The introduction of the use of Javax Internet
The introduction of the use of Javax Internet
Overview:
The Javax Interableptor API is part of the Java EE specification and is used to define and applied interceptors.The interceptor is a mechanism that performs additional logic before and after the method calls, which allows you to add general functions to the context without modifying the original code, such as logging, performance monitoring, transaction processing, etc.This article will introduce the basic concepts and usage of the Javax Interceptor API.
Definition of interceptor:
The interceptor is a Java class that realizes Javax.interCepptor.interCepTor interface.The interface defines an method Invoke (InvocationContext), which receives an InvoCATIONCONTExt object as a parameter to perform additional logic.
InvocationContext is an interface that contains the relevant information.It provides the ability to obtain target objects, getMethod () methods to obtain target methods, and getParameters () methods to obtain method parameters through the gettarget () method to obtain method parameters.By calling the process () method in the Invoke method in the interceptor implementation class, the original method can be performed.
Application of interceptor:
The following steps are required to use the interceptor in the Java library:
1. Create a class to implement the interceptor interface, for example::
public class LoggingInterceptor implements Interceptor {
@Override
public Object invoke(InvocationContext context) throws Exception {
System.out.println("Entering method: " + context.getMethod().getName());
// Execute the original method
Object result = context.proceed();
System.out.println("Exiting method: " + context.getMethod().getName());
return result;
}
}
2. Add @Interceptor annotation to the target class or method, apply the interceptor to the target class or method, for example:
@InterceptorBinding
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface Loggable {
}
3. Add @loggable annotation to the implementation class of the interceptor, indicating that the interceptor is applied to the class/method modified by @loggable annotations, for example:
@Loggable
public class MyClass {
public void myMethod() {
System.out.println("Executing myMethod...");
}
}
4. Create an interceptor class to manage the order order of the interceptor and the conditions of the interceptor application, such as:
@Interceptor
@Loggable
public class LoggingInterceptor {
@AroundInvoke
public Object logMethodEntry(InvocationContext context) throws Exception {
System.out.println("Entering method: " + context.getMethod().getName());
// Execute the original method
Object result = context.proceed();
System.out.println("Exiting method: " + context.getMethod().getName());
return result;
}
}
5. In the application configuration file, add the statement and call order of the interceptor, for example:
<interceptors>
<class>com.example.LoggingInterceptor</class>
</interceptors>
In this way, when calling MyClass's MyMethod method, LoggingInterceptor will perform the corresponding logic before and after the method calls.
Summarize:
Through the Javax Interceptor API, the interceptor can be used in the Java class library to achieve universal functions.The interceptor can be added to the code by defining the class to implement the interceptor interface, and apply @Interceptor annotation to the code in the target class or method.In the interceptor implementation class, by calling the method of the INVOCATIONCONTEXT object, the relevant information of the access method can be accessed, and the original method can be performed through the proceed () method.In the application configuration file, the interceptor's execution order can be determined by the configuration of the statement and call order of the interceptor.
The above is the introduction of the Javax Interceptor API in the Java class library and the explanation of related configurations.
