Spring ComponentScan注解的简介说明

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Spring ComponentScan注解的简介说明

下文笔者讲述Spring中ComponentScan注解的简介说明，如下所示：

ComponentScan注解的功能

定义的扫描路径，把符合扫描规则的类装配到spring的bean容器中

ComponentScan注解的源码

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
@Documented
@Repeatable(ComponentScans.class)
public @interface ComponentScan {
    @AliasFor("basePackages")
    String[] value() default {};
 
    @AliasFor("value")
    String[] basePackages() default {};
 
    Class[] basePackageClasses() default {};
 
    Class nameGenerator() default BeanNameGenerator.class;
 
    Class scopeResolver() default AnnotationScopeMetadataResolver.class;
 
    ScopedProxyMode scopedProxy() default ScopedProxyMode.DEFAULT;
 
    String resourcePattern() default "**/*.class";
    boolean useDefaultFilters() default true;
    ComponentScan.Filter[] includeFilters() default {};
    ComponentScan.Filter[] excludeFilters() default {};
    boolean lazyInit() default false;
    @Retention(RetentionPolicy.RUNTIME)
    @Target({})
    public @interface Filter {
        FilterType type() default FilterType.ANNOTATION;
        @AliasFor("classes")
        Class[] value() default {};
        @AliasFor("value")
        Class[] classes() default {};
        String[] pattern() default {};
    }
}

basePackages与value:? 用于指定包的路径，进行扫描
basePackageClasses: 用于指定某个类的包的路径进行扫描
nameGenerator: bean的名称的生成器
useDefaultFilters: 是否开启对@Component，@Repository，@Service，@Controller的类进行检测
includeFilters: 包含的过滤条件 FilterType.ANNOTATION：按照注解过滤,
                 FilterType.ASSIGNABLE_TYPE：按照给定的类型,
	             FilterType.ASPECTJ：使用ASPECTJ表达式,
	             FilterType.REGEX：正则,
	             FilterType.CUSTOM：自定义规则
excludeFilters: 排除的过滤条件，用法和includeFilters一样

注解示例分享

 扫描包
@ComponentScan(basePackages ="")     //单个
@ComponentScan(basePackages = {"xxx","com.java265.","..."})   //多个
注意：可以省略“basePackages =”

@Configuration
@ComponentScan("com.java265.spring.service")
public class MyConfig {}

@Configuration
@ComponentScan("com.java265.spring.dao","com.java265.spring.service")
public class MyConfig {}

@Configuration
@ComponentScan("com.java265.spring.*")   //通配符匹配所有的包
public class MyConfig {}
2. 扫描类
@ComponentScan(basePackageClasses ="")   //单个
@ComponentScan(basePackageClasses = {"aaa","bbb","…"})  //多个
注意：不可以省略“basePackageClasses =”

@Configuration
@ComponentScan(basePackageClasses = HelloController.class)
public class MyConfig {
}

Spring ComponentScan注解有以下特性
   1.自定扫描路径下边带有@Controller，@Service，@Repository，@Component注解加入spring容器
   2.通过includeFilters加入扫描路径下没有以上注解的类加入spring容器
   3.通过excludeFilters过滤出不用加入spring容器的类
   4.自定义增加了@Component注解的注解方式