Spring Cloud学习项目

JDK版本

1.8

Maven版本

3.5.3

Spring Boot版本

1.5.18.RELEASE

Spring Cloud版本

Edgware.SR5

SOA

Service-oriented architecture (SOA) is a style of software design where services are provided to the other components by application components, through a communication protocol over a network. The basic principles of service-oriented architecture are independent of vendors, products and technologies.A service is a discrete unit of functionality that can be accessed remotely and acted upon and updated independently, such as retrieving a credit card statement online.

微服务

Microservices are a software development technique—a variant of the service-oriented architecture (SOA) architectural style that structures an application as a collection of loosely coupled (松散耦合)services. In a microservices architecture, services are fine-grained and the protocols are lightweight. The benefit of decomposing(分解) an application into different smaller services is that it improves modularity. This makes the application easier to understand, develop, test, and become more resilient (有弹力)to architecture erosion(分解).It parallelizes development by enabling small autonomous(自治) teams to develop, deploy and scale their respective services independently.It also allows the architecture of an individual service to emerge(展现) through continuous refactoring.Microservices-based architectures enable continuous delivery and deployment.

Endpoint

• org.springframework.cloud.context.restart.RestartEndpoint
• org.springframework.cloud.context.restart.RestartEndpoint.PauseEndpoint
• org.springframework.cloud.context.restart.RestartEndpoint.ResumeEndpoint

Event

• java.util.EventObject
  • org.springframework.context.ApplicationEvent

Listener

• java.util.EventListener

  • org.springframework.context.ApplicationListener

    • org.springframework.boot.context.config.ConfigFileApplicationListener

      • org.springframework.boot.context.config.ConfigFileApplicationListener.Loader#load()
      • org.springframework.boot.env.PropertySourcesLoader#load(org.springframework.core.io.Resource, java.lang.String, java.lang.String, java.lang.String)

      读取SpringBoot配置文件

      优先级:Ordered.HIGHEST_PRECEDENCE + 10

    • org.springframework.cloud.bootstrap.BootstrapApplicationListener

      读取SpringCloud配置文件

      优先级:DEFAULT_ORDER = Ordered.HIGHEST_PRECEDENCE + 5

      BootstrapApplicationListener加载优先级高于SpringBoot的ConfigFileApplicationListener

    • org.springframework.boot.SpringApplication#prepareEnvironment方法调用

      将会触发ApplicationEnvironmentPreparedEvent事件,从而被org.springframework.cloud.bootstrap.BootstrapApplicationListener监听到,从而创建SpringCloud上下文

    • org.springframework.boot.SpringApplication#createApplicationContext方法创建SpringBoot应用上下文

      ApplicationEnvironmentPreparedEvent事件也将触发ConfigFileApplicationListener监听器

PropertySourceLoader

• org.springframework.boot.env.PropertySourceLoader
  • org.springframework.boot.env.PropertiesPropertySourceLoader
  • org.springframework.boot.env.YamlPropertySourceLoader

ApplicationContext

• org.springframework.context.ApplicationContext
  • org.springframework.context.ConfigurableApplicationContext
    • org.springframework.context.annotation.AnnotationConfigApplicationContext
    • org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext

Environment

• org.springframework.core.env.Environment

  • org.springframework.core.env.AbstractEnvironment

    • org.springframework.core.env.StandardEnvironment
    • org.springframework.web.context.support.StandardServletEnvironment
    • org.springframework.mock.env.MockEnvironment

  • org.springframework.core.env.ConfigurableEnvironment

    void setActiveProfiles(String... profiles);
    void addActiveProfile(String profile);
    void setDefaultProfiles(String... profiles);
    MutablePropertySources getPropertySources();
    Map<String, Object> getSystemProperties();
    Map<String, Object> getSystemEnvironment();
    void merge(ConfigurableEnvironment parent);

PropertySource

• org.springframework.core.env.ConfigurableEnvironment

  MutablePropertySources getPropertySources();

• org.springframework.core.env.MutablePropertySources implements PropertySources

• org.springframework.core.env.PropertySources extends Iterable<PropertySource<?>>

• org.springframework.core.env.PropertySource

  key就是env接口返回的JSON数据的key

  value是泛型

  • org.springframework.core.env.MapPropertySource
  • org.springframework.core.env.PropertiesPropertySource
  • org.springframework.core.env.CommandLinePropertySource

注意事项

由于BootstrapApplicationListener优先于ConfigFileApplicationListener加载,所以不能通过SpringBoot默认配置文件去修改SpringCloud特定地属性

修改SpringCloud配置(通过命令行)

• 关闭Bootstrap上下文

--spring.cloud.bootstrap.enabled=false

• 指定配置文件名称

--spring.cloud.bootstrap.name=spring-cloud

• 指定配置文件位置(默认位置为classpath根路径,同时需要指定配置文件名称)

--spring.cloud.bootstrap.location=classpath:cloud/spring-cloud.yml

命令行读取参数

• org.springframework.boot.SpringApplication

  • 第一步

  public static ConfigurableApplicationContext run(Object source, String... args) {
  		return run(new Object[] { source }, args);
  }

  • 第二步

  public static ConfigurableApplicationContext run(Object[] sources, String[] args) {
  		return new SpringApplication(sources).run(args);
  }

