springboot

文章目录

1. 1. 自动装配
2. 2. 嵌入式容器
3. 3. 为生产做准备
4. 4. springboot踩坑记录

springboot三大特性(2.1.6)

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自动装配

springboot核心注解 @SpringBootApplication。该注解是由下面三个注解组合而成的。

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@ComponentScan 默认会去扫描当前类所在包下面的所有类或者所有包，将这些类创建为spring所管理的bean。可以通过添加basePackages或者是basePackageClasses属性来指定扫描的包路径。

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@EnableAutoConfiguration

关于META-INF/spring-autoconfigure-metadata.properties文件与META-INF/spring.factories文件

# spring-autoconfigure-metadata.properties

#Tue Jun 18 23:47:55 GMT 2019
org.springframework.boot.autoconfigure.security.servlet.SecurityFilterAutoConfiguration.AutoConfigureAfter=org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration
org.springframework.boot.autoconfigure.data.cassandra.CassandraDataAutoConfiguration.Configuration=
org.springframework.boot.autoconfigure.data.neo4j.Neo4jBookmarkManagementConfiguration.Configuration=
org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration=
org.springframework.boot.autoconfigure.kafka.KafkaAnnotationDrivenConfiguration.Configuration=
org.springframework.boot.autoconfigure.influx.InfluxDbAutoConfiguration.ConditionalOnClass=org.influxdb.InfluxDB

# spring.factories，类似于 java 或者是 dubbo 中的 spi

# PropertySource Loaders
org.springframework.boot.env.PropertySourceLoader=\
org.springframework.boot.env.PropertiesPropertySourceLoader,\
org.springframework.boot.env.YamlPropertySourceLoader

# Run Listeners
org.springframework.boot.SpringApplicationRunListener=\
org.springframework.boot.context.event.EventPublishingRunListener

该注解的实现主要依赖于@Import注解引入的AutoConfigurationImportSelector类的selectImports方法。

// 注解定义-》关键点：AutoConfigurationImportSelector类
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@AutoConfigurationPackage
@Import(AutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {
	String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration";

	Class<?>[] exclude() default {};

	String[] excludeName() default {};
}

// 导入筛选实现类 AutoConfigurationImportSelector
public class AutoConfigurationImportSelector implements DeferredImportSelector, BeanClassLoaderAware, ResourceLoaderAware, BeanFactoryAware, EnvironmentAware, Ordered {
    ....
	// 若是 getAutoConfiguration 方法判断出用户关闭了自动装配，就返回该对象。    
    private static final AutoConfigurationEntry EMPTY_ENTRY = new AutoConfigurationEntry();    
        
	@Override
	public String[] selectImports(AnnotationMetadata annotationMetadata) {
        // 1. 判断是否可以导入，若是不可以导入，直接返回一个空数组 {}
		if (!isEnabled(annotationMetadata)) {
			return NO_IMPORTS;
		}
        // 2. 使用自动装配元信息加载类(AutoConfigurationMetadataLoader)的 loadMetadata 方法加载自动装配元信息。返回的AutoConfigurationMetadata对象包含了一个Properties类型的属性。(具体分析见 AutoConfigurationMetadataLoader的loadMetadata方法。)
		AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader.loadMetadata(this.beanClassLoader);
        // 3. 根据步骤2返回的自动装配元信息(AutoConfigurationMetadata)和 注解元信息(AnnotationMetadata)做进一步处理。
		AutoConfigurationEntry autoConfigurationEntry = getAutoConfigurationEntry(autoConfigurationMetadata,annotationMetadata);
		// 4. 转化未String数组返回
        return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());
	}
    
    // 判断是否可以导入的逻辑，若是用户在配置文件中配置了spring.boot.enableautoconfiguration属性未false，则不执行自动装配。默认执行自动装配。
    protected boolean isEnabled(AnnotationMetadata metadata) {
		if (getClass() == AutoConfigurationImportSelector.class) {
			return getEnvironment().getProperty(EnableAutoConfiguration.ENABLED_OVERRIDE_PROPERTY, Boolean.class, true);
		}
		return true;
	}
    
