Spring的7种事务传播行为分析实例（一）

偏执的太偏执、 2021-12-11 07:01 285阅读 0赞

今天任务不多，闲来没事的时候看到一篇关于事务传播机制的博客，里面除了对7种事务传播机制的介绍和讲解，还谈到了事务的传播机制定义在TransactionDefinition接口中，我们也可以通过枚举类Propagation类调用，然后正好也没事做，我就去看了一下TransactionDefinition接口和Propagation类的源码，看完之后发现里面就是对7种事务传播机制的定义还有几个获取事务的传播行为、隔离级别等的方法，想起面试那时候死记硬背事务的传播机制，到现在还是不知道原理，于是我就想做个demo实战一下，帮助我们进一步理解事务传播机制的原理。

这里关于7种事务传播机制我就不再重复介绍了，大家若有对定义还不清楚的可以自行百度，好了，话不多说，进入正题。

### 一、新建/导入项目 ###

考虑到做一个小demo，我马上就想到SpringBoot，于是老规矩直接到SpringBoot官网下载一个基本的SpringBoot的demo，当然我们也可以创建一个SpringBoot项目，然后可以开始写实例了。

### 二、pom.xml ###

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    	<modelVersion>4.0.0</modelVersion>
    	<parent>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-parent</artifactId>
    		<version>2.1.6.RELEASE</version>
    		<relativePath/> 
    	</parent>
    	<groupId>com.example</groupId>
    	<artifactId>demo</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<name>demo</name>
    	<description>Demo project for Spring Boot</description>
    
    	<properties>
    		<java.version>1.8</java.version>
    	</properties>
    
    	<dependencies>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter</artifactId>
    		</dependency>
            
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-test</artifactId>
    			<scope>test</scope>
    		</dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
            </dependency>
            
            <dependency>
                <groupId>io.springfox</groupId>
                <artifactId>springfox-swagger2</artifactId>
                <version>2.7.0</version>
            </dependency>
            
            <dependency>
                <groupId>io.springfox</groupId>
                <artifactId>springfox-swagger-ui</artifactId>
                <version>2.7.0</version>
            </dependency>
    		
    		<dependency>
    			<groupId>org.postgresql</groupId>
    			<artifactId>postgresql</artifactId>
    			<scope>runtime</scope>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-data-jpa</artifactId>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-data-rest</artifactId>
    		</dependency>
    	</dependencies>
    	<build>
    		<plugins>
    			<plugin>
    				<groupId>org.springframework.boot</groupId>
    				<artifactId>spring-boot-maven-plugin</artifactId>
    			</plugin>
    		</plugins>
    	</build>
    
    </project>

注：Swagger是一个接口测试工具，我开始使用的数据库是postgresql，后来又改用oracle进行了测试，所以没有用这两个的不用添加它们相关的依赖。

### 三、application.yml/application.properties ###

配置数据库，我比较习惯用yml文件，配置如下：

spring:
      jpa:
        database: oracle
        show-sql: true
        hibernate:
              dialect: org.hibernate.dialect.OracleDialect
      datasource:
          url: jdbc:oracle:thin:@localhost:1521:orcl
          username: root
          password: root
          driverClassName: oracle.jdbc.driver.OracleDriver
      #spring:
      #  jpa:
      #    database: postgresql
      #    show-sql: true
      #    hibernate:
      #          ddl-auto: update
      #          dialect: org.hibernate.dialect.PostgreSQLDialect
      #    properties:
      #          hibernate:
      #            temp:
      #              use_jdbc_metadata_defaults: false
      #database:
      #  driverClassName: org.postgresql.Driver
      #datasource:
      # platform: postgres
      #  url: jdbc:postgresql://localhost:5432/mydb
      #  username: postgres
      #  password: 12345

### 四、创建controller层、service层、dao层以及vo ###

controller：

@RestController
    @RequestMapping("/user/*")
    public class UserController {
    
        private final static List<User> userList = new ArrayList<>();
    
        @Autowired
        UserRepository userRepository;
    
