声明式事物

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本文对应视频教程：http://www.vgxit.com/course/23

1，概述

声明式式事物是一种约定性的事物，在大部分情况下，当数据库使用事物的时候。一般我们都是发生了异常就需要事物回滚，如果没有繁盛异常，那么久提交事物。从这一点出发，Spring给了我们一个约定，就是没有异常提交事物，有异常回滚事务。通过这种思想，为我们提供了声明式事物。

2，具体实现：

我们这里要实现必须通过一个注解@Transactional。被这个注解修饰的方法就自动的会按照Spring给我们的约定管理起了事务。
1，我们首先在xml中开启申明式事务：

<tx:annotation-driven transaction-manager="transactionManager"/>

2，编写对应的业务逻辑代码：

package com.vgxit.learn.springtransaction.bk;

import lombok.Getter;
import lombok.Setter;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.transaction.annotation.Transactional;

@Getter
@Setter
@Transactional
public class User1Service {
    private JdbcTemplate jdbcTemplate;

    public void updateUser() {
        jdbcTemplate.update("update user set name=? where id=?", "111111", 31);
        throw new RuntimeException();
    }
}

3，编写对应的测试代码：

private static void testShenmingTransaction() {
    ApplicationContext ctx = new ClassPathXmlApplicationContext("spring-cfg.xml");
    User1Service user1Service = ctx.getBean(User1Service.class);
    user1Service.updateUser();
}

4，我们的Transactional注解，可以配置在类上，也可以配置在方法上，配置在类上，所有的类的public方法都会起作用，如果作用在方法上，对应的方法起作用

3，纯注解的方式实现申明式事物

1，定义配置类：

package com.vgxit.learn.spring.ktdm.trananno.config;

import com.alibaba.druid.pool.DruidDataSourceFactory;
import com.vgxit.learn.spring.ktdm.trananno.base.BaseMapper;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.TransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.sql.DataSource;
import java.io.InputStream;
import java.util.Properties;

@Configuration
@ComponentScan("com.vgxit.learn.spring.ktdm.trananno")
@EnableTransactionManagement//启用申明式事物
public class TranannoConfig {
    @Bean
    public DataSource dataSource() throws Exception {
        Properties properties = new Properties();
        InputStream druidInputStream = TranannoConfig.class.getClassLoader().getResourceAsStream("datasource.properties");
        properties.load(druidInputStream);
        DataSource dataSource = DruidDataSourceFactory.createDataSource(properties);
        return dataSource;
    }

    @Bean("sqlSessionFactoryBean")
    public SqlSessionFactoryBean sqlSessionFactoryBean(@Autowired DataSource dataSource) throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        Resource resource = new ClassPathResource("mybatis-config.xml");
        sqlSessionFactoryBean.setConfigLocation(resource);
        return sqlSessionFactoryBean;
    }

    @Bean
    public MapperScannerConfigurer mapperScannerConfigurer() {
        MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
        mapperScannerConfigurer.setBasePackage("com.vgxit.learn.spring.ktdm.trananno.mapper");
        mapperScannerConfigurer.setSqlSessionFactoryBeanName("sqlSessionFactoryBean");
        mapperScannerConfigurer.setMarkerInterface(BaseMapper.class);
        return mapperScannerConfigurer;
    }

    @Bean
    public TransactionManager transactionManager(@Autowired DataSource dataSource) throws Exception {
        DataSourceTransactionManager transactionManager = new DataSourceTransactionManager();
        transactionManager.setDataSource(dataSource);
        return transactionManager;
    }
}

2，定义对应的UserService:

package com.vgxit.learn.spring.ktdm.trananno.service;

import com.vgxit.learn.spring.ktdm.trananno.mapper.UserMapper;
import com.vgxit.learn.spring.ktdm.trananno.po.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;

@Component
public class UserService {
    @Autowired
    private UserMapper userMapper;

    @Transactional
    public void add(User user) {
        userMapper.add(user);
//        int x = 1 / 0;
    }
}

3，具体的注入方法：

package com.vgxit.learn.spring.ktdm.trananno.test;

import com.vgxit.learn.spring.ktdm.trananno.config.TranannoConfig;
import com.vgxit.learn.spring.ktdm.trananno.po.User;
import com.vgxit.learn.spring.ktdm.trananno.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class TranannoTest001 {
    public static void main(String[] args) {
        ApplicationContext ctx = new AnnotationConfigApplicationContext(TranannoConfig.class);
        UserService userService = ctx.getBean(UserService.class);
        User user = User.builder().name("沙悟净").age(550).gender((short) 1).nickName("卷帘大将").build();
        userService.add(user);
    }
}