Frequently Asked Questions: Javax Interceptor API's common questions in the development of Java libraries
Frequently Asked Questions: Javax Interceptor API's common questions in the development of Java libraries
preface:
Javax Interceptor API is an important feature of Java for the interceptor function.In the development of the Java library, the interceptor can be applied to various levels, including the control layer, business layer, and durable layer, which is used to achieve logging, authority verification, performance monitoring and other functions.This article will answer common questions in the development of using the Javax Interceptor API.
Question 1: What is Javax Internetor API?
The Javax Interceptor API is a set of API defined in the Java EE specification for the interceptor function.The interceptor is a method of cutting -oriented programming that allows developers to perform additional logic such as before and after the method execution, abnormal throwing.Javax Interceptor API provides annotations and interfaces to define and realize interceptors.
Question 2: How to use the Javax Interceptor API to add a block?
To use the Javax Interceptor API to add a interceptor, you need to follow the steps below:
1. Create a Java class to implement the interface of `javax.interceptor.invocontext`.This interface contains the context information of the method execution, such as interception methods, method parameters, etc.
2. Use the `@Internetor` annotation on the interceptor class, indicating that this is a interceptor class.
3. Use the annotation of a interceptor binding type with the `@InternetorBinding` annotation to identify the target category and method of the interceptor.
4. Define the entry point in the interceptor class, even if the method is marked with a method of the annotation of `@aroundinvoke` as the execution logic of the interceptor.
5. Use the `@Internetors` annotation on the target class or method, specify the interceptor to be applied.
Question 3: How does the Javax Interceptor API implement the log record?
To use the Javax Interceptor API to implement the log record, you can follow the steps below:
1. Create a interceptor class and use the `@Internetor` annotation on the class.
2. Use the@InternetorBinding `annotation to define a interceptor binding type, specify the` @RETENTION (Runtime) `in the annotation, so that the annotation information can be kept at runtime.
3. Define the entry point method in the interceptor class, and use the method of `@aroundinvoke` in the method.
4. In the entry point method, use the `InvocationContext` object to obtain the interception method object object.
5. The method name of the method of use the method of use the method object to obtain the method name, and combine other information that needs to be recorded to record the log file or output to the console.
Question 4: What are the configuration files of the Javax Internetor API?
The configuration file of the Javax Interceptor API is `Beans.xml`, located in the` meta-inf` directory of the project.This file is used to configure the enlightenment and disability of the interceptor, as well as the order of the specified interceptor class.In the `Beans.xml`, you can use the` interceptors` element to configure the interceptor.
The example code and configuration file are as follows:
import javax.interceptor.AroundInvoke;
import javax.interceptor.Interceptor;
import javax.interceptor.InvocationContext;
@Interceptor
@LoggingInterceptorBinding
public class LoggingInterceptor {
@AroundInvoke
public Object logMethodCall(InvocationContext context) throws Exception {
System.out.println("Method called: " + context.getMethod().getName());
// Execute other log record logic
return context.proceed();
}
}
import javax.interceptor.InterceptorBinding;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@InterceptorBinding
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
public @interface LoggingInterceptorBinding {
}
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/beans_1_1.xsd"
bean-discovery-mode="all">
<interceptors>
<class>com.example.LoggingInterceptor</class>
</interceptors>
</beans>
Summarize:
In the development of the Java class library, the Javax Interceptor API is an important feature to achieve the interceptor function.This article answers the common questions in the development of the Javax Interceptor API for development, including the concept, usage method, implementation log records, and configuration files of the Javax Interceptor API.Through reasonable use of the Javax Interceptor API, more flexible and reusable code can be achieved.
