springboot的Configuration使用

1、定义

springboot推荐使用用java代码的形式申明注册bean。 
@Configuration注解可以用java代码的形式实现spring中xml配置文件配置的效果。

2、通过java代码注册bean

@Configuration
public class TestMybaitsConf {

    @Bean
    public DataSource dataSource() {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        try {
            dataSource.setDriverClass("com.mysql.jdbc.Driver");
            dataSource.setJdbcUrl("jdbc:mysql://192.168.100.25:6660/TXSMS?useUnicode=true&characterEncoding=utf-8");
            dataSource.setUser("root");
            dataSource.setPassword("123456");
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        return dataSource;
    }

    @Bean
    public SqlSessionFactory sqlSessionFactory(DataSource dataSource) {
        SqlSessionFactory factory = null;
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        bean.setConfigLocation(resolver.getResource("classpath:mybatis.xml"));
        try {
            factory = bean.getObject();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        return factory;
    }

    @Bean
    public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }

    @Bean
    public PlatformTransactionManager transactionManager(DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
}

3、使用xml注册bean

@Configuration
@ImportResource("classpath:spring-mybatis.xml")
public class TestMybaitsConf {

}

spring-mybatis.xml ：

<?xml version="1.0" encoding="UTF-8" ?>
<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:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:jee="http://www.springframework.org/schema/jee" xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc  http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
        http://www.springframework.org/schema/jee  http://www.springframework.org/schema/jee/spring-jee-4.0.xsd
        http://www.springframework.org/schema/beans  http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
        http://www.springframework.org/schema/context  http://www.springframework.org/schema/context/spring-context-4.0.xsd
        http://www.springframework.org/schema/tx  http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd">

    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="jdbcUrl" value="jdbc:mysql://192.168.100.25:6660/TXSMS?useUnicode=true&amp;characterEncoding=utf-8"></property>
        <property name="user" value="root"></property>
        <property name="password" value="123456"></property>
    </bean>

    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"></property>
        <property name="configLocation" value="classpath:mybatis.xml"></property>
    </bean>

    <bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
        <constructor-arg index="0" ref="sqlSessionFactory"></constructor-arg>
    </bean>

    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"></property>
    </bean>

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

4、总结

2、3两种注册bean的效果完全一样，但springboot推荐使用2中的方式，使用java代码注册bean。

5.项目中的示例：

@Configuration
public class EventBusConfig {

    @Bean
    public EventBus eventBus() {
        return new AsyncEventBus(new ThreadPoolExecutor(5, 5,
                0, TimeUnit.MILLISECONDS, new ArrayBlockingQueue<>(1024),
                new ThreadFactoryBuilder().setNameFormat("content-updated-event-%d").build()));
    }

    @Resource
    private ApplicationContext applicationContext;

    @PostConstruct
    public void registerEventListener() {
        Map<String, Subscribed> beans = applicationContext.getBeansOfType(Subscribed.class);
        beans.forEach((key, value) -> this.eventBus().register(value));
    }

}

这里创建一个eventBus的bean,并且在项目启动的时候，就拿到所有的是Subscribed类型的类注册到eventBus上

参考文档：https://blog.csdn.net/sz85850597/article/details/79133242