Spring学习(十三)-组件注册@Import

分手后的思念是犯贱 2024-02-19 16:04 48阅读 0赞

@Import：快速给容器中导入一个组件。

@Import导入组件，id默认是组件的全类名。

源码：

@Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface Import {
    
    	/**
    	 * {@link Configuration}, {@link ImportSelector}, {@link ImportBeanDefinitionRegistrar}
    	 * or regular component classes to import.
    	 */
    	Class<?>[] value();
    
    }

1）、@Import(要导入到容器中的组件)；容器中就会自动注册这个组件，id默认是全类名
    2）、ImportSelector:返回需要导入的组件的全类名数组；
    3）、ImportBeanDefinitionRegistrar:手动注册bean到容器中。

测试：

public class Color {
    	
    	private Car car;
    
    	public Car getCar() {
    		return car;
    	}
    
    	public void setCar(Car car) {
    		this.car = car;
    	}
    
    	@Override
    	public String toString() {
    		return "Color [car=" + car + "]";
    	}
    	
    }

配置类:

@Configuration
    @Import({Color.class})
    //@Import导入组件，id默认是组件的全类名
    public class MainConfig2 {
    
    }

测试类:

AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig2.class);
    	
    	
    	@Test
    	public void testImport(){
    		printBeans(applicationContext);
    	}
    	
    	private void printBeans(AnnotationConfigApplicationContext applicationContext){
    		String[] definitionNames = applicationContext.getBeanDefinitionNames();
    		for (String name : definitionNames) {
    			System.out.println(name);
    		}
    	}

结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70][]

ImportSelector:返回需要导入的组件的全类名数组；从而向容器中注入该组件。

如：

public class Blue {
    	
    	public Blue(){
    		System.out.println("blue...constructor");
    	}
    	
    	public void init(){
    		System.out.println("blue...init...");
    	}
    	
    	public void detory(){
    		System.out.println("blue...detory...");
    	}
    	
    	
    
    }

//自定义逻辑返回需要导入的组件名称
    public class MyImportSelector implements ImportSelector {
    
    	//返回值:就是要导入容器中的组件全类名
    	//AnnotationMetadata:就是当前标注@Import注解的类的所有注解信息
    	public String[] selectImports(AnnotationMetadata importingClassMetadata) {
    		Set<String> annotationTypes = importingClassMetadata.getAnnotationTypes();
    
    		annotationTypes.stream().forEach(s ->
    				System.out.println(s));
    
    		return new String[]{"com.spring.bean.Blue"};
    	}
    
    }

配置类：

@Configuration
    @Import({MyImportSelector.class})
    //@Import导入组件，id默认是组件的全类名
    public class MainConfig2 {
    
    }

测试类：

@Test
    	public void testImport(){
    		AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig2.class);
    		Blue bean = applicationContext.getBean(Blue.class);
    		System.out.println(bean);
    
    	}

结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 1][]

ImportBeanDefinitionRegistrar:手动注册bean到容器中。

测试：

public class RainBow {
    
    }

public class Person {
    
    	private String name;
    	private Integer age;
    	
    	private String nickName;
    	public String getNickName() {
    		return nickName;
    	}
    	public void setNickName(String nickName) {
    		this.nickName = nickName;
    	}
    	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 + ", nickName=" + nickName + "]";
    	}
    
    }

设置类:

public class MyImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar {
    
    	/**
    	 * AnnotationMetadata:当前类的注解信息
    	 * BeanDefinitionRegistry:BeanDefinition注册类
    	 * 		把所有需要注册到容器中bean调用
    	 * 		BeanDefinitionRegistry.registerBeanDefinition手动注册到容器中
    	 */
    	@Override
    	public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
    		
    		boolean definition = registry.containsBeanDefinition("person");
    		if(definition){
    			//指定的定义信息（bean的类型）
    			RootBeanDefinition beanDefinition = new RootBeanDefinition(RainBow.class);
    			//注册一个bean指定bean的名称
    			registry.registerBeanDefinition("rainBow", beanDefinition);
    		}
    	}
    
    }

配置类：

@Configuration
    @Import({MyImportBeanDefinitionRegistrar.class})
    public class MainConfig2 {
    
        /**
         * 注册person对象
         * @return
         */
    	@Bean("person")
    	public Person person(){
    		System.out.println("给容器添加person....");
    		return new Person("person", 25);
    	}
    
    }

测试类:

@Test
    public void testImport(){
           AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig2.class);
            Person bean = applicationContext.getBean(Person.class);
    		System.out.println(bean);
            RainBow rainBow = applicationContext.getBean(RainBow.class);
            System.out.println(rainBow);
    
    	}

结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 2][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/304c13b6475047849179a0bd6e1121e0.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 1]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/43863aefc0344e9cb3afabe62e0449ec.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 2]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/c949c98fd1b0471e84edb8676cae428d.png