【Spring源码解析】事务流程解析

1、定义

以方法为单位，进行事务控制；抛出异常，事务回滚。最小的执行单位为方法。决定执行成败是通过是否抛出异常来判断的，抛出异常即执行失败。

2、代码

(1) mysql建表语句

CREATE TABLE `t_student` (
  `c_id` int(11) NOT NULL AUTO_INCREMENT,
  `c_name` varchar(255) DEFAULT NULL,
  `c_age` int(12) DEFAULT NULL,
  PRIMARY KEY (`c_id`)
) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=utf8;

(2) pom

<dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>5.0.6.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aspects</artifactId>
        <version>5.0.6.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>5.0.6.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>c3p0</groupId>
        <artifactId>c3p0</artifactId>
        <version>0.9.1.2</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.44</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.6</version>
    </dependency>
</dependencies>

(3) 配置文件

/**
* @Description:
* @Auther: zhurongsheng
* @Date: 2020/3/1 00:15
*/
@ComponentScan("com.spring")
@Configuration
@EnableTransactionManagement
public class SpringConfig {
    //创建数据源
    @Bean
    public DataSource dataSource() throws PropertyVetoException {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setUser("root");
        dataSource.setPassword("123456");
        dataSource.setDriverClass("com.mysql.jdbc.Driver");
        dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/test");
        return dataSource;
    }
    //jdbcTemplate能简化增删改查的操作
    @Bean
    public JdbcTemplate jdbcTemplate() throws PropertyVetoException{
        return new JdbcTemplate(dataSource());
    }
    
    @Bean
    public PlatformTransactionManager platformTransactionManager() throws PropertyVetoException {
        return new DataSourceTransactionManager(dataSource());
    }
}

(4) dao

/**
* @Description:
* @Auther: zhurongsheng
* @Date: 2020/3/1 00:14
*/
@Repository
public class StudentDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;
    //操作数据的方法
    public void insert() {
        String sql = "insert into `t_student` (c_name, c_age) values(?,?)";
        jdbcTemplate.update(sql, "张三", 18);
        throw new RuntimeException("IOC 测试");
    }
}

(5) service

@Service
public class StudentService {
    @Autowired
    private StudentDao studentDao;
    @Transactional
    public void addStudent(){
        studentDao.insert();
        System.out.println("student insert success");
    }
}

(6) 应用程序

public class SpringApplicationContext {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext applicationContext =
                new AnnotationConfigApplicationContext(SpringConfig.class);
        StudentService studentService = applicationContext.getBean(StudentService.class);
        studentService.addStudent();
    }
}

3、@EnableTransactionManagement

(1) 作用：开启事务

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
/**
* 引入TransactionManagementConfigurationSelector.class
*/
@Import(TransactionManagementConfigurationSelector.class)
public @interface EnableTransactionManagement {
    
    boolean proxyTargetClass() default false;
    /**
     * 默认模式
     */
    AdviceMode mode() default AdviceMode.PROXY;
    
    int order() default Ordered.LOWEST_PRECEDENCE;
}

(2`) TransactionManagementConfigurationSelector

4、 AutoProxyRegistrar类作用

（1）引入InfrastructureAdvisorAutoProxyCreator类




(2) InfrastructureAdvisorAutoProxyCreator分析
看类图得到，跟切面AnnotationAwareAspectJAutoProxyCreator类图很很像：
InstantiationAwareBeanPostProcessor：bean创建的后置加强
Ordered：IOC初始化时，具有高优先级。

5、ProxyTransactionManagementConfiguration类作用

(1) 源码

@Configuration
public class ProxyTransactionManagementConfiguration extends AbstractTransactionManagementConfiguration {
    
    @Bean(name = TransactionManagementConfigUtils.TRANSACTION_ADVISOR_BEAN_NAME)
    @Role(BeanDefinition.ROLE_INFRASTRUCTURE)
    public BeanFactoryTransactionAttributeSourceAdvisor transactionAdvisor() {
        //事务属性工厂
        BeanFactoryTransactionAttributeSourceAdvisor advisor = new BeanFactoryTransactionAttributeSourceAdvisor();
        //设置事务本身属性
        advisor.setTransactionAttributeSource(transactionAttributeSource());
        //设置拦截方法
        advisor.setAdvice(transactionInterceptor());
        if (this.enableTx != null) {
            advisor.setOrder(this.enableTx.<Integer>getNumber("order"));
        }
        return advisor;
    }
    
    /**
     * transactionAttributeSource bean：事务增强器需要用事务注解信息，使用这个类解析事务注解
     */
    @Bean
    @Role(BeanDefinition.ROLE_INFRASTRUCTURE)
    public TransactionAttributeSource transactionAttributeSource() {
        //获取事务所有注解
        return new AnnotationTransactionAttributeSource();
    }
    
    @Bean
    @Role(BeanDefinition.ROLE_INFRASTRUCTURE)
    public TransactionInterceptor transactionInterceptor() {
        //声明方法拦截    
        TransactionInterceptor interceptor = new TransactionInterceptor();
        //设置事务属性                  
        interceptor.setTransactionAttributeSource(transactionAttributeSource());
        //如果事务管理器不为NULL，设置事务管理器
        if (this.txManager != null) {
            interceptor.setTransactionManager(this.txManager);
        }
        return interceptor;
    }
}

(2) 核心bean

(3) 调用方法

(4) TransactionAspectSupport invokeWithinTransaction方法