Spring Boot application 文件加载

如何找到这个加载的过程

  1. 创建配置文件application.yml

  2. 全局搜索 yml

    image-20200319083048849

  3. 换成properties搜索

    image-20200319083140225

  4. 我们以yml为例打上断点开始源码追踪

看到调用堆栈

image-20200319083345067

  • 一步一步回上去看如何调用具体方法的

ConfigFileApplicationListener

  • 配置文件监听器

调用过程

image-20200319082131146

image-20200319082544653

org.springframework.boot.context.config.ConfigFileApplicationListener#addPropertySources

  1. protected void addPropertySources(ConfigurableEnvironment environment, ResourceLoader resourceLoader) {
  2.         RandomValuePropertySource.addToEnvironment(environment);
  3.         // 加载器加载信息
  4.         new Loader(environment, resourceLoader).load();
  5.     }

Loader

  • 配置资源加载器

构造方法

  1.         Loader(ConfigurableEnvironment environment, ResourceLoader resourceLoader) {
  2.             // 环境配置
  3.             this.environment = environment;
  4.             // 占位符处理器
  5.             this.placeholdersResolver = new PropertySourcesPlaceholdersResolver(this.environment);
  6.             // 资源加载器
  7.             this.resourceLoader = (resourceLoader != null) ? resourceLoader : new DefaultResourceLoader();
  8.             // 配置信息加载器初始化
  9.             this.propertySourceLoaders = SpringFactoriesLoader.loadFactories(PropertySourceLoader.class,
  10.                     getClass().getClassLoader());
  11.         }

  • 熟悉的老朋友this.propertySourceLoaders = SpringFactoriesLoader.loadFactories(PropertySourceLoader.class, getClass().getClassLoader())， 看看spring.factories有什么

    • 搜索目标: org.springframework.boot.env.PropertySourceLoader

      image-20200319084141748

image-20200319084151997

观察发现里面有一个YamlPropertySourceLoader和我们之前找 yml 字符串的时候找到的类是一样的。说明搜索方式没有什么问题。

image-20200319084357652

初始化完成，后续进行解析了

load 方法

  1.         void load() {
  2.             FilteredPropertySource.apply(this.environment, DEFAULT_PROPERTIES, LOAD_FILTERED_PROPERTY,
  3.                     (defaultProperties) -> {
  4.                         this.profiles = new LinkedList<>();
  5.                         this.processedProfiles = new LinkedList<>();
  6.                         this.activatedProfiles = false;
  7.                         this.loaded = new LinkedHashMap<>();
  8.                         // 初始化配置文件
  9.                         initializeProfiles();
  10.                         while (!this.profiles.isEmpty()) {
  11.                             Profile profile = this.profiles.poll();
  12.                             if (isDefaultProfile(profile)) {
  13.                                 addProfileToEnvironment(profile.getName());
  14.                             }
  15.                             load(profile, this::getPositiveProfileFilter,
  16.                                     addToLoaded(MutablePropertySources::addLast, false));
  17.                             this.processedProfiles.add(profile);
  18.                         }
  19.                         load(null, this::getNegativeProfileFilter, addToLoaded(MutablePropertySources::addFirst, true));
  20.                         addLoadedPropertySources();
  21.                         applyActiveProfiles(defaultProperties);
  22.                     });
  23.         }

initializeProfiles

  • 初始化private Deque<Profile> profiles; 属性
  • image-20200319084902957

load

  • org.springframework.boot.context.config.ConfigFileApplicationListener.Loader#load(org.springframework.boot.context.config.ConfigFileApplicationListener.Profile, org.springframework.boot.context.config.ConfigFileApplicationListener.DocumentFilterFactory, org.springframework.boot.context.config.ConfigFileApplicationListener.DocumentConsumer)
  1. private void load(Profile profile, DocumentFilterFactory filterFactory, DocumentConsumer consumer) {
  2.             getSearchLocations().forEach(
  3.                     // 本地路径
  4.                     (location) -> {
  5.                         // 是不是文件夹
  6.                         boolean isFolder = location.endsWith("/");
  7.                         // 文件名,默认application
  8.                         Set<String> names = isFolder ? getSearchNames() : NO_SEARCH_NAMES;
  9.                         // 循环加载
  10.                         names.forEach((name) -> {
  11.                             load(location, name, profile, filterFactory, consumer);
  12.                         });
  13.                     });
  14.         }
  • 资源路径可能性

