思往事，惜流芳。易成伤。拟歌先敛，欲笑还颦，最断人肠。
SpringBoot的environment分析
Environment就是环境，是springboot运行的环境信息，简单理解为获取系统配置信息的对象；
那么这些配置信息可以从本地加载也可以从远程获取；
这里分析SpringBoot启动时加载配置设置环境信息的流程；
启动流程
- 启动
//启动时可以配置命令行参数，包装成ApplicationArguments
ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
//具体初始化环境
ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
- 配置环境信息
//根据系统类别选择创建的环境
ConfigurableEnvironment environment = getOrCreateEnvironment();
//将命令行参数配置到环境里
configureEnvironment(environment, applicationArguments.getSourceArgs());
//附加配置configurationProperties
ConfigurationPropertySources.attach(environment);
//真正的加载和解析配置添加到环境对象，具体事件机制实现
listeners.environmentPrepared(environment);
bindToSpringApplication(environment);
if (!this.isCustomEnvironment) {
environment = new EnvironmentConverter(getClassLoader()).convertEnvironmentIfNecessary(environment,
deduceEnvironmentClass());
}
ConfigurationPropertySources.attach(environment);
- 创建上下文环境
private ConfigurableEnvironment getOrCreateEnvironment() {
if (this.environment != null) {
return this.environment;
}
switch (this.webApplicationType) {
case SERVLET:
return new StandardServletEnvironment();
case REACTIVE:
return new StandardReactiveWebEnvironment();
default:
return new StandardEnvironment();
}
}
事件加载
- 启动时注册了监听器
org.springframework.boot.SpringApplicationRunListener=\
org.springframework.boot.context.event.EventPublishingRunListener
- 监听器触发
//监听者发布环境准备事件listeners.environmentPrepared(environment);
//类EventPublishingRunListener中发布
public void environmentPrepared(ConfigurableEnvironment environment) {
this.initialMulticaster
.multicastEvent(new ApplicationEnvironmentPreparedEvent(this.application, this.args, environment));
}
- 之前配置启动的监听器
# Application Listeners
org.springframework.context.ApplicationListener=\
org.springframework.boot.context.config.ConfigFileApplicationListener
...
- 具体触发器
public class ConfigFileApplicationListener implements EnvironmentPostProcessor, SmartApplicationListener, Ordered {
//触发应用事件
@Override
public void onApplicationEvent(ApplicationEvent event) {
if (event instanceof ApplicationEnvironmentPreparedEvent) {
onApplicationEnvironmentPreparedEvent((ApplicationEnvironmentPreparedEvent) event);
}
if (event instanceof ApplicationPreparedEvent) {
onApplicationPreparedEvent(event);
}
}
//环境配置的处理
private void onApplicationEnvironmentPreparedEvent(ApplicationEnvironmentPreparedEvent event) {
List<EnvironmentPostProcessor> postProcessors = loadPostProcessors();
//自己也是环境处理器
postProcessors.add(this);
AnnotationAwareOrderComparator.sort(postProcessors);
for (EnvironmentPostProcessor postProcessor : postProcessors) {
postProcessor.postProcessEnvironment(event.getEnvironment(), event.getSpringApplication());
}
}
}
- 环境处理器
org.springframework.boot.env.EnvironmentPostProcessor=\
org.springframework.boot.cloud.CloudFoundryVcapEnvironmentPostProcessor,\
org.springframework.boot.env.SpringApplicationJsonEnvironmentPostProcessor,\
//systemEnvironment处理器
org.springframework.boot.env.SystemEnvironmentPropertySourceEnvironmentPostProcessor,\
org.springframework.boot.reactor.DebugAgentEnvironmentPostProcessor
- ConfigFileApplicationListener的环境处理器
protected void addPropertySources(ConfigurableEnvironment environment, ResourceLoader resourceLoader) {
//添加随机值配置功能，${random.long}
RandomValuePropertySource.addToEnvironment(environment);
new Loader(environment, resourceLoader).load();
}
void load() {
//具体加载配置文件
FilteredPropertySource.apply(this.environment, DEFAULT_PROPERTIES, LOAD_FILTERED_PROPERTY,
(defaultProperties) -> {
this.profiles = new LinkedList<>();
this.processedProfiles = new LinkedList<>();
this.activatedProfiles = false;
this.loaded = new LinkedHashMap<>();
//查找配置的profiles
initializeProfiles();
//支持配置的多个profiles
while (!this.profiles.isEmpty()) {
Profile profile = this.profiles.poll();
if (isDefaultProfile(profile)) {
addProfileToEnvironment(profile.getName());
}