    // 获取自动装配的元素
    protected AutoConfigurationEntry getAutoConfigurationEntry(AutoConfigurationMetadata autoConfigurationMetadata, AnnotationMetadata annotationMetadata) {
        // 1. 若是判断出不能自动装配，注解返回一个 AutoConfigurationEntry 空对象
		if (!isEnabled(annotationMetadata)) {
			return EMPTY_ENTRY;
		}
        // 2. 获取到 EnableAutoConfiguration 注解的属性值
		AnnotationAttributes attributes = getAttributes(annotationMetadata);
        // 3. 读取候选装配组件-> EnableAutoConfiguration所对应的配置类
		List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes);
        // 4. 对这些配置类去重
		configurations = removeDuplicates(configurations);
        // 5. 获取用户配置的排除项(不自动装配)-> exclude,excludeName以及 spring.autoconfigure.exclude
		Set<String> exclusions = getExclusions(annotationMetadata, attributes);
        // 6. 检查需要排除的项是否合法，非法的将抛出异常
		checkExcludedClasses(configurations, exclusions);
        // 7. 将这些排除向从配置中移除
		configurations.removeAll(exclusions);
        // 8. 执行过滤
		configurations = filter(configurations, autoConfigurationMetadata);
        // 9. 触发相关事件
		fireAutoConfigurationImportEvents(configurations, exclusions);
        // 10. 返回
		return new AutoConfigurationEntry(configurations, exclusions);
	}
    
    // 读取给定注解元信息AnnotationMetadata的属性AnnotationAttributes
    protected AnnotationAttributes getAttributes(AnnotationMetadata metadata) {
        // 1. 获取到自动装配注解 EnableAutoConfiguration 的包名
        // 如：org.springframework.boot.autoconfigure.EnableAutoConfiguration
		String name = getAnnotationClass().getName();
        // 2. 获取注解 @EnableAutoConfiguration 的属性值，该注解包含了两个属性 exclude 和 excludeName
		AnnotationAttributes attributes = AnnotationAttributes.fromMap(metadata.getAnnotationAttributes(name, true));
		// 3. 返回注解属性 AnnotationAttributes
		return attributes;
	}
    // 返回 @EnableAutoConfiguration 注解的 Class
    protected Class<?> getAnnotationClass() {
		return EnableAutoConfiguration.class;
	}
    
    // 根据注解元信息 AnnotationMetadata 和注解属性 AnnotationAttributes 获取候选组件
    protected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) {
        // 调用 SpringFactoriesLoader 类的 loadFactoryNames 方法加载
        // 参数值分别为 EnableAutoConfiguration.class 和 ClassLoader，该方法返回的是 
        // EnableAutoConfiguration 所对应的所有配置类
		List<String> configurations = SpringFactoriesLoader.loadFactoryNames(getSpringFactoriesLoaderFactoryClass(),
				getBeanClassLoader());
		...
        // 返回该配置列表    
		return configurations;
	}
    // 返回EnableAutoConfiguration.class
    protected Class<?> getSpringFactoriesLoaderFactoryClass() {
		return EnableAutoConfiguration.class;
	}
    // 返回ClassLoader
    protected ClassLoader getBeanClassLoader() {
		return this.beanClassLoader;
	}
    
    // List列表去重-> list转为LinkedHashSet,然后在转为ArrayList
    protected final <T> List<T> removeDuplicates(List<T> list) {
		return new ArrayList<>(new LinkedHashSet<>(list));
	}
    
    // 获取排除的自动装配项
    protected Set<String> getExclusions(AnnotationMetadata metadata, AnnotationAttributes attributes) {
		Set<String> excluded = new LinkedHashSet<>();
        // @EnableAutoConfiguration注解的exclude属性值
		excluded.addAll(asList(attributes, "exclude"));
        // @EnableAutoConfiguration注解的excludeName属性值
		excluded.addAll(Arrays.asList(attributes.getStringArray("excludeName")));
        // 在 application.properties配置文件中配置的排除项
		excluded.addAll(getExcludeAutoConfigurationsProperty());
		return excluded;
	}
    
