【spring】@ConditionalOnResource注解学习

`@ConditionalOnResource` 介绍

@ConditionalOnResource 是Spring框架中的一个条件化注解，它允许你根据类路径中是否存在指定的资源来决定是否加载特定的Bean定义或配置类。这个注解可以用于类级别或方法级别。

具体@Conditional使用请看这篇文章【spring】@Conditional注解学习-CSDN博客

类似`@ConditionalOnResource注解还有下面：`

@`ConditionalOnResource` 源码

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Conditional({OnResourceCondition.class})
public @interface ConditionalOnResource {
    String[] resources() default {};
}

@`ConditionalOnResource` 属性介绍

resources，它是一个字符串数组，用于指定需要检查的资源路径。你可以通过这个属性来指定多个资源路径，Spring框架会检查这些资源是否存在于类路径中。

@ConditionalOnResource(resources = { "classpath:conditional-config.xml", "classpath:conditional-other-config.properties" })

resources 属性支持通配符，例如 * 和 ?。你可以使用通配符来匹配多个资源。例如：

@ConditionalOnResource(resources = "classpath:conditional-config*.xml")

@`Conditional`测试示例代码

示例代码一

ConditionalDemo类

package com.yang.SpringTest.annotation.conditionalLearn;

import lombok.Data;

/**
 * <p>description</p>
 *
 * @author By: chengxuyuanshitang
 * Package com.yang.SpringTest.annotation.conditionalLearn
 * Ceate Time 2024-03-20 14:55
 */
@Data
public class ConditionalDemo {
}

创建conditional.properties文件

ConditionalDemoConfig配置类

package com.yang.SpringTest.annotation.conditionalLearn;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.autoconfigure.condition.ConditionalOnResource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;

/**
 * <p>配置类</p>
 *
 * @author By: chengxuyuanshitang
 * Package com.yang.SpringTest.annotation.conditionalLearn
 * Ceate Time 2024-03-20 14:54
 */
@Slf4j
@Configuration
@ConditionalOnResource(resources = "classpath:conditional.properties")
public class ConditionalDemoConfig {
    @Bean
    public ConditionalDemo demo() {
        log.info("------------- ConditionalDemo init -------------");
        return new ConditionalDemo();
    }
}

ConditionalTest测试类

package com.yang.SpringTest.annotation.conditionalLearn;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import java.util.Arrays;

/**
 * <p>测试类</p>
 *
 * @author By: chengxuyuanshitang
 * Package com.yang.SpringTest.annotation.conditionalLearn
 * Ceate Time 2024-03-20 14:58
 */

public class ConditionalTest{
        public static void main(String[] args) {
            AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(ConditionalDemoConfig.class);
            String[] definitionNames = context.getBeanDefinitionNames();
            Arrays.stream(definitionNames).forEach((definitionName) -> System.out.println(definitionName));
        }
}