spring源码之Environment

SpringApplication

public ConfigurableApplicationContext run(String... args) {

      ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments); //准备好了Environment，此刻Environment中都有哪些配置参数
      configureIgnoreBeanInfo(environment);


    }
    catch (Throwable ex) {
      handleRunFailure(context, ex, exceptionReporters, listeners);
      throw new IllegalStateException(ex);
    }

    try {
      listeners.running(context); //发布running中事件  ApplicationReadyEvent
    }
    catch (Throwable ex) {
      handleRunFailure(context, ex, exceptionReporters, null);
      throw new IllegalStateException(ex);
    }
    return context; // 返回ok的ConfigurableApplicationContext
  }

private ConfigurableEnvironment getOrCreateEnvironment() {
    if (this.environment != null) {
      return this.environment;
    }
    switch (this.webApplicationType) {
    case SERVLET:
      return new StandardServletEnvironment(); //servlet
    case REACTIVE:
      return new StandardReactiveWebEnvironment();
    default:
      return new StandardEnvironment();
    }
}

​AbstractEnvironment​

public abstract class AbstractEnvironment implements ConfigurableEnvironment {

    public AbstractEnvironment() {
        customizePropertySources(this.propertySources); //子类覆盖
    }

}


# 调用关系
# AbstractEnvironment 构造函数 -> StandardServletEnvironment.customizePropertySources -> StandardEnvironment.customizePropertySources

​StandardServletEnvironment​

public class StandardServletEnvironment extends StandardEnvironment implements ConfigurableWebEnvironment {

  /** Servlet context init parameters property source name: {@value}. */
  public static final String SERVLET_CONTEXT_PROPERTY_SOURCE_NAME = "servletContextInitParams";

  /** Servlet config init parameters property source name: {@value}. */
  public static final String SERVLET_CONFIG_PROPERTY_SOURCE_NAME = "servletConfigInitParams";

  /** JNDI property source name: {@value}. */
  public static final String JNDI_PROPERTY_SOURCE_NAME = "jndiProperties";



  @Override
  protected void customizePropertySources(MutablePropertySources propertySources) {
    propertySources.addLast(new StubPropertySource(SERVLET_CONFIG_PROPERTY_SOURCE_NAME)); //添加servletConfigInitParams propertysource
    propertySources.addLast(new StubPropertySource(SERVLET_CONTEXT_PROPERTY_SOURCE_NAME)); //添加servletContextInitParams  propertysource
    if (JndiLocatorDelegate.isDefaultJndiEnvironmentAvailable()) {
      propertySources.addLast(new JndiPropertySource(JNDI_PROPERTY_SOURCE_NAME)); //jndiProperties
    }
    super.customizePropertySources(propertySources); // 添加systemEnvironment systemProperties
  }

}

​StandardEnvironment ​

public class StandardEnvironment extends AbstractEnvironment {

  /** System environment property source name: {@value}. */
  public static final String SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME = "systemEnvironment";

  /** JVM system properties property source name: {@value}. */
  public static final String SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME = "systemProperties";



  @Override
  protected void customizePropertySources(MutablePropertySources propertySources) {
    propertySources.addLast( //系统参数 (比如vm options)
        new PropertiesPropertySource(SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME, getSystemProperties())); // addLast systemProperties
    propertySources.addLast( // 环境变量
        new SystemEnvironmentPropertySource(SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME, getSystemEnvironment())); // addLast systemEnvironment
  }

}