    protected final List<String> asList(AnnotationAttributes attributes, String name) {
		String[] value = attributes.getStringArray(name);
		return Arrays.asList((value != null) ? value : new String[0]);
	}
    // 获取配置文件中配置的 spring.autoconfigure.exclude 属性值
    private List<String> getExcludeAutoConfigurationsProperty() {
		if (getEnvironment() instanceof ConfigurableEnvironment) {
			Binder binder = Binder.get(getEnvironment());
			return binder.bind(PROPERTY_NAME_AUTOCONFIGURE_EXCLUDE, String[].class).map(Arrays::asList)
					.orElse(Collections.emptyList());
		}
		String[] excludes = getEnvironment().getProperty(PROPERTY_NAME_AUTOCONFIGURE_EXCLUDE, String[].class);
		return (excludes != null) ? Arrays.asList(excludes) : Collections.emptyList();
	}
    // 检查配置的排除项是否合法，需要参数：自动装配列表，排除项列表
    private void checkExcludedClasses(List<String> configurations, Set<String> exclusions) {
        // 1. 创建一个无效的排除项列表 invalidExcludes
		List<String> invalidExcludes = new ArrayList<>(exclusions.size());
        // 2. 循环遍历这些排除项，将无效的放到 invalidExcludes列表中
		for (String exclusion : exclusions) {
            // 排除项无效的判断依据：是对应类加载器加载并且没有包含在 configurations列表中
			if (ClassUtils.isPresent(exclusion, getClass().getClassLoader()) && !configurations.contains(exclusion)) {
				invalidExcludes.add(exclusion);
			}
		}
        // 3.若是排除项为非空，处理这些排除项
		if (!invalidExcludes.isEmpty()) {
			handleInvalidExcludes(invalidExcludes);
		}
	}   
    // 封装非法的排除项，并抛出运行时异常
    protected void handleInvalidExcludes(List<String> invalidExcludes) {
		StringBuilder message = new StringBuilder();
		for (String exclude : invalidExcludes) {
			message.append("\t- ").append(exclude).append(String.format("%n"));
		}
		throw new IllegalStateException(String.format(
				"The following classes could not be excluded because they are" + " not auto-configuration classes:%n%s",
				message));
	}
    
    
    
    /*************************执行fileter过滤*******************/
    private List<String> filter(List<String> configurations, AutoConfigurationMetadata autoConfigurationMetadata) {
        // 1. 获取开始的时间(纳秒)
		long startTime = System.nanoTime();
        // 2. 将候选组件转为数组
		String[] candidates = StringUtils.toStringArray(configurations);
        // 3. 创建一个boolean类型的数组，长度为candidates.length
		boolean[] skip = new boolean[candidates.length];
		boolean skipped = false;
        // 4. 循环遍历这些过滤器
		for (AutoConfigurationImportFilter filter : getAutoConfigurationImportFilters()) {
            // 设置相关的属性值
			invokeAwareMethods(filter);
            // 调用该过滤器的 match 方法，通过参数 candidates 和 autoConfigurationMetadata 来判断是否匹配该过滤器。
			boolean[] match = filter.match(candidates, autoConfigurationMetadata);
 			// 遍历 match 列表
			for (int i = 0; i < match.length; i++) {
                // 若是第 i 项需要被过滤，将该项的 skip 设置为 true，并将该项设置为 null, 并将 skipped标识设置为 true
				if (!match[i]) {
					skip[i] = true;
					candidates[i] = null;
					skipped = true;
				}
			}
		}
        // 若是没有出现被过滤的，直接返回原始的
		if (!skipped) {
			return configurations;
		}
        // 若是有出现被过滤的，将被过滤的去掉，返回未被过滤的
		List<String> result = new ArrayList<>(candidates.length);
		for (int i = 0; i < candidates.length; i++) {
			if (!skip[i]) {
				result.add(candidates[i]);
			}
		}
		...
		return new ArrayList<>(result);
	}
    // 获取自动装配导入过滤器
    protected List<AutoConfigurationImportFilter> getAutoConfigurationImportFilters() {
        // 1. 通过SpringFactoriesLoader加载这些过滤器
        // 该版本存在三个过滤器 OnBeanCondition OnClassCondition OnWebApplicationCondition
		return SpringFactoriesLoader.loadFactories(AutoConfigurationImportFilter.class, this.beanClassLoader);
	}
    
