Spring聲明式事務(wù)操作簡單，我們平常開發(fā)過程中，只需要在需要事務(wù)控制的方法上面加上@Transactional注解就可以綁定事務(wù)控制济赎。但是其中的參數(shù)配置今天給大家捋一捋，并且有個(gè)AOP的神坑需要大家注意约巷。

常用的屬性一般是REQUIRED和REQUIRES_NEW這兩個(gè)。
下面我們用代碼來驗(yàn)證一下這常見的兩個(gè)屬性：

1.開啟事務(wù)支持 @EnableTransactionManagement

/**
 * @author wangzhi
 */
@SpringBootApplication
@EnableTransactionManagement
public class DemoApplication {
    public static void main(String[] args) {
        new SpringApplication(DemoApplication.class).run(args);
    }
}

2.實(shí)體類和數(shù)據(jù)庫

/**
 * @author wangzhi
 */
@Data
@TableName("course")
public class CourseEntity {
    
    @TableId(type = IdType.AUTO)
    private Integer id;
    
    private String courseName;
    
    private BigDecimal price;
}

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3.service層業(yè)務(wù)代碼

我們先檢驗(yàn)一下REQUIRED

/**
 * @author wangzhi
 */
@Service
public class TransactionService {

    @Autowired
    private CourseMapper courseMapper;

    @Transactional(rollbackFor = Exception.class,propagation = Propagation.REQUIRED)
    public void save() {
        CourseEntity course = new CourseEntity();
        course.setCourseName("語文");
        course.setPrice(new BigDecimal(100));
        courseMapper.insert(course);
        //故意制造異常
        System.out.println(1/0);
    }

    @Transactional(rollbackFor = Exception.class,propagation = Propagation.REQUIRED)
    public void saveInit() {
        CourseEntity course = new CourseEntity();
        course.setCourseName("數(shù)學(xué)");
        course.setPrice(new BigDecimal(100));
        courseMapper.insert(course);
        //調(diào)用save方法
        try{
            save();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

4.測試一下尤蒿，你們猜數(shù)據(jù)庫有幾條記錄郑气？

@RunWith(SpringRunner.class)
@SpringBootTest
@ContextConfiguration(classes = DemoApplication.class)
class DemoApplicationTests {

    @Autowired
    TransactionService transactionService;

    @Test
    public void transactionTest() throws Exception {
        transactionService.saveInit();
    }

}

5.看結(jié)果

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4.別急，再看看REQUIRES_NEW

/**
 * @author wangzhi
 */
@Service
public class TransactionService {

    @Autowired
    private CourseMapper courseMapper;

    @Transactional(rollbackFor = Exception.class,propagation = Propagation.REQUIRES_NEW)
    public void save() {
        CourseEntity course = new CourseEntity();
        course.setCourseName("語文");
        course.setPrice(new BigDecimal(100));
        courseMapper.insert(course);
        //故意制造異常
        System.out.println(1/0);
    }

    @Transactional(rollbackFor = Exception.class,propagation = Propagation.REQUIRED)
    public void saveInit() {
        CourseEntity course = new CourseEntity();
        course.setCourseName("數(shù)學(xué)");
        course.setPrice(new BigDecimal(100));
        courseMapper.insert(course);
        //調(diào)用save方法
        try {
            save();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

在這里插入圖片描述

5.之所以出現(xiàn)如此情況腰池，并不是事務(wù)傳播有問題尾组，而是動(dòng)態(tài)代理造成的忙芒。在同一個(gè)類里面互相調(diào)用事務(wù)方法，切面切的是發(fā)起事務(wù)的方法讳侨，而內(nèi)部不管調(diào)用的什么事務(wù)方法都會(huì)默認(rèn)為this當(dāng)前對(duì)象去調(diào)動(dòng)普通方法呵萨，這些事務(wù)注解說白了就是不管用。事務(wù)是根據(jù)動(dòng)態(tài)代理生成的動(dòng)態(tài)對(duì)象去執(zhí)行事務(wù)的控制爷耀，所以在同類方法內(nèi)部調(diào)用其他事務(wù)方法必須要獲取其對(duì)應(yīng)的代理對(duì)象去調(diào)用才生效甘桑，否則必須放在不同的類里面。結(jié)局方法：

6.引入AOP

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>

7.@EnableAspectJAutoProxy(exposeProxy = true)

/**
 * @author wangzhi
 */
@SpringBootApplication
@EnableTransactionManagement
@MapperScan("com.example.mapper")
@EnableAspectJAutoProxy(exposeProxy = true)
public class DemoApplication {
    public static void main(String[] args) {
        new SpringApplication(DemoApplication.class).run(args);
    }
}

8.改造一下service

/**
 * @author wangzhi
 */
@Service
public class TransactionService {

    @Autowired
    private CourseMapper courseMapper;

    @Transactional(rollbackFor = Exception.class,propagation = Propagation.REQUIRES_NEW)
    public void save() {
        CourseEntity course = new CourseEntity();
        course.setCourseName("語文");
        course.setPrice(new BigDecimal(100));
        courseMapper.insert(course);
        //故意制造異常
        System.out.println(1/0);
    }

    @Transactional(rollbackFor = Exception.class,propagation = Propagation.REQUIRED)
    public void saveInit() {
        CourseEntity course = new CourseEntity();
        course.setCourseName("數(shù)學(xué)");
        course.setPrice(new BigDecimal(100));
        courseMapper.insert(course);
        //調(diào)用save方法
        try {
            TransactionService proxy = (TransactionService)AopContext.currentProxy();
            proxy.save();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

看看結(jié)果：

在這里插入圖片描述

這樣的結(jié)果就對(duì)了歹叮！所以我們在開發(fā)過程中遇到A方法調(diào)用B方法跑杭，如果AB方法都在同一個(gè)類里面，想要B方法的事務(wù)生效必須用代理方式執(zhí)行咆耿。當(dāng)然AB方法不在同一個(gè)類里面可以生效德谅，因?yàn)閯?dòng)態(tài)代理是運(yùn)行時(shí)才構(gòu)造的代理對(duì)象。而且萨螺，類似的技術(shù)點(diǎn)不僅僅出現(xiàn)在事務(wù)這里窄做，比如@Async注解同樣還是這樣，同一個(gè)類里面調(diào)用依然不是異步執(zhí)行慰技，當(dāng)涉及到動(dòng)態(tài)代理相關(guān)都要注意此點(diǎn)椭盏。