Spring Boot的properties配置文件读取

  private ConfigurableEnvironment prepareEnvironment(
      SpringApplicationRunListeners listeners,
      ApplicationArguments applicationArguments) {
    // Create and configure the environment
    ConfigurableEnvironment environment = getOrCreateEnvironment();
    configureEnvironment(environment, applicationArguments.getSourceArgs());

　　　　//此处读取
    listeners.environmentPrepared(environment);

    if (isWebEnvironment(environment)
        && this.webApplicationType == WebApplicationType.NONE) {
      environment = convertToStandardEnvironment(environment);
    }
    return environment;
  }

  public void environmentPrepared(ConfigurableEnvironment environment) {
    for (SpringApplicationRunListener listener : this.listeners) {
      listener.environmentPrepared(environment);
    }
  }

  protected void addPropertySources(ConfigurableEnvironment environment,
      ResourceLoader resourceLoader) {
    RandomValuePropertySource.addToEnvironment(environment);
    new Loader(environment, resourceLoader).load();
  }

    Loader(ConfigurableEnvironment environment, ResourceLoader resourceLoader) {
      this.environment = environment;
      this.resourceLoader = resourceLoader == null ? new DefaultResourceLoader()
          : resourceLoader;
    }

    this.classLoader = ClassUtils.getDefaultClassLoader();
    //其实也就是Thread.currentThread().getContextClassLoader();

      this.propertiesLoader = new PropertySourcesLoader();
      this.activatedProfiles = false;
      this.profiles = Collections.asLifoQueue(new LinkedList<Profile>());
      this.processedProfiles = new LinkedList<>();

      // Pre-existing active profiles set via Environment.setActiveProfiles()
      // are additional profiles and config files are allowed to add more if
      // they want to, so don't call addActiveProfiles() here.
      Set<Profile> initialActiveProfiles = initializeActiveProfiles();
      this.profiles.addAll(getUnprocessedActiveProfiles(initialActiveProfiles));

        for (String location : getSearchLocations()) {
          if (!location.endsWith("/")) {
            // location is a filename already, so don't search for more
            // filenames
            load(location, null, profile);
          }
          else {
            for (String name : getSearchNames()) {
              load(location, name, profile);
            }
          }
        }

  private Map<String, ?> loadProperties(Resource resource) throws IOException {
    String filename = resource.getFilename();
    if (filename != null && filename.endsWith(XML_FILE_EXTENSION)) {
      return (Map) PropertiesLoaderUtils.loadProperties(resource);
    }
    return new OriginTrackedPropertiesLoader(resource).load();
  }

  private void put(Map<String, OriginTrackedValue> result, String key,
      OriginTrackedValue value) {
    if (!key.isEmpty()) {
      result.put(key, value);
    }
  }