03-Sping transaction implementation: XML-based implementation of declarative transactions

XML implementation of declarative transactions

Development steps

Step 1: Introduce AOP-related aspectj dependencies

<!--aspectj dependency-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-aspects</artifactId>
  <version>6.0.0-M2</version>
</dependency>

Step 2: Write the dao layer interface and its implementation class

public interface AccountDao {<!-- -->
    // Check the balance based on the account number
    Account selectByActno(String actno);
    //Update account information
    int update(Account act);
}

@Repository("accountDao")
public class AccountDaoImpl implements AccountDao {<!-- -->
    @Resource(name = "jdbcTemplate")
    private JdbcTemplate jdbcTemplate;

    @Override
    public Account selectByActno(String actno) {<!-- -->
        String sql = "select actno, balance from t_act where actno = ?";
        Account account = jdbcTemplate.queryForObject(sql, new BeanPropertyRowMapper<>(Account.class), actno);
        return account;
    }

    @Override
    public int update(Account act) {<!-- -->
        String sql = "update t_act set balance = ? where actno = ?";
        int count = jdbcTemplate.update(sql, act.getBalance(), act.getActno());
        return count;
    }

}

Step 3: Write the Service interface and its implementation class. Here we no longer use the @Transactional annotation but implement declarative transactions based on XML configuration

@Service("accountService")
public class AccountServiceImpl implements AccountService {<!-- -->
    @Resource(name = "accountDao")
    private AccountDao accountDao;
    @Override
    public void transfer(String fromActno, String toActno, double money) {<!-- -->
        // Check whether the balance of the transfer-out account is sufficient
        Account fromAct = accountDao.selectByActno(fromActno);
        if (fromAct.getBalance() < money) {<!-- -->
            throw new RuntimeException("Insufficient balance!!!");
        }
        // The balance is sufficient
        Account toAct = accountDao.selectByActno(toActno);

        // Modify the balance of the two objects in the memory first
        fromAct.setBalance(fromAct.getBalance() - money);
        toAct.setBalance(toAct.getBalance() + money);

        //Database update
        int count = accountDao.update(fromAct);

        // Simulate exception
        String s = null;
        s.toString();

        count + = accountDao.update(toAct);

        if(count != 2) {<!-- -->
            throw new RuntimeException("Transfer failed, contact the bank!");
        }
    }

}

Step 4: Add the context, aop and tx namespaces and their constraint files in the spring configuration file, and then configure the data source and JdbcTemplate ,transaction manager,notification,aspect

Tag	Description
tx:advice	Customize a transaction notification
tx:method	Configure the method of transaction notification and the related attributes of the transaction
advice-ref	Introducing custom notifications

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
                           http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
                           http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
    <!--Component scanning-->
    <context:component-scan base-package="com.powernode.bank"/>

    <!--Configuring data source-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/spring6"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
    </bean>

    <!--Configuring JdbcTemplate-->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <!--Configuration transaction manager-->
    <bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <!--Associate the configured transaction manager, and then configure transaction-related notifications. This enhanced transaction-related code has been encapsulated by Spring-->
    <tx:advice id="txAdvice" transaction-manager="txManager">
        <!--Configure which business methods the transaction notification controls, and set the relevant transaction attributes-->
        <tx:attributes>
            <!--Exact match-->
            <tx:method name="transfer" propagation="REQUIRED" rollback-for="java.lang.Throwable"/>
            <!--Fuzzy matching-->
            <tx:method name="save*" propagation="REQUIRED" rollback-for="java.lang.Throwable"/>
            <tx:method name="delete*" propagation="REQUIRED" rollback-for="java.lang.Throwable"/>
            <tx:method name="update*" propagation="REQUIRED" rollback-for="java.lang.Throwable"/>
            <tx:method name="modify*" propagation="REQUIRED" rollback-for="java.lang.Throwable"/>
            <tx:method name="query*" read-only="true"/>
            <tx:method name="select*" read-only="true"/>
            <tx:method name="find*" read-only="true"/>
            <tx:method name="get*" read-only="true"/>
        </tx:attributes>
    </tx:advice>
    
    <!--Configuration aspects-->
    <aop:config>
        <!--General pointcut expression, here represents all methods in AccountServiceImpl-->
        <aop:pointcut id="txPointcut" expression="execution(* com.powernode.bank.service..*(..))"/>
        <!--Aspect = notification + pointcut. Although the pointcut here is all the methods of the business class, the txAdvice notification we configured ourselves has specified the specific business method-->
        <aop:advisor advice-ref="txAdvice" pointcut-ref="txPointcut"/>
    </aop:config>
</beans>

Step 5: Test whether the configured transaction notification can play a transaction control role in the target method of the target object

@Test
public void testTransferXml(){<!-- -->
    ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
    AccountService accountService = applicationContext.getBean("accountService", AccountService.class);
    try {<!-- -->
        accountService.transfer("act-001", "act-002", 10000);
        System.out.println("Transfer successful");
    } catch (Exception e) {<!-- -->
        e.printStackTrace();
    }
}