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This article mainly introduces "the running process of springboot2.0.6 and the run method of how to execute SpringApplication". In the daily operation, it is believed that many people have doubts about the running process of springboot2.0.6 and how to implement the run method of SpringApplication. The editor consulted all kinds of materials and sorted out simple and useful operation methods. I hope it will be helpful for you to answer the doubts about "the running process of springboot2.0.6 and how to implement the run method of SpringApplication"! Next, please follow the editor to study!

1. Startup flow chart

two。 Startup structure diagram

3. Run process 1. Initialize SpringApplication

Set up resourceload

By setting primarySources, you can load startup classes into the spring container

Determine the environment in which the current application should run, that is, get webApplicationType (program application type)

Load ApplicationContextInitializer in all META-INF/spring.factories under classpath

Load ApplicationListener in all META-INF/spring.factories under classpath

MainApplicationClass: find the class started by the main method

two。 Execute the run method of SpringApplication 1. Set the Java.awt.headless system variable 2. Get listener SpringApplicationRunListeners

Load all the META-INF/spring.factories files under classpath and get the collection of SpringApplicationRunListener, that is, load SpringApplicationRunListener in all spring.factories files

Call the starting method of SpringApplicationRunListener in turn, and finally call the onApplicationEvent method of ApplicationListener to issue the springboot startup event

3. Instantiate the ApplicationArguments object to get the application parameter 4. Create and set up ConfigurableEnvironment (configurable environment)

ConfigurableEnvironment: represents two meanings: one is profiles, which is used to describe which bean definitions is available; the other is properties, which is used to describe the configuration of the system, which may come from configuration files, JVM properties files, operating system environment variables, and so on.

Create ConfigurableEnvironment, that is, execute the getOrCreateEnvironment () method to create different Environment objects according to webApplicationType

Configure environment, that is, execute the configureEnvironment (XX) method. Mainly configure the runtime method parameters to environment

Set properties through configurePropertySources (environment, args)

Set profiles through configureProfiles (environment, args)

Execute the listeners.environmentPrepared (environment) method to issue the environmentPrepared event, that is, the onApplicationEvent event that invokes ApplicationListener

Execute the bindToSpringApplication method, that is, bind the current environment to the current springApplication

If it is not a web environment, but it is web's environment, convert it to a standard environment

Execute the ConfigurationPropertySources.attach (environment) method to put ConfigurationPropertySource into the first in the propertysource of environment

5. Print Banner6. Create a container for spring

Set different contextClass (class type of container) according to different webApplicationType, and then generate different container instance objects.

When generating a container instance, use the 'primary' constructor to instantiate a class for the Kotlin class. If not, use the default constructor to generate the instance object based on the resulting constructor. If the constructor is not public, we try to change and access the

7. Execute the getSpringFactorInstances method to get the concrete implementation class 8. Prepare the container, prepare the container before ready to refresh the container

Execute the context.setEnvironment (environment) method to set the environment of the spring container

Execute the postProcessApplicationContext (context) method to set beanNameGenerator (which is injected into the container without empty time) and resourceLoader (which loads objects without empty time)

Execute applyInitializers (context), call back all initialize of ApplicationContextInitializer to initialize context, and also detect whether each ApplicationContextInitializer accepts this type of container.

Execute listeners.contextPrepared (context), calling the contextPrepared method of SpringApplicationRunListener, but it is currently an empty implementation.

Register the bean springApplicationArguments and springBootBanner with the container in turn

GetAllSources is to get our primarySources and sources.

Load all resources into context, that is, call the load (context, sources.toArray (new Object [0])) method to create BeanDefinitionLoader, set the sources,annotatedReader,xmlReader,scanner of the loader, and add the ExcludeFilter of scanner (that is, the startup class of filtering springboot). If the user sets beanNameGenerator,resourceLoader,environment when starting, then replace the properties we set. At the same time, choose different load methods according to the type of source. Here we are load (class) to determine whether it is a component annotation. If so, register the startup class as bean through annotatedReader.

Execute the listeners.contextLoaded (context) method to determine whether ApplicationListener belongs to ApplicationContextAware, if so, assign the spring container to the listener, then assign the ApplicationListener to the spring container, and then call the onApplicationEvent method of ApplicationListener

9. Perform refreshContext (context) to refresh spring container 1. Refresh (context)

Perform the prepareRefresh () method to set up some initial operations. For example, enable activation, start date, initialize propertySource.

Get beanFactory

Execute prepareBeanFactory (beanFactory), set beanFactory's classloader,BeanExpressionResolver,PropertyEditorRegistrar, ApplicationContextAwareProcessor and ignore xxxxAware, registration dependency, and ApplicationListenerDetector

Automatic injection does not refer to @ AutoWire but refers to the default-autowire= "byType" of beans or the autowire= "byType" of bean, so that spring will go to the ioc container to find a type of similar type to inject into it. If the xxaware interface of spring is implemented, automatic injection will not record filterPropertyDescriptorsForDependencyCheck and delete the same attributes as the input parameter type.

