【Sharding-JDBC】（五）整合mybatis-plus 解决分布式事务（基于XA）

官网解释：

功能

支持数据分片后的跨库XA事务
两阶段提交保证操作的原子性和数据的强一致性
服务宕机重启后，提交/回滚中的事务可自动恢复
SPI机制整合主流的XA事务管理器，默认Atomikos，可以选择使用Narayana和Bitronix
同时支持XA和非XA的连接池
提供spring-boot和namespace的接入端

不支持项

服务宕机后，在其它机器上恢复提交/回滚中的数据

一、准备环境：

ps:两个order_db分布在不同的服务器上，192.168.87.133节点的order_db库中有三张表，t_dict,t_order_1,t_order_2，192.168.87.134节点上的order_db库中有两张表，t_order_1,t_order_2。

二、(三)Sharding-JDBC 整合mybatis-plus 水平分库、分表改造

application.yml:

#服务端口
server:port: 56081
#服务名
spring:application:name: sharding-jdbc-exampleshttp:encoding:enabled: truecharset: utf-8force: truemain:allow-bean-definition-overriding: true#shardingsphere相关配置shardingsphere:datasource:names: m1,m2   #配置库的名字，随意m1:   #配置目前m1库的数据源信息type: com.alibaba.druid.pool.DruidDataSourcedriverClassName: com.mysql.jdbc.Driverurl: jdbc:mysql://192.168.87.133:3306/order_db?useUnicode=trueusername: rootpassword: 123456m2:type: com.alibaba.druid.pool.DruidDataSourcedriverClassName: com.mysql.jdbc.Driverurl: jdbc:mysql://192.168.87.134:3306/order_db?useUnicode=trueusername: rootpassword: 123456sharding:tables:t_order:key-generator:column: user_idtype: SNOWFLAKEactual-data-nodes: m$->{1..2}.t_order_$->{1..2}   # 分库策略，以user_id为分片键，分片策略为user_id % 2 + 1，user_id为偶数操作m1数据源，否则操作m2。database‐strategy:  #分库策略inline:sharding‐column: user_idalgorithm‐expression: m$->{user_id % 2 + 1}table‐strategy: #分表策略inline:sharding‐column: order_idalgorithm‐expression: t_order_$->{order_id % 2 + 1}defaultDataSourceName: m1props:sql:show: true   #打印sql#日志打印
logging:level:root: infoorg.springframework.web: infocom.lucifer.sharding.dao: debugdruid.sql: debug

ps:由于t_dist这张表只出现在192.168.87.133这个服务器节点的order_db库中，因此需要配置属性defaultDataSourceName，设置默认数据库。否则会出现找不到数据库名为null的数据库名。

测试方法：t_dict这个表只存在192.168.87.133的order_db库中的，而t_order_*这个存在于两个库中，既有分库策略也有分表策略。

  @Testpublic void add() {Dict dict = new Dict();dict.setCode("111");dict.setType("性别");dict.setValue("男");dictDao.insert(dict);//伪造异常int a=1/0;Order order = new Order();order.setPrice(BigDecimal.valueOf(0.1));order.setStatus("0");orderDao.insert(order);}

1.首先看下未使用事务的情况：

2020-01-19 10:30:36.538  INFO 6980 --- [           main] ShardingSphere-SQL                       : Actual SQL: m1 ::: INSERT INTO t_dict   (dict_id, code, type, value) VALUES (?, ?, ?, ?) ::: [1218722393623670785, 111, 性别, 男]
2020-01-19 10:30:36.572 DEBUG 6980 --- [           main] com.lucifer.sharding.dao.DictDao.insert  : <==    Updates: 1java.lang.ArithmeticException: / by zeroat com.lucifer.sharding.ShardingJdbcExamplesApplicationTests.add(ShardingJdbcExamplesApplicationTests.java:33)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:498)at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)

控制台输出，可以看出在执行完m1库（192.168.87.133的order_db库中的t_dict）sql操作完后，报错。因此这个时候只有一条sql执行了。数据未回滚。

2.使用事务的情况

2.1.pom.xml:引入两个jar包

        <dependency><groupId>io.shardingsphere</groupId><artifactId>sharding-transaction-2pc-xa</artifactId><version>3.1.0</version></dependency><dependency><groupId>io.shardingsphere</groupId><artifactId>sharding-transaction-spring</artifactId><version>3.1.0</version></dependency>

或使用下面这个jar包

        <dependency><groupId>io.shardingsphere</groupId><artifactId>sharding-transaction-spring-boot-starter</artifactId><version>3.1.0</version></dependency>

