学习SpringBoot容器功能及注解原理

@Configuration(proxyBeanMethods = false)//告诉SpringBoot这是一个配置类=配置文件
public class MyConfig {

    @Bean//给容器中添加组件。以方法名作为组件的id。返回类型就是组件类型。返回的值，就是组件在容器中的实例
    public User user01() {
        User zhangsan = new User("zhangsan", 18);
        return zhangsan;
    }

    @Bean("tom")//也可以自己设置id代替方法名作为id
    public Pet tomcatPet() {
        return new Pet("tomcat");
    }

}

@SpringBootApplication
public class Boot01HelloworldApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext run = SpringApplication.run(Boot01HelloworldApplication.class, args);
        MyConfig bean = run.getBean(MyConfig.class);
        System.out.println(bean);//com.atguigu.boot.config.MyConfig@d67d8
        //如果@Configuration(proxyBeanMethods = true)代理对象调用方法。SpringBoot总会检查这个组件是否在容器中有。
        //保持组件单实例
        User user = bean.user01();
        User user1 = bean.user01();
        //(proxyBeanMethods = true)返回true
        //(proxyBeanMethods = false)返回false
        System.out.println(user == user1);
    }

}

@Configuration(proxyBeanMethods = true)//告诉SpringBoot这是一个配置类=配置文件
public class MyConfig {

    @Bean//给容器中添加组件。以方法名作为组件的id。返回类型就是组件类型。返回的值，就是组件在容器中的实例
    public User user01() {
        User zhangsan = new User("zhangsan", 18);
        //user组件依赖了Pet组件
        zhangsan.setPet(tomcatPet());
        return zhangsan;
    }
    @Bean("tom")//也可以自己设置id代替方法名作为id
    public Pet tomcatPet() {
        return new Pet("tomcat");
    }

}

@SpringBootApplication
public class Boot01HelloworldApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext run = SpringApplication.run(Boot01HelloworldApplication.class, args);
        MyConfig bean = run.getBean(MyConfig.class);
        System.out.println(bean);
        User user01 = run.getBean("user01", User.class);
        Pet tom = run.getBean("tom", Pet.class);
		//(proxyBeanMethods = true)返回(用户的宠物：true)
        //(proxyBeanMethods = false)返回(用户的宠物：false)
        System.out.println("用户的宠物："+(user01.getPet() == tom));
    }

}

//给容器中自动无参构造创建出这两个类型的组件、默认组件的名字就是全类名
@Import({User.class, DBHelper.class})
@Configuration(proxyBeanMethods = false) //告诉SpringBoot这是一个配置类 == 配置文件
public class MyConfig {
}

@SpringBootApplication
public class Boot01HelloworldApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext run = SpringApplication.run(Boot01HelloworldApplication.class, args);
        //获取组件
        String[] beanNamesForType = run.getBeanNamesForType(User.class);
        for (String s : beanNamesForType) {
            System.out.println(s);
        }
        DBHelper bean = run.getBean(DBHelper.class);
        System.out.println(bean);
    }
}

<?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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
    <bean id="haha" class="com.atguigu.boot.bean.User">
        <property name="name" value="zhangsan"></property>
        <property name="age" value="18"></property>
    </bean>
    <bean id="hehe" class="com.atguigu.boot.bean.Pet">
        <property name="name" value="tomcat"></property>
    </bean>
</beans>

@Configuration(proxyBeanMethods = true)//告诉SpringBoot这是一个配置类=配置文件
@ImportResource("classpath:beans.xml")
public class MyConfig {
}

@SpringBootApplication
public class Boot01HelloworldApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext run = SpringApplication.run(Boot01HelloworldApplication.class, args);

        boolean haha = run.containsBean("haha");
        boolean hehe = run.containsBean("hehe");
        System.out.println(haha);//true
        System.out.println(hehe);//true
    }
}

public class getProperties {
     public static void main(String[] args) throws FileNotFoundException, IOException {
         Properties pps = new Properties();
         pps.load(new FileInputStream("a.properties"));
         Enumeration enum1 = pps.propertyNames();//得到配置文件的名字
         while(enum1.hasMoreElements()) {
             String strKey = (String) enum1.nextElement();
             String strValue = pps.getProperty(strKey);
             System.out.println(strKey + "=" + strValue);
             //封装到JavaBean。
         }
     }
 }

//只有在容器中的组件，才会拥有SpringBoot提供的强大功能
@Component
@ConfigurationProperties(prefix = "mycar")
//Lombok注解简化开发
@Data
@NoArgsConstructor
@ToString
@AllArgsConstructor
public class Car {
    private String brand;
    private Integer price;
}

@RestController
public class HelloController {
    @Autowired
    Car car;
    @RequestMapping("/car")
    public Car car(){
        return car;
    }
}

@Configuration(proxyBeanMethods = true)//告诉SpringBoot这是一个配置类=配置文件
@EnableConfigurationProperties(Car.class)
//1.开启Car属性配置绑定功能
//2.把Car这个组件自动注册到容器中
public class MyConfig {
}

@ConfigurationProperties(prefix = "mycar")
@Data
@NoArgsConstructor
@ToString
@AllArgsConstructor
public class Car {
    private String brand;
    private Integer price;
}