFactory());//使用上面配置的Factory
returntemplate;
}

//關(guān)于事務(wù)管理器，不管是JPA還是JDBC等都實(shí)現(xiàn)自接口PlatformTransactionManager
//如果你添加的是 spring-boot-starter-jdbc 依賴，框架會(huì)默認(rèn)注入 DataSourceTransactionManager 實(shí)例。
//在Spring容器中，我們手工注解@Bean 將被優(yōu)先加載，框架不會(huì)重新實(shí)例化其他的 PlatformTransactionManager 實(shí)現(xiàn)類。
/*@Bean(name="transactionManager")
@Primary
publicDataSourceTransactionManagermasterTransactionManager(){
//MyBatis自動(dòng)參與到spring事務(wù)管理中，無需額外配置，只要org.mybatis.spring.SqlSessionFactoryBean引用的數(shù)據(jù)源
//與DataSourceTransactionManager引用的數(shù)據(jù)源一致即可，否則事務(wù)管理會(huì)不起作用。
returnnewDataSourceTransactionManager(ds);
}*/

}

MybatisDatasource2Config.java

packagecom.zjt.config;

importcom.zjt.util.MyMapper;
importorg.apache.ibatis.session.SqlSessionFactory;
importorg.mybatis.spring.SqlSessionFactoryBean;
importorg.mybatis.spring.SqlSessionTemplate;
importorg.mybatis.spring.annotation.MapperScan;
importorg.springframework.beans.factory.annotation.Autowired;
importorg.springframework.beans.factory.annotation.Qualifier;
importorg.springframework.context.annotation.Bean;
importorg.springframework.context.annotation.Configuration;
importorg.springframework.core.io.support.PathMatchingResourcePatternResolver;
importorg.springframework.core.io.support.ResourcePatternResolver;

importjavax.sql.DataSource;

/**
*
*@description
*/
@Configuration
//精確到mapper目錄，以便跟其他數(shù)據(jù)源隔離
@MapperScan(basePackages="com.zjt.mapper2",markerInterface=MyMapper.class,sqlSessionFactoryRef="sqlSessionFactory2")
publicclassMybatisDatasource2Config{

@Autowired
@Qualifier("businessDataSource")
privateDataSourceds;

@Bean
publicSqlSessionFactorysqlSessionFactory2()throwsException{
SqlSessionFactoryBeanfactoryBean=newSqlSessionFactoryBean();
factoryBean.setDataSource(ds);
//指定mapperxml目錄
ResourcePatternResolverresolver=newPathMatchingResourcePatternResolver();
factoryBean.setMapperLocations(resolver.getResources("classpath:mapper2/*.xml"));
returnfactoryBean.getObject();

}

@Bean
publicSqlSessionTemplatesqlSessionTemplate2()throwsException{
SqlSessionTemplatetemplate=newSqlSessionTemplate(sqlSessionFactory2());//使用上面配置的Factory
returntemplate;
}

//關(guān)于事務(wù)管理器，不管是JPA還是JDBC等都實(shí)現(xiàn)自接口PlatformTransactionManager
//如果你添加的是 spring-boot-starter-jdbc 依賴，框架會(huì)默認(rèn)注入 DataSourceTransactionManager 實(shí)例。
//在Spring容器中，我們手工注解@Bean 將被優(yōu)先加載，框架不會(huì)重新實(shí)例化其他的 PlatformTransactionManager 實(shí)現(xiàn)類。
/*@Bean(name="transactionManager2")
@Primary
publicDataSourceTransactionManagermasterTransactionManager(){
//MyBatis自動(dòng)參與到spring事務(wù)管理中，無需額外配置，只要org.mybatis.spring.SqlSessionFactoryBean引用的數(shù)據(jù)源
//與DataSourceTransactionManager引用的數(shù)據(jù)源一致即可，否則事務(wù)管理會(huì)不起作用。
returnnewDataSourceTransactionManager(ds);
}*/

}

由于我們本例中只使用一個(gè)事務(wù)管理器：xatx，故就不在使用TxAdviceInterceptor.java和TxAdvice2Interceptor.java中配置的事務(wù)管理器了；有需求的童鞋可以自己配置其他的事務(wù)管理器；(見DruidConfig.java中查看)

五、新建分布式業(yè)務(wù)測(cè)試接口JtaTestService.java和實(shí)現(xiàn)類JtaTestServiceImpl.java

其實(shí)就是一個(gè)很簡(jiǎn)單的test01()方法，在該方法中我們分別先后調(diào)用classService.saveOrUpdateTClass(tClass);和teacherService.saveOrUpdateTeacher(teacher);

實(shí)現(xiàn)先后操作兩個(gè)數(shù)據(jù)源：然后我們可以自己debug跟蹤事務(wù)的提交時(shí)機(jī)，此外，也可以在在兩個(gè)方法全執(zhí)行結(jié)束之后，手動(dòng)制造一個(gè)運(yùn)行時(shí)異常，來檢查分布式事務(wù)是否全部回滾；

注意：

在實(shí)現(xiàn)類的方法中我使用的是：

@Transactional(transactionManager="xatx",propagation=Propagation.REQUIRED,rollbackFor={java.lang.RuntimeException.class})

