spring boot - 管理事务和多个数据源

Posted 2023-02-26

【中文标题】spring boot - 管理事务和多个数据源

【英文标题】：spring boot - managing transactions & multiple datasources

【发布时间】：2016-09-25 23:07:29

【问题描述】：

我尝试将 Spring Boot 指南中的 Managing Transactions 示例扩展到两个数据源，但 @Transaction 注释似乎仅适用于其中一个数据源。

在“Application.java”中，我为两个数据源及其 JdbcTemplates 添加了 bean。在“BookingService.java”中，我使用了属于第二个数据源的 JdbcTemplate。

这是我的“Application.java”：

package hello;

import javax.sql.DataSource;

import org.junit.Assert;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Primary;
import org.springframework.jdbc.core.JdbcTemplate;

@SpringBootApplication
public class Application 

    private static final Logger log = LoggerFactory.getLogger(Application.class);

    @Bean
    BookingService bookingService() 
        return new BookingService();
    

    @Primary
    @Bean(name="datasource1")
    @ConfigurationProperties(prefix="datasource1")
    DataSource datasource1() 
        return DataSourceBuilder.create().build();
    

    @Bean(name="jdbcTemplate1")
    @Autowired
    JdbcTemplate jdbcTemplate1(@Qualifier ("datasource1") DataSource datasource) 
        return new JdbcTemplate(datasource);
    

    @Bean(name="datasource2")
    @ConfigurationProperties(prefix="datasource2")
    DataSource datasource2() 
        return DataSourceBuilder.create().build();
    

    @Bean(name="jdbcTemplate2")
    @Autowired
    JdbcTemplate jdbcTemplate2(@Qualifier ("datasource2") DataSource dataSource) 
        JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
        log.info("Creating tables");
        jdbcTemplate.execute("drop table BOOKINGS if exists");
        jdbcTemplate.execute("create table BOOKINGS("
                + "ID serial, FIRST_NAME varchar(5) NOT NULL)");
        return jdbcTemplate;
    

    public static void main(String[] args) 
        ApplicationContext ctx = SpringApplication.run(Application.class, args);

        BookingService bookingService = ctx.getBean(BookingService.class);
        bookingService.book("Alice", "Bob", "Carol");
        Assert.assertEquals("First booking should work with no problem", 3,
                bookingService.findAllBookings().size());

        try 
            bookingService.book("Chris", "Samuel");
        
        catch (RuntimeException e) 
            log.info("v--- The following exception is expect because 'Samuel' is too big for the DB ---v");
            log.error(e.getMessage());
        

        for (String person : bookingService.findAllBookings()) 
            log.info("So far, " + person + " is booked.");
        
        log.info("You shouldn't see Chris or Samuel. Samuel violated DB constraints, and Chris was rolled back in the same TX");
        Assert.assertEquals("'Samuel' should have triggered a rollback", 3,
                bookingService.findAllBookings().size());

        try 
            bookingService.book("Buddy", null);
        
        catch (RuntimeException e) 
            log.info("v--- The following exception is expect because null is not valid for the DB ---v");
            log.error(e.getMessage());
        

        for (String person : bookingService.findAllBookings()) 
            log.info("So far, " + person + " is booked.");
        
        log.info("You shouldn't see Buddy or null. null violated DB constraints, and Buddy was rolled back in the same TX");
        Assert.assertEquals("'null' should have triggered a rollback", 3, bookingService
                .findAllBookings().size());
    

这里是“BookingService.java”：

package hello;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.transaction.annotation.Transactional;

public class BookingService 

    private final static Logger log = LoggerFactory.getLogger(BookingService.class);

    @Autowired
    @Qualifier("jdbcTemplate2")
    JdbcTemplate jdbcTemplate;

    @Transactional
    public void book(String... persons) 
        for (String person : persons) 
            log.info("Booking " + person + " in a seat...");
            jdbcTemplate.update("insert into BOOKINGS(FIRST_NAME) values (?)", person);
        
