Use AOP Alliance to realize the horizontal section of the Java library

Use AOP ALLIANCE to implement the horizontal section focus point of the Java library AOP (facing surface programming) is a programming paradigm, which aims to solve the problems separated from the main business logic from the main business logic.AOP Alliance is an open source project for the Java environment. It provides a set of standard interfaces and specifications to share and interact between different AOP frameworks. Cross -cutting attention points refer to code fragments that repeatedly appear in a number of different places in one application, such as log records, security checks, and abnormal processing.Traditional object -oriented programming is not suitable for handling these horizontal sectaries, because they will scatter each part of the application, resulting in repeated code and difficulty in maintaining code.By using AOP, you can concentrate these concerns together, and by modifying them and abstracting, the code is easier to understand and maintain. AOP Alliance achieved standardization of AOP by defining a set of interfaces.These interfaces include aspect, Join Point, PointCut, notification (Advice), and weaving (weaving).Let's take a look at how to use AOP Alliance to achieve the horizontal sectaries of the Java library. First, we need to add the Aop Alliance to our project.It can be imported through building tools. Next, we need to define an aspect.The cut surface is an ordinary Java class that uses standard annotations in AOP Alliance to identify where it woven the cross -cutting point.For example, we can create a log cut and weave it into the method that needs to record the log. import org.aopalliance.intercept.MethodInterceptor; import org.aopalliance.intercept.MethodInvocation; public class LogAspect implements MethodInterceptor { @Override public Object invoke(MethodInvocation methodInvocation) throws Throwable { System.out.println("Before method: " + methodInvocation.getMethod().getName()); Object result = methodInvocation.proceed(); System.out.println("After method: " + methodInvocation.getMethod().getName()); return result; } } In the above example, the Logaspect class implements the MethodInterceptor interface, which defines the logic of the logic before and after the method calls.In the INVOKE method, we can write custom horizontal cutting logic.In this example, we simply print the name of the method before and after the method call. Finally, we need to weave the cut surface into our code.This can be completed by the weaving mechanism provided by the AOP Alliance framework.Weaving can be performed during compilation, when loading or running. import org.aopalliance.aop.Advice; import org.aopalliance.intercept.MethodInterceptor; import org.springframework.aop.framework.ProxyFactory; public class Main { public static void main(String[] args) { // Create the target object UserService userService = new UserServiceImpl(); // Create cut surface MethodInterceptor logAspect = new LogAspect(); // Create an advice object Advice advice = logAspect; // Create proxy factories ProxyFactory proxyFactory = new ProxyFactory(); proxyFactory.setTarget(userService); proxyFactory.addAdvice(advice); // Get the proxy object UserService proxy = (UserService) proxyFactory.getProxy(); // Use the proxy object to call the target method proxy.addUser("John Doe"); } } In the above examples, we first created a target object Userservice, and then created the logaspect surface and advice objects.Next, we used ProxyFactory to create a proxy factory and bind the target objects and cut surfaces into the factory.Finally, we obtained the proxy object through the getProxy method and used it to call the target method. To sum up, using AOP Alliance can more easily achieve the horizontal section of the Java library.We only need to define a cut surface and weave it into our code to achieve centralized management of cross -section attention points such as log records and security checks.