myBatis之事务管理

2022-09-04 16:23:39

1. myBatis单独使用时，使用SqlSession来处理事务：

public class MyBatisTxTest {
private static SqlSessionFactory sqlSessionFactory;
private static Reader reader;
@BeforeClass
public static void setUpBeforeClass() throws Exception {
try {
reader = Resources.getResourceAsReader("Configuration.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
} finally {
if (reader != null) {
reader.close();
}
}
}
@Test
public void updateUserTxTest() {
SqlSession session = sqlSessionFactory.openSession(false); // 打开会话，事务开始
try {
IUserMapper mapper = session.getMapper(IUserMapper.class);
User user = new User(9, "Test transaction");
int affectedCount = mapper.updateUser(user); // 因后面的异常而未执行commit语句
User user = new User(10, "Test transaction continuously");
int affectedCount2 = mapper.updateUser(user2); // 因后面的异常而未执行commit语句
int i = 2 / 0; // 触发运行时异常
session.commit(); // 提交会话，即事务提交
} finally {
session.close(); // 关闭会话，释放资源
}
}
}

2. 和Spring集成后，使用Spring的事务管理：

a. @Transactional方式：

在类路径下创建beans-da-tx.xml文件，在beans-da.xml（系列五）的基础上加入事务配置：

<bean id="txManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource" />
</bean>
<tx:annotation-driven transaction-manager="txManager" />
<bean id="userService" class="com.john.hbatis.service.UserService" />

服务类：

@Service("userService")
public class UserService {
@Autowired
IUserMapper mapper;
public int batchUpdateUsersWhenException() { // 非事务性
User user = new User(9, "Before exception");
int affectedCount = mapper.updateUser(user); // 执行成功
User user2 = new User(10, "After exception");
int i = 1 / 0; // 抛出运行时异常
int affectedCount2 = mapper.updateUser(user2); // 未执行
if (affectedCount == 1 && affectedCount2 == 1) {
return 1;
}
return 0;
}
@Transactional
public int txUpdateUsersWhenException() { // 事务性
User user = new User(9, "Before exception");
int affectedCount = mapper.updateUser(user); // 因后面的异常而回滚
User user2 = new User(10, "After exception");
int i = 1 / 0; // 抛出运行时异常，事务回滚
int affectedCount2 = mapper.updateUser(user2); // 未执行
if (affectedCount == 1 && affectedCount2 == 1) {
return 1;
}
return 0;
}
}

在测试类中加入：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:beans-da-tx.xml" })
public class SpringIntegrateTxTest {
@Resource
UserService userService;
@Test
public void updateUsersExceptionTest() {
userService.batchUpdateUsersWhenException();
}
@Test
public void txUpdateUsersExceptionTest() {
userService.txUpdateUsersWhenException();
}
}

b. TransactionTemplate方式

在beans-da-tx.xml中添加：

<bean id="txTemplate" class="org.springframework.transaction.support.TransactionTemplate">
<constructor-arg type="org.springframework.transaction.PlatformTransactionManager" ref="transactionManager" />
</bean>

在UserService类加入：

@Autowired(required = false)
TransactionTemplate txTemplate;
public int txUpdateUsersWhenExceptionViaTxTemplate() {
int retVal = txTemplate.execute(new TransactionCallback<Integer>() {
@Override
public Integer doInTransaction(TransactionStatus status) { // 事务操作
User user = new User(9, "Before exception");
int affectedCount = mapper.updateUser(user); // 因后面的异常而回滚
User user2 = new User(10, "After exception");
int i = 1 / 0; // 抛出运行时异常并回滚
int affectedCount2 = mapper.updateUser(user2); // 未执行
if (affectedCount == 1 && affectedCount2 == 1) {
return 1;
}
return 0;
}
});
return retVal;
}

在SpringIntegrateTxTest类中加入：

@Test
public void updateUsersWhenExceptionViaTxTemplateTest() {
userService.txUpdateUsersWhenExceptionViaTxTemplate(); //
}

注：不可catch Exception或RuntimeException而不抛出：

@Transactional
public int txUpdateUsersWhenExceptionAndCatch() { // 事务性操作，但是外围框架捕获不到异常，认为执行正确而提交。
try {
User user = new User(9, "Before exception");
int affectedCount = mapper.updateUser(user); // 执行成功
User user2 = new User(10, "After exception");
int i = 1 / 0; // 抛出运行时异常
int affectedCount2 = mapper.updateUser(user2); // 未执行
if (affectedCount == 1 && affectedCount2 == 1) {
return 1;
}
} catch (Exception e) { // 所有异常被捕获而未抛出
e.printStackTrace();
}
return 0;
}