//具体查询具体配置的文件
load(profile, this::getPositiveProfileFilter,
addToLoaded(MutablePropertySources::addLast, false));
this.processedProfiles.add(profile);
}
load(null, this::getNegativeProfileFilter, addToLoaded(MutablePropertySources::addFirst, true));
//创建具体的MutablePropertySources，并放入 environment.getPropertySources中
addLoadedPropertySources();
//激活spring.profiles.include，spring.profiles.active
applyActiveProfiles(defaultProperties);
});
}
- load过程
private void load(String location, String name, Profile profile, DocumentFilterFactory filterFactory,DocumentConsumer consumer) {
Set<String> processed = new HashSet<>();
//遍历所有propertySourceLoaders，根据具体需要选择进行加载
for (PropertySourceLoader loader : this.propertySourceLoaders) {
for (String fileExtension : loader.getFileExtensions()) {
if (processed.add(fileExtension)) {
loadForFileExtension(loader, location + name, "." + fileExtension, profile, filterFactory,consumer);
}
}
}
}
属性资源加载器
- springFactorys中配置
org.springframework.boot.env.PropertySourceLoader=\
org.springframework.boot.env.PropertiesPropertySourceLoader,\
org.springframework.boot.env.YamlPropertySourceLoader
- 介绍一种Properties的资源加载器
public class PropertiesPropertySourceLoader implements PropertySourceLoader {
private static final String XML_FILE_EXTENSION = ".xml";
//支持的文件类型
@Override
public String[] getFileExtensions() {
return new String[] { "properties", "xml" };
}
//如果是该资源，创建propertyResources列表
@Override
public List<PropertySource<?>> load(String name, Resource resource) throws IOException {
Map<String, ?> properties = loadProperties(resource);
if (properties.isEmpty()) {
return Collections.emptyList();
}
return Collections
.singletonList(new OriginTrackedMapPropertySource(name, Collections.unmodifiableMap(properties), true));
}
//将上述符合条件的Resources返回key-value值
@SuppressWarnings({ "unchecked", "rawtypes" })
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();
}
}
加载顺序
- servlet环境首先加载标准参数
protected void customizePropertySources(MutablePropertySources propertySources) {
propertySources.addLast(new StubPropertySource(SERVLET_CONFIG_PROPERTY_SOURCE_NAME));
propertySources.addLast(new StubPropertySource(SERVLET_CONTEXT_PROPERTY_SOURCE_NAME));
if (JndiLocatorDelegate.isDefaultJndiEnvironmentAvailable()) {
propertySources.addLast(new JndiPropertySource(JNDI_PROPERTY_SOURCE_NAME));
}
super.customizePropertySources(propertySources);
}
//1:servletConfigInitParams
//2:servletContextInitParams
//3:jndiProperties
- 调用父类加载
protected void customizePropertySources(MutablePropertySources propertySources) {
propertySources.addLast(new PropertiesPropertySource("systemProperties", this.getSystemProperties()));
propertySources.addLast(new SystemEnvironmentPropertySource("systemEnvironment", this.getSystemEnvironment()));
}
//4:systemProperties
//5:systemEnvironment
- 加载ConfigFile中的Random
protected void addPropertySources(ConfigurableEnvironment environment, ResourceLoader resourceLoader) {
RandomValuePropertySource.addToEnvironment(environment);
new Loader(environment, resourceLoader).load();
}
//6:RandomValueProperty
- 加载命令行中
configureEnvironment(environment, applicationArguments.getSourceArgs());
//7:加入命令行参数
- 加载配置文件
//8:加载配置了profile中的配置
//9:加载默认的配置
while (!this.profiles.isEmpty()) {
Profile profile = this.profiles.poll();
if (isDefaultProfile(profile)) {
addProfileToEnvironment(profile.getName());
}
load(profile, this::getPositiveProfileFilter,addToLoaded(MutablePropertySources::addLast, false));
this.processedProfiles.add(profile);
}
load(null, this::getNegativeProfileFilter, addToLoaded(MutablePropertySources::addFirst, true));
addLoadedPropertySources();
applyActiveProfiles(defaultProperties);
使用
- 具体注入使用
@Value("${java.version}")
private String javaVersion;
- 使用环境注入
@Autowired
Environment environment;
@GetMapping("/javaVersion")
public String javaVersion(){
return environment.getProperty("java.version");
}