Spring注解系列一：组件注册-@Configuration和@Bean

亦凉 2022-02-04 03:19 245阅读 0赞

1、引入依赖

<dependency>
        <groupId>org.springframework</groupId>
    	<artifactId>spring-context</artifactId>
    	<version>4.3.12.RELEASE</version>
    </dependency>

2、创建类Person

public class Person {
    
    	private String name;
    	private Integer age;
    	
    	
    	public String getName() {
    		return name;
    	}
    	public void setName(String name) {
    		this.name = name;
    	}
    	public Integer getAge() {
    		return age;
    	}
    	public void setAge(Integer age) {
    		this.age = age;
    	}
    	
    	public Person(String name, Integer age) {
    		super();
    		this.name = name;
    		this.age = age;
    	}
    	public Person() {
    		super();
    		// TODO Auto-generated constructor stub
    	}
    	@Override
    	public String toString() {
    		return "Person [name=" + name + ", age=" + age + "]";
    	}
    
    }

3、创建配置文件beans.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"
           xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
        
        <bean id="person" class="com.atguigu.bean.Person">
            <property name="age" value="18"></property>
            <property name="name" value="zhangsan"></property>
        </bean>
        
    </beans>

4、创建测试类

public class MainTest {
    	
    	@SuppressWarnings("resource")
    	public static void main(String[] args) {
    		//根据配置文件获取applicationContext 
    		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
    		//根据bean的名称获取组件
    		Person bean = (Person) applicationContext.getBean("person");
    		System.out.println(bean);
    	}
    
    }

5、用配置类代替配置文件

//配置类就相当于配置文件
    @Configuration  //告诉Spring这是一个配置类
    public class MainConfig {
    	
    	//给容器中注册一个Bean;类型为返回值的类型，id默认是用方法名作为id。也可以在括号内指定id
    	@Bean("person")
    	public Person person01(){
    		return new Person("lisi", 20);
    	}
    }

6、修改测试类

public class MainTest {
    	
    	@SuppressWarnings("resource")
    	public static void main(String[] args) {
    		//根据配置类获取applicationContext 
    		ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);
    		//根据bean的类型获取组件
    		Person bean = applicationContext.getBean(Person.class);
    		System.out.println(bean);
    		
    		//根据bean的类型获取组件名称
    		String[] namesForType = applicationContext.getBeanNamesForType(Person.class);
    		for (String name : namesForType) {
    			System.out.println(name);
    		}
    	}
    
    }

![在这里插入图片描述][20190506194859246.png]

[20190506194859246.png]: /images/20220204/384e6a988dd14bb0864d412f3e8ee296.png