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Spring Boot的properties配置文件读取

我在自己写点东西玩的时候需要读配置文件,又不想引包,于是打算扣点Spring Boot读取配置文件的代码出来,当然只是读配置文件没必要这么麻烦,不过反正闲着也是闲着,扣着玩了。
具体启动过程以前的博客写过Spring Boot启动过程(一),这次入口在SpringApplication类中:
    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; }

  关于监听器的过程在开头说的那篇的一系列中也说的挺细的,这里不介绍了:

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   都是监听器相关的部分,略了,SpringApplicationRunListeners类中:

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

   EventPublishingRunListener:

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  onApplicationEnvironmentPreparedEvent事件触发org\springframework\boot\spring-boot\2.0.0.BUILD-SNAPSHOT\spring-boot-2.0.0.BUILD-20170421.122111-547-sources.jar!\org\springframework\boot\context\config\ConfigFileApplicationListener.java监听器执行:

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 现在这个postProcessors中包含Json之类其他的监听器,不过我现在只想扣出properties的代码,别的先略过,反正其实也没什么,本来也是想看看它的思路,扣着玩,不要太在意。

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

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        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();

   下面就是真正加载了配置文件的load方法了,先是初始化PropertySourcesLoader和一些临时的集合:

            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));

  这些集合其实如果没配置Profile基本是没用的,这东西现在已经很少用到了,这个环境当然是没配的:

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  主要是下面这部分:

                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);
                        }
                    }
                }

   就是去指定目录下去找各种以application为名字的指定类型的配置文件:

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   我只关心application.properties,它是上面循环中的一次,走进了doLoadIntoGroup方法的下面那句:

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    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();
    }

   这个resource其实只是封装了一下InputStream,具体的读取。。。反正也没啥特别的读法:

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  读出的key和value放在Map<String, OriginTrackedValue>:

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

   以上。

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Spring Boot的properties配置文件读取