Javax Internet usage and precautions
Javax Internet usage and precautions
The Javax Interceptor API is a AOP (programming programming) mechanism in Java, which provides a way to intercept and processes before and after the implementation of the method.By using the Javax Interceptor API, we can apply some universal processing logic, such as log records, performance monitoring, etc., and apply it to multiple methods to improve the replication and maintenance of the code.
usage:
1. Define a interceptor class, implement javax.interceptor.interceptor interface, and rewrite the method.In these methods, we can write our own processing logic, such as printing logs before and after the method execution.
public class LoggingInterceptor implements Interceptor {
@Override
public Object intercept(InvocationContext context) throws Exception {
System.out.println("Method " + context.getMethod().getName() + " is called.");
Object result = context.proceed();
System.out.println("Method " + context.getMethod().getName() + " is completed.");
return result;
}
}
2. In the method or class that needs to be used, use@javax.interceptor.interceptors to comment that the interceptor to be used.Multiple interceptors can be specified at the same time, which will be executed in the specified order.
@Interceptors(LoggingInterceptor.class)
public class MyClass {
public void myMethod() {
// Some logic
}
}
Precautions:
1. The interceