阅读 231

Springboot项目实现将类从@ComponentScan中排除

这篇文章主要介绍了Springboot项目实现将类从@ComponentScan中排除，具有很好的参考价值，希望对大家有所帮助。如有错误或未考虑完全的地方，望不吝赐教

目录

  • 将类从@ComponentScan中排除

    • 问题描述

    • 方案一

    • 方案二

    • 方案三

    • 方案四

  • @ComponentScan 详解

    将类从@ComponentScan中排除

    问题描述

    最近在学习SpringCloud的Ribbon，在使用

    1
    2
    @RibbonClient(name = "SPRINGCLOUD-P-DEPT",
       configuration = RibbonConfig.class)

    为服务指定负载均衡策略的时候，根据Ribbon官方文档介绍，自定义的Ribbon配置类不允许被Springboot的**@ComponentScan**注解扫描到，所以需要将自定义的配置类RibbonConfig从在Springboot自动注入的范围内排除

    方案一

    我们都知道，Springboot的**@SpringBootApplication**会自动扫描本类所在包下的所有类和子类，所以只需要将RibbonConfig定义在Springboot启动类所在包外面即可

    方案二

    通过在启动类中添加

    1
    2
    3
    @ComponentScan(excludeFilters = @ComponentScan.Filter(
      type = FilterType.ASSIGNABLE_TYPE,
      classes = RibbonConfig.class))

    通过FilterType.ASSIGNABLE_TYPE来指定要排除的类

    如果需要排除的类太多了这个就很麻烦

    方案三

    通过自定义注解实现

    1
    2
    3
    @ComponentScan(excludeFilters = @ComponentScan.Filter(
      type = FilterType.ANNOTATION,
      classes = ScanIgnore.class))

    与方案二不同的是，这里用的是FilterType.ANNOTATION

    方案四

    通过实现TypeFilter类来自定义过滤器

    1
    2
    3
    4
    5
    6
    7
    @ComponentScan(excludeFilters = {
     @Filter(
      type = FilterType.CUSTOM,
      classes = TypeExcludeFilter.class),
     @Filter(
      type = FilterType.CUSTOM,
      classes = AutoConfigurationExcludeFilter.class) })

    此处给出的就是**@SpringbootApplication中的实现方式，通过FilterType.CUSTOM**来根据自动一过滤器来排除bean

    最后贴出枚举类FilterType：

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    /*
     * Copyright 2002-2013 the original author or authors.
     *
     * Licensed under the Apache License, Version 2.0 (the "License");
     * you may not use this file except in compliance with the License.
     * You may obtain a copy of the License at
     *
     *      https://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */
    package org.springframework.context.annotation;
    /**
     * Enumeration of the type filters that may be used in conjunction with
     * {@link ComponentScan @ComponentScan}.
     *
     * @author Mark Fisher
     * @author Juergen Hoeller
     * @author Chris Beams
     * @since 2.5
     * @see ComponentScan
     * @see ComponentScan#includeFilters()
     * @see ComponentScan#excludeFilters()
     * @see org.springframework.core.type.filter.TypeFilter
     */
    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
    }

    @ComponentScan 详解

    @ComponentScan 的作用就是根据定义的扫描路径，把符合扫描规则的类装配到spring容器中，注解定义如下。

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    @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<? extends BeanNameGenerator> nameGenerator() default BeanNameGenerator.class;
        Class<? extends ScopeMetadataResolver> 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

    我的工程结构如下，测试对controller和service的扫描，其中HelloController没有加@Controller等任何注解，就是一个普通类。

    修改配置类如下：应用默认的过滤器，扫描service包：

    1
    2
    3
    4
    5
    6
    @Configuration
    @ComponentScan(value = "com.xhx.spring.service",
            useDefaultFilters = true
    )
    public class MyConfig {
    }

    系统注入了两个service进去

    改成如下所示：HelloController所在的包的类也被扫描了进去

    1
    2
    3
    4
    5
    6
    7
    @Configuration
    @ComponentScan(value = "com.xhx.spring.service",
            useDefaultFilters = true,
            basePackageClasses = HelloController.class
    )
    public class MyConfig {
    }

    系统中会注入下面就给类

    把默认的过滤器关掉，扫描带Controller注解的。

    1
    2
    3
    4
    5
    6
    7
    8
    9
    @Configuration
    @ComponentScan(value = "com.xhx.spring",
            useDefaultFilters = false,
            includeFilters = {
                @ComponentScan.Filter(type = FilterType.ANNOTATION,classes = {Controller.class})
            }
    )
    public class MyConfig {
    }

    按照类的类型扫描，虽然HelloController没有加注解，但是被注入到了spring容器中

    1
    2
    3
    4
    5
    6
    7
    8
    9
    @Configuration
    @ComponentScan(value = "com.xhx.spring",
            useDefaultFilters = false,
            includeFilters = {
                @ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE,classes = {HelloController.class})
            }
    )
    public class MyConfig {
    }

    自定义扫描过滤器

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    package com.xhx.spring.componentscan.config;
    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;
      
    /**
     * xuhaixing
     * 2018/9/18 23:07
     **/
    public class MyTypeFilter implements TypeFilter {
        @Override
        public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory) throws IOException {
            String className = metadataReader.getClassMetadata().getClassName();
            if(className.contains("Controller")){
                return true;
            }
            return false;
        }
    }

    修改配置类

    1
    2
    3
    4
    5
    6
    7
    8
    9
    @Configuration
    @ComponentScan(value = "com.xhx.spring",
            useDefaultFilters = false,
            includeFilters = {
                @ComponentScan.Filter(type = FilterType.CUSTOM,classes = {MyTypeFilter.class})
            }
    )
    public class MyConfig {
    }

    输出结果：

    输出spring容器中的bean的测试类：只过滤输出了名字中含有hello的类。

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    package com.xhx.spring.componentscan;
    import com.xhx.spring.componentscan.config.MyConfig;
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.boot.test.context.SpringBootTest;
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    import org.springframework.test.context.junit4.SpringRunner;
    import java.util.Arrays;
    import java.util.List;
    import java.util.stream.Collectors;
      
    @RunWith(SpringRunner.class)
    @SpringBootTest
    public class ComponentScanApplicationTests {
        @Test
        public void testLoads() {
            AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MyConfig.class);
            List<String> hello = Arrays.stream(context.getBeanDefinitionNames()).collect(Collectors.toList());
            hello.stream().filter(name->name.contains("hello")).peek(System.out::println).count();
        }
    }

    以上为个人经验，希望能给大家一个参考

    原文链接：https://blog.csdn.net/java_doctor/article/details/104602066


    文章分类
    文章标签
    springboot
    项目
    componentscan
    版权声明：本站是系统测试站点，无实际运营。本文内容由互联网用户自发贡献，该文观点仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌抄袭侵权/违法违规的内容， 请发送邮件至 XXXXXXo@163.com 举报，一经查实，本站将立刻删除。
    相关推荐