    ;

    public List<String> findAllBookings() 
        return jdbcTemplate.query("select FIRST_NAME from BOOKINGS", new RowMapper<String>() 
            @Override
            public String mapRow(ResultSet rs, int rowNum) throws SQLException 
                return rs.getString("FIRST_NAME");
            
        );
    

这些是“application.yml”中的应用属性：

datasource1:
    url:        "jdbc:h2:~/h2/ds1;DB_CLOSE_ON_EXIT=FALSE"
    username:   "sa"

datasource2:
    url:        "jdbc:h2:~/h2/ds2;DB_CLOSE_ON_EXIT=FALSE"
    username:   "sa"

这里的“pom.xml”和Managing Transactions一样。

当 @Primary 注释位于 datasource2 bean 上时，一切都按预期工作。 当 @Primary 注释在 datasource1 bean 上时，datasource2 中的写入不是事务性的，并且会得到以下输出：

...

2016-05-27 16:01:23.775  INFO 884 --- [           main] hello.Application                        : So far, Alice is booked.
2016-05-27 16:01:23.775  INFO 884 --- [           main] hello.Application                        : So far, Bob is booked.
2016-05-27 16:01:23.775  INFO 884 --- [           main] hello.Application                        : So far, Carol is booked.
2016-05-27 16:01:23.775  INFO 884 --- [           main] hello.Application                        : So far, Chris is booked.
2016-05-27 16:01:23.775  INFO 884 --- [           main] hello.Application                        : You shouldn't see Chris or Samuel. Samuel violated DB constraints, and Chris was rolled back in the same TX
Exception in thread "main" 2016-05-27 16:01:23.776  INFO 884 --- [       Thread-2] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@3901d134: startup date [Fri May 27 16:01:22 CEST 2016]; root of context hierarchy
java.lang.AssertionError: 'Samuel' should have triggered a rollback expected:<3> but was:<4>
    at org.junit.Assert.fail(Assert.java:88)
    at org.junit.Assert.failNotEquals(Assert.java:834)
    at org.junit.Assert.assertEquals(Assert.java:645)
    at hello.Application.main(Application.java:84)
2016-05-27 16:01:23.778  INFO 884 --- [       Thread-2] o.s.j.e.a.AnnotationMBeanExporter        : Unregistering JMX-exposed beans on shutdown

所以“克里斯”没有回滚。

我想这与正确初始化两个数据库有关。这是一个错误，还是我在这里遗漏了什么？

谢谢！

【问题讨论】：

您还需要多个事务管理器并指定@Transactional 使用 2 个 tx 管理器中的哪一个。

【参考方案1】：

我在“Application.java”中添加了两个bean：

@Bean(name="tm1") 
@Autowired
DataSourceTransactionManager tm1(@Qualifier ("datasource1") DataSource datasource) 
    DataSourceTransactionManager txm  = new DataSourceTransactionManager(datasource);
    return txm;


@Bean(name="tm2") 
@Autowired
DataSourceTransactionManager tm2(@Qualifier ("datasource2") DataSource datasource) 
    DataSourceTransactionManager txm  = new DataSourceTransactionManager(datasource);
    return txm;

并将“BookingService.java”中的@Transactional 更改为：

@Transactional("tm2")

所以现在我们有两个资源本地事务管理器，每个数据源一个，它按预期工作。

非常感谢 M.Deinum！

【讨论】：

这个解决方案有两点我不喜欢，首先它没有使用 javax.transaction.Transactional。我知道这是一个弹簧应用程序，可能到处都是春天，但是如果这是我不喜欢的第二件事，我将我的服务分成一个以与 DI 无关的方式开发的单独工件，那么这个解决方案将失败完成目标。

它是否适用于两个以上的数据库？如果是这样，我们需要做任何额外的配置吗？

调查了2天。你的解决方案做到了。