    private void invokeAwareMethods(Object instance) {
		if (instance instanceof Aware) {
			if (instance instanceof BeanClassLoaderAware) {
				((BeanClassLoaderAware) instance).setBeanClassLoader(this.beanClassLoader);
			}
			if (instance instanceof BeanFactoryAware) {
				((BeanFactoryAware) instance).setBeanFactory(this.beanFactory);
			}
			if (instance instanceof EnvironmentAware) {
				((EnvironmentAware) instance).setEnvironment(this.environment);
			}
			if (instance instanceof ResourceLoaderAware) {
				((ResourceLoaderAware) instance).setResourceLoader(this.resourceLoader);
			}
		}
	}  
    
    /*************************触发相关事件*******************/
    private void fireAutoConfigurationImportEvents(List<String> configurations, Set<String> exclusions) {
        // 1. 获取到 AutoConfigurationImportListener 列表
		List<AutoConfigurationImportListener> listeners = getAutoConfigurationImportListeners();
        // 2. 若是列表非空，循环遍历 AutoConfigurationImportListener, 触发事件
		if (!listeners.isEmpty()) {
            // 创建一个 AutoConfigurationImportEvent 事件
			AutoConfigurationImportEvent event = new AutoConfigurationImportEvent(this, configurations, exclusions);
			for (AutoConfigurationImportListener listener : listeners) {
				invokeAwareMethods(listener);
				listener.onAutoConfigurationImportEvent(event);
			}
		}
	}
    
    ...
}

/*********************AutoConfigurationMetadataLoader**********************/
/*
自动装配元信息加载类，该类在自动装配方面的作用就是加载了 PATH 路径下面的资源文件，并将其转换为 Properties 文件，该文件会做为 AutoConfigurationMetadata 对象的一个属性(properties)。
在自动装配注解 @EnableAutoConfiguration 的拦截装配类 AutoConfigurationImportSelector的 selectImports 方法的第二步，通过自动装配元信息加载类 AutoConfigurationMetadata 的 loadMetadata 方法来加载自动装配的一些元信息。
*/
final class AutoConfigurationMetadataLoader {
    
    // 自动装配元信息的存储路径
    protected static final String PATH = "META-INF/" + "spring-autoconfigure-metadata.properties";
    
    // 根据给定的 ClassLoader 获取到自动装配元信息
    public static AutoConfigurationMetadata loadMetadata(ClassLoader classLoader) {
		return loadMetadata(classLoader, PATH);
	}
 	
    // 根据给定的 ClassLoader 和 path 获取自动装配元信息
    static AutoConfigurationMetadata loadMetadata(ClassLoader classLoader, String path) {
		try {
            // 1. 读取到 PATH 路径下的资源文件，并将其以 key - value 的形式存储在 Properties文件中
			Enumeration<URL> urls = (classLoader != null) ? classLoader.getResources(path): ClassLoader.getSystemResources(path);
			Properties properties = new Properties();
			while (urls.hasMoreElements()) {
				properties.putAll(PropertiesLoaderUtils.loadProperties(new UrlResource(urls.nextElement())));
			}
            // 2. 返回 AutoConfigurationMetadata 对象，该对象持有 Properties:properties属性
			return loadMetadata(properties);
		} catch (IOException ex) {
			...
		}
	}
    
    // 通过给定的一个Properties对象，获取到一个 AutoConfigurationMetadata对象，该方法返回的是实现类为 PropertiesAutoConfigurationMetadata。
    static AutoConfigurationMetadata loadMetadata(Properties properties) {
		return new PropertiesAutoConfigurationMetadata(properties);
	}
    
    // AutoConfigurationMetadata 实现类 PropertiesAutoConfigurationMetadata 的定义，该类持有一个类型为 Properties 的属性 properties。
    private static class PropertiesAutoConfigurationMetadata implements AutoConfigurationMetadata {

		private final Properties properties;

		PropertiesAutoConfigurationMetadata(Properties properties) {
			this.properties = properties;
		}
    }  
}


