org.springframework.web.method.ControllerAdviceBean#isApplicableToBeanType 作用

org.springframework.web.method.ControllerAdviceBean#isApplicableToBeanType(@Nullable Class<?> beanType)

判断当前类是否被ControllerAdviceBean修饰，判断依据位 ControllerAdviceBean上设置的注解@ControllerAdvice内的参数

package org.springframework.web.bind.annotation;

import java.lang.annotation.Annotation;

import java.lang.annotation.Documented;

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

import org.springframework.core.annotation.AliasFor;

import org.springframework.stereotype.Component;

@Target(ElementType.TYPE)

@Retention(RetentionPolicy.RUNTIME)

@Documented

@Component

public @interface ControllerAdvice {

	@AliasFor("basePackages")

	String[] value() default {};

	@AliasFor("value")

	String[] basePackages() default {};

	Class<?>[] basePackageClasses() default {};

	Class<?>[] assignableTypes() default {};

	Class<? extends Annotation>[] annotations() default {};

}

其内部使用 HandlerTypePredicate beanTypePredicate 进行判断，如果@ControllerAdvice注解内无参数则可以修饰所有类。

由该段代码判断：

ControllerAdvice annotation = (beanType != null ?

		AnnotatedElementUtils.findMergedAnnotation(beanType, ControllerAdvice.class) : null);

if (annotation != null) {

	this.beanTypePredicate = HandlerTypePredicate.builder()

			.basePackage(annotation.basePackages())

			.basePackageClass(annotation.basePackageClasses())

			.assignableType(annotation.assignableTypes())

			.annotation(annotation.annotations())

			.build();

}

else {

	this.beanTypePredicate = HandlerTypePredicate.forAnyHandlerType();

}

HandlerTypePredicate.forAnyHandlerType(); 改方法实现如下：

return new HandlerTypePredicate(Collections.emptySet(), Collections.emptyList(), Collections.emptyList());

=====

实际会调用org.springframework.web.method.HandlerTypePredicate#test

if (!hasSelectors()) {
   return true;
}

org.springframework.web.method.HandlerTypePredicate#hasSelectors

private boolean hasSelectors() {

   return (!this.basePackages.isEmpty() || !this.assignableTypes.isEmpty() || !this.annotations.isEmpty());

}

巴特西

org.springframework.web.method.ControllerAdviceBean#isApplicableToBeanType 作用

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