Spring5源码 - Spring IOC 注解复习

「爱情、让人受尽委屈。」 2022-12-13 11:23 181阅读 0赞

### 文章目录 ###

*  Pre
 *  xml配置文件
 *  JavaConfig
 *  @CompentScan
 *   *  在配置类上写@CompentScan注解来进行包扫描
     *  excludeFilters
     *  includeFilters
     *  @ComponentScan.Filter type的类型
     *   *  使用自定义过滤器CUSTOM
 *  @Scope
 *  @Lazy
 *  @Conditional 条件判断

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

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

# Pre #

为了更好地学习源码，我们有必要对基础知识进行一次简单的复习，只有在知道如何使用的基础上，再去阅读源码才能明白spring这些源码是对哪些功能的支持。

这里简单的梳理一下

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

# xml配置文件 #

【配置文件 】

【读取Bean】

ClassPathXmlApplicationContext cx = new ClassPathXmlApplicationContext("classpath:spring.xml");
    System.out.println(cx.getBean("artisan").getClass().getSimpleName());
    	}

【输出】  
![在这里插入图片描述][20201011094318474.png_pic_center]

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

# JavaConfig #

【POJO】

public class Bean1 { 
    }

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

【配置文件 】

@Configuration
    public class MainConfig { 
    
    	@Bean
    	public Bean1 bean1(){ 
    		return new Bean1();
    	}
    }

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

【读取Bean— 传入配置类】

public static void main(String[] args) { 
    		AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(MainConfig.class);
    		System.out.println(ac.getBean("bean1"));
    	}

**@Bean**的形式， bean的默认名称是方法名，若@Bean(value=“bean的名称”) ,那么bean的名称是指定的名称。

【测试结果】

![在这里插入图片描述][20201011141652529.png_pic_center]

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

# @CompentScan #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 1]

## 在配置类上写@CompentScan注解来进行包扫描 ##

【配置类】

package com.artisan.base.componentscan.config;
    
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    
    @Configuration
    @ComponentScan("com.artisan.base.componentscan")
    public class CSMainConfig { 
    
    }

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

【c - s -d 】

package com.artisan.base.componentscan.controller;
    
    import org.springframework.stereotype.Controller;
    
    @Controller
    public class ArtisanInfoController { 
    }

package com.artisan.base.componentscan.service;
    
    import org.springframework.stereotype.Service;
    
    @Service
    public class ArtisanService { 
    }

package com.artisan.base.componentscan.dao;
    
    import org.springframework.stereotype.Repository;
    
    @Repository
    public class ArtisanDao { 
    }

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

【测试类】

package com.artisan.base.componentscan;
    
    import com.artisan.base.componentscan.config.CSMainConfig;
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    
    
    public class CMTest { 
    
    	public static void main(String[] args) { 
    
    		AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(CSMainConfig.class);
    		// 输出 单例池中的单例bean的名字
    		for (String beanDefinitionName : ac.getBeanDefinitionNames()) { 
    			System.out.println("bdName:" + beanDefinitionName);
    		}
    
    	}
    }

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

【输出】

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 2]

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

## excludeFilters ##

【配置类】

import com.artisan.base.componentscan.service.ArtisanService;
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.FilterType;
    import org.springframework.stereotype.Controller;
    
    @Configuration
    @ComponentScan(
    		basePackages = { "com.artisan.base.componentscan"},
    		excludeFilters = { 
    			@ComponentScan.Filter(type = FilterType.ANNOTATION,value = { Controller.class}),
    			@ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE,value = { ArtisanService.class})
    })
    public class CSMainConfig { 
    
    }

重点配置

@ComponentScan(
    		basePackages = { "com.artisan.base.componentscan"},
    		excludeFilters = { 
    			@ComponentScan.Filter(type = FilterType.ANNOTATION,value = { Controller.class}),
    			@ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE,value = { ArtisanService.class})
    })

excludeFilters(排除@Controller注解的,和ArtisanService的)

【测试结果】

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 3]

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

## includeFilters ##

@Configuration
    @ComponentScan(
    		basePackages = { "com.artisan.base.componentscan"},
    		includeFilters =
    				{ @ComponentScan.Filter(type = FilterType.ANNOTATION, value = { Controller.class})},
    		useDefaultFilters = false)、
    public class CSMainConfig { 
    
    }

若使用包含的用法， 需要把useDefaultFilters属性设置为false（true表示扫描全部的）

【测试结果】

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 4]