/***************************SpringFactoriesLoader*****************/
/*
SpringFactoriesLoader是Spring Framework工厂机制的加载器，该类的作用是加载 FACTORIES_RESOURCE_LOCATION 路径下的资源
*/
public final class SpringFactoriesLoader {
    // 资源加载路径
    public static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";
    // 缓存，存储每个ClassLoader下的资源
    private static final Map<ClassLoader, MultiValueMap<String, String>> cache = new ConcurrentReferenceHashMap<>();
    
    // 通过给定的 Class 和 ClassLoader加载在配置文件中配置的类
	// 参数分别为EnableAutoConfiguration和ClassLoader
    public static List<String> loadFactoryNames(Class<?> factoryClass, @Nullable ClassLoader classLoader) {
        	// 1. 首先获取给定参数 Class<?> factoryClass 的类完全限定名
            // 如：org.springframework.boot.autoconfigure.EnableAutoConfiguration
            String factoryClassName = factoryClass.getName();
        	// 2. 返回参数 ClassLoader 对应 MultiValueMap 中键为 factoryClassName 的列表
            return loadSpringFactories(classLoader).getOrDefault(factoryClassName, Collections.emptyList());
    }
      
    // 根据给定的ClassLoader，返回一个 MultiValueMap 类型的资源
    private static Map<String, List<String>> loadSpringFactories(@Nullable ClassLoader classLoader) {
        // 1. 首先从缓存中获取
		MultiValueMap<String, String> result = cache.get(classLoader);
		if (result != null) {
			return result;
		}
        // 2.若是缓存中加载不到，就去 FACTORIES_RESOURCE_LOCATION 路径加载
		try {
            // 2.1 通过 ClassLoader和路径获取到 URL集合
			Enumeration<URL> urls = (classLoader != null ?
					classLoader.getResources(FACTORIES_RESOURCE_LOCATION) :
					ClassLoader.getSystemResources(FACTORIES_RESOURCE_LOCATION));
			result = new LinkedMultiValueMap<>();
            // 2.2 遍历这些URL集合
			while (urls.hasMoreElements()) {
				URL url = urls.nextElement();
				UrlResource resource = new UrlResource(url);
                // 2.3 将其转化为properties文件
				Properties properties = PropertiesLoaderUtils.loadProperties(resource);
				for (Map.Entry<?, ?> entry : properties.entrySet()) {
					String factoryClassName = ((String) entry.getKey()).trim();
					for (String factoryName : StringUtils.commaDelimitedListToStringArray((String) entry.getValue())) {
						result.add(factoryClassName, factoryName.trim());
					}
				}
			}
            // 2.4 将结果放入到缓存中去
			cache.put(classLoader, result);
			return result;
		} catch (IOException ex) {}
	}
    
    
    public static <T> List<T> loadFactories(Class<T> factoryClass, @Nullable ClassLoader classLoader) {
        // 确定使用的ClassLoader
		ClassLoader classLoaderToUse = classLoader;
		if (classLoaderToUse == null) {
			classLoaderToUse = SpringFactoriesLoader.class.getClassLoader();
		}
        // 调用 loadFactoryNames 返回 factoryClass 所对应的配置
		List<String> factoryNames = loadFactoryNames(factoryClass, classLoaderToUse);
        /// 创建一个集合，存放这些 class 的对象
		List<T> result = new ArrayList<>(factoryNames.size());
		for (String factoryName : factoryNames) {
			result.add(instantiateFactory(factoryName, factoryClass, classLoaderToUse));
		}
        // 排序后返回结果
		AnnotationAwareOrderComparator.sort(result);
		return result;
	} 
    // 通过反射实例化
    private static <T> T instantiateFactory(String instanceClassName, Class<T> factoryClass, ClassLoader classLoader) {
		try {
			Class<?> instanceClass = ClassUtils.forName(instanceClassName, classLoader);
			if (!factoryClass.isAssignableFrom(instanceClass)) {
				...
			}
			return (T) ReflectionUtils.accessibleConstructor(instanceClass).newInstance();
		}
		catch (Throwable ex) {
			...
		}
	}
}

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关于 AutoConfigurationImportFilter

