@Configuration容器中注册组件

import boot.bean.Stu;
import boot.bean.User;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * 1.配置类里面使用@Bean标注在方法上给容器注册组件，默认也是单实例
 * 2.配置类本身也是组件
 * 3.@Configuration中的属性：proxyBeanMethods，设为true：@Configuration(proxyBeanMethods=true),外部无论对配置类中的
 * 这个组件注册方法调用多少次都返回之前注册容器中的单例对象。如果为false，则每次调用新new一个对象
 */
@Configuration//告诉springboot这是一个配置类
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(){
        return new User("张三",20);
    }

    @Bean("tom")//命名组件名为“tom”
    public Stu stu01(){
        return new Stu("汤姆");
    }
}

 

public class Stu {
    private String name;

    public Stu(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Stu{" +
                "name='" + name + '\'' +
                '}';
    }
}

　　

public class User {
    private String name;
    private int age;

    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

　　

　

@SpringBootApplication
public class MainApplication {
    public static void main(String[] args) {
        //返回IOC容器
        ConfigurableApplicationContext run = SpringApplication.run(MainApplication.class, args);
        //查看容器里面的组件
        String[] names = run.getBeanDefinitionNames();
        /*for (String name : names) {
            System.out.println(name);
        }*/
        //从容器中获取组件
        Stu tom1 = run.getBean("tom", Stu.class);
        tom1.setName("杰瑞");
        Stu tom2 = run.getBean("tom", Stu.class);
        System.out.println(tom2);//Stu{name='杰瑞'}
    }
}