Spring boot 项目启动过程中：
org.springframework.boot.SpringApplication#prepareEnvironment
当程序步入listeners.environmentPrepared(environment);这里后，就会读取配置文件中信息。
private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners,
ApplicationArguments applicationArguments) {
// Create and configure the environment
ConfigurableEnvironment environment = getOrCreateEnvironment();
configureEnvironment(environment, applicationArguments.getSourceArgs());
listeners.environmentPrepared(environment);
bindToSpringApplication(environment);
if (!this.isCustomEnvironment) {
environment = new EnvironmentConverter(getClassLoader()).convertEnvironmentIfNecessary(environment,
deduceEnvironmentClass());
}
ConfigurationPropertySources.attach(environment);
return environment;
}
这句代码不好调试listeners.environmentPrepared(environment);
但可以换一种方式，找到上图中的这个类：org.springframework.boot.env.OriginTrackedMapPropertySource
在断点处打上断点，就可以看到系统是如何运行的：下面是堆栈信息
在堆栈信息中，可以看到这个类：org.springframework.boot.context.config.ConfigFileApplicationListener
这个类里面的包含一些配置信息：
private static final String DEFAULT_PROPERTIES = "defaultProperties";
// Note the order is from least to most specific (last one wins)
private static final String DEFAULT_SEARCH_LOCATIONS = "classpath:/,classpath:/config/,file:./,file:./config/";
private static final String DEFAULT_NAMES = "application";
private static final Set<String> NO_SEARCH_NAMES = Collections.singleton(null);
private static final Bindable<String[]> STRING_ARRAY = Bindable.of(String[].class);
/**
* The "active profiles" property name.
*/
public static final String ACTIVE_PROFILES_PROPERTY = "spring.profiles.active";
/**
* The "includes profiles" property name.
*/
public static final String INCLUDE_PROFILES_PROPERTY = "spring.profiles.include";
/**
* The "config name" property name.
*/
public static final String CONFIG_NAME_PROPERTY = "spring.config.name";
/**
* The "config location" property name.
*/
public static final String CONFIG_LOCATION_PROPERTY = "spring.config.location";
一个properties. 一个yaml配置sourceloader
加载yaml文件的类是YamlPropertySourceLoader
public class YamlPropertySourceLoader implements PropertySourceLoader {
@Override
public String[] getFileExtensions() {
return new String[] { "yml", "yaml" };
}
@Override
public List<PropertySource<?>> load(String name, Resource resource) throws IOException {
if (!ClassUtils.isPresent("org.yaml.snakeyaml.Yaml", null)) {
throw new IllegalStateException(
"Attempted to load " + name + " but snakeyaml was not found on the classpath");
}
List<Map<String, Object>> loaded = new OriginTrackedYamlLoader(resource).load();
if (loaded.isEmpty()) {
return Collections.emptyList();
}
List<PropertySource<?>> propertySources = new ArrayList<>(loaded.size());
for (int i = 0; i < loaded.size(); i++) {
String documentNumber = (loaded.size() != 1) ? " (document #" + i + ")" : "";
propertySources.add(new OriginTrackedMapPropertySource(name + documentNumber, loaded.get(i)));
}
return propertySources;
}
}
注如果是云环境，则首先加载的是bootstrap.yml, environment也是StandardEnvironment,非servlet环境。这是和Spring boot有很大的不同，加载完成后，再嵌套一StandardServletEnvironment.
加载完成后，再嵌套一StandardServletEnvironment.