SpringBoot读写分离配置与事务

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
    <version>3.5.1</version>
</dependency>

spring:
  datasource:
    dynamic:
      primary: master
      # 严格匹配数据源,默认false. true未匹配到指定数据源时抛异常,false使用默认数据源
      strict: true
      datasource:
        master:
          url: jdbc:mysql://192.168.101.128:3307/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
          username: root
          password: 123456
        slave:
          url: jdbc:mysql://192.168.101.128:3308/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
          username: root
          password: 123456

# 按需开启日志
logging:
  level:
    com.baomidou.dynamic: debug

com.baomidou.dynamic.datasource.aop.DynamicDataSourceAnnotationInterceptor

public Object invoke(MethodInvocation invocation) throws Throwable {
    String dsKey = determineDatasourceKey(invocation);
    //获取注解值入栈
    DynamicDataSourceContextHolder.push(dsKey);
    try {
        return invocation.proceed();
    } finally {
        //方法结束后出栈
        DynamicDataSourceContextHolder.poll();
    }
}

public Connection getConnection() throws SQLException {
    String xid = TransactionContext.getXID();
    if (StringUtils.isEmpty(xid)) {
        return determineDataSource().getConnection();
    } else {
        //获取栈顶的一个值
        String ds = DynamicDataSourceContextHolder.peek();
        ds = StringUtils.isEmpty(ds) ? "default" : ds;
        //根据值获取对应数据库的连接
        ConnectionProxy connection = ConnectionFactory.getConnection(ds);
        return connection == null ? getConnectionProxy(ds, determineDataSource().getConnection()) : connection;
    }
}

@Autowired
@Lazy
CurrentService currentService;

@DS("master")
@Transactional
public void updateUser() {
	baseMapper.updateById(user);
    System.out.println(currentService.get());
}

@DS("slave")
public User get() {
	return baseMapper.selectById(1);
}

if (isExistingTransaction(transaction)) {
	//找到现有事务 -> 检查传播行为以了解行为方式
    //当前已经存在一个事务
    return handleExistingTransaction(def, transaction, debugEnabled);
}

//判断当前方法的隔离属性是否为PROPAGATION_REQUIRES_NEW
if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW) {
    if (debugEnabled) {
        logger.debug("Suspending current transaction, creating new transaction with name [" + definition.getName() + "]");
    }
    SuspendedResourcesHolder suspendedResources = suspend(transaction);
    try {
        return startTransaction(definition, transaction, debugEnabled, suspendedResources);
    }
    catch (RuntimeException | Error beginEx) {
        resumeAfterBeginException(transaction, suspendedResources, beginEx);
        throw beginEx;
    }
}

private TransactionStatus startTransaction(TransactionDefinition definition, Object transaction,
			boolean debugEnabled, @Nullable SuspendedResourcesHolder suspendedResources) {

    boolean newSynchronization = (getTransactionSynchronization() != SYNCHRONIZATION_NEVER);
    DefaultTransactionStatus status = newTransactionStatus(definition, transaction, true, newSynchronization, debugEnabled, suspendedResources);
    doBegin(transaction, definition);
    prepareSynchronization(status, definition);
    return status;
}

if (!txObject.hasConnectionHolder() || txObject.getConnectionHolder().isSynchronizedWithTransaction()) {
	//获取当前的数据源, 此处才能让@DS注解生效
    Connection newCon = obtainDataSource().getConnection();
	if (logger.isDebugEnabled()) {
		logger.debug("Acquired Connection [" + newCon + "] for JDBC transaction");
	}
    //将数据库连接绑定到事务
	txObject.setConnectionHolder(new ConnectionHolder(newCon), true);
}

public static void notify(Boolean state) {
    try {
        Map<String, ConnectionProxy> concurrentHashMap = CONNECTION_HOLDER.get();
        //获取当前线程所有的数据库连接, 通知其进行回滚/提交, 可能存在某一个事务提交成功, 某一事务提交失败.
        //并不能保证最终一致性
        for (ConnectionProxy connectionProxy : concurrentHashMap.values()) {
            connectionProxy.notify(state);
        }
    } finally {
        CONNECTION_HOLDER.remove();
    }
}

<dependency>
    <groupId>io.seata</groupId>
    <artifactId>seata-spring-boot-starter</artifactId>
    <version>1.4.2</version>
</dependency>

spring:
  datasource:
    dynamic:
      #seata1.0之后支持自动代理 这里直接配置true
      seata: true