二 Spring Boot自动配置原理与实践

前言在之前的博文（Spring Boot自动配置原理与实践（一））中，已经介绍了Spring boot的自动配置的相关原理与概念，本篇主要是对自动配置的实践，即自定义Starter，对原理与概念加深理解。
本篇是我在实际工作中配置的用于弱口令检查的Starter，能方便嵌入到用户模块中的相关密码接口或方法，对弱口令进行检查并反馈，当然由于是公司内部代码，部分代码省略。
一、Starter实践1、配置Maven依赖Spring Boot自动化配置主要依赖如下两个包：

spring-boot-starter：打包starter主要依赖
configuration-processor：自动化配置主要依赖

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-configuration-processor</artifactId><optional>true</optional></dependency>2、创建实体类映射配置信息众所周知，SpringBoot Starter最厉害的就是可以通过最简单的properties/yaml文件配置，达到最终目的。配置文件需要通过解析生成对应的实体类
@ConfigurationProperties(prefix = "weak.password")public class CheckWeakPasswordProperties {private Boolean enabled = true;/*** 需要检查的URI数组*/private String[] checkUri;/*** 拦截检查的方式 1-interceptor 2-filter 3-aop*/private Integer checkType = 1;private String ip = "127.0.0.1";private String port = "8501";/*** 客户端名称*/private String clientName = "cloud-user";/*** 校验失败信息提示*/private String failureMessage = "密码等级不够";

...// 省略getter/setter方法其中prefix = "weak.password"，标明配置文件以“weak.password”开头的字段（对应实体类中的字段）都是需要解析的。在配置文件中输入前缀后，会进行提示说明

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3、定义配置类这一步非常关键，是自动装配的核心，通过配置文件配置灵活的参数产生相关的Bean，完成一系列初始化操作，关键的几个注解在这里就不解释了，具体可以看Spring Boot自动配置原理与实践（一）。
@Configuration@EnableConfigurationProperties(CheckWeakPasswordProperties.class)@ConditionalOnProperty(prefix = "weak.password", name = "enabled", havingValue = "https://tazarkount.com/read/true")public class CheckWeakPasswordAutoConfiguration {public CheckWeakPasswordAutoConfiguration() {}@Bean@ConditionalOnProperty(prefix = "weak.password", name = "checkType", havingValue = "https://tazarkount.com/read/2")public CheckPasswordInterceptor checkPasswordInterceptor(){return new CheckPasswordInterceptor();}@Bean@ConditionalOnProperty(prefix = "weak.password", name = "checkType", havingValue = "https://tazarkount.com/read/2")public CheckPasswordFilter checkPasswordFilter(){return new CheckPasswordFilter();}@Bean@ConditionalOnProperty(name = "weak.password.check-type", havingValue = "https://tazarkount.com/read/2")public CheckPasswordFilterConfig checkPasswordFilterConfig() {return new CheckPasswordFilterConfig();}@Bean@ConditionalOnProperty(prefix = "weak.password", name = "checkType", havingValue = "https://tazarkount.com/read/1")public CheckPasswordInterceptorConfig checkPasswordInterceptorConfig(){return new CheckPasswordInterceptorConfig();}}4、创建spring.factories文件　之前三步所有的操作都已经完成，那么将Starter当引入工程中是如何发现并自动装配的，这就需要spring.factory文件中标明，在resource/META-INF在新建spring.factory文件

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在该文件中指明AutoConfiguration的全Class路径

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这样打包的时候就能将spring.factory文件打包，项目启动的时候就会扫描并装配

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【二 Spring Boot自动配置原理与实践】同时生成spring-configuration-metadata.json文件，其内容就是提供配置文件智能化提示的
{"groups": [{"name": "weak.password","type": "com.yunchuang.password.properties.CheckWeakPasswordProperties","sourceType": "com.yunchuang.password.properties.CheckWeakPasswordProperties"}],"properties": [{"name": "weak.password.check-type","type": "java.lang.Integer","description": "拦截检查的方式 1-interceptor 2-filter 3-aop","sourceType": "com.yunchuang.password.properties.CheckWeakPasswordProperties","defaultValue": 1},{"name": "weak.password.check-uri","type": "java.lang.String[]","description": "需要检查的URI数组","sourceType": "com.yunchuang.password.properties.CheckWeakPasswordProperties"},{"name": "weak.password.client-name","type": "java.lang.String","description": "客户端名称","sourceType": "com.yunchuang.password.properties.CheckWeakPasswordProperties","defaultValue": "cloud-user"},{"name": "weak.password.enabled","type": "java.lang.Boolean","sourceType": "com.yunchuang.password.properties.CheckWeakPasswordProperties","defaultValue": true},{"name": "weak.password.failure-message","type": "java.lang.String","description": "校验失败信息提示","sourceType": "com.yunchuang.password.properties.CheckWeakPasswordProperties","defaultValue": "密码等级不够"},{"name": "weak.password.ip","type": "java.lang.String","sourceType": "com.yunchuang.password.properties.CheckWeakPasswordProperties","defaultValue": "127.0.0.1"},{"name": "weak.password.port","type": "java.lang.String","sourceType": "com.yunchuang.password.properties.CheckWeakPasswordProperties","defaultValue": "8501"}],"hints": []}二、自定义Starter使用首先引入自定义的Starter包依赖到相关应用中

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然后在配置文件中打开开关，或者某些条件才能开启自动配置，以我的代码示例举例的话，就是需要指定enabled为true

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其次可以观察启动的时候相关的Bean是否被自动装配，可以打开debug模式查看日志，或者在idea中查看Endpoints-->Beans-->application，可以看到相关的自动配置启动时加载了，并且相应的Bean也注入了。

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最后就是验证是否符合业务逻辑