Spring5 - 向IOC容器中添加组件的4种方式

客官°小女子只卖身不卖艺 2022-12-13 12:48 172阅读 0赞

### 文章目录 ###

*  概述
 *  方式一: @CompentScan
 *   *  适用场景
     *  Code
 *  方式二： @Bean
 *   *  适用场景
     *  Code
 *  方式三: @Import
 *   *  适用场景
     *  Code Demo1
     *  Code Demo2 + 实现 ImportSelector接口
     *  Code Demo3 + 实现 ImportBeanDefinitionRegistrar接口
 *  方式四 FacotryBean
 *   *  适用场景
     *  Code

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# 概述 #

简单来说，4种方式

*  @CompentScan + @Controller @Service @Respository @compent等注解
 *  @Bean
 *  @Import
 *  FacotryBean

接下来我们针对每种方式，来演示一下

--------------------

# 方式一: @CompentScan #

## 适用场景 ##

一般我们自己写的代码都是通过这种方式来实现的bean加载到ioc容器中

## Code ##

查考： [Spring5源码 - Spring IOC 注解复习][Spring5_ - Spring IOC] @CompentScan 部分

--------------------

# 方式二： @Bean #

## 适用场景 ##

通常我们初始化Redis 、数据库等等，都会使用这种方式，即 适用于导入第三方组件的类

--------------------

## Code ##

举个例子

@Bean
        public JedisPool redisPoolFactory() { 
            JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();
            jedisPoolConfig.setMaxIdle(maxIdle);
            jedisPoolConfig.setMaxWaitMillis(maxWaitMillis);
            JedisPool jedisPool = new JedisPool(jedisPoolConfig, host, port, timeout, password);
            return jedisPool;
        }

--------------------

# 方式三: @Import #

## 适用场景 ##

第三方的组件 可以使用这种方式

导入的组件的id为类的全路径名

--------------------

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## Code Demo1 ##

【components】

package com.artisan.base.importTest.component;
    
    public class Bean7 { 
     
    }

package com.artisan.base.importTest.component;
    
    public class Bean8 { 
    
    
    
    }

【配置类】

package com.artisan.base.importTest.config;
    
    import com.artisan.base.importTest.component.Bean7;
    import com.artisan.base.importTest.component.Bean8;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.Import;
    
    @Configuration
    @Import(value = { Bean7.class, Bean8.class})
    public class IMPConfig { 
     
    }

--------------------

【验证】

package com.artisan.base.importTest;
    
    import com.artisan.base.importTest.config.IMPConfig;
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    
    /** * @author 小工匠 * @version 1.0 * @description: TODO * @date 2020/10/11 19:05 * @mark: show me the code , change the world */
    public class Test { 
    
    	public static void main(String[] args) { 
    		AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(IMPConfig.class);
    		for (String beanDefinitionName : ac.getBeanDefinitionNames()) { 
    			System.out.println(beanDefinitionName);
    		}
    		System.out.println("========================");
    		// beanname为全路径名
    		System.out.println(ac.getBean("com.artisan.base.importTest.component.Bean7"));
    
    	}
    }

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--------------------

## Code Demo2 + 实现 ImportSelector接口 ##

【自定義ImportSelector】

package com.artisan.base.importTest.importSelector;
    
    import org.springframework.context.annotation.ImportSelector;
    import org.springframework.core.type.AnnotationMetadata;
    
    /** * @author 小工匠 * @version 1.0 * @description: * @date 2020/10/11 19:20 * @mark: show me the code , change the world */
    public class ArtisanImportSelector  implements ImportSelector { 
    	@Override
    	public String[] selectImports(AnnotationMetadata importingClassMetadata) { 
    		return new String[]{ "com.artisan.base.importTest.component.Bean6666"};
    	}
    }

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--------------------

【测试】

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--------------------

## Code Demo3 + 实现 ImportBeanDefinitionRegistrar接口 ##

package com.artisan.base.importTest.importSelector;
    
    import com.artisan.base.importTest.component.Bean7777;
    import org.springframework.beans.factory.support.BeanDefinitionRegistry;
    import org.springframework.beans.factory.support.RootBeanDefinition;
    import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
    import org.springframework.core.type.AnnotationMetadata;
    
    /** * @author 小工匠 * @version 1.0 * @description: TODO * @date 2020/10/11 19:26 * @mark: show me the code , change the world */
    public class ArtisanBeanDefinitionRegister implements ImportBeanDefinitionRegistrar  { 
    	@Override
    	public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) { 
    		RootBeanDefinition rootBeanDefinition = new RootBeanDefinition(Bean7777.class);
    		registry.registerBeanDefinition("bean7777",rootBeanDefinition);
    	}
    }

【配置类】  
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【测试结果】  
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--------------------

# 方式四 FacotryBean #

## 适用场景 ##

比如整合第三方框架，MyBatis

[Spring5源码 - 08 BeanFactory和FactoryBean 源码解析 & 使用场景][Spring5_ - 08 BeanFactory_FactoryBean _ _]

--------------------

## Code ##

【FactoryBean】

package com.artisan.base.factoryBean;
    
    import org.springframework.beans.factory.FactoryBean;
    
    /** * @author 小工匠 * @version 1.0 * @description: TODO * @date 2020/10/11 21:49 * @mark: show me the code , change the world */
    public class ArtisanFactoryBean  implements FactoryBean { 
    	@Override
    	public Object getObject() throws Exception { 
    		return new Bean8();
    	}
    
    	@Override
    	public Class<?> getObjectType() { 
    		return Bean8.class;
    	}
    
    	@Override
    	public boolean isSingleton() { 
    		return true;
    	}
    }

--------------------

【配置类】

package com.artisan.base.factoryBean;
    
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    @Configuration
    public class FBConfig { 
    
    	// 实例化ArtisanFactoryBean
    	@Bean  
    	public ArtisanFactoryBean artisanFactoryBean() { 
    		return new ArtisanFactoryBean();
    	}
    
    }

--------------------

【pojo】

package com.artisan.base.factoryBean;
    
    
    public class Bean8 { 
    
    	public Bean8() { 
    
    		System.out.println("Bean8 Create");
    	}
    }

【测试】

package com.artisan.base.factoryBean;
    
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    
    public class Test { 
    
    	public static void main(String[] args) { 
    		AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(FBConfig.class);
    
    		System.out.println("=========================");
    		// 调用FactoryBean的getObject方法
    		System.out.println(ac.getBean("artisanFactoryBean"));
    
    		// & 获取FactoryBean本身
    		System.out.println(ac.getBean("&artisanFactoryBean"));
    
    	}
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 7]

--------------------

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center]: /images/20221123/ab057cdfa4834deab44517ffb1b940f1.png
[Spring5_ - Spring IOC]: https://artisan.blog.csdn.net/article/details/109007939
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 5]: /images/20221123/d5b738dce05448e0a6c622e5e11786c6.png
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[Spring5_ - 08 BeanFactory_FactoryBean _ _]: https://blog.csdn.net/yangshangwei/article/details/108755621
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