Understand the annotations and application scenarios in the Javax Internet

JAX-RS (Java API For Restful Web Services) is part of the Java EE standard and is used to build a web service based on the REST architecture style.JAX-RS provides several annotations to simplify the work of developers in writing Web services.Among them, the Javax Interceptor API framework provides a set of annotations to define and configure the interceptor to realize the interception and processing of methods and resources. In the Javax Interceptor API, the following annotations are mainly included: 1. @Interceptor: This annotation is used to define an interceptor class. The interceptor class must implement javax.interCeptor.interceptor interface, and use @InterCepptor annotation to mark.The interceptor class can contain the front and rear processing logic, which is used to perform some additional operations before and after the method execution. 2. @interceptorBinding: This annotation is used to define a custom interceptor binding annotation.The interceptor binding annotation is used to mark the target class or method that needs to be intercepted by the interceptor. 3. @Aroundinvoke: This annotation is used to define a method to implement the specific logic of the interceptor.The method marked by @AnDinvoke annotation will be executed before and after the interception method. 4. @priority: This annotation is used to specify the execution order of the interceptor.There are multiple interceptors, and each interceptor can specify a priority.The high -priority interceptor will be executed first. The annotations of the Javax Interceptor API can be applied to multiple scenarios.Here are some common application scenarios: 1. Logging: By defining a interceptor, the log logic logic is applied to key methods to call, and it is used to record information such as parameters, exit and execution time of the method. 2. Safety certification: By defining a interceptor, intercept the method that needs to be verified, verify the request before the method execution, and refuse to access when the verification fails. 3. Performance surveillance: By defining a interceptor, performance statistics are performed before and after the method execution, such as indicators such as the execution time, memory occupation of the record method, and used to monitor and optimize system performance. Next, we use a simple example to demonstrate the use of the Javax Interceptor API: import javax.interceptor.AroundInvoke; import javax.interceptor.Interceptor; import javax.interceptor.InterceptorBinding; import javax.interceptor.InvocationContext; @InterceptorBinding @Retention(RetentionPolicy.RUNTIME) @Target({ElementType.TYPE, ElementType.METHOD}) public @interface LogExecutionTime { } @Interceptor @LogExecutionTime public class ExecutionTimeInterceptor { @AroundInvoke public Object logExecutionTime(InvocationContext context) throws Exception { long startTime = System.currentTimeMillis(); try { return context.proceed(); } finally { long executionTime = System.currentTimeMillis() - startTime; System.out.println("Method execution time: " + executionTime + "ms"); } } } @LogExecutionTime public class UserService { public void createUser(String username, String password) { // Create the logic of users } } In the above example, we define a customized interceptor binding annotation @logexecuTINTIME and marked the interceptor class ExecutionTimeInterceptor through the @Interceptor annotation.The logic of the interceptor is implemented through the logExecuctionTime method annotated by @AroundinVoke. This method will be executed before and after the interception method to record the execution time of the recording method. Finally, we used @logexecutionTime annotations on the CreateUser method of the UserService class to indicate that the method needs to be intercepted by the interceptor.Whenever this method is called, the interceptor will perform the execution time of the record method and output to the console. The above is the introduction of the annotation of the Javax Interceptor API framework and its application scenarios, and the explanation of an example code.These annotations can help developers more conveniently realize the logic of interception and processing, and improve the scalability and maintenance of the system.