EnvironmentPostProcessor

SpringBoot支持动态的读取文件，留下的扩展接口org.springframework.boot.env.EnvironmentPostProcessor。这个接口是spring包下的，使用这个进行配置文件的集中管理，而不需要每个项目都去配置配置文件。这种方法也是springboot框架留下的一个扩展（可以自己去扩展）

demo

在/Users/naeshihiroshi/study/studySummarize/SpringBoot/（自己测试也可以随机在一个目录下建立一文件），目录下建立一个名为springboot.properties文件，

springboot.properties中定义一些配置，配置如下：

jdbc.root.user=zhihao.miao

jdbc.root.password=242312321

定义MyEnvironmentPostProcessor实现EnvironmentPostProcessor接口

@Componentpublic class MyEnvironmentPostProcessor implements EnvironmentPostProcessor {

@Override public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {

try{

InputStream inputStream = new FileInputStream("/Users/naeshihiroshi/study/studySummarize/SpringBoot/springboot.properties"); Properties properties = new Properties();

properties.load(inputStream);

PropertiesPropertySource propertiesPropertySource = new PropertiesPropertySource("my",properties); environment.getPropertySources().addLast(propertiesPropertySource);

}catch (IOException e){ e.printStackTrace(); } }}

在classpath定义一个META-INF文件夹然后在其下面先建spring.factories文件，在其中指定：

org.springframework.boot.env.EnvironmentPostProcessor=com.zhihao.miao.processor.MyEnvironmentPostProcessor‘

启动类测试：

@SpringBootApplication

public class Application {

public static void main(String[] args) {

ConfigurableApplicationContext context = SpringApplication.run(Application.class,args);

String username = context.getEnvironment().getProperty("jdbc.root.user");

String password = context.getEnvironment().getProperty("jdbc.root.password");

System.out.println("username==="+username);

System.out.println("password==="+password); context.close(); }}

EnvironmentPostProcessor接口官网说明

Allows for customization of the application's {

@link Environment} prior to the application context being refreshed.

允许定制应用的上下文的应用环境优于应用的上下文之前被刷新。（意思就是在spring上下文构建之前可以设置一些系统配置）

EnvironmentPostProcessor implementations have to be registered inMETA-INF/spring.factories, using the fully qualified name of this class as the key.EnvironmentPostProcessor的实现类必须要在META-INF/spring.factories文件中去注册，并且注册的是全类名。

EnvironmentPostProcessor processors are encouraged to detect whether Spring'sorg.springframework.core.Ordered Ordered interface has been implemented or if the @org.springframework.core.annotation.Order Order annotation is present and to sort instances accordingly if so prior to invocation.鼓励EnvironmentPostProcessor处理器检测Org.springframework.core.Ordered注解，这样相应的实例也会按照@Order注解的顺序去被调用。

顺道加一个官网上的说明：

Encrypting Properties

Spring Boot does not provide any built in support for encrypting property values, however, it does provide the hook points necessary to modify values contained in the Spring Environment. The EnvironmentPostProcessor interface allows you to manipulate the Environment before the application starts. See Section 76.3, “Customize the Environment or ApplicationContext Before It Starts” for details.If you’re looking for a secure way to store credentials and passwords, the Spring Cloud Vault project provides support for storing externalized configuration in HashiCorp Vault.

作者：二月_春风

链接：https://www.jianshu.com/p/be6c818fe6ff

來源：简书

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