@Order(Ordered.LOWEST_PRECEDENCE)
class OnBeanCondition extends FilteringSpringBootCondition implements ConfigurationCondition {
    ...
}

@Order(Ordered.HIGHEST_PRECEDENCE)
class OnClassCondition extends FilteringSpringBootCondition {
    ...
}

@Order(Ordered.HIGHEST_PRECEDENCE + 20)
class OnWebApplicationCondition extends FilteringSpringBootCondition {
    ...
}

abstract class FilteringSpringBootCondition extends SpringBootCondition
		implements AutoConfigurationImportFilter, BeanFactoryAware, BeanClassLoaderAware {
		
	// match方法，自动装配时会被自动调用	
	@Override
	public boolean[] match(String[] autoConfigurationClasses, AutoConfigurationMetadata autoConfigurationMetadata) {
		ConditionEvaluationReport report = ConditionEvaluationReport.find(this.beanFactory);
		ConditionOutcome[] outcomes = getOutcomes(autoConfigurationClasses, autoConfigurationMetadata);
		boolean[] match = new boolean[outcomes.length];
		for (int i = 0; i < outcomes.length; i++) {
			match[i] = (outcomes[i] == null || outcomes[i].isMatch());
			if (!match[i] && outcomes[i] != null) {
				logOutcome(autoConfigurationClasses[i], outcomes[i]);
				if (report != null) {
					report.recordConditionEvaluation(autoConfigurationClasses[i], this, outcomes[i]);
				}
			}
		}
		return match;
	}
}

关于 @AutoConfigurationPackage 注解

// 关于该注解定义
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Import(AutoConfigurationPackages.Registrar.class)
public @interface AutoConfigurationPackage {

}

public abstract class AutoConfigurationPackages {
    
    private static final String BEAN = AutoConfigurationPackages.class.getName();
    
    
    static class Registrar implements ImportBeanDefinitionRegistrar, DeterminableImports {

		@Override
		public void registerBeanDefinitions(AnnotationMetadata metadata, BeanDefinitionRegistry registry) {
			register(registry, new PackageImport(metadata).getPackageName());
		}

		@Override
		public Set<Object> determineImports(AnnotationMetadata metadata) {
			return Collections.singleton(new PackageImport(metadata));
		}

	}
    
    public static void register(BeanDefinitionRegistry registry, String... packageNames) {
		if (registry.containsBeanDefinition(BEAN)) {
			BeanDefinition beanDefinition = registry.getBeanDefinition(BEAN);
			ConstructorArgumentValues constructorArguments = beanDefinition.getConstructorArgumentValues();
			constructorArguments.addIndexedArgumentValue(0, addBasePackages(constructorArguments, packageNames));
		}
		else {
			GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
			beanDefinition.setBeanClass(BasePackages.class);
			beanDefinition.getConstructorArgumentValues().addIndexedArgumentValue(0, packageNames);
			beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
			registry.registerBeanDefinition(BEAN, beanDefinition);
		}
	}
    
    private static String[] addBasePackages(ConstructorArgumentValues constructorArguments, String[] packageNames) {
		String[] existing = (String[]) constructorArguments.getIndexedArgumentValue(0, String[].class).getValue();
		Set<String> merged = new LinkedHashSet<>();
		merged.addAll(Arrays.asList(existing));
		merged.addAll(Arrays.asList(packageNames));
		return StringUtils.toStringArray(merged);
	}
}

@SpringBootConfiguration

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核心事件

ApplicationEnvironmentPreparedEvent
ApplicationPreparedEvent
ApplicationStartingEvent
ApplicationReadyEvent
ApplicationFailedEvent

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系统属性 System:getProperties

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环境变量System:getEnv

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嵌入式容器

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为生产做准备

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springboot踩坑记录

1. 当我们在springboot的配置文件中将启动端口配置为随机端口时 server.port=0，我们使用下面的方式无法获取到启动的真正端口，该port的值任然为0。

@Value("${server.port}")
private int port;

可以通过使用下面这种方式来获取真正的启动端口

private final Environment environment;
public OtherController(Environment environment) {
	this.environment = environment;
}
private String getPort() {
	return environment.getProperty("local.server.port");
}