spring boot中的bean

@Test
    public void getBean(){
        HelloController bean = (HelloController) applicationContext.getBean("helloController");
        System.out.println(bean);

        HelloController bean1 = applicationContext.getBean(HelloController.class);
        System.out.println(bean1);

        HelloController bean2=applicationContext.getBean("helloController", HelloController.class);
        System.out.println(bean2);
    }
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注意点:
Spring 默认的 bean 名称是 类名首字母小写，即：

HelloController → helloController

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bean默认是单例的,如果想要bean变成多例的,需要使用@scope("prototype")注解;

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如果要引入第三方的bean不是自己写的,将其放入ioc容器中管理,需要用到@bean注解;
例如:
@Bean
    public RedisTemplate redisTemplate(RedisConnectionFactory redisConnectionFactory){
        log.info("开始创建redis模板对象");
        RedisTemplate redisTemplate = new RedisTemplate();
        //设置redis的连接工厂对象
        redisTemplate.setConnectionFactory(redisConnectionFactory);
        //设置redis的序列化器
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        return redisTemplate;
    }
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可以通过@bean注解的name/value属性指定bean的名称,如果未指定bean的名字,就默认是方法名首字母小写;