spring笔记(2)spring的3种IOC容器配置方式

1.通过 @Configuration 和 @bean 实现

@Configuration
public class Ch2BeanConfiguration {

    @Bean
    public AccountService accountService(){
        AccountServiceImpl bean = new AccountServiceImpl();
        bean.setAccountDao(accountDao());
        return bean;
    }

    public AccountDao accountDao(){
        AccountDaoInMemoryImpl bean = new AccountDaoInMemoryImpl();
        return bean;
    }
}
public class Main

{
    public static void main( String[] args )
    {
        AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(Ch2BeanConfiguration.class);
        //在容器中获取bean类
        AccountService accountService = applicationContext.getBean("accountService", AccountService.class);

        System.out.println("Before money transfer");
        System.out.println("Account 1 balance :" + accountService.getAccount(1L).getBalance());
        System.out.println("Account 2 balance :" + accountService.getAccount(2L).getBalance());
        accountService.transferMoney(1L,2L,5.0);
        System.out.println("After money transfer");
        System.out.println("Account 1 balance :" + accountService.getAccount(1L).getBalance());
        System.out.println("Account 2 balance :" + accountService.getAccount(2L).getBalance());
    }
}


2.通过 xml 实现

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

        <bean id="accountService" class="org.lin.maven.test.AccountServiceImpl">
            <property name="accountDao" ref="accountDao"/>
        </bean>

        <bean id="accountDao" class="org.lin.maven.test.AccountDaoInMemoryImpl"></bean>
</beans>

public class Main
{
    public static void main( String[] args )
    {
        ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("file:E:\\spring-book-ch2\\src\\main\\resources\\ch2-beans.xml");
        //在容器中获取bean类
        AccountService accountService = applicationContext.getBean("accountService", AccountService.class);

        System.out.println("Before money transfer");
        System.out.println("Account 1 balance :" + accountService.getAccount(1L).getBalance());
        System.out.println("Account 2 balance :" + accountService.getAccount(2L).getBalance());
        accountService.transferMoney(1L,2L,5.0);
        System.out.println("After money transfer");
        System.out.println("Account 1 balance :" + accountService.getAccount(1L).getBalance());
        System.out.println("Account 2 balance :" + accountService.getAccount(2L).getBalance());
    }
}

3.通过 注解 和 xml 实现
在对应的类上写@Component @Repository @Service @Controller 

@Component	最普通的组件，可以被注入到spring容器进行管理
@Repository	作用于持久层
@Service	作用于业务逻辑层
@Controller	作用于表现层（spring-mvc的注解）

因为原生的java操作数据库所产生的异常只定义了几种，但是产生数据库异常的原因却有很多种，这样对于数据库操作的报错排查造成了一定的影响；而Spring拓展了原生的持久层异常，针对不同的产生原因有了更多的异常进行描述。所以，在注解了@Repository的类上如果数据库操作中抛出了异常，就能对其进行处理，转而抛出的是翻译后的spring专属数据库异常，方便我们对异常进行排查处理 

public class Main
{
    public static void main( String[] args )
    {
        
        ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("file:E:\\spring-book-ch2\\src\\main\\java\\org\\lin\\maven\\test\\resources\\ch2-beans.xml");
        //在容器中获取bean类
        AccountService accountService = applicationContext.getBean("accountService", AccountService.class);

        System.out.println("Before money transfer");
        System.out.println("Account 1 balance :" + accountService.getAccount(1L).getBalance());
        System.out.println("Account 2 balance :" + accountService.getAccount(2L).getBalance());
        accountService.transferMoney(1L,2L,5.0);
        System.out.println("After money transfer");
        System.out.println("Account 1 balance :" + accountService.getAccount(1L).getBalance());
        System.out.println("Account 2 balance :" + accountService.getAccount(2L).getBalance());
    }
}

注:ClassPathXmlApplicationContext路劲如果找不到,直接用("file:绝对路径")