{"id":2009,"date":"2023-04-01T12:15:42","date_gmt":"2023-04-01T04:15:42","guid":{"rendered":"https:\/\/www.appblog.cn\/?p=2009"},"modified":"2023-04-07T10:38:17","modified_gmt":"2023-04-07T02:38:17","slug":"interview-question-can-you-explain-the-principle-of-spring-boot-automatic-assembly","status":"publish","type":"post","link":"https:\/\/www.appblog.cn\/index.php\/2023\/04\/01\/interview-question-can-you-explain-the-principle-of-spring-boot-automatic-assembly\/","title":{"rendered":"\u9762\u8bd5\u9898\uff1a\u8bf4\u4e00\u4e0b Spring Boot \u81ea\u52a8\u88c5\u914d\u539f\u7406\uff1f"},"content":{"rendered":"<p>\u6bcf\u6b21\u95ee\u5230 Spring Boot\uff0c \u9762\u8bd5\u5b98\u975e\u5e38\u559c\u6b22\u95ee\u8fd9\u4e2a\u95ee\u9898\uff1a\u201c\u8bb2\u8ff0\u4e00\u4e0b SpringBoot \u81ea\u52a8\u88c5\u914d\u539f\u7406\uff1f\u201d\u3002<\/p>\n<p>\u6211\u89c9\u5f97\u6211\u4eec\u53ef\u4ee5\u4ece\u4ee5\u4e0b\u51e0\u4e2a\u65b9\u9762\u56de\u7b54\uff1a<\/p>\n<ul>\n<li>\u4ec0\u4e48\u662f SpringBoot \u81ea\u52a8\u88c5\u914d\uff1f<\/li>\n<li>SpringBoot \u662f\u5982\u4f55\u5b9e\u73b0\u81ea\u52a8\u88c5\u914d\u7684\uff1f\u5982\u4f55\u5b9e\u73b0\u6309\u9700\u52a0\u8f7d\uff1f<\/li>\n<li>\u5982\u4f55\u5b9e\u73b0\u4e00\u4e2a Starter\uff1f<\/li>\n<\/ul>\n<p><!-- more --><\/p>\n<p>\u4f7f\u7528\u8fc7 Spring \u7684\u5c0f\u4f19\u4f34\uff0c\u4e00\u5b9a\u6709\u88ab XML \u914d\u7f6e\u7edf\u6cbb\u7684\u6050\u60e7\u3002\u5373\u4f7f Spring \u540e\u9762\u5f15\u5165\u4e86\u57fa\u4e8e\u6ce8\u89e3\u7684\u914d\u7f6e\uff0c\u6211\u4eec\u5728\u5f00\u542f\u67d0\u4e9b Spring \u7279\u6027\u6216\u8005\u5f15\u5165\u7b2c\u4e09\u65b9\u4f9d\u8d56\u7684\u65f6\u5019\uff0c\u8fd8\u662f\u9700\u8981\u7528 XML \u6216 Java \u8fdb\u884c\u663e\u5f0f\u914d\u7f6e\u3002<\/p>\n<p>\u4e3e\u4e2a\u4f8b\u5b50\u3002\u6ca1\u6709 Spring Boot \u7684\u65f6\u5019\uff0c\u6211\u4eec\u5199\u4e00\u4e2a RestFul Web \u670d\u52a1\uff0c\u8fd8\u9996\u5148\u9700\u8981\u8fdb\u884c\u5982\u4e0b\u914d\u7f6e\u3002<\/p>\n<pre><code class=\"language-java\">@Configuration\npublic class RESTConfiguration {\n    @Bean\n    public View jsonTemplate() {\n        MappingJackson2JsonView view = new MappingJackson2JsonView();\n        view.setPrettyPrint(true);\n        return view;\n    }\n\n    @Bean\n    public ViewResolver viewResolver() {\n        return new BeanNameViewResolver();\n    }\n}<\/code><\/pre>\n<p>spring-servlet.xml<\/p>\n<pre><code class=\"language-xml\">&lt;beans xmlns=&quot;http:\/\/www.springframework.org\/schema\/beans\n    xmlns:xsi=&quot;http:\/\/www.w3.org\/2001\/XMLSchema-instance&quot; xmlns:context=&quot;http:\/\/www.springframework-org\/schema\/context&quot; \n    xmlns:mvc=&quot;http:\/\/www.springframework.org\/schema\/mvc&quot;\n    xsi:schemaLocation=&quot;http:\/\/www.springframework.org\/schema\/beans http:\/\/www.springframework.org\/schema\/beans\/spring-beans.xsd \n    http:\/\/www.springframework.org\/schema\/context\/ http:\/\/www.springframework.org\/schema\/context\/spring-context.xsd \n    http:\/\/www.springframework.org\/schema\/mvc\/ http:\/\/www.springframework.org\/schema\/mvc\/spring-mvc.xsd&quot;&gt;\n\n    &lt;context:component-scan base-package=&quot;cn.appblog.demo&quot; \/&gt;\n    &lt;mvc:annotation-driven \/&gt;\n\n    &lt;!