在一個(gè)Spring Boot項(xiàng)目中赶么，連接多個(gè)數(shù)據(jù)源還是比較常見的频蛔。之前也介紹了如何在幾種常用框架的場景下配置多數(shù)據(jù)源，具體可見：
- Spring Boot 2.x基礎(chǔ)教程：JdbcTemplate的多數(shù)據(jù)源配置
- Spring Boot 2.x基礎(chǔ)教程：Spring Data JPA的多數(shù)據(jù)源配置
- Spring Boot 2.x基礎(chǔ)教程：MyBatis的多數(shù)據(jù)源配置
當(dāng)我們采用多數(shù)據(jù)源的時(shí)候误算，同時(shí)也會(huì)出現(xiàn)一個(gè)這樣的特殊場景：我們希望對A數(shù)據(jù)源的更新和B數(shù)據(jù)源的更新具備事務(wù)性般码。這樣的例子很常見，比如：在訂單庫中創(chuàng)建一條訂單記錄被丧，同時(shí)還需要在商品庫中扣減商品庫存盟戏。如果庫存扣減失敗，那么我們希望訂單創(chuàng)建也能夠回滾甥桂。
如果這兩條數(shù)據(jù)在一個(gè)數(shù)據(jù)庫中柿究，那么通過之前介紹的事務(wù)管理就能輕松解決了。但是黄选，當(dāng)這兩個(gè)操作位于不同的數(shù)據(jù)庫中蝇摸，那么就無法實(shí)現(xiàn)了。
本文就來介紹一種解決這類問題的方法：JTA事務(wù)办陷。
什么是JTA
JTA貌夕，全稱：Java Transaction API。JTA事務(wù)比JDBC事務(wù)更強(qiáng)大民镜。一個(gè)JTA事務(wù)可以有多個(gè)參與者啡专，而一個(gè)JDBC事務(wù)則被限定在一個(gè)單一的數(shù)據(jù)庫連接。所以制圈，當(dāng)我們在同時(shí)操作多個(gè)數(shù)據(jù)庫的時(shí)候们童，使用JTA事務(wù)就可以彌補(bǔ)JDBC事務(wù)的不足畔况。
在Spring Boot 2.x中，整合了這兩個(gè)JTA的實(shí)現(xiàn)：
- Atomikos：可以通過引入
spring-boot-starter-jta-atomikos依賴來使用 - Bitronix：可以通過引入
spring-boot-starter-jta-bitronix依賴來使用
由于Bitronix自Spring Boot 2.3.0開始不推薦使用慧库，所以在下面的動(dòng)手環(huán)節(jié)中跷跪，我們將使用Atomikos作為例子來介紹JTA的使用。
動(dòng)手試試
下面我們就來實(shí)操一下完沪，如何在Spring Boot中使用JTA來實(shí)現(xiàn)多數(shù)據(jù)源下的事務(wù)管理域庇。
準(zhǔn)備工作
這里我們將使用最基礎(chǔ)的JdbcTemplate來實(shí)現(xiàn)數(shù)據(jù)訪問，所以如果你還不會(huì)使用JdbcTemplate配置多數(shù)據(jù)源覆积，建議先看一下JdbcTemplate的多數(shù)據(jù)源配置听皿。
場景設(shè)定：
- 假設(shè)我們有兩個(gè)庫，分別為：test1和test2
- 這兩個(gè)庫中都有一張User表宽档，我們希望這兩張表中的數(shù)據(jù)是一致的
- 假設(shè)這兩張表中都已經(jīng)有一條數(shù)據(jù)：name=aaa尉姨，age=30；因?yàn)檫@兩張表中數(shù)據(jù)是一致的吗冤，所以要update的時(shí)候又厉，就必須兩個(gè)庫中的User表更新時(shí)候，要么都成功椎瘟，要么都失敗覆致。
本文首發(fā)：https://blog.didispace.com/spring-boot-learning-24-3-12/ ，后期修改更新主要以原文為主肺蔚。
操作詳細(xì)
- 在
pom.xml中加入JTA的實(shí)現(xiàn)Atomikos的Starter
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jta-atomikos</artifactId>
</dependency>
- 在
application.properties配置文件中配置兩個(gè)test1和test2數(shù)據(jù)源
spring.jta.enabled=true
spring.jta.atomikos.datasource.primary.xa-properties.url=jdbc:mysql://localhost:3306/test1
spring.jta.atomikos.datasource.primary.xa-properties.user=root
spring.jta.atomikos.datasource.primary.xa-properties.password=12345678
spring.jta.atomikos.datasource.primary.xa-data-source-class-name=com.mysql.cj.jdbc.MysqlXADataSource
spring.jta.atomikos.datasource.primary.unique-resource-name=test1
spring.jta.atomikos.datasource.primary.max-pool-size=25
spring.jta.atomikos.datasource.primary.min-pool-size=3
spring.jta.atomikos.datasource.primary.max-lifetime=20000
spring.jta.atomikos.datasource.primary.borrow-connection-timeout=10000
spring.jta.atomikos.datasource.secondary.xa-properties.url=jdbc:mysql://localhost:3306/test2
spring.jta.atomikos.datasource.secondary.xa-properties.user=root
spring.jta.atomikos.datasource.secondary.xa-properties.password=12345678
spring.jta.atomikos.datasource.secondary.xa-data-source-class-name=com.mysql.cj.jdbc.MysqlXADataSource
spring.jta.atomikos.datasource.secondary.unique-resource-name=test2
spring.jta.atomikos.datasource.secondary.max-pool-size=25
spring.jta.atomikos.datasource.secondary.min-pool-size=3
spring.jta.atomikos.datasource.secondary.max-lifetime=20000
spring.jta.atomikos.datasource.secondary.borrow-connection-timeout=10000
- 創(chuàng)建多數(shù)據(jù)源配置類
@Configuration
public class DataSourceConfiguration {
@Primary
@Bean
@ConfigurationProperties(prefix = "spring.jta.atomikos.datasource.primary")
