Learn about Jakarta Interceptors framework technical principles in the Java class library

Jakarta Interceptors is an important framework technology in the Java class library that plays a key role in enterprise -level application development.This article will introduce the principle of the Jakarta Interceptors framework and provide some Java code examples to help readers better understand and use this framework. First, let's find out what interceptors are.The interceptor is a design pattern for cutting -oriented programming (AOP), which allows developers to insert custom logic before and after the method call.The interceptor can be used in logging, performance monitoring, transaction management, etc. to enhance or modify the original method. Jakarta Interceptors provides a standardized interceptor solution and has become part of the Java EE 8 specification.It is widely used in Java enterprise -level applications to increase the maintenance and flexibility of code.The core concept of Jakarta Interceptors is the annotation and interceptor chain. First, we need to define an interceptor annotation.The following is an example: @Inherited @InterceptorBinding @Retention(RetentionPolicy.RUNTIME) @Target({ ElementType.TYPE, ElementType.METHOD }) public @interface LoggingInterceptor { } In this example,@LoggingInterceptor is a defined custom annotation, which is used to indicate a method or class that needs to be intercepted.Note must be marked with @InterceptorBinding and @RETENTION (RetentionPolicy.runtime) to ensure that it can take effect at runtime. Next, we need to implement a interceptor class that will process the method or class of the annotation mark.The following is an example: @LoggingInterceptor @Interceptor public class LoggingInterceptorImpl { @AroundInvoke public Object logMethodInvocation(InvocationContext context) throws Exception { // Insert logic before the method call System.out.println ("Method before calling:" + context.getMethod (). Getname ()); try { // Execute the original method Object result = context.proceed(); // Insert logic after the method calls System.out.println ("Method after calling:" + context.getMethod (). Getname ()); return result; } catch (Exception e) { // Insert logic when the method call is abnormal System.out.println ("Method call abnormal:" + e.getMessage ()); throw e; } } } In this example,@LoggingInterceptor is used to mark the commentary of the interceptor.@Interceptor annotation indicates that the LoggingInterceptorIMPL class is a interceptor.Through the @AnDinvoke annotation, we can define the logic inserted before and after the method call.In this example, we simply call the information calling information on the console. To use the Jakarta Interceptors framework, we need to bind the interceptor to the target class or method.The following is an example: @LoggingInterceptor public class ExampleService { public void someMethod() { System.out.println ("Execute some operations ..."); } } In this example, the ExampleService class is marked by @loggingInterceptor annotation, indicating that the method of this class will be affected by the loggingInterceptorImpl interceptor. When we call the method in the Exampleservice class, the interceptor will automatically intercept the call of the method and processed according to the defined logic. In summary, Jakarta Interceptors is an important Java framework technology that uses the concept of the interceptor to achieve cut -oriented programming.By defining the interceptor annotation and the realization of the interceptor class, developers can insert the behavior of custom logic to enhance or modify methods.The Jakarta Interceptors framework provides a standardized way to realize the interceptor, making the code more maintainable and flexible.By using Jakarta Internet, developers can better organize and manage enterprise -level applications.