Spring事务管理知识讲解请见:Spring事务知识点讲解
下面演示一个代码示例进行理解。
需求
两个账户相互转账,并记录日志,即使有转账失败也要记录
需求分析
这里主要是需要开启事务机制来控制转入和转出:
1,创建一个表,模拟银行账户表,并插入两条数据,模拟两个账户
2,先模拟转账成功:转出和转入都成功才算成功
3,再模拟转出成功,转入失败,看看是不是都进行了回滚,且仍然记录了转账记录
为了实现上述的业务需求,我们可以按照下面步骤来实现下:
①:数据层提供基础操作,指定账户减钱(outMoney),指定账户加钱(inMoney)
②:业务层提供转账操作(transfer),调用减钱与加钱的操作
③:提供2个账号和操作金额执行转账操作
④:基于Spring整合MyBatis环境搭建上述操作
代码开发
步骤1:准备数据库表
create database spring_db character set utf8;
use spring_db;
create table tbl_account(id int primary key auto_increment,name varchar(35),money double
);
insert into tbl_account values(1,'Tom',1000);
insert into tbl_account values(2,'Jerry',1000);
步骤2:创建项目导入jar包
项目的pom.xml添加相关依赖
<dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.2.10.RELEASE</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.1.16</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.6</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.47</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>5.2.10.RELEASE</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>1.3.0</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version><scope>test</scope></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-test</artifactId><version>5.2.10.RELEASE</version></dependency></dependencies>
步骤3:根据表创建模型类
public class Account implements Serializable {private Integer id;private String name;private Double money;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Double getMoney() {return money;}public void setMoney(Double money) {this.money = money;}@Overridepublic String toString() {return "Account{" +"id=" + id +", name='" + name + '\'' +", money=" + money +'}';}
}
步骤4:创建转账Dao接口
public interface AccountDao {@Update("update tbl_account set money = money + #{money} where name = #{name}")void inMoney(@Param("name") String name, @Param("money") Double money);@Update("update tbl_account set money = money - #{money} where name = #{name}")void outMoney(@Param("name") String name, @Param("money") Double money);
}
步骤5:创建记录日志Dao接口
public interface LogDao {@Insert("insert into tbl_log (info,createDate) values(#{info},now())")void log(String info);
}
步骤6:创建转账Service接口和实现类
public interface AccountService {/*** 转账操作* @param out 传出方* @param in 转入方* @param money 金额*///rollback:设置当前事务参与回滚的异常,默认非运行时异常不参与回滚
// @Transactional(rollbackFor = IOException.class)@Transactionalpublic void transfer(String out,String in ,Double money) throws IOException;
}//实现类
@Service
public class AccountServiceImpl implements AccountService {@Autowiredprivate AccountDao accountDao;@Autowiredprivate LogService logService;public void transfer(String out,String in ,Double money) {try{System.out.println("开始给账户A扣减50");accountDao.outMoney(out,money);System.out.println("账户A扣减50执行完成");//先注释掉 1/0,模拟转账成功;//再去掉注释,模拟转账失败int i = 1/0;System.out.println("开始给账户B增加50");accountDao.inMoney(in,money);System.out.println("账户B增加50执行完成");}finally {logService.log(out,in,money);}}}
步骤7:创建记录日志Service接口和实现类
public interface LogService {//propagation设置事务属性:传播行为设置为当前操作需要新事务@Transactional(propagation = Propagation.REQUIRES_NEW)void log(String out, String in, Double money);
}//实现类
@Service
public class LogServiceImpl implements LogService {@Autowiredprivate LogDao logDao;public void log(String out,String in,Double money ) {logDao.log("转账操作由"+out+"到"+in+",金额:"+money);}
}
步骤8:添加jdbc.properties文件
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/spring_db?useSSL=false
jdbc.username=root
jdbc.password=fage
步骤9:创建JdbcConfig配置类
public class JdbcConfig {@Value("${jdbc.driver}")private String driver;@Value("${jdbc.url}")private String url;@Value("${jdbc.username}")private String userName;@Value("${jdbc.password}")private String password;@Beanpublic DataSource dataSource(){DruidDataSource ds = new DruidDataSource();ds.setDriverClassName(driver);ds.setUrl(url);ds.setUsername(userName);ds.setPassword(password);return ds;}@Beanpublic PlatformTransactionManager transactionManager(DataSource dataSource){DataSourceTransactionManager ptm = new DataSourceTransactionManager();ptm.setDataSource(dataSource);return ptm;}
}
步骤10:创建MybatisConfig配置类
public class MybatisConfig {@Beanpublic SqlSessionFactoryBean sqlSessionFactory(DataSource dataSource){SqlSessionFactoryBean ssfb = new SqlSessionFactoryBean();ssfb.setTypeAliasesPackage("com.itheima.domain");ssfb.setDataSource(dataSource);return ssfb;}@Beanpublic MapperScannerConfigurer mapperScannerConfigurer(){MapperScannerConfigurer msc = new MapperScannerConfigurer();msc.setBasePackage("com.itheima.dao");return msc;}
}
步骤11:创建SpringConfig配置类
@Configuration
@ComponentScan("com.itheima")
@PropertySource("classpath:jdbc.properties")
@Import({JdbcConfig.class,MybatisConfig.class})
@EnableTransactionManagement
public class SpringConfig {
}
步骤12:编写测试类
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = SpringConfig.class)
public class AccountServiceTest {@Autowiredprivate AccountService accountService;@Testpublic void testTransfer() throws IOException {accountService.transfer("Tom","Jerry",50D);}}
步骤13:运行验证
- 运行前,账户表有两个账户,余额都是1000;日志表没有记录
- 执行test后发现一个账户减少了50,另个账户增加了50;日志表记录了一条记录
查看运行日志:
步骤14:模拟转账失败
在对操作两个账号之间增加一个 1/0异常,看看是否事务机制生效,是否日志记录了
步骤15:运行测试类查看
发现转账事务回滚了,但日志仍然记录了,因为日志配置了开启新事物:
查看运行日志:发现扣减完账户A50后遇到错误后,账户B的加钱操作就不再执行了:
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