public DataSource primaryDataSource() {
return new AtomikosDataSourceBean();
}
@Bean
@ConfigurationProperties(prefix = "spring.jta.atomikos.datasource.secondary")
public DataSource secondaryDataSource() {
return new AtomikosDataSourceBean();
}
@Bean
public JdbcTemplate primaryJdbcTemplate(@Qualifier("primaryDataSource") DataSource primaryDataSource) {
return new JdbcTemplate(primaryDataSource);
}
@Bean
public JdbcTemplate secondaryJdbcTemplate(@Qualifier("secondaryDataSource") DataSource secondaryDataSource) {
return new JdbcTemplate(secondaryDataSource);
}
}
注意煌妈，這里除了家在的配置不同之外，DataSource也采用了AtomikosDataSourceBean注意與之前配置多數(shù)據(jù)源使用的配置和實(shí)現(xiàn)類的區(qū)別宣羊。
- 創(chuàng)建一個(gè)Service實(shí)現(xiàn)璧诵，模擬兩種不同的情況。
@Service
public class TestService {
private JdbcTemplate primaryJdbcTemplate;
private JdbcTemplate secondaryJdbcTemplate;
public TestService(JdbcTemplate primaryJdbcTemplate, JdbcTemplate secondaryJdbcTemplate) {
this.primaryJdbcTemplate = primaryJdbcTemplate;
this.secondaryJdbcTemplate = secondaryJdbcTemplate;
}
@Transactional
public void tx() {
// 修改test1庫中的數(shù)據(jù)
primaryJdbcTemplate.update("update user set age = ? where name = ?", 30, "aaa");
// 修改test2庫中的數(shù)據(jù)
secondaryJdbcTemplate.update("update user set age = ? where name = ?", 30, "aaa");
}
@Transactional
public void tx2() {
// 修改test1庫中的數(shù)據(jù)
primaryJdbcTemplate.update("update user set age = ? where name = ?", 40, "aaa");
// 模擬：修改test2庫之前拋出異常
throw new RuntimeException();
}
}
這里tx函數(shù)仇冯，是兩句update操作之宿，一般都會(huì)成功；而tx2函數(shù)中苛坚，我們?nèi)藶榈闹圃炝艘粋€(gè)異常比被，這個(gè)異常是在test1庫中的數(shù)據(jù)更新后才產(chǎn)生的，這樣就可以測試一下test1更新成功泼舱，之后是否還能在JTA的幫助下實(shí)現(xiàn)回滾等缀。
- 創(chuàng)建測試類，編寫測試用例
@SpringBootTest(classes = Chapter312Application.class)
public class Chapter312ApplicationTests {
@Autowired
protected JdbcTemplate primaryJdbcTemplate;
@Autowired
protected JdbcTemplate secondaryJdbcTemplate;
@Autowired
private TestService testService;
@Test
public void test1() throws Exception {
// 正確更新的情況
testService.tx();
Assertions.assertEquals(30, primaryJdbcTemplate.queryForObject("select age from user where name=?", Integer.class, "aaa"));
Assertions.assertEquals(30, secondaryJdbcTemplate.queryForObject("select age from user where name=?", Integer.class, "aaa"));
}
@Test
public void test2() throws Exception {
// 更新失敗的情況
try {
testService.tx2();
} catch (Exception e) {
e.printStackTrace();
} finally {
// 部分更新失敗柠掂，test1中的更新應(yīng)該回滾
Assertions.assertEquals(30, primaryJdbcTemplate.queryForObject("select age from user where name=?", Integer.class, "aaa"));
Assertions.assertEquals(30, secondaryJdbcTemplate.queryForObject("select age from user where name=?", Integer.class, "aaa"));
}
}
}
這里有兩個(gè)測試用例：
- test1：因?yàn)闆]有故意制造的異常项滑，不出意外兩個(gè)庫的update都會(huì)成功，所以根據(jù)name=aaa去把兩個(gè)數(shù)據(jù)查出來，看age是否都被更新到了30枪狂。
- test2：tx2函數(shù)會(huì)把test1中name=aaa的用戶age更新為40危喉，然后拋出異常，JTA事務(wù)生效的話州疾，會(huì)把a(bǔ)ge回滾回30辜限，所以這里的檢查也是兩個(gè)庫的aaa用戶的age應(yīng)該都為30，這樣就意味著JTA事務(wù)生效严蓖，保證了test1和test2兩個(gè)庫中的User表數(shù)據(jù)更新一致薄嫡，沒有制造出臟數(shù)據(jù)。
測試驗(yàn)證
將上面編寫的單元測試運(yùn)行起來:
觀察一下啟動(dòng)階段的日志颗胡，可以看到這些Atomikos初始化日志輸出：
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.default_max_wait_time_on_shutdown = 9223372036854775807
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.allow_subtransactions = true
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.recovery_delay = 10000
