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: debugps: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。
