spring boot EnableConfigurationProperties ConfigurationProperties 怎么配合使用的

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先看我的demo实现

第一步： 配置ConfigurationProperties属性
@ConfigurationProperties(prefix = "redis.proxy")
@Getter
@Setter
public class RedisProperties {/** 服务器列表*/private List<String> configServerList;/** 可选配置，Redis运行模式，默认值singleton模式，枚举值Singleton,Sentinel,Sharded，从1.1.8-snapshot开始支持*/private RedisCacheMode mode;/** 可选配置（仅当模式为Sentinel时需要配置），表示master的名称*/private String masterName;private String password;
}
第二步： 配置bean
@Configuration
@EnableConfigurationProperties({RedisProperties.class})
public class RedisConfig {这里注意要将RedisProperties 作为入参传进来，并将属性set进行@Bean(initMethod = "init")@ConditionalOnMissingBeanpublic RedisCacheManager redisCacheManager(RedisProperties redisProperties){RedisCacheManager redisCacheManager = new RedisCacheManager();redisCacheManager.setConfigServerList(redisProperties.getConfigServerList());redisCacheManager.setMasterName(redisProperties.getMasterName());redisCacheManager.setMode(redisProperties.getMode());redisCacheManager.setPassword(redisProperties.getPassword());return redisCacheManager;}

源码分析
先看@EnableConfigurationProperties源码

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
这里导入了EnableConfigurationPropertiesImportSelector
@Import(EnableConfigurationPropertiesImportSelector.class)  
public @interface EnableConfigurationProperties {/*** Convenient way to quickly register {@link ConfigurationProperties} annotated beans* with Spring. Standard Spring Beans will also be scanned regardless of this value.* @return {@link ConfigurationProperties} annotated beans to register*/Class<?>[] value() default {};}

再看EnableConfigurationPropertiesImportSelector ，关于EnableConfigurationPropertiesImportSelector 是怎么被调用到的，请查看我的博客 https://blog.csdn.net/tszxlzc/article/details/88113819 （可以跳到博客最下面查看时序图了解全流程）

class EnableConfigurationPropertiesImportSelector implements ImportSelector {//下面的selectImports方法返回的类private static final String[] IMPORTS = {ConfigurationPropertiesBeanRegistrar.class.getName(),ConfigurationPropertiesBindingPostProcessorRegistrar.class.getName() };// selectImports方法会在org.springframework.context.annotation.ConfigurationClassParser#processImports方法里被调用@Overridepublic String[] selectImports(AnnotationMetadata metadata) {return IMPORTS;}

下图是通过debug查看org.springframework.context.annotation.ConfigurationClassParser#processImports方法调用EnableConfigurationPropertiesImportSelector 选择器的返回结果，正好是org.springframework.boot.context.properties.EnableConfigurationPropertiesImportSelector#IMPORTS数组中的类
在这里插入图片描述
说说这两个类吧
ConfigurationPropertiesBeanRegistrar 和ConfigurationPropertiesBindingPostProcessorRegistrar这两个类是处理
@ EnableConfigurationProperties和 @ConfigurationProperties注解的
ConfigurationPropertiesBeanRegistrar类核心源码如下
registerBeanDefinitions方法会在
org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader#loadBeanDefinitionsFromRegistrars方法中调用，而loadBeanDefinitionsFromRegistrars方法又会在org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader#loadBeanDefinitionsForConfigurationClass方法中调用，loadBeanDefinitionsForConfigurationClass方法又会在org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader#loadBeanDefinitions方法中被调用，loadBeanDefinitions方法又会在org.springframework.context.annotation.ConfigurationClassPostProcessor#processConfigBeanDefinitions方法中调用，processConfigBeanDefinitions方法又会在org.springframework.context.annotation.ConfigurationClassPostProcessor#postProcessBeanDefinitionRegistry方法中调用，
最后就倒退到了ConfigurationClassPostProcessor 这个bean后处理器（配置的入口）
ConfigurationClassPostProcessor 是怎么调到loadBeanDefinitions方法的看时序图，是在配置解析之后
在这里插入图片描述

public static class ConfigurationPropertiesBeanRegistrarimplements ImportBeanDefinitionRegistrar {//注册bean定义（ConfigurationProperties注解的bean）@Overridepublic void registerBeanDefinitions(AnnotationMetadata metadata,BeanDefinitionRegistry registry) {getTypes(metadata).forEach((type) -> register(registry,(ConfigurableListableBeanFactory) registry, type));}// 获取EnableConfigurationProperties注解的属性值，即ConfigurationProperties注解配置的属性文件private List<Class<?>> getTypes(AnnotationMetadata metadata) {MultiValueMap<String, Object> attributes = metadata.getAllAnnotationAttributes(EnableConfigurationProperties.class.getName(), false);return collectClasses((attributes != null) ? attributes.get("value"): Collections.emptyList());}private List<Class<?>> collectClasses(List<?> values) {return values.stream().flatMap((value) -> Arrays.stream((Object[]) value)).map((o) -> (Class<?>) o).filter((type) -> void.class != type).collect(Collectors.toList());}//  将ConfigurationProperties注解的属性文件注册到容器中private void register(BeanDefinitionRegistry registry,ConfigurableListableBeanFactory beanFactory, Class<?> type) {String name = getName(type);if (!containsBeanDefinition(beanFactory, name)) {registerBeanDefinition(registry, name, type);}}private String getName(Class<?> type) {ConfigurationProperties annotation = AnnotationUtils.findAnnotation(type,ConfigurationProperties.class);String prefix = (annotation != null) ? annotation.prefix() : "";return (StringUtils.hasText(prefix) ? prefix + "-" + type.getName(): type.getName());}private boolean containsBeanDefinition(ConfigurableListableBeanFactory beanFactory, String name) {if (beanFactory.containsBeanDefinition(name)) {return true;}BeanFactory parent = beanFactory.getParentBeanFactory();if (parent instanceof ConfigurableListableBeanFactory) {return containsBeanDefinition((ConfigurableListableBeanFactory) parent,name);}return false;}private void registerBeanDefinition(BeanDefinitionRegistry registry, String name,Class<?> type) {assertHasAnnotation(type);GenericBeanDefinition definition = new GenericBeanDefinition();definition.setBeanClass(type);registry.registerBeanDefinition(name, definition);}private void assertHasAnnotation(Class<?> type) {Assert.notNull(AnnotationUtils.findAnnotation(type, ConfigurationProperties.class),() -> "No " + ConfigurationProperties.class.getSimpleName()+ " annotation found on  '" + type.getName() + "'.");}}

总结：通过以上解析注册后，被ConfigurationProperties注册的属性bean最终被注册到spring容器中，属性bean就可以在被EnableConfigurationProperties注册的bean或者被@bean配置的bean实例化时被依赖注入（set注入或构造方法注入），其实最终发现EnableConfigurationProperties ConfigurationProperties都是配置了一个bean被使用，spring可真是面向bean编程啊

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