Introduction to JAKARTA Interceptors framework in Java Library

The Jakarta Interceptors framework is an important technology in the Java class library. It provides an interceptor-based method to achieve ASPECT-OrIiented Programming (AOP).In this article, we will introduce the principle of the Jakarta Interceptors framework and better understand it through some Java code examples. 1. The basic concept of Jakarta Interceptors The interceptor is a mechanism that inserts a specific logic before and after executing the target method.It can capture the method to call and perform additional processing before and after the method execution.The Jakarta Interceptors framework allows us to insert specific behaviors by defining the interceptor. These behaviors can be a common focus on multiple application modules, such as transaction management and log records. 2. The working principle of Jakarta Internet The Jakarta Interceptors framework is implemented based on the decorative mode.In the application, we can bind the interceptor to the target method and perform the logic defined by the interceptor before and after calling the target method. First of all, we need to define an interceptor class that implements the Interceptor interface.The following is a simple example: class LoggingInterceptor implements Interceptor { @Override public Object invoke(InvocationContext ctx) throws Exception { // The logic before executing the target method System.out.println ("Before the target method"); // Call the target method Object result = ctx.proceed(); // Logic after executing the target method System.out.println ("After the target method"); return result; } } In the above example, we define a loggingInterceptor interceptor and implement its Invoke method.This method will be executed before and after the target method is called. Next, we need to bind the interceptor to the target method.The Jakarta Interceptors framework provides a variety of binding methods, such as manually binding through annotations or manually in the code. The example of binding through annotations is as follows: @Interceptors(LoggingInterceptor.class) class MyClass { public void myMethod() { // The logic of the target method System.out.println ("Performing Target Method"); } } In the above example, we added @Interceptors annotations to the MyMethod method and specified the LoggingInterCector interceptor class.In this way, when the Mymethod method is called, the INVOKE method of LoggingInterceptor is automatically executed. 3. The application scenario of Jakarta Internet Through the Jakarta Interceptors framework, we can easily implement many general functions, such as transaction management, log records, security verification, etc.By drawing these universal functions into the interceptor, we can achieve higher -level code reuse and modularization. For example, we can create a transaction from the motion processing method of a transaction management interceptor, instead of expressing the transaction management code in each method. class TransactionInterceptor implements Interceptor { @Inject private TransactionManager transactionManager; @Override public Object invoke(InvocationContext ctx) throws Exception { // Open transaction transactionManager.beginTransaction(); try { // Execute the target method Object result = ctx.proceed(); // Submit a transaction transactionManager.commit(); return result; } catch (Exception e) { // Roll back transactions transactionManager.rollback(); throw e; } } } Through the above example code, we can see the simple implementation principle of the Jakarta Interceptors framework and its application in AOP programming.By defining the interceptor and binding it into the target method, we can easily insert the logic we need before and after the goal method execution.This can greatly enhance the maintenance and reuse of the code, while reducing the degree of code repetition.