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This article introduces how to transfer context between SpringBoot asynchronous threads, the content is very detailed, interested friends can refer to, hope to be helpful to you.

Context transfer requirements between asynchronous threads

In SpringBoot projects, @ Async is often used to start a child thread to complete asynchronous operations. The user information in the main thread needs to be passed to the child thread

Implement and enable asynchronous function

Add @ EnableAsync annotation to the startup class

@ EnableAsync@SpringBootApplicationpublic class Application {} configure async

Create a new configuration class, implement the AsyncConfigurer interface, and override the getAsyncExecutor method

@ Configurationpublic class AsyncConfig implements AsyncConfigurer {@ Override public Executor getAsyncExecutor () {ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor (); executor.setCorePoolSize (10); executor.setMaxPoolSize (50); executor.setThreadNamePrefix ("async-pool-"); / / this step is the key, asynchronous Task decorator executor.setTaskDecorator (new MyContextDecorator ()); executor.initialize (); return executor;}} configure the task decorator

Create a new asynchronous task decorator, implement the TaskDecorator interface, and override the decorate method

Public class MyContextDecorator implements TaskDecorator {@ Override @ Nonnull public Runnable decorate (@ Nonnull Runnable runnable) {/ / get the request information in the main thread (our user information is also included) RequestAttributes attributes = RequestContextHolder.getRequestAttributes (); return ()-> {try {/ / set the request information of the main thread to RequestContextHolder.setRequestAttributes (attributes) in the child thread / / execute the child thread, do not forget runnable.run ();} finally {/ / thread ends, clear this information, otherwise it may cause memory leak RequestContextHolder.resetRequestAttributes ();}};}

Add: RequestContextHolder is internally implemented based on ThreadLocal, so when using set get, it is bound to the current thread. Of course, the user's user information is not necessarily put in the RequestContextHolder, the reader can expand it.

At this point, you can get the Request information in the parent thread normally through the child thread started by @ Async.

Enable multithreaded security context unable to share problem between threads

Multi-thread add data in the project, mybatisplus metadata fill function, fill the creator, the data is from spring security SecurityContextHolder.getContext.getAuthentication, synchronous operation, can be obtained normally, and asynchronously execute spatio-temporal pointer exception.

Solution

Configure the security context global policy SecurityContextHolder.setStrategyName (SecurityContextHolder.MODE_INHERITABLETHREADLOCAL)

Principle

The default policy for Spring Security security context is the MODE_THREADLOCAL,ThreadLocal mechanism to save the security context for each consumer.

This means that as long as the logical execution for a consumer is in the same thread, the security context can be obtained by each method through the SecurityContextHolder tool, even if its security context is not passed as parameters between methods.

This way of using ThreadLocal is safe as long as the security context in ThreadLocal is cleared after processing the current consumer's request.

MODE_GLOBAL: all threads in JVM use the same security context

MODE_INHERITABLETHREADLOCAL: some applications will have their own thread creation, and it is hoped that these new threads will also be able to use the creator's security context. This effect can be achieved by configuring SecurityContextHolder as a MODE_INHERITABLETHREADLOCAL policy.

Result

Add to the configuration file:

@ PostConstructpublic void init () {SecurityContextHolder.setStrategyName (SecurityContextHolder.MODE_INHERITABLETHREADLOCAL);}

The @ PostConstruct annotation is thought by many to be provided by Spring. It's actually Java's own comment.

The note in Java: @ PostConstruct this annotation is used to modify a non-static void () method. Methods modified by @ PostConstruct will run when the server loads Servlet and will only be executed by the server once. PostConstruct is executed after the constructor and before the init () method.

Usually we use @ PostConstruct to annotate the order of execution of this annotation in the entire Bean initialization in the Spring framework:

Constructor (constructor)-> @ Autowired (dependency injection)-> @ PostConstruct (annotated method)

On the SpringBoot asynchronous thread transfer context is how to share here, I hope that the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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