分布式事务之事务实现模式与技术（四）

1.start message transaction
2.receive message
3.start database transaction
4.update database
5.commit database transaction
6.commit message transaction   ##当这一步出现错误时，上面的因为已经commit，所以不会rollback

1.start message transaction
2.receive message
3.start JTA transaction on DB
4.update database
5.phase-1 commit on DB transaction
6.commit message transaction  ##当这一步出现错误时，上面的因为是XA的第一次提交预备状态，所以可以rollback
7.phase-2 commit on DB transaction  ##当这一步出现错误时，因为message不是XA方式，commit后无法rollback

1.start message transaction
2.receive message
3.start database transaction
4.update database   #数据库操作出错，消息被放回MQ队列，重试重新触发该方法
5.commit database transaction
6.commit message transaction  

1.start message transaction
2.receive message
3.start database transaction
4.update database
5.commit database transaction   
6.commit message transaction  #提交MQ事务出错，消息放回至MQ队列，重试重新触发该方法

# 默认的Datasource配置
# spring.datasource.url = jdbc:mysql://localhost:3307/user
# spring.datasource.username = root
# spring.datasource.password = 123456
# spring.datasource.driverClassName = com.mysql.jdbc.Driver
spring.ds_user.url = jdbc:mysql://localhost:3307/js_user
spring.ds_user.username = root
spring.ds_user.password = 123456
spring.ds_user.driver-class-name = com.mysql.jdbc.Driver
spring.ds_order.url = jdbc:mysql://localhost:3307/js_order
spring.ds_order.username = root
spring.ds_order.password = 123456
spring.ds_order.driver-class-name = com.mysql.jdbc.Driver

@Configuration
public class DBConfiguration{
    @Bean
    @Primary
    @ConfigurationProperties(prefix="spring.ds_user") #设置读取在properties文件内容的前缀
    public DataSourceProperties userDataSourceProperties() {
        return new DataSourceProperties();
    }
    @Bean
    @Primary
    public DataSource userDataSource(){
        return userDataSourceProperties().initializeDataSourceBuilder().type(HikariDataSource.class).build();
    }
    @Bean
    public JdbcTemplate userJdbcTemplate(@Qualifier("userDataSource") DataSource userDataSource){
        return new JdbcTemplate(userDataSource);
    }
    @Bean
    @ConfigurationProperties(prefix="spring.ds_order") #设置读取在properties文件内容的前缀
    public DataSourceProperties orderDataSourceProperties() {
        return new DataSourceProperties();
    }
    @Bean
    public DataSource orderDataSource(){
        return userDataSourceProperties().initializeDataSourceBuilder().type(HikariDAtaSource.class).build();
    }
    @Bean
    public JdbcTemplate orderJdbcTemplate(@Qualifier("orderDataSource") DataSource orderDataSource){
        return new JdbcTemplate(orderDataSource);
    }
}

public class CustomerService{
    @Autowired
    @Qualifier("userJdbcTemplate")
    private jdbcTemplate userJdbcTemplate;
    @Autowired
    @Qualifier("orderJdbcTemplate")
    private jdbcTemplate orderJdbcTemplate;
    private static final String UPDATE_CUSTOMER_SQL;
    private static final String INSERT_ORDER_SQL;
    @Transactional  #事务管理注解
    public void createOrder(Order order){
        userJdbcTemplate.update(UPDATE_CUSTOMER_SQL, order)
        if(order.getTitle().contains("error1")){     #模拟异常出现
            throw new RuntimeException("error1")
        }
        orderJdbcTemplate.update(INSERT_ORDER_SQL, order)  #没有使用事务，直接提交
         if(order.getTitle().contains("error2")){    #模拟异常出现
            throw new RuntimeException("error2")
        }
    }
}

@Bean
public PlatformTransactionManager transactionManager(){
    DataSourceTransactionManager userTM = new DataSourceTransactionManager(userDataSource()) #看似方法调用，实则从spring容器中获取
    DataSourceTransactionManager orderTM = new DataSourceTransactionManager(orderDataSource())
    # orderTM.setDataSource(orderDataSource())   如果使用这种方式则不是从容器中去获取了,因为orderTM不是spring容器管理
    ChainedTransactionManager tm = new ChainedTransactionManager(userTM, orderTM)  ## order先执行，user后执行
    return tm;
}

public OrderService{
    Map disMap;  # 用于存放已经处理的id
    @Transactional
    void ticketOrder(BuyTickerDTO dto){
        String uid = createUUID(dto);  # 创建并获取数据的唯一id
        if(!diMap.contains(uuid){    #disMap还没有处理过这个数据唯一id,则进入创建
            Order order = createOrder(dto);  
            disMap.append(uid)    ## 追加Map
        }
    }
    userService.charge(dto);   #调用user微服务
}

#通过调节限定，只有第一次支付的时候才会扣余额，被重复调用的时候就不会重复扣费用,通过paystatus判断
UPDATE customer SET deposit = deposit - ${value}, paystatus = 'PAID' WHERE orderId = ${id} and paystatus = 'UNPAID'