  • 第三步

  public ConfigurableApplicationContext run(String... args) {
  		StopWatch stopWatch = new StopWatch();
  		stopWatch.start();
  		ConfigurableApplicationContext context = null;
  		FailureAnalyzers analyzers = null;
  		configureHeadlessProperty();
  		SpringApplicationRunListeners listeners = getRunListeners(args);
  		listeners.starting();
  		try {
  			ApplicationArguments applicationArguments = new DefaultApplicationArguments(
  					args);
  			ConfigurableEnvironment environment = prepareEnvironment(listeners,
  					applicationArguments);
  			Banner printedBanner = printBanner(environment);
              // 省略代码...
             	if (this.logStartupInfo) {
                      new StartupInfoLogger(this.mainApplicationClass)
  						.logStarted(getApplicationLog(), stopWatch);
  			}
  			return context;
          } catch (Throwable ex) {
  			handleRunFailure(context, listeners, analyzers, ex);
  			throw new IllegalStateException(ex);
  		}
   }

  • 第四步

  private ConfigurableEnvironment prepareEnvironment(
  			SpringApplicationRunListeners listeners,
  			ApplicationArguments applicationArguments) {
      // Create and configure the environment
      ConfigurableEnvironment environment = getOrCreateEnvironment();
      configureEnvironment(environment, applicationArguments.getSourceArgs());
      listeners.environmentPrepared(environment);
      if (!this.webEnvironment) {
          environment = new EnvironmentConverter(getClassLoader())
              .convertToStandardEnvironmentIfNecessary(environment);
      }
      return environment;
  }

  • 第五步

  protected void configureEnvironment(ConfigurableEnvironment environment,
  			String[] args) {
      configurePropertySources(environment, args);
      configureProfiles(environment, args);
  }

  • 第六步

  protected void configurePropertySources(ConfigurableEnvironment environment,
  			String[] args) {
  		MutablePropertySources sources = environment.getPropertySources();
  		if (this.defaultProperties != null && !this.defaultProperties.isEmpty()) {
              sources.addLast(new MapPropertySource("defaultProperties", this.defaultProperties));
          }
      if (this.addCommandLineProperties && args.length > 0) {
          String name = CommandLinePropertySource.COMMAND_LINE_PROPERTY_SOURCE_NAME;
          if (sources.contains(name)) {
              PropertySource<?> source = sources.get(name);
              CompositePropertySource composite = new CompositePropertySource(name);
              composite.addPropertySource(new SimpleCommandLinePropertySource(
                  name + "-" + args.hashCode(), args));
              composite.addPropertySource(source);
              sources.replace(name, composite);
          }
          else {
              sources.addFirst(new SimpleCommandLinePropertySource(args));
          }
      }
  }

覆盖远程属性(Overriding the Values of Remote Properties)

• SpringCloud默认开启了远程属性覆盖

spring.cloud.config.allowOverride=true

• 通过Spring原生方式

@Configuration
public class CustomBootstrapConfiguration implements ApplicationContextInitializer {

    @Override
    public void initialize(ConfigurableApplicationContext context) {
        // 获取环境
        ConfigurableEnvironment environment = context.getEnvironment();
        // 获取属性资源
        MutablePropertySources propertySources = environment.getPropertySources();
        // 添加自定义属性
        Map<String, Object> source = new HashMap<>(8);
        source.put("lx.name", "xiangqian");
        source.put("lx.sex", "male");
        source.put("lx.age", 25);
        PropertySource mapPropertySource = new MapPropertySource("diyPersonBySpring", source);
        // 添加到指定属性资源key地前面(通过env接口查看key)
        propertySources.addBefore("applicationConfig: [classpath:/bootstrap.yml]", mapPropertySource);
    }
}

• 通过SpringCloud方式

@Configuration
public class CustomPropertySourceLocator implements PropertySourceLocator {

    @Override
    public PropertySource<?> locate(Environment environment) {
        // 代码类似于CustomBootstrapConfiguration的方式
        return new MapPropertySource("diyPropertyByCloud",
                Collections.singletonMap("lx.color", "blue"));
    }
}

• 配置spring.factories

org.springframework.cloud.bootstrap.BootstrapConfiguration=\
org.liangxiong.springcloud.config.CustomBootstrapConfiguration,\
org.liangxiong.springcloud.config.CustomPropertySourceLocator

项目组合关系

Spring Cloud配置入门

• cloud-config-introduction

普通配置服务器和客户端

• cloud-config-server-git
• cloud-config-client-git

Eureka客户端和服务端

• cloud-server-eureka
• cloud-client-eureka
• cloud-config-server-as-client-for-eureka(也是作为eureka客户端,同时作为配置中心)

Eureka高可用

• cloud-client-eureka-high-available
• cloud-server-eureka-high-available

Spring Cloud Consul与Eureka客户端集成

• cloud-client-consul
• consul本地安装应用程序(hostname:localhost,port:8500)

负载均衡

• cloud-server-eureka(注册中心)
• cloud-client-ribbon
• cloud-server-user(服务提供方)
• cloud-api-user

短路器

• cloud-client-ribbon
• cloud-server-user(服务提供方)
• cloud-api-user
• cloud-dashboard-hystrix
• cloud-server-eureka(注册中心)

服务调用

• cloud-client-ribbon(客户端包含:负载均衡/断路器/服务调用/服务发现/配置客户端)
• cloud-server-user(服务提供方)
• cloud-api-user(集成了feign)
• cloud-server-eureka(注册中心)
• cloud-config-server-as-client-for-eureka(配置中心)

自定义Cloud Stream Binder实现

• cloud-stream-binder-activemq
• cloud-client-ribbon
• cloud-server-user
• cloud-config-server-as-client-for-eureka
• cloud-server-eureka(注册中心)