從而指定了使用哪個(gè)事務(wù)管理器，事務(wù)隔離級(jí)別(一般都用我這個(gè)默認(rèn)的)，回滾的條件(一般可以使用Exception)，這三個(gè)可以自己根據(jù)業(yè)務(wù)實(shí)際修改；

packagecom.zjt.service3;

importjava.util.Map;

publicinterfaceJtaTestService{

publicMaptest01();

}

packagecom.zjt.service3.impl;


importcom.zjt.entity.TClass;
importcom.zjt.entity.Teacher;
importcom.zjt.service.TClassService;
importcom.zjt.service2.TeacherService;
importcom.zjt.service3.JtaTestService;
importorg.springframework.beans.factory.annotation.Autowired;
importorg.springframework.beans.factory.annotation.Qualifier;
importorg.springframework.stereotype.Service;
importorg.springframework.transaction.annotation.Propagation;
importorg.springframework.transaction.annotation.Transactional;

importjava.util.LinkedHashMap;
importjava.util.Map;

@Service("jtaTestServiceImpl")
publicclassJtaTestServiceImplimplementsJtaTestService{

@Autowired
@Qualifier("teacherServiceImpl")
privateTeacherServiceteacherService;
@Autowired
@Qualifier("tclassServiceImpl")
privateTClassServicetclassService;

@Override
@Transactional(transactionManager="xatx",propagation=Propagation.REQUIRED,rollbackFor={java.lang.RuntimeException.class})
publicMap<String,Object>test01(){
LinkedHashMapresultMap=newLinkedHashMap();
TClasstClass=newTClass();
tClass.setName("8888");
tclassService.saveOrUpdateTClass(tClass);

Teacherteacher=newTeacher();
teacher.setName("8888");
teacherService.saveOrUpdateTeacher(teacher);

System.out.println(1/0);

resultMap.put("state","success");
resultMap.put("message","分布式事務(wù)同步成功");
returnresultMap;
}
}

六、建立JtaTestContoller.java，接受一個(gè)來自前端的http請(qǐng)求，觸發(fā)JtaTestService 的test01方法:

packagecom.zjt.web;


importcom.zjt.service3.JtaTestService;
importorg.springframework.beans.factory.annotation.Autowired;
importorg.springframework.beans.factory.annotation.Qualifier;
importorg.springframework.stereotype.Controller;
importorg.springframework.web.bind.annotation.RequestMapping;
importorg.springframework.web.bind.annotation.ResponseBody;

importjava.util.LinkedHashMap;
importjava.util.Map;

@Controller
@RequestMapping("/jtaTest")
publicclassJtaTestContoller{

@Autowired
@Qualifier("jtaTestServiceImpl")
privateJtaTestServicetaTestService;



@ResponseBody
@RequestMapping("/test01")
publicMaptest01(){
LinkedHashMapresultMap=newLinkedHashMap();
try{
returntaTestService.test01();
}catch(Exceptione){
resultMap.put("state","fail");
resultMap.put("message","分布式事務(wù)同步失敗");
returnresultMap;
}
}
}

七、在test.ftl中增加一個(gè)按鈕來測(cè)試；

//分布式事務(wù)測(cè)試
$("#JTATest").click(function(){
    $.ajax({
        type: "POST",
        url: "${basePath!}/jtaTest/test01",
        data: {}    ,
        async: false,
        error: function (request) {
            layer.alert("與服務(wù)器連接失敗/(ㄒoㄒ)/~~");
            return false;
        },
        success: function (data) {
            if (data.state == 'fail') {
                layer.alert(data.message);
                return false;
            }else if(data.state == 'success'){
                layer.alert(data.message);
            }
        }
    });
});
 
同時(shí)向班級(jí)和老師表插入名為8888的班級(jí)和老師

八、啟動(dòng)服務(wù)，驗(yàn)證結(jié)果：

點(diǎn)擊這個(gè)按鈕，跳轉(zhuǎn)到controller：

當(dāng)正常執(zhí)行了sql語句之后，我們可以發(fā)現(xiàn)數(shù)據(jù)庫并沒有變化，因?yàn)檎麄€(gè)方法的事務(wù)還沒有走完，當(dāng)我們走到1/0這步時(shí)：

拋出運(yùn)行時(shí)異常，并被spring事務(wù)攔截器攔截，并捕獲異常：

在this.completeTransactionAfterThrowing(txInfo, var16);方法中會(huì)將事務(wù)全部回滾：

2204.243logback[http-nio-8080-exec-5]INFOc.a.i.imp.CompositeTransactionImp-rollback()doneoftransaction192.168.1.103.tm0000400006

此時(shí)，當(dāng)我們?cè)俅未蜷_數(shù)據(jù)庫驗(yàn)證，依舊沒有變化，證明分布式事務(wù)配置成功；

大家可以基于我的代碼自己練習(xí)一下，自己嘗試著使用多事務(wù)管理器的情況下的靈活配置；

九、后記：

本文源代碼：

https://github.com/zhaojiatao/springboot-zjt-chapter10-springboot-atomikos-mysql-mybatis-druid.git

代碼在tomcat和jetty環(huán)境下均可完成事務(wù)回滾；

在事務(wù)回滾時(shí)可能報(bào)一個(gè)Transactional not active的警告，我google后，老外也說不出這個(gè)具體作用，大部分人認(rèn)為這只是一個(gè)警告，可以忽略；

-End-