-- JSON Support --&gt;\n    &lt;bean name=&quot;viewResolver&quot; class=&quot;org.springframework.web.servlet.view.BeanNameViewResolver&quot;\/&gt;\n    &lt;bean name=&quot;jsonTemplate&quot; class=&quot;org.springframework.web.servlet.view.json.MappingJackson2JsonView&quot;\/&gt;\n\n&lt;\/beans&gt;<\/code><\/pre>\n<p>\u4f46\u662f\uff0cSpring Boot \u9879\u76ee\uff0c\u6211\u4eec\u53ea\u9700\u8981\u6dfb\u52a0\u76f8\u5173\u4f9d\u8d56\uff0c\u65e0\u9700\u914d\u7f6e\uff0c\u901a\u8fc7\u542f\u52a8\u4e0b\u9762\u7684<code>main<\/code>\u65b9\u6cd5\u5373\u53ef\u3002<\/p>\n<pre><code class=\"language-java\">@SpringBootApplication\npublic class DemoApplication {\n\n    public static void main(String[] args) {\n        SpringApplication.run(DemoApplication.class, args);\n    }\n}<\/code><\/pre>\n<p>\u5e76\u4e14\uff0c\u6211\u4eec\u901a\u8fc7 Spring Boot \u7684\u5168\u5c40\u914d\u7f6e\u6587\u4ef6<code>application.properties<\/code>\u6216<code>application.yml<\/code>\u5373\u53ef\u5bf9\u9879\u76ee\u8fdb\u884c\u8bbe\u7f6e\u6bd4\u5982\u66f4\u6362\u7aef\u53e3\u53f7\uff0c\u914d\u7f6e JPA \u5c5e\u6027\u7b49\u7b49\u3002<\/p>\n<p>\u4e3a\u4ec0\u4e48 Spring Boot \u4f7f\u7528\u8d77\u6765\u8fd9\u4e48\u9178\u723d\u5462\uff1f\u8fd9\u5f97\u76ca\u4e8e\u5176\u81ea\u52a8\u88c5\u914d\u3002\u81ea\u52a8\u88c5\u914d\u53ef\u4ee5\u8bf4\u662f Spring Boot \u7684\u6838\u5fc3\uff0c\u90a3\u7a76\u7adf\u4ec0\u4e48\u662f\u81ea\u52a8\u88c5\u914d\u5462\uff1f<\/p>\n<h2>\u4ec0\u4e48\u662f SpringBoot \u81ea\u52a8\u88c5\u914d\uff1f<\/h2>\n<p>\u6211\u4eec\u73b0\u5728\u63d0\u5230\u81ea\u52a8\u88c5\u914d\u7684\u65f6\u5019\uff0c\u4e00\u822c\u4f1a\u548c Spring Boot \u8054\u7cfb\u5728\u4e00\u8d77\u3002\u4f46\u662f\uff0c\u5b9e\u9645\u4e0a Spring Framework \u65e9\u5c31\u5b9e\u73b0\u4e86\u8fd9\u4e2a\u529f\u80fd\u3002Spring Boot \u53ea\u662f\u5728\u5176\u57fa\u7840\u4e0a\uff0c\u901a\u8fc7 SPI \u7684\u65b9\u5f0f\uff0c\u505a\u4e86\u8fdb\u4e00\u6b65\u4f18\u5316\u3002<\/p>\n<blockquote>\n<p>SpringBoot \u5b9a\u4e49\u4e86\u4e00\u5957\u63a5\u53e3\u89c4\u8303\uff0c\u8fd9\u5957\u89c4\u8303\u89c4\u5b9a\uff1aSpringBoot \u5728\u542f\u52a8\u65f6\u4f1a\u626b\u63cf\u5916\u90e8\u5f15\u7528 jar \u5305\u4e2d\u7684<code>META-INF\/spring.factories<\/code>\u6587\u4ef6\uff0c\u5c06\u6587\u4ef6\u4e2d\u914d\u7f6e\u7684\u7c7b\u578b\u4fe1\u606f\u52a0\u8f7d\u5230 Spring \u5bb9\u5668\uff08\u6b64\u5904\u6d89\u53ca\u5230 JVM \u7c7b\u52a0\u8f7d\u673a\u5236\u4e0e Spring \u7684\u5bb9\u5668\u77e5\u8bc6\uff09\uff0c\u5e76\u6267\u884c\u7c7b\u4e2d\u5b9a\u4e49\u7684\u5404\u79cd\u64cd\u4f5c\u3002\u5bf9\u4e8e\u5916\u90e8 jar \u6765\u8bf4\uff0c\u53ea\u9700\u8981\u6309\u7167 SpringBoot \u5b9a\u4e49\u7684\u6807\u51c6\uff0c\u5c31\u80fd\u5c06\u81ea\u5df1\u7684\u529f\u80fd\u88c5\u7f6e\u8fdb SpringBoot\u3002<\/p>\n<\/blockquote>\n<p>\u6ca1\u6709 Spring Boot \u7684\u60c5\u51b5\u4e0b\uff0c\u5982\u679c\u6211\u4eec\u9700\u8981\u5f15\u5165\u7b2c\u4e09\u65b9\u4f9d\u8d56\uff0c\u9700\u8981\u624b\u52a8\u914d\u7f6e\uff0c\u975e\u5e38\u9ebb\u70e6\u3002\u4f46\u662f\uff0cSpring Boot \u4e2d\uff0c\u6211\u4eec\u76f4\u63a5\u5f15\u5165\u4e00\u4e2a starter \u5373\u53ef\u3002\u6bd4\u5982\u4f60\u60f3\u8981\u5728\u9879\u76ee\u4e2d\u4f7f\u7528 