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

## @ComponentScan.Filter type的类型 ##

看下源码

public enum FilterType { 
    
    	/** * Filter candidates marked with a given annotation. * @see org.springframework.core.type.filter.AnnotationTypeFilter */
    	ANNOTATION,
    
    	/** * Filter candidates assignable to a given type. * @see org.springframework.core.type.filter.AssignableTypeFilter */
    	ASSIGNABLE_TYPE,
    
    	/** * Filter candidates matching a given AspectJ type pattern expression. * @see org.springframework.core.type.filter.AspectJTypeFilter */
    	ASPECTJ,
    
    	/** * Filter candidates matching a given regex pattern. * @see org.springframework.core.type.filter.RegexPatternTypeFilter */
    	REGEX,
    
    	/** Filter candidates using a given custom * {@link org.springframework.core.type.filter.TypeFilter} implementation. */
    	CUSTOM
    
    }

*  ANNOTATION 注解形式 举个例子比如 `@Compent @Controller @Service @Repository .......`
 *  ASSIGNABLE\_TYPE 指定类型的 `FilterType.ASSIGNABLE_TYPE` 举个例子

@ComponentScan.Filter(type =
    FilterType.ASSIGNABLE_TYPE,value = { ArtisanService.class})

*  ASPECTJ 类型的 FilterType.ASPECTJ 不常用
 *  REGEX 正则表达式的 FilterType.REGEX 不常用
 *  CUSTOM 自定义类型

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

### 使用自定义过滤器CUSTOM ###

package com.artisan.base.componentscan.customFilterType;
    
    
    import org.springframework.core.io.Resource;
    import org.springframework.core.type.AnnotationMetadata;
    import org.springframework.core.type.ClassMetadata;
    import org.springframework.core.type.classreading.MetadataReader;
    import org.springframework.core.type.classreading.MetadataReaderFactory;
    import org.springframework.core.type.filter.TypeFilter;
    
    import java.io.IOException;
    
    
    public class ArtisanFilterType  implements TypeFilter { 
    
    
    	@Overridez
    	public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory) throws IOException { 
    		//获取当前类的注解源信息
    		AnnotationMetadata annotationMetadata = metadataReader.getAnnotationMetadata();
    		//获取当前类的class的源信息
    		ClassMetadata classMetadata = metadataReader.getClassMetadata();
    		//获取当前类的资源信息
    		Resource resource =  metadataReader.getResource();
    		System.out.println("类的路径:"+classMetadata.getClassName());
    		// 排除包含Artisan的Bean
    		if(classMetadata.getClassName().contains("Artisan")) { 
    			return true;
    		}
    		return false;
    	}
    }

【配置类】

@Configuration
    @ComponentScan(basePackages = { "com.artisan.base.componentscan"},
    		excludeFilters = { @ComponentScan.Filter(type = FilterType.CUSTOM, value = { ArtisanFilterType.class})})
    public class CSMainConfig { 
    
    }

【测试结果】

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 5]

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

# @Scope #

[https://docs.spring.io/spring-framework/docs/current/spring-framework-reference/core.html\#beans-factory-scopes][https_docs.spring.io_spring-framework_docs_current_spring-framework-reference_core.html_beans-factory-scopes]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 6]

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

public class Bean2 { 
    
    	public Bean2() { 
    		System.out.println("Bean2 Created");
    	}
    }

public class Bean3 { 
    
    	public Bean3() { 
    
    		System.out.println("Bean3 Created");
    	}
    }

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

【config】

package com.artisan.base.scope;
    
    
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.Scope;
    
    @Configuration
    public class Config { 
    
    
    	@Bean()
    	public Bean2 bean2(){ 
    		return new Bean2();
    	}
    
     
    	@Bean()
    	@Scope(value = "prototype")
    	public Bean3 bean3(){ 
    		return new Bean3();
    	}
    
    
    }

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

【测试bean的加载】

package com.artisan.base.scope;
    
    
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    
    public class TestScope { 
    
    	public static void main(String[] args) { 
    		AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(Config.class);
    
    		System.out.println("========================");
    		// 每次调用都会实例化一个新的Bean3+
    		System.out.println(ac.getBean("bean3"));
    		System.out.println(ac.getBean("bean3"));
    	}
    }

【输出】

![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]

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

【结论】

*  在不指定@Scope的情况下，所有的bean都是单实例的bean,而且是饿汉加载 即 容器启动实例就创建好了
 *  指定@Scope为 prototype 表示为原型bean，而且还是懒汉模式加载 , 即IOC容器启动的时候，并不会创建对象，而是 在第一次使用的时候才会创建 ，并且每次调用，都会实例化一个新的对象