image-20200319085446640

该方法采用循环每个路径下面都去尝试一遍

  • 中间过程省略，我们直接看最后的加载行为
    • org.springframework.boot.context.config.ConfigFileApplicationListener.Loader#loadDocuments
  1.         private List<Document> loadDocuments(PropertySourceLoader loader, String name, Resource resource)
  2.                 throws IOException {
  3.             // 文档的缓存key
  4.             DocumentsCacheKey cacheKey = new DocumentsCacheKey(loader, resource);
  5.             // 文档信息
  6.             List<Document> documents = this.loadDocumentsCache.get(cacheKey);
  7.             if (documents == null) {
  8.                 // 执行加载，将配置文件读取返回
  9.                 List<PropertySource<?>> loaded = loader.load(name, resource);
  10.                 // 数据转换
  11.                 documents = asDocuments(loaded);
  12.                 // 缓存设置
  13.                 this.loadDocumentsCache.put(cacheKey, documents);
  14.             }
  15.             return documents;
  16.         }

此处的loader.load()调用具体的 loader 实现类进行执行方法

yml 解析

  1.     @Override
  2.     public List<PropertySource<?>> load(String name, Resource resource) throws IOException {
  3.         if (!ClassUtils.isPresent("org.yaml.snakeyaml.Yaml", null)) {
  4.             throw new IllegalStateException(
  5.                     "Attempted to load " + name + " but snakeyaml was not found on the classpath");
  6.         }
  7.         // 将资源转换成集合对象
  8.         List<Map<String, Object>> loaded = new OriginTrackedYamlLoader(resource).load();
  9.         if (loaded.isEmpty()) {
  10.             return Collections.emptyList();
  11.         }
  12.         List<PropertySource<?>> propertySources = new ArrayList<>(loaded.size());
  13.         for (int i = 0; i < loaded.size(); i++) {
  14.             String documentNumber = (loaded.size() != 1) ? " (document #" + i + ")" : "";
  15.             // 放入返回结果中
  16.             propertySources.add(new OriginTrackedMapPropertySource(name + documentNumber,
  17.                     Collections.unmodifiableMap(loaded.get(i)), true));
  18.         }
  19.         return propertySources;
  20.     }

image-20200319090446231

  • PropertiesPropertySourceLoader解析同理不在次展开描述了

asDocuments

  1.         /**
  2.          * 将 {@link PropertySource} 转换成 {@link Document}
  3.          * @param loaded
  4.          * @return
  5.          */
  6.         private List<Document> asDocuments(List<PropertySource<?>> loaded) {
  7.             if (loaded == null) {
  8.                 return Collections.emptyList();
  9.             }
  10.             return loaded.stream().map(
  11.                     // 循环创建新对象
  12.                     (propertySource) -> {
  13.                         // 对象创建
  14.                         Binder binder = new Binder(ConfigurationPropertySources.from(propertySource),
  15.                                 this.placeholdersResolver);
  16.                         /**
  17.                          * 通过 {@link Binder} 将数据进行绑定，创建 {@link Document}进行返回
  18.                          */
  19.                         return new Document(propertySource, binder.bind("spring.profiles", STRING_ARRAY).orElse(null),
  20.                                 getProfiles(binder, ACTIVE_PROFILES_PROPERTY),
  21.                                 getProfiles(binder, INCLUDE_PROFILES_PROPERTY));
  22.                     }).collect(Collectors.toList());
  23.         }