redis \u7684\u8bdd\uff0c\u76f4\u63a5\u5728\u9879\u76ee\u4e2d\u5f15\u5165\u5bf9\u5e94\u7684 starter \u5373\u53ef\u3002<\/p>\n<pre><code class=\"language-xml\">&lt;dependency&gt;\n    &lt;groupId&gt;org.springframework.boot&lt;\/groupId&gt;\n    &lt;artifactId&gt;spring-boot-starter-data-redis&lt;\/artifactId&gt;\n&lt;\/dependency&gt;<\/code><\/pre>\n<p>\u5f15\u5165 starter \u4e4b\u540e\uff0c\u6211\u4eec\u901a\u8fc7\u5c11\u91cf\u6ce8\u89e3\u548c\u4e00\u4e9b\u7b80\u5355\u7684\u914d\u7f6e\u5c31\u80fd\u4f7f\u7528\u7b2c\u4e09\u65b9\u7ec4\u4ef6\u63d0\u4f9b\u7684\u529f\u80fd<\/p>\n<p>\u5728\u6211\u770b\u6765\uff0c\u81ea\u52a8\u88c5\u914d\u53ef\u4ee5\u7b80\u5355\u7406\u89e3\u4e3a\uff1a<strong>\u901a\u8fc7\u6ce8\u89e3\u6216\u8005\u4e00\u4e9b\u7b80\u5355\u7684\u914d\u7f6e\u5c31\u80fd\u5728 Spring Boot \u7684\u5e2e\u52a9\u4e0b\u5b9e\u73b0\u67d0\u5757\u529f\u80fd<\/strong><\/p>\n<h2>SpringBoot \u662f\u5982\u4f55\u5b9e\u73b0\u81ea\u52a8\u88c5\u914d\u7684\uff1f<\/h2>\n<h3>\u6838\u5fc3\u6ce8\u89e3 @SpringBootApplication \u62c6\u89e3<\/h3>\n<p>\u6211\u4eec\u5148\u770b\u4e00\u4e0b SpringBoot \u7684\u6838\u5fc3\u6ce8\u89e3<code>@SpringBootApplication<\/code><\/p>\n<pre><code class=\"language-java\">@Target({ElementType.TYPE})\n@Retention(RetentionPolicy.RUNTIME)\n@Documented\n@Inherited\n@SpringBootConfiguration\n@EnableAutoConfiguration\n@ComponentScan(\n    excludeFilters = {@Filter(\n    type = FilterType.CUSTOM,\n    classes = {TypeExcludeFilter.class}\n), @Filter(\n    type = FilterType.CUSTOM,\n    classes = {AutoConfigurationExcludeFilter.class}\n)}\n)\npublic @interface SpringBootApplication {\n    ...\n}<\/code><\/pre>\n<pre><code class=\"language-java\">@Target({ElementType.TYPE})\n@Retention(RetentionPolicy.RUNTIME)\n@Documented\n@Configuration    \/\/\u5b9e\u9645\u4e0a\u5b83\u4e5f\u662f\u4e00\u4e2a\u914d\u7f6e\u7c7b\npublic @interface SpringBootConfiguration {\n    ...\n}<\/code><\/pre>\n<p>\u5927\u6982\u53ef\u4ee5\u628a<code>@SpringBootApplication<\/code>\u770b\u4f5c\u662f<code>@Configuration<\/code>\u3001<code>@EnableAutoConfiguration<\/code>\u3001<code>@ComponentScan<\/code>\u6ce8\u89e3\u7684\u96c6\u5408\u3002\u6839\u636e SpringBoot \u5b98\u7f51\uff0c\u8fd9\u4e09\u4e2a\u6ce8\u89e3\u7684\u4f5c\u7528\u5206\u522b\u662f\uff1a<\/p>\n<ul>\n<li><code>@EnableAutoConfiguration<\/code>\uff1a\u542f\u7528 SpringBoot \u7684\u81ea\u52a8\u914d\u7f6e\u673a\u5236<\/li>\n<li><code>@Configuration<\/code>\uff1a\u5141\u8bb8\u5728\u4e0a\u4e0b\u6587\u4e2d\u6ce8\u518c\u989d\u5916\u7684 bean \u6216\u5bfc\u5165\u5176\u4ed6\u914d\u7f6e\u7c7b<\/li>\n<li><code>@ComponentScan<\/code>\uff1a\u626b\u63cf\u88ab<code>@Component (@Service, @Controller)<\/code>\u6ce8\u89e3\u7684 bean\uff0c\u6ce8\u89e3\u9ed8\u8ba4\u4f1a\u626b\u63cf\u542f\u52a8\u7c7b\u6240\u5728\u7684\u5305\u4e0b\u6240\u6709\u7684\u7c7b\uff0c\u53ef\u4ee5\u81ea\u5b9a\u4e49\u4e0d\u626b\u63cf\u67d0\u4e9b bean\u3002\u5982\u4e0a\u5bb9\u5668\u4e2d\u5c06\u6392\u9664<code>TypeExcludeFilter<\/code>\u548c<code>AutoConfigurationExcludeFilter<\/code><\/li>\n<\/ul>\n<p><code>@EnableAutoConfiguration<\/code>\u662f\u5b9e\u73b0\u81ea\u52a8\u88c5\u914d\u7684\u91cd\u8981\u6ce8\u89e3\uff0c\u6211\u4eec\u4ee5\u8fd9\u4e2a\u6ce8\u89e3\u5165\u624b\u3002<\/p>\n<h3>@EnableAutoConfiguration: \u5b9e\u73b0\u81ea\u52a8\u88c5\u914d\u7684\u6838\u5fc3\u6ce8\u89e3<\/h3>\n<p><code>@EnableAutoConfiguration<\/code>\u53ea\u662f\u4e00\u4e2a\u7b80\u5355\u5730\u6ce8\u89e3\uff0c\u81ea\u52a8\u88c5\u914d\u6838\u5fc3\u529f\u80fd\u7684\u5b9e\u73b0\u5b9e\u9645\u662f\u901a\u8fc7<code>AutoConfigurationImportSelector<\/code>\u7c7b<\/p>\n<pre><code class=\"language-java\">@Target({ElementType.TYPE})\n@Retention(RetentionPolicy.RUNTIME)\n@Documented\n@Inherited\n@AutoConfigurationPackage\n@Import({AutoConfigurationImportSelector.class})\npublic @interface EnableAutoConfiguration {\n    String ENABLED_OVERRIDE_PROPERTY = &quot;spring.boot.enableautoconfiguration&quot;;\n\n    Class&lt;?&gt;[] exclude() default {};\n\n    String[] excludeName() default {};\n}<\/code><\/pre>\n<p>\u6211\u4eec\u73b0\u5728\u91cd\u70b9\u5206\u6790\u4e0b<code>AutoConfigurationImportSelector<\/code>\u7c7b\u5230\u5e95\u505a\u4e86\u4ec0\u4e48\uff1f<\/p>\n<h3>AutoConfigurationImportSelector: \u52a0\u8f7d\u81ea\u52a8\u88c5\u914d\u7c7b<\/h3>\n<p><code>AutoConfigurationImportSelector<\/code>\u7c7b\u7684\u7ee7\u627f\u4f53\u7cfb\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-java\">public class AutoConfigurationImportSelector implements DeferredImportSelector, BeanClassLoaderAware, ResourceLoaderAware, BeanFactoryAware, EnvironmentAware, Ordered {\n\n}<\/code><\/pre>\n<pre><code class=\"language-java\">public interface DeferredImportSelector extends ImportSelector {\n\n}<\/code><\/pre>\n<pre><code class=\"language-java\">public interface ImportSelector {\n    String[] selectImports(AnnotationMetadata var1);\n\n    @Nullable\n    default Predicate&lt;String&gt; getExclusionFilter() {\n        return null;\n    }\n}<\/code><\/pre>\n<p>\u53ef\u4ee5\u770b\u51fa\uff0c<code>AutoConfigurationImportSelector<\/code>\u7c7b\u5b9e\u73b0\u4e86<code>ImportSelector<\/code>\u63a5\u53e3\uff0c\u4e5f\u5c31\u5b9e\u73b0\u4e86\u8fd9\u4e2a\u63a5\u53e3\u4e2d\u7684<code>selectImports<\/code>\u65b9\u6cd5\uff0c\u8be5\u65b9\u6cd5\u4e3b\u8981\u7528\u4e8e<strong>\u83b7\u53d6\u6240\u6709\u7b26\u5408\u6761\u4ef6\u7684\u7c7b\u7684\u5168\u9650\u5b9a\u7c7b\u540d\uff0c\u8fd9\u4e9b\u7c7b\u9700\u8981\u88ab\u52a0\u8f7d\u5230 IoC \u5bb9\u5668\u4e2d<\/strong>\u3002<\/p>\n<pre><code class=\"language-java\">private static final String[] NO_IMPORTS = new String[0];\n\npublic String[] selectImports(AnnotationMetadata annotationMetadata) {\n    \/\/ &lt;1&gt;.\u5224\u65ad\u81ea\u52a8\u88c5\u914d\u5f00\u5173\u662f\u5426\u6253\u5f00\n    if (!this.isEnabled(annotationMetadata)) {\n        return NO_IMPORTS;\n    } else {\n        \/\/ &lt;2&gt;.\u83b7\u53d6\u6240\u6709\u9700\u8981\u88c5\u914d\u7684bean\n        AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader.loadMetadata(this.beanClassLoader);\n        AutoConfigurationImportSelector.AutoConfigurationEntry autoConfigurationEntry = this.getAutoConfigurationEntry(autoConfigurationMetadata, annotationMetadata);\n        return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());\n    }\n}<\/code><\/pre>\n<p>\u8fd9\u91cc\u6211\u4eec\u9700\u8981\u91cd\u70b9\u5173\u6ce8\u4e00\u4e0b<code>getAutoConfigurationEntry()<\/code>\u65b9\u6cd5\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u4e3b\u8981\u8d1f\u8d23\u52a0\u8f7d\u81ea\u52a8\u914d\u7f6e\u7c7b\u7684\u3002<\/p>\n<p>\u8be5\u65b9\u6cd5\u8c03\u7528\u94fe\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-java\">AutoConfigurationImportSelector.getAutoConfigurationEntry(autoConfigurationMetadata, annotationMetadata)\n\nAutoConfigurationImportSelector.getCandidateConfigurations(annotationMetadata, attributes)\n\n\/\/\u83b7\u53d6\u6240\u6709\u81ea\u52a8\u914d\u7f6e\u7c7b\u540d\nSpringFactoriesLoader.loadFactoryNames(this.getSpringFactoriesLoaderFactoryClass(), this.getBeanClassLoader())\n\nSpringFactoriesLoader.loadSpringFactories(classLoader).getOrDefault(factoryTypeName, Collections.emptyList());\n\n\/\/\u4eceMETA-INF\/spring.factories\u52a0\u8f7d\u81ea\u52a8\u914d\u7f6e\u7c7b\nSpringFactoriesLoader.loadSpringFactories(@Nullable ClassLoader classLoader)<\/code><\/pre>\n<p>\u73b0\u5728\u6211\u4eec\u7ed3\u5408<code>getAutoConfigurationEntry()<\/code>\u7684\u6e90\u7801\u6765\u8be6\u7ec6\u5206\u6790\u4e00\u4e0b\uff1a<\/p>\n<pre><code class=\"language-java\">private static final AutoConfigurationEntry EMPTY_ENTRY = new AutoConfigurationEntry();\n\nAutoConfigurationEntry getAutoConfigurationEntry(AutoConfigurationMetadata autoConfigurationMetadata, AnnotationMetadata annotationMetadata) {\n    \/\/&lt;1&gt;.\n    if (!this.isEnabled(annotationMetadata)) {\n        return EMPTY_ENTRY;\n    } else {\n        \/\/&lt;2&gt;.\n        AnnotationAttributes attributes = this.getAttributes(annotationMetadata);\n        \/\/&lt;3&gt;.\n        List&lt;String&gt; configurations = this.getCandidateConfigurations(annotationMetadata, attributes);\n        \/\/&lt;4&gt;.\n        configurations = this.removeDuplicates(configurations);\n        Set&lt;String&gt; exclusions = this.getExclusions(annotationMetadata, attributes);\n        this.checkExcludedClasses(configurations, exclusions);\n        configurations.removeAll(exclusions);\n        configurations = this.filter(configurations, autoConfigurationMetadata);\n        this.fireAutoConfigurationImportEvents(configurations, exclusions);\n        return new AutoConfigurationImportSelector.AutoConfigurationEntry(configurations, exclusions);\n    }\n}<\/code><\/pre>\n<p>\u7b2c 1 \u6b65\uff1a<\/p>\n<p>\u5224\u65ad\u81ea\u52a8\u88c5\u914d\u5f00\u5173\u662f\u5426\u6253\u5f00\u3002\u9ed8\u8ba4<code>spring.boot.enableautoconfiguration=true<\/code>\uff0c\u53ef\u5728<code>application.properties<\/code>\u6216<code>application.yml<\/code>\u4e2d\u8bbe\u7f6e<\/p>\n<p><img decoding=\"async\" src=\"http:\/\/www.yezhou.me\/AppBlog\/images\/Java\/\u5224\u65ad\u81ea\u52a8\u88c5\u914d\u5f00\u5173\u662f\u5426\u6253\u5f00.png\" alt=\"\u5224\u65ad\u81ea\u52a8\u88c5\u914d\u5f00\u5173\u662f\u5426\u6253\u5f00\" \/><\/p>\n<p>\u7b2c 2 \u6b65\uff1a<\/p>\n<p>\u7528\u4e8e\u83b7\u53d6<code>EnableAutoConfiguration<\/code>\u6ce8\u89e3\u4e2d\u7684<code>exclude<\/code>\u548c<code>excludeName<\/code><\/p>\n<p><img decoding=\"async\" src=\"http:\/\/www.yezhou.me\/AppBlog\/images\/Java\/\u83b7\u53d6EnableAutoConfiguration\u6ce8\u89e3\u4e2d\u7684exclude\u548cexcludeName.png\" alt=\"\u83b7\u53d6EnableAutoConfiguration\u6ce8\u89e3\u4e2d\u7684exclude\u548cexcludeName\" \/><\/p>\n<p>\u7b2c 