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

# @Lazy #

Bean的懒加载@Lazy **主要针对单实例的bean** 容器启动的时候，不创建对象，在第一次使用的时候才会创建该对象 ，后续调用不会新建对象，而是从单例池中获取缓存的bean。

继续使用上面的例子 ，给Bean2 加上Lazy注解

@Bean()
    	@Lazy
    	public Bean2 bean2(){ 
    		return new Bean2();
    	}

【测试】

import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    
    public class TestScope { 
    
    	public static void main(String[] args) { 
    		AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(Config.class);
    
    		System.out.println(ac.getBean("bean2"));
    		System.out.println(ac.getBean("bean2"));
    
    
    	}
    }

【结果】

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 8]

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

# @Conditional 条件判断 #

![在这里插入图片描述][20201011174419888.png_pic_center]

需求： 只有容器中有bean5 才装载bean6

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

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 9]

value 是一个class数组， 需要实现Condition 接口 ， 那我们也弄个呗

【自定义Condition 】

package com.artisan.base.condition;
    
    import org.springframework.context.annotation.Condition;
    import org.springframework.context.annotation.ConditionContext;
    import org.springframework.core.type.AnnotatedTypeMetadata;
    
    
    public class ArtisanCondition implements Condition { 
    
    	@Override
    	public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) { 
    		//判断容器中是否有Bean5 ，有的话 返回true
    		if(context.getBeanFactory().containsBean("bean5")) { 
    			return true;
    		}
    		return false;
    	}
    }

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

【config 】

package com.artisan.base.condition;
    
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Conditional;
    import org.springframework.context.annotation.Configuration;
    
    @Configuration
    public class CDConfig { 
    
    	@Bean
    	public Bean5 bean5(){ 
    		return new Bean5();
    	}
    
    
    	// Conditional的条件返回true，才装载Bean6
    	@Bean
    	@Conditional(value = ArtisanCondition.class)
    	public Bean6 bean6(){ 
    		return new Bean6();
    	}
    
    }

【beans】

public class Bean5 { 
    
    	public Bean5() { 
    		System.out.println("Bean5 Created");
    	}
    }

public class Bean6 { 
    
    	public Bean6() { 
    		System.out.println("Bean6 Created");
    	}
    }

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

【正常情况】

package com.artisan.base.condition;
    
    
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    
    public class CDTest { 
    
    	public static void main(String[] args) { 
    		AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(CDConfig.class);
    
    		for (String beanDefinitionName : ac.getBeanDefinitionNames()) { 
    			System.out.println(beanDefinitionName);
    		}
    	}
    }

我们看到了 CDConfig中 bean5 上标注了@Bean

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 10]

现在我们把Bean5的@Bean去掉

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 11]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center]: /images/20221123/2f7a6c21ff244e3f861122abbb1440c5.png
[20201011094318474.png_pic_center]: /images/20221123/65770283291d4c0485212e8af9824498.png
[20201011141652529.png_pic_center]: /images/20221123/2a497a77c757426e94de9fc7f29ede69.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221123/782d339c070d459daa63baa48c9b2da7.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 2]: /images/20221123/0ea5651909fb4f73aeb22275cbb2b0ea.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 3]: /images/20221123/5f80d890d968470fba6e74bb331c0c93.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 4]: /images/20221123/bb5acaf6712d4082a651675921b07059.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 5]: /images/20221123/d9c47e2678c04695a53624dd5c6b5ceb.png
[https_docs.spring.io_spring-framework_docs_current_spring-framework-reference_core.html_beans-factory-scopes]: https://docs.spring.io/spring-framework/docs/current/spring-framework-reference/core.html#beans-factory-scopes
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 6]: /images/20221123/314f00956cbb4e49bbfe8ffc868277d1.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 7]: /images/20221123/b875bc0cd9b74333885312a4329b78b6.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 8]: /images/20221123/ff22db944ac142aea75d8df8ea8f2365.png
[20201011174419888.png_pic_center]: /images/20221123/e8de8ed74cb94b8f8aef67f1ffdcedc3.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 9]: /images/20221123/22e42d6dbbd24f0bb0f9c3f295872e82.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 10]: /images/20221123/8e6490d314ce4aad96c6145da25c6ec9.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lhbmdzaGFuZ3dlaQ_size_16_color_FFFFFF_t_70_pic_center 11]: /images/20221123/d4498ad0903c42f3b8b6c907b6bf07fa.png