背景
框架之前实现了多数据源的动静切换及事务的解决，想更近一步提供一个简略的跨库事务处理性能，通过网上的搜寻调研，大抵有XA事务/SEGA事务/TCC事务等计划，因为业务次要波及政府及企业且并发量不大，所以采纳XA事务，尽管性能有所损失，然而能够保证数据的强一致性
方案设计
针对注册的数据源拷贝一份用于XA事务，使得本地事务和XA全局事务互相独立可抉择的应用
Maven配置
引入atomikos第三方组件
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jta-atomikos</artifactId> </dependency>注册XA数据源
应用Druid连接池，须要应用DruidXADataSource数据源对象，再应用AtomikosDataSourceBean进行包装
注册数据源时针对同一个连贯注册两份，一份失常数据源，一份用于XA事务的数据源，数据源标识辨别并关联
因为spring默认注册了XA事务管理器后，所有事务操作不再走本地事务，咱们通过切换不同的数据源决定走本地事务还是XA事务
//主数据源xa模式 @Bean @Qualifier("masterXADataSource") public DataSource masterXADataSource() { DruidXADataSource datasource = new DruidXADataSource(); if(driverClassName.equals("com.mysql.cj.jdbc.Driver")){ if(!dbUrl.contains("useOldAliasMetadataBehavior")){ dbUrl += "&useOldAliasMetadataBehavior=true"; } if(!dbUrl.contains("useAffectedRows")){ dbUrl += "&useAffectedRows=true"; } } datasource.setUrl(this.dbUrl); datasource.setUsername(username); datasource.setPassword(password); datasource.setDriverClassName(driverClassName); //configuration datasource.setInitialSize(1); datasource.setMinIdle(3); datasource.setMaxActive(20); datasource.setMaxWait(60000); datasource.setTimeBetweenEvictionRunsMillis(60000); datasource.setMinEvictableIdleTimeMillis(60000); datasource.setValidationQuery("select 'x'"); datasource.setTestWhileIdle(true); datasource.setTestOnBorrow(false); datasource.setTestOnReturn(false); datasource.setPoolPreparedStatements(true); datasource.setMaxPoolPreparedStatementPerConnectionSize(20); datasource.setLogAbandoned(false); //移除泄露连贯产生是是否记录日志 try { datasource.setFilters("stat,slf4j"); } catch (SQLException e) { logger.error("druid configuration initialization filter", e); } datasource.setConnectionProperties("druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000");//connectionProperties); AtomikosDataSourceBean atomikosDataSourceBean = new AtomikosDataSourceBean(); atomikosDataSourceBean.setXaDataSourceClassName("com.alibaba.druid.pool.xa.DruidXADataSource"); atomikosDataSourceBean.setUniqueResourceName("master-xa"); atomikosDataSourceBean.setXaDataSource(datasource); atomikosDataSourceBean.setPoolSize(5); atomikosDataSourceBean.setMaxPoolSize(20); atomikosDataSourceBean.setTestQuery("select 1"); return atomikosDataSourceBean; }注册XA事务管理器
应用spring内置的JtaTransactionManager事务管理器对象，设置AllowCustomIsolationLevels为true，否则指定自定义事务隔离级别会报错
//xa模式全局事务管理器 @Bean(name = "jtaTransactionManager") public PlatformTransactionManager transactionManager() throws Throwable { UserTransactionManager userTransactionManager = new UserTransactionManager(); UserTransaction userTransaction = new UserTransactionImp(); JtaTransactionManager jtaTransactionManager = new JtaTransactionManager(userTransaction, userTransactionManager); jtaTransactionManager.setAllowCustomIsolationLevels(true); return jtaTransactionManager; }定义XA事务切面
自定义注解@GlobalTransactional并定义对应切面，应用指定注解时在ThreadLocal变量值进行标识，组合
@Transactional注解指定XA事务管理器，在切换数据原时判断以后是否在XA事物中，从而切换不同的数据源
@Target({ElementType.METHOD})@Retention(RetentionPolicy.RUNTIME)@Inherited@Documented@Transactional(rollbackFor = Exception.class,isolation = Isolation.READ_UNCOMMITTED,transactionManager = "jtaTransactionManager")public @interface GlobalTransactional {}@Aspect@Component@Order(value = 99)public class GlobalTransitionAspect { private static Logger logger = LoggerFactory.getLogger(GlobalTransitionAspect.class); @Autowired private DynamicDataSource dynamicDataSource; /** * 切面点 指定注解 */ @Pointcut("@annotation(com.code2roc.fastkernel.datasource.GlobalTransactional) " + "|| @within(com.code2roc.fastkernel.datasource.GlobalTransactional)") public void dataSourcePointCut() { } /** * 拦挡办法指定为 dataSourcePointCut */ @Around("dataSourcePointCut()") public Object around(ProceedingJoinPoint point) throws Throwable { MethodSignature signature = (MethodSignature) point.getSignature(); Method method = signature.getMethod(); GlobalTransactional methodAnnotation = method.getAnnotation(GlobalTransactional.class); if (methodAnnotation != null) { DataSourceContextHolder.tagGlobal(); logger.info("标记全局事务"); } try { return point.proceed(); } finally { logger.info("革除全局事务"); DataSourceContextHolder.clearGlobal(); } }}public class DataSourceContextHolder { private static Logger log = LoggerFactory.getLogger(DataSourceContextHolder.class); // 对以后线程的操作-线程平安的 private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>(); private static final ThreadLocal<String> contextGlobalHolder = new ThreadLocal<String>(); // 调用此办法，切换数据源 public static void setDataSource(String dataSource) { contextHolder.set(dataSource); log.debug("已切换到数据源:{}", dataSource); } // 获取数据源 public static String getDataSource() { String value = contextHolder.get(); if (StringUtil.isEmpty(value)) { value = "master"; } if (!StringUtil.isEmpty(getGlobal())) { value = value + "-xa"; } return value; } // 删除数据源 public static void clearDataSource() { contextHolder.remove(); log.debug("已切换到主数据源"); } //====================全局事务标记================ public static void tagGlobal() { contextGlobalHolder.set("1"); } public static String getGlobal() { String value = contextGlobalHolder.get(); return value; } public static void clearGlobal() { contextGlobalHolder.remove(); } //===================================================}配置XA事务日志
通过在resource文件夹下创立transactions.properties文件能够指定XA事务日志的存储门路
com.atomikos.icatch.log_base_dir= tempfiles/transition/