3 \u6b65\uff1a<\/p>\n<p>\u83b7\u53d6\u9700\u8981\u81ea\u52a8\u88c5\u914d\u7684\u6240\u6709\u914d\u7f6e\u7c7b\uff0c\u8bfb\u53d6<code>META-INF\/spring.factories<\/code><\/p>\n<pre><code>spring-boot\/spring-boot-project\/spring-boot-autoconfigure\/src\/main\/resources\/META-INF\/spring.factories<\/code><\/pre>\n<p><img decoding=\"async\" src=\"http:\/\/www.yezhou.me\/AppBlog\/images\/Java\/\u83b7\u53d6\u9700\u8981\u81ea\u52a8\u88c5\u914d\u7684\u6240\u6709\u914d\u7f6e\u7c7b.png\" alt=\"\u83b7\u53d6\u9700\u8981\u81ea\u52a8\u88c5\u914d\u7684\u6240\u6709\u914d\u7f6e\u7c7b\" \/><\/p>\n<p>\u4ece\u4e0b\u56fe\u53ef\u4ee5\u770b\u5230\u8fd9\u4e2a\u6587\u4ef6\u7684\u914d\u7f6e\u5185\u5bb9\u90fd\u88ab\u6211\u4eec\u8bfb\u53d6\u5230\u4e86\u3002<code>XXXAutoConfiguration<\/code>\u7684\u4f5c\u7528\u5c31\u662f\u6309\u9700\u52a0\u8f7d\u7ec4\u4ef6<\/p>\n<p><img decoding=\"async\" src=\"http:\/\/www.yezhou.me\/AppBlog\/images\/Java\/spring-boot-autoconfigure\u914d\u7f6e\u52a0\u8f7d.png\" alt=\"spring-boot-autoconfigure\u914d\u7f6e\u52a0\u8f7d\" \/><\/p>\n<p>\u4e0d\u5149\u662f\u8fd9\u4e2a\u4f9d\u8d56\u4e0b\u7684<code>META-INF\/spring.factories<\/code>\u88ab\u8bfb\u53d6\u5230\uff0c\u6240\u6709 Spring Boot Starter \u4e0b\u7684<code>META-INF\/spring.factories<\/code>\u90fd\u4f1a\u88ab\u8bfb\u53d6\u5230<\/p>\n<p>\u6240\u4ee5\uff0c\u53ef\u4ee5\u6e05\u695a\u6ef4\u770b\u5230\uff0cdruid \u6570\u636e\u5e93\u8fde\u63a5\u6c60\u7684 Spring Boot Starter \u5c31\u521b\u5efa\u4e86<code>META-INF\/spring.factories<\/code>\u6587\u4ef6<\/p>\n<p>\u5982\u679c\uff0c\u6211\u4eec\u81ea\u5df1\u8981\u521b\u5efa\u4e00\u4e2a Spring Boot Starter\uff0c\u8fd9\u4e00\u6b65\u662f\u5fc5\u4e0d\u53ef\u5c11\u7684\u3002<\/p>\n<p><img decoding=\"async\" src=\"http:\/\/www.yezhou.me\/AppBlog\/images\/Java\/druid-spring-boot-starter\u914d\u7f6e\u52a0\u8f7d.png\" alt=\"druid-spring-boot-starter\u914d\u7f6e\u52a0\u8f7d\" \/><\/p>\n<p>\u7b2c 4 \u6b65\uff1a<\/p>\n<p>\u5230\u8fd9\u91cc\u53ef\u80fd\u9762\u8bd5\u5b98\u4f1a\u95ee\u4f60\uff1a\u201cspring.factories\u4e2d\u8fd9\u4e48\u591a\u914d\u7f6e\uff0c\u6bcf\u6b21\u542f\u52a8\u90fd\u8981\u5168\u90e8\u52a0\u8f7d\u4e48\uff1f\u201d<\/p>\n<p>\u5f88\u660e\u663e\uff0c\u8fd9\u662f\u4e0d\u73b0\u5b9e\u7684\u3002\u6211\u4eec debug \u5230\u540e\u9762\u4f60\u4f1a\u53d1\u73b0\uff0cconfigurations \u7684\u503c\u53d8\u5c0f\u4e86<\/p>\n<p><img decoding=\"async\" src=\"http:\/\/www.yezhou.me\/AppBlog\/images\/Java\/configurations\u503c\u53d8\u5c0f.png\" alt=\"configurations\u503c\u53d8\u5c0f\" \/><\/p>\n<p>\u56e0\u4e3a\uff0c\u8fd9\u4e00\u6b65\u53c8\u7ecf\u5386\u4e86\u4e00\u904d\u7b5b\u9009\uff0c<code>@ConditionalOnXXX<\/code>\u4e2d\u7684\u6240\u6709\u6761\u4ef6\u90fd\u6ee1\u8db3\uff0c\u8be5\u7c7b\u624d\u4f1a\u751f\u6548<\/p>\n<pre><code class=\"language-java\">@Configuration\n\/\/ \u68c0\u67e5\u76f8\u5173\u7684\u7c7b\uff1aRabbitTemplate \u548c Channel\u662f\u5426\u5b58\u5728\n\/\/ \u5b58\u5728\u624d\u4f1a\u52a0\u8f7d\n@ConditionalOnClass({ RabbitTemplate.class, Channel.class })\n@EnableConfigurationProperties(RabbitProperties.class)\n@Import(RabbitAnnotationDrivenConfiguration.class)\npublic class