什么是JTA
JTA，全稱：Java Transaction API。JTA事務比JDBC事務更強大。一個JTA事務可以有多個參與者，而一個JDBC事務則被限定在一個單一的數據庫連接。所以，當我們在同時操作多個數據庫的時候，使用JTA事務就可以彌補JDBC事務的不足。
在Spring Boot 2.x中，整合了這兩個JTA的實現：
- 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，所以在下面的動手環節中，我們將使用Atomikos作為例子來介紹JTA的使用。
#動手試試
下面我們就來實操一下，如何在Spring Boot中使用JTA來實現多數據源下的事務管理。
準備工作
- 這里我們將使用最基礎的JdbcTemplate來實現數據訪問，所以如果你還不會使用JdbcTemplate配置多數據源，建議先看一下JdbcTemplate的多數據源配置。
- 場景設定：
- 假設我們有兩個庫，分別為：test1和test2
- 這兩個庫中都有一張User表，我們希望這兩張表中的數據是一致的
- 假設這兩張表中都已經有一條數據：name=aaa，age=30；因為這兩張表中數據是一致的，所以要update的時候，就必須兩個庫中的User表更新時候，要么都成功，要么都失敗。
操作詳細
- 在
pom.xml中加入JTA的實現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test1和test2數據源
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
- 創建多數據源配置類
@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，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據源使用的配置和實現類的區別。
- 創建一個Service實現，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庫中的數據
primaryJdbcTemplate.update("update user set age = ? where name = ?", 30, "aaa");
// 修改test2庫中的數據
secondaryJdbcTemplate.update("update user set age = ? where name = ?", 30, "aaa");
}
@Transactional
public void tx2() {
// 修改test1庫中的數據
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，是兩句update操作，一般都會成功；而tx2函數中，我們人為的制造了一個異常，這個異常是在test1庫中的數據更新后才產生的，這樣就可以測試一下test1更新成功，之后是否還能在JTA的幫助下實現回滾。
- 創建測試類，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，test1中的更新應該回滾
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"));
}
}
}
這里有兩個測試用例：
- test1：因為沒有故意制造的異常，不出意外兩個庫的update都會成功，所以根據name=aaa去把兩個數據查出來，看age是否都被更新到了30。
- test2：tx2函數會把test1中name=aaa的用戶age更新為40，然后拋出異常，JTA事務生效的話，會把age回滾回30，所以這里的檢查也是兩個庫的aaa用戶的age應該都為30，這樣就意味著JTA事務生效，保證了test1和test2兩個庫中的User表數據更新一致，沒有制造出臟數據。
#測試驗證
將上面編寫的單元測試運行起來:
觀察一下啟動階段的日志，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，我們在transaction-logs目錄下，還能找到關于事務的日志信息：
{"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"}]}
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#代碼示例
本文的相關例子可以查看下面倉庫中的chapter3-12目錄：
