【Spring进阶系列丨最终篇】一文详解Spring中的事务控制

0、说明

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一、Spring事务控制

• 事务需要放在业务层(service)
• Spring的事务是基于AOP的
• Spring的事务控制有两种：编程式事务【了解】和声明式事务【重点】
• 声明式事务分为：基于xml配置和基于注解配置

1、事务的环境准备

1.1、导入依赖

<dependencies>

        
        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-contextartifactId>
            <version>5.2.1.RELEASEversion>
        dependency>

        
        <dependency>
            <groupId>org.aspectjgroupId>
            <artifactId>aspectjweaverartifactId>
            <version>1.9.4version>
        dependency>

        
        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-txartifactId>
            <version>5.2.1.RELEASEversion>
        dependency>

        
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <version>5.1.48version>
        dependency>
  	
  		
  		<dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-jdbcartifactId>
            <version>5.2.1.RELEASEversion>
        dependency>

        
        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>4.12version>
            <scope>testscope>
        dependency>
dependencies>
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1.2、添加AOP的约束

<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:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/tx
        https://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">
beans>
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1.3、数据库准备

create database bank;

use bank;

create table t_account(
	id int primary key auto_increment,
  	name varchar(30),
  	balance int
);

insert into t_account(name,balance) values('段康家',2000);
insert into t_account(name,balance) values('彭依凝',2000);
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1.4、定义Bean

// 定义实体
public class Account {
    
    private Integer id;
    
    private String name;
    
    private Integer balance;
}
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// 业务接口
public interface AccountService {

    public void transfer(Integer srcId,Integer destId,Integer money);

}
public class AccountServiceImpl implements AccountService {

    @Override
    public void transfer(Integer srcId, Integer destId, Integer money) {
        // 源账号
        Account srcAccount = accountDao.selectById(srcId);
        Integer srcBalance = srcAccount.getBalance();
        srcAccount.setBalance(srcBalance - money);
        
        accountDao.updateById(srcAccount);
        
        // 目标账号
        Account destAccount = accountDao.selectById(destId);
        Integer destBalance = destAccount.getBalance();
        destAccount.setBalance(destBalance + money);
        
        accountDao.updateById(destAccount);
    }
}
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// dao接口
public interface AccountDao {
    
    public Account selectById(Integer id);
    
    public void updateById(Account account);
    
}
// dao实现类
public class AccountDaoImpl implements AccountDao {
    @Override
    public Account selectById(Integer id) {

        String sql = "select id,name,balance from t_account where id = ?";

        List<Account> accounts = getJdbcTemplate().query(sql,new BeanPropertyRowMapper<Account>(Account.class),id);

        return accounts.get(0);
    }

    @Override
    public void updateById(Account account) {

        String sql = "update t_account set balance = ? where id = ?";

        getJdbcTemplate().update(sql,account.getBalance(),account.getId());
    }
}
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1.5、主配置文件定义

<beans> 
	
    <bean id="accountDao" class="cn.bdqn.dao.impl.AccountDaoImpl">
        <property name="dataSource" ref=""/>
    bean>

    
    <bean id="accountService" class="cn.bdqn.service.impl.AccountServiceImpl">
        <property name="accountDao" ref="accountDao">property>
    bean>

    
    <bean id="dataSource" 																class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver">property>
        <property name="url" value="jdbc:mysql:///bank">property>
        <property name="username" value="root">property>
        <property name="password" value="root">property>
    bean>

beans>
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1.6、测试

@Test
public void testTransfer() throws Exception{

        ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml");
        AccountService accountService = (AccountService) ac.getBean("accountService");
        accountService.transfer(1,2,100);
}
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2、基于xml的声明式事务

2.1、配置事务管理器

<bean id="transactionManager" 																																		class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
bean>
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2.2、配置事务的通知

 
<tx:advice id="txAdvice" transaction-manager="transactionManager"/>
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2.3、配置AOP

​ 重点是配置切入点表达式及事务通知和切入点表达式的关系

<aop:config>
        <aop:pointcut id="pt" expression="execution(* cn.bdqn.service.impl.*.*(..))"/>
        <aop:advisor advice-ref="txAdvice" pointcut-ref="pt"/>
aop:config>
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2.4、配置事务的属性

​ 注意：事务的属性在tx:advice标签的内部。

isolation：用于指定事务的隔离级别。默认值是DEFAULT，表示使用数据库的默认隔离级别。

propagation：用于指定事务的传播行为。默认值是REQUIRED，表示一定会有事务，增删改的选择。查询方法可以选择SUPPORTS。

read-only：用于指定事务是否只读。只有查询方法才能设置为true。默认值是false，表示读写。

timeout：用于指定事务的超时时间，默认值是-1，表示永不超时。如果指定了数值，以秒为单位。

rollback-for：用于指定一个异常，当产生该异常时，事务回滚，产生其他异常时，事务不回滚。没有默认值。表示任何异常都回滚。

no-rollback-for：用于指定一个异常，当产生该异常时，事务不回滚，产生其他异常时事务回滚。没有默认值。表示任何异常都回滚。

<tx:advice id="txAdvice" transaction-manager="transactionManager">
   
   <tx:attributes>
        <tx:method name="transfer" isolation="DEFAULT" propagation="REQUIRED" 
                   read-only="false"/>
   tx:attributes>
tx:advice>
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3、基于注解的声明式事务

3.1、配置事务管理器

<bean id="transactionManager" 																																				class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
bean>
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3.2、在业务类添加注解

@Service("accountService")
public class AccountServiceImpl implements AccountService {

    @Autowired
    private AccountDao accountDao;

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3.3、配置JdbcTemplate模板

<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
    <property name="dataSource" ref="dataSource"/>
bean>
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3.4、在Dao类添加注解

@Repository("accountDao")
public class AccountDaoImpl implements AccountDao {

    @Autowired
    private JdbcTemplate jdbcTemplate;
}
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3.5、配置类中扫描包

<context:component-scan base-package="cn.bdqn"/>
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3.6、开启spring对注解事务的支持

<tx:annotation-driven transaction-manager="transactionManager"/>
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3.7、在业务层@Transactional注解

@Service("accountService")
@Transactional
public class AccountServiceImpl implements AccountService {

    @Autowired
    private AccountDao accountDao;
}
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3.8、测试

@Test
public void testTransfer() throws Exception{

        ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml");
        AccountService accountService = (AccountService) ac.getBean("accountService");
        accountService.transfer(1,2,100);
}

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