2.2.springboot主配置类的SpringBootApplication注解去掉JtaAutoConfiguration这个配置类这个注入。

/*** @author Lucifer*/
@MapperScan("com.lucifer.sharding.dao")
@SpringBootApplication(exclude = JtaAutoConfiguration.class)
public class ShardingJdbcExamplesApplication {public static void main(String[] args) {SpringApplication.run(ShardingJdbcExamplesApplication.class, args);}}

2.3测试方法： @ShardingTransactionType(value = TransactionType.XA)

@Transactional(rollbackFor =Exception.class) 两个注解需要配合使用。

    @ShardingTransactionType(value = TransactionType.XA)@Transactional(rollbackFor = Exception.class)@Testpublic void add() {Dict dict = new Dict();dict.setCode("111");dict.setType("性别");dict.setValue("男");dictDao.insert(dict);int a=1/0;Order order = new Order();order.setPrice(BigDecimal.valueOf(0.1));order.setStatus("0");orderDao.insert(order);}

控制台输出：

2020-01-19 10:55:36.735  INFO 4660 --- [           main] ShardingSphere-SQL                       : Actual SQL: m1 ::: INSERT INTO t_dict   (dict_id, code, type, value) VALUES (?, ?, ?, ?) ::: [1218728685880786946, 111, 性别, 男]
2020-01-19 10:55:36.757 DEBUG 4660 --- [           main] com.lucifer.sharding.dao.DictDao.insert  : <==    Updates: 1
2020-01-19 10:55:36.776  INFO 4660 --- [           main] o.s.t.c.transaction.TransactionContext   : Rolled back transaction for test: [DefaultTestContext@563e4951 testClass = ShardingJdbcExamplesApplicationTests, testInstance = com.lucifer.sharding.ShardingJdbcExamplesApplicationTests@278fe428, testMethod = add@ShardingJdbcExamplesApplicationTests, testException = java.lang.ArithmeticException: / by zero, mergedContextConfiguration = [WebMergedContextConfiguration@4066c471 testClass = ShardingJdbcExamplesApplicationTests, locations = '{}', classes = '{class com.lucifer.sharding.ShardingJdbcExamplesApplication, class com.lucifer.sharding.ShardingJdbcExamplesApplication}', contextInitializerClasses = '[]', activeProfiles = '{}', propertySourceLocations = '{}', propertySourceProperties = '{org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true}', contextCustomizers = set[org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@140c9f39, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@7690781, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.web.client.TestRestTemplateContextCustomizer@be35cd9, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@0, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@193f604a], resourceBasePath = 'src/main/webapp', contextLoader = 'org.springframework.boot.test.context.SpringBootContextLoader', parent = [null]], attributes = map['org.springframework.test.context.web.ServletTestExecutionListener.activateListener' -> true, 'org.springframework.test.context.web.ServletTestExecutionListener.populatedRequestContextHolder' -> true, 'org.springframework.test.context.web.ServletTestExecutionListener.resetRequestContextHolder' -> true]]java.lang.ArithmeticException: / by zeroat com.lucifer.sharding.ShardingJdbcExamplesApplicationTests.add(ShardingJdbcExamplesApplicationTests.java:39)

数据库t_dict也回滚了。

测试异常在后的情况：

    @ShardingTransactionType(value = TransactionType.XA)@Transactional(rollbackFor = Exception.class)@Testpublic void add() {Dict dict = new Dict();dict.setCode("111");dict.setType("性别");dict.setValue("男");dictDao.insert(dict);Order order = new Order();order.setPrice(BigDecimal.valueOf(0.1));order.setStatus("0");orderDao.insert(order);int a=1/0;}

根据控制台输出，知道t_dict执行成功，而order的数据库操作最终是落在m2库的t_order_1表中。

2020-01-19 11:13:13.146 DEBUG 11876 --- [           main] com.lucifer.sharding.dao.DictDao.insert  : ==>  Preparing: INSERT INTO t_dict ( dict_id, code, type, value ) VALUES ( ?, ?, ?, ? )
2020-01-19 11:13:13.164 DEBUG 11876 --- [           main] com.lucifer.sharding.dao.DictDao.insert  : ==> Parameters: 1218733118769360898(Long), 111(String), 性别(String), 男(String)2020-01-19 11:13:19.666  INFO 11876 --- [           main] ShardingSphere-SQL                       : Actual SQL: m2 ::: INSERT INTO t_order_1   (order_id, price, status, user_id) VALUES (?, ?, ?, ?) ::: [1218733137404653570, 0.1, 0, 425612793970950145]
2020-01-19 11:13:21.182 DEBUG 11876 --- [           main] c.lucifer.sharding.dao.OrderDao.insert   : <==    Updates: 1

查看数据库发现均回滚了。