RabbitAutoConfiguration {\n}<\/code><\/pre>\n<p>\u6709\u5174\u8da3\u7684\u7ae5\u978b\u53ef\u4ee5\u8be6\u7ec6\u4e86\u89e3\u4e0b Spring Boot \u63d0\u4f9b\u7684\u6761\u4ef6\u6ce8\u89e3<\/p>\n<ul>\n<li><code>@ConditionalOnBean<\/code>\uff1a\u5f53\u5bb9\u5668\u91cc\u6709\u6307\u5b9a Bean \u7684\u6761\u4ef6\u4e0b<\/li>\n<li><code>@ConditionalOnMissingBean<\/code>\uff1a\u5f53\u5bb9\u5668\u91cc\u6ca1\u6709\u6307\u5b9a Bean \u7684\u60c5\u51b5\u4e0b<\/li>\n<li><code>@ConditionalOnSingleCandidate<\/code>\uff1a\u5f53\u6307\u5b9a Bean \u5728\u5bb9\u5668\u4e2d\u53ea\u6709\u4e00\u4e2a\uff0c\u6216\u8005\u867d\u7136\u6709\u591a\u4e2a\u4f46\u662f\u6307\u5b9a\u9996\u9009 Bean<\/li>\n<li><code>@ConditionalOnClass<\/code>\uff1a\u5f53\u7c7b\u8def\u5f84\u4e0b\u6709\u6307\u5b9a\u7c7b\u7684\u6761\u4ef6\u4e0b<\/li>\n<li><code>@ConditionalOnMissingClass<\/code>\uff1a\u5f53\u7c7b\u8def\u5f84\u4e0b\u6ca1\u6709\u6307\u5b9a\u7c7b\u7684\u6761\u4ef6\u4e0b<\/li>\n<li><code>@ConditionalOnProperty<\/code>\uff1a\u6307\u5b9a\u7684\u5c5e\u6027\u662f\u5426\u6709\u6307\u5b9a\u7684\u503c<\/li>\n<li><code>@ConditionalOnResource<\/code>\uff1a\u7c7b\u8def\u5f84\u662f\u5426\u6709\u6307\u5b9a\u7684\u503c<\/li>\n<li><code>@ConditionalOnExpression<\/code>\uff1a\u57fa\u4e8e SpEL \u8868\u8fbe\u5f0f\u4f5c\u4e3a\u5224\u65ad\u6761\u4ef6<\/li>\n<li><code>@ConditionalOnJava<\/code>\uff1a\u57fa\u4e8e Java \u7248\u672c\u4f5c\u4e3a\u5224\u65ad\u6761\u4ef6<\/li>\n<li><code>@ConditionalOnJndi<\/code>\uff1a\u5728 JNDI \u5b58\u5728\u7684\u6761\u4ef6\u4e0b\u5dee\u5728\u6307\u5b9a\u7684\u4f4d\u7f6e<\/li>\n<li><code>@ConditionalOnNotWebApplication<\/code>\uff1a\u5f53\u524d\u9879\u76ee\u4e0d\u662f Web \u9879\u76ee\u7684\u6761\u4ef6\u4e0b<\/li>\n<li><code>@ConditionalOnWebApplication<\/code>\uff1a\u5f53\u524d\u9879\u76ee\u662f Web \u9879 \u76ee\u7684\u6761\u4ef6\u4e0b<\/li>\n<\/ul>\n<h2>\u5982\u4f55\u5b9e\u73b0\u4e00\u4e2a Starter<\/h2>\n<p>\u5149\u8bf4\u4e0d\u7ec3\u5047\u628a\u5f0f\uff0c\u73b0\u5728\u5c31\u6765\u64b8\u4e00\u4e2a starter\uff0c\u5b9e\u73b0\u81ea\u5b9a\u4e49\u7ebf\u7a0b\u6c60<\/p>\n<p>\u7b2c\u4e00\u6b65\uff0c\u521b\u5efa<code>threadpool-spring-boot-starter<\/code>\u5de5\u7a0b<\/p>\n<p>\u7b2c\u4e8c\u6b65\uff0c\u5f15\u5165 Spring Boot \u76f8\u5173\u4f9d\u8d56<\/p>\n<pre><code class=\"language-xml\">&lt;parent&gt;\n    &lt;groupId&gt;org.springframework.boot&lt;\/groupId&gt;\n    &lt;artifactId&gt;spring-boot-starter-parent&lt;\/artifactId&gt;\n    &lt;version&gt;2.2.6.RELEASE&lt;\/version&gt;\n&lt;\/parent&gt;\n&lt;groupId&gt;cn.appblog&lt;\/groupId&gt;\n&lt;artifactId&gt;threadpool-spring-boot-starter&lt;\/artifactId&gt;\n&lt;version&gt;1.0.0-SNAPSHOT&lt;\/version&gt;\n\n&lt;dependencies&gt;\n    &lt;!-- \u5f15\u5165 Spring Boot Starter \u57fa\u7840\u5e93 --&gt;\n    &lt;dependency&gt;\n        &lt;groupId&gt;org.springframework.boot&lt;\/groupId&gt;\n        &lt;artifactId&gt;spring-boot-starter&lt;\/artifactId&gt;\n    &lt;\/dependency&gt;\n&lt;dependencies&gt;<\/code><\/pre>\n<p>\u7b2c\u4e09\u6b65\uff0c\u521b\u5efa<code>ThreadPoolAutoConfiguration<\/code><\/p>\n<pre><code class=\"language-java\">package cn.appblog;\n\nimport org.springframework.boot.autoconfigure.condition.ConditionalOnClass;\nimport