myBatis系列之七：事务管理

傷城~ 2022-04-11 06:42 274阅读 0赞

**一.myBatis单独使用时，使用SqlSession来处理事务**

在前面的MyBatisStudy02工程中，新增MyBatisTxTest.java的测试类。

package com.bijian.study.test;
    
    import java.io.Reader;
    
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    import org.junit.BeforeClass;
    import org.junit.Test;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    import com.bijian.study.dao.IUserMapper;
    import com.bijian.study.model.User;
    
    public class MyBatisTxTest {
    
    	private static final Logger log = LoggerFactory.getLogger(MyBatisTxTest.class);
    	
    	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(1, "Test transaction");
    			user.setName("bijian2");
    			user.setAge(18);
    			int affectedCount = mapper.updateUser(user); // 因后面的异常而未执行commit语句
    			log.info("{} new record was inserted successfully whose id: {}", affectedCount, user.getId());
    			User user2 = new User(1, "Test transaction continuously");
    			user2.setName("bijian3");
    			user2.setAge(28);
    			int affectedCount2 = mapper.updateUser(user2); // 因后面的异常而未执行commit语句
    			log.info("{} new record was inserted successfully whose id: {}", affectedCount2, user2.getId());
    			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
    		}
    	}
    }

测试前数据库表user表的数据如下：

mysql> select * from user;
    +----+--------+------+-------------------+
    | id | name   | age  | address           |
    +----+--------+------+-------------------+
    |  1 | bijian |  120 | hangzhou,westlake |
    +----+--------+------+-------------------+
    1 row in set (0.00 sec)

运行上面的单元测试，抛出java.lang.ArithmeticException:/ by zero异常。控制台输出如下内容：

21:29:59.797 [main] INFO  com.bijian.study.test.MyBatisTxTest - 1 new record was inserted successfully whose id: 1
    21:29:59.799 [main] INFO  com.bijian.study.test.MyBatisTxTest - 1 new record was inserted successfully whose id: 1

此时我们再查看数据库表user表的数据如下：

**二.和Spring集成后，使用Spring的事务管理**

**1.@Transactional方式**

将工程MyBatisStudy03工程/WEB-INF/下的applicationContext.xml拷贝到类路径下，加入如下事务配置：

<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.bijian.study.service.UserService" />

服务类：

package com.bijian.study.service;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import org.springframework.transaction.TransactionStatus;
    import org.springframework.transaction.annotation.Transactional;
    import org.springframework.transaction.support.TransactionCallback;
    import org.springframework.transaction.support.TransactionTemplate;
    
    import com.bijian.study.dao.IUserMapper;
    import com.bijian.study.model.User;
    
    @Service("userService")
    public class UserService {
    
    	private static final Logger log = LoggerFactory.getLogger(UserService.class);
    	
    	@Autowired
    	private IUserMapper mapper;
    
    	public int batchUpdateUsersWhenException() { // 非事务性
    		User user = new User(1, "Before exception");
    		int affectedCount = mapper.updateUser(user); // 执行成功
    		log.info("{} new record was inserted successfully whose id: {}", affectedCount, user.getId());
    		User user2 = new User(1, "After exception");
    		int i = 1 / 0; // 抛出运行时异常
    		int affectedCount2 = mapper.updateUser(user2); // 未执行
    		log.info("{} new record was inserted successfully whose id: {}", affectedCount2, user.getId());
    		if (affectedCount == 1 && affectedCount2 == 1) {
    			return 1;
    		}
    		return 0;
    	}
    
    	@Transactional
    	public int txUpdateUsersWhenException() { // 事务性
    		User user = new User(1, "Before exception");
    		int affectedCount = mapper.updateUser(user); // 因后面的异常而回滚
    		log.info("{} new record was inserted successfully whose id: {}", affectedCount, user.getId());
    		User user2 = new User(1, "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
    		log.info("{} new record was inserted successfully whose id: {}", affectedCount2, user.getId());
    		if (affectedCount == 1 && affectedCount2 == 1) {
    			return 1;
    		}
    		return 0;
    	}
    }

SpringIntegrateTxTest测试类如下：

package com.bijian.study.test;
    
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    import com.bijian.study.service.UserService;
    
    public class SpringIntegrationTest {
    	
        private static ApplicationContext ctx;
        
        static {
        	ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        }
        
        @Test  
        public void updateUsersExceptionTest() {
        	
        	UserService userService = (UserService) ctx.getBean("userService");
            userService.batchUpdateUsersWhenException();
        }  
      
        @Test  
        public void txUpdateUsersExceptionTest() {
        	
        	UserService userService = (UserService) ctx.getBean("userService");
            userService.txUpdateUsersWhenException();  
        }
    }

运行单元测试updateUsersExceptionTest前数据库表user中的数据如下：

运行单元测试updateUsersExceptionTest后数据库表user中的数据如下：

mysql> select * from user;
    +----+------+------+------------------+
    | id | name | age  | address          |
    +----+------+------+------------------+
    |  1 | NULL |    0 | Before exception |
    +----+------+------+------------------+
    1 row in set (0.00 sec)

恢复数据库表user中的数据如下：

运行单元测试txUpdateUsersExceptionTest后数据库表user中的数据如下：

从上面的单元测试结果不难发现txUpdateUsersWhenException方法上面因注解了@Transactional事务生效了。

**2.TransactionTemplate方式**

在上面的application.xml中添加：

在UserService类加上如下内容：

@Autowired(required = false)
    private 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(1, "Before exception");
    			int affectedCount = mapper.updateUser(user); // 因后面的异常而回滚
    			User user2 = new User(1, "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类中加上如下测试方法：

@Test
    public void updateUsersWhenExceptionViaTxTemplateTest() {
    	
    	UserService userService = (UserService) ctx.getBean("userService");
    	userService.txUpdateUsersWhenExceptionViaTxTemplate();
    }

运行单元测试updateUsersWhenExceptionViaTxTemplateTest前数据库表user中的数据如下：

运行单元测试updateUsersWhenExceptionViaTxTemplateTest后数据库表user中的数据如下，没有发生变化：

说明txUpdateUsersWhenExceptionViaTxTemplate方法因抛出运行时异常事务发生了回滚。

**PS:**

**1.在有@****Transactional注解的方法中，不可catch异常后不抛出**

在有@Transactional注解的方法中，不可catch异常后不抛出，如不抛出，外围框架捕获不到异常，认为执行正确而提交。

@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;  
    }

**2.****The prefix "tx" for element "tx:annotation-driven " is not bound**

配置spring是碰到tx:annotation-driven is not bound 的问题，这个错误的原因很简单是在定义申明AOP的时候没有加载schema。修改applicationContext.xml配置文件头如下：

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:p="http://www.springframework.org/schema/p" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
                         http://www.springframework.org/schema/beans/spring-beans.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
                         http://www.springframework.org/schema/context 
                         http://www.springframework.org/schema/context/spring-context.xsd">

**3.****运行时抛出java.lang.NoClassDefFoundError: org/aopalliance/intercept/MethodInterceptor异常**

原因是缺少包aopalliance-1.0.jar。

参考文章：[http://czj4451.iteye.com/blog/2037759][http_czj4451.iteye.com_blog_2037759]

[http_czj4451.iteye.com_blog_2037759]: http://czj4451.iteye.com/blog/2037759