        @Autowired
        BusinessService businessService;
    
        @RequestMapping(value = "/save")
        @Transactional(propagation = Propagation.REQUIRED, isolation = Isolation.DEFAULT, rollbackFor = Exception.class)
        public String doA() throws Exception {
            User user = new User();
            user.setId(6);
            user.setName("aaa");
            user.setPassword("bbb");
            userRepository.save(user);
    
            System.out.println("是否是代理调用，AopUtils.isAopProxy(businessService) : " + AopUtils.isAopProxy(businessService));
            System.out.println("是否是cglib类代理调用，AopUtils.isCglibProxy(businessService) : " + AopUtils.isCglibProxy(businessService));
            System.out.println("是否是jdk动态接口代理调用，AopUtils.isJdkDynamicProxy(businessService) : "
                    + AopUtils.isJdkDynamicProxy(businessService));
            //使用代理调用方法doB()
            businessService.doB();
    
            int i = 1 / 0;// 抛出异常
            return "success";
        }
    
        @RequestMapping(value = "/userList", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
        public List<User> findAll() {
            final List<User> resultList = new ArrayList<>();
            final Iterable<User> all = userRepository.findAll();
            all.forEach(new Consumer<User>() {
                @Override
                public void accept(User user) {
                    resultList.add(user);
                }
            });
            return resultList;
        }
    
        /*@RequestMapping(value = "/save", produces = MediaType.APPLICATION_JSON_VALUE)
        public void create() {
            try {
                doA();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }*/
    
        /*@Transactional(propagation = Propagation.REQUIRES_NEW,isolation=Isolation.DEFAULT,rollbackFor=Exception.class)
        public String doB() throws Exception {
            User user = new User();
            user.setId(7);
            user.setName("ccc");
            user.setPassword("ddd");
            userRepository.save(user);
            return "success";
        }*/
    }

service：

public interface BusinessService {
        public String doB();
    }

@Service("businessService")
    public class BusinessServiceImpl implements BusinessService{
        @Autowired
        UserRepository userRepository;
    
        @Transactional(propagation = Propagation.REQUIRES_NEW,isolation= Isolation.DEFAULT,rollbackFor=Exception.class)
        public String doB() {
            User user = new User();
            user.setId(7);
            user.setName("ccc");
            user.setPassword("ddd");
            userRepository.save(user);
            return "success";
        }
    }

dao:

@Repository
    public interface UserRepository extends CrudRepository<User,Integer> {
    }

vo:

@Entity
    @Table(name = "USER_")
    public class User implements Serializable {
        @Id
        @Column(name = "ID")
        private int id;
        @Column(name = "NAME")
        private String name;
        @Column(name = "PASSWORD")
        private String password;
    
        public User() {
    
        }
    
        public User(int id, String name, String password) {
            this.id = id;
            this.name = name;
            this.password = password;
        }
    
        public int getId() {
            return id;
        }
    
        public void setId(int id) {
            this.id = id;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public String getPassword() {
            return password;
        }
    
        public void setPassword(String password) {
            this.password = password;
        }
    
        @Override
        public String toString() {
            return "User{" +
                    "id='" + id + '\'' +
                    ", name='" + name + '\'' +
                    ", password='" + password + '\'' +
                    '}';
        }
    }

### 五、测试 ###

到这里基本上案例已经写好了，已经减少了很多配置和代码了，先来看一下数据库：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5MDUyODMz_size_16_color_FFFFFF_t_70][]

启动SpringBoot项目，先测一下数据库连接有没有问题，在浏览器中输入路径[http://localhost:8080/user/userList][http_localhost_8080_user_userList]，如显示出数据说明配置没问题。

上面是准备工作，环境搭建好以后，后面将会对Spring的7种事务传播行为类型进行实例演示。未完待续。。。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5MDUyODMz_size_16_color_FFFFFF_t_70]: /images/20211211/eeb3504abdfc4347823fa9f9fc81697a.png
[http_localhost_8080_user_userList]: http://localhost:8080/user/userList