org.springframework.context.annotation.Bean;\nimport org.springframework.context.annotation.Configuration;\n\nimport java.util.concurrent.ArrayBlockingQueue;\nimport java.util.concurrent.ThreadPoolExecutor;\nimport java.util.concurrent.TimeUnit;\n\n@Configuration\npublic class ThreadPoolAutoConfiguration {\n\n    @Bean\n    @Conditional0nClass(ThreadPoo1Executor.class) \/\/\u9700\u8981\u9879\u76ee\u4e2d\u5b58\u5728ThreadPoo1Executor\u7c7b\uff0c\u8be5\u7c7b\u4e3aJDK\u81ea\u5e26\uff0c\u6240\u4ee5\u4e00\u5b9a\u6210\u7acb\n    public ThreadPoolExecutor HyThreadPool() {\n        return new ThreadPoolExecutor(corePoolSize\uff1a10, maximumPoolSize: 10, keepAliveTime\uff1a10, TimeUnit.S\u00a3COWOS, new ArrayBlockingQueue(capacity: 108));\n    }\n}<\/code><\/pre>\n<p>\u7b2c\u56db\u6b65\uff0c\u5728<code>threadpool-spring-boot-starter<\/code>\u5de5\u7a0b\u7684<code>resources<\/code>\u5305\u4e0b\u521b\u5efa<code>META-INF\/spring.factories<\/code>\u6587\u4ef6<\/p>\n<pre><code class=\"language-java\">org.springframewonk.boot.autoconfigure.EnableAutoConfiguration=\\\ncn.appblog.ThreadPoolAutoConfiguration<\/code><\/pre>\n<p>\u7b2c\u4e94\u6b65\uff0c\u6700\u540e\u65b0\u5efa\u5de5\u7a0b\u5f15\u5165threadpool-spring-boot-starter<\/p>\n<pre><code class=\"language-java\">@SpringBootTest\n@RunWith(SpringRunner.class)\npublic class Test {\n    @Autowired\n    private ThreadPoolExecutor myThreadPool;\n\n    @Test\n    public void test() {\n        System.out.println(&quot;CorePoolSize=&quot; + myThreadPool.getCorePoolSize());\n    }\n}<\/code><\/pre>\n<p>\u6d4b\u8bd5\u901a\u8fc7\uff01\uff01\uff01<\/p>\n<h2>\u603b\u7ed3<\/h2>\n<p>Spring Boot \u901a\u8fc7<code>@EnableAutoConfiguration<\/code>\u5f00\u542f\u81ea\u52a8\u88c5\u914d\uff0c\u901a\u8fc7<code>SpringFactoriesLoader<\/code>\u6700\u7ec8\u52a0\u8f7d<code>META-INF\/spring.factories<\/code>\u4e2d\u7684\u81ea\u52a8\u914d\u7f6e\u7c7b\u5b9e\u73b0\u81ea\u52a8\u88c5\u914d\uff0c\u81ea\u52a8\u914d\u7f6e\u7c7b\u5176\u5b9e\u5c31\u662f\u901a\u8fc7<code>@Conditional<\/code>\u6309\u9700\u52a0\u8f7d\u7684\u914d\u7f6e\u7c7b\uff0c\u60f3\u8981\u5176\u751f\u6548\u5fc5\u987b\u5f15\u5165<code>spring-boot-starter-xxx<\/code>\u5305\u5b9e\u73b0\u8d77\u6b65\u4f9d\u8d56<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6bcf\u6b21\u95ee\u5230 Spring Boot\uff0c \u9762\u8bd5\u5b98\u975e\u5e38\u559c\u6b22\u95ee\u8fd9\u4e2a\u95ee\u9898\uff1a\u201c\u8bb2\u8ff0\u4e00\u4e0b SpringBoot \u81ea\u52a8\u88c5\u914d\u539f\u7406\uff1f [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[41],"tags":[444],"class_list":["post-2009","post","type-post","status-publish","format-standard","hentry","category-spring-boot","tag-spring-boot-starter"],"_links":{"self":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts\/2009","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/comments?post=2009"}],"version-history":[{"count":0,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts\/2009\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/media?parent=2009"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/categories?post=2009"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/tags?post=2009"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}