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.automatic_resource_registration = true
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.oltp_max_retries = 5
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.client_demarcation = false
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.threaded_2pc = false
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.serial_jta_transactions = true
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.log_base_dir = /Users/didi/Documents/GitHub/SpringBoot-Learning/2.x/chapter3-12/transaction-logs
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.rmi_export_class = none
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.max_actives = 50
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.checkpoint_interval = 500
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.enable_logging = true
2021-02-02 19:00:36.145 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.log_base_name = tmlog
2021-02-02 19:00:36.146 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.max_timeout = 300000
2021-02-02 19:00:36.146 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.trust_client_tm = false
2021-02-02 19:00:36.146 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: java.naming.factory.initial = com.sun.jndi.rmi.registry.RegistryContextFactory
2021-02-02 19:00:36.146 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.tm_unique_name = 127.0.0.1.tm
2021-02-02 19:00:36.146 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.forget_orphaned_log_entries_delay = 86400000
2021-02-02 19:00:36.146 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.oltp_retry_interval = 10000
2021-02-02 19:00:36.146 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: java.naming.provider.url = rmi://localhost:1099
2021-02-02 19:00:36.146 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.force_shutdown_on_vm_exit = false
2021-02-02 19:00:36.146 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : USING: com.atomikos.icatch.default_jta_timeout = 10000
2021-02-02 19:00:36.147 INFO 8868 --- [ main] c.a.icatch.provider.imp.AssemblerImp : Using default (local) logging and recovery...
2021-02-02 19:00:36.184 INFO 8868 --- [ main] c.a.d.xa.XATransactionalResource : test1: refreshed XAResource
2021-02-02 19:00:36.203 INFO 8868 --- [ main] c.a.d.xa.XATransactionalResource : test2: refreshed XAResource
同時(shí)毫深，我們在transaction-logs目錄下，還能找到關(guān)于事務(wù)的日志信息：
{"id":"127.0.0.1.tm161226409083100001","wasCommitted":true,"participants":[{"uri":"127.0.0.1.tm1","state":"COMMITTING","expires":1612264100801,"resourceName":"test1"},{"uri":"127.0.0.1.tm2","state":"COMMITTING","expires":1612264100801,"resourceName":"test2"}]}
{"id":"127.0.0.1.tm161226409083100001","wasCommitted":true,"participants":[{"uri":"127.0.0.1.tm1","state":"TERMINATED","expires":1612264100804,"resourceName":"test1"},{"uri":"127.0.0.1.tm2","state":"TERMINATED","expires":1612264100804,"resourceName":"test2"}]}
{"id":"127.0.0.1.tm161226409092800002","wasCommitted":false,"participants":[{"uri":"127.0.0.1.tm3","state":"TERMINATED","expires":1612264100832,"resourceName":"test1"}]}
更多本系列免費(fèi)教程連載「點(diǎn)擊進(jìn)入?yún)R總目錄」
代碼示例
本文的相關(guān)例子可以查看下面?zhèn)}庫中的chapter3-12目錄：
- Github：https://github.com/dyc87112/SpringBoot-Learning/
- Gitee：https://gitee.com/didispace/SpringBoot-Learning/
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