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

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 = "true") public class CheckWeakPasswordAutoConfiguration { public CheckWeakPasswordAutoConfiguration() { } @Bean @ConditionalOnProperty(prefix = "weak.password", name = "checkType", havingValue = "2") public CheckPasswordInterceptor checkPasswordInterceptor(){ return new CheckPasswordInterceptor(); } @Bean @ConditionalOnProperty(prefix = "weak.password", name = "checkType", havingValue = "2") public CheckPasswordFilter checkPasswordFilter(){ return new CheckPasswordFilter(); } @Bean @ConditionalOnProperty(name = "weak.password.check-type", havingValue = "2") public CheckPasswordFilterConfig checkPasswordFilterConfig() { return new CheckPasswordFilterConfig(); } @Bean @ConditionalOnProperty(prefix = "weak.password", name = "checkType", havingValue = "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

在该文件中指明AutoConfiguration的全Class路径

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

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": [] }