ApplicationContextAwareProcessor: just pass applicationContext to ApplicationContextAwareProcessor to facilitate subsequent xxxAware calls

Ignore xxxxAware: ignore the automatic injection of properties in these Aware interface implementation classes of the same type as the input parameters in the interface set method, thus ensuring that the critical classes are generated by the spring container itself and not injected by us.

Registration dependency: that is, to specify that the automatically injected instances of some classes are instance objects specified by spring

ApplicationListenerDetector: detects implementation classes that implement ApplicationListener, because some implementation classes are not available through getBeanNamesForType.

Execute the postProcessBeanFactory (beanFactory) method to set ignoreDependencyInterface (ServletContextAware) and annotatedClasses,basePackages if present.

Execute the invokeBeanFactoryPostProcessors (beanFactory) method, get the BeanFactoryPostProcessor from the beanFactoryPostProcessors, then execute the postProcessBeanDefinitionRegistry of the BeanDefinitionRegistryPostProcessor type first, continue to obtain the bean of the BeanDefinitionRegistryPostProcessor type from the beanFactory, and then execute the postProcessBeanDefinitionRegistry, and execute the process according to PriorityOrdered,Ordered, the ordinary type, then give priority to the execution of the postProcessBeanFactory of the registryProcessors in the execution of the postProcessBeanFactory of the regularPostProcessors, and then obtain the PriorityOrdered,Ordered from BeanFactory, and the three types of BeanFactoryPostProcessor of the ordinary type are executed sequentially. Summary: from the previously added beanFactoryPostProcessor, first execute postProcessBeanDefinitionRegistry (if it is BeanDefinitionRegistryPostProcessor), then execute the postProcessBeanFactory method, then get the BeanFactoryPostProcessor from beanFactory and then execute postProcessBeanFactory, all in the order of PriorityOrdered,Ordered, the common type and three types.

Execute the egisterBeanPostProcessors method to get the BeanPostProcessor from beanFactory and register the BeanPostProcessor according to PriorityOrdered,Ordered, the common type, respectively

BeanPostProcessor and BeanFactoryPostProcessor: the former sets bean before and after initialization, while the latter can modify beanFactory or modify beanDefinition or add or initialize bean that is eager to initialize in advance.

Execute the initMessageSource () method to initialize our internationalized file

Execute the initApplicationEventMulticaster () method and set applicationEventMulticaster,spring to publish various events depending on him, which uses the same class as the springboot publishing event

Execute the onRefresh () method, initialize the bean in other subcontainer classes, and create a built-in container for spring (tomcat)

Execute the registerListeners () method, add the user setting applicationListeners, then get the ApplicationListener from beanFactory, and then publish the event that requires earlyApplicationEvents

Execute the inishBeanFactoryInitialization (beanFactory) method to instantiate the remaining bean of the non-lazy load

Execute the finishRefresh method, clean up the resource cache, initialize lifecycle, call the onrefresh of lifecycle, publish the event of ContextRefreshedEvent, activate JMX, start tomcat

2. Context.registerShutdownHook ()

Register a thread, which mainly points to the doclose method. The logic of the doClose method is: delete the current container from the applicationContexts collection, MBeanServer uninstall the MBean, issue the container close event, call the bean,destroyBeans,closeBeanFactory,onClose that implements the lifecycleProcessor interface: disable the built-in tomcat,active and set it to false

10. Execute the afterRefresh (context, applicationArguments) method (currently an empty implementation) 11. Execute the listeners.started (context) method to issue the started event 12. Execute the callRunners (context, applicationArguments) method

Get the ApplicationRunner and CommandLineRunner objects from the spring container, sort them in order, and call their run methods in a loop

13. Execute the handleRunFailure (context, ex, exceptionReporters, listeners) method

Handle different exception states, then call listeners.failed (context, exception) and close the spring container

14. Listeners.running (context)

Publish running events

4. Automatic configuration

The configuration module mainly uses SpringFactoriesLoader, that is, the Spring factory loader. The object provides the loadFactoryNames method. The input parameters are factoryClass and classLoader, that is, the factory class name in the above figure and the corresponding class loader need to be passed. According to the specified classLoader, the method will load the specified file under the search path of the class adder, that is, the spring.factories file, the incoming factory class is the interface, and the corresponding class in the file is the implementation class of the interface, or finally as the implementation class. Therefore, there are generally one-to-many collections of class names in the file. After obtaining the class names of these implementation classes, the loadFactoryNames method returns the collection of class names. After the method callers get these collections, they obtain the class objects and constructors of these classes through reflection, and finally generate instances.

At this point, the study on "the running process of springboot2.0.6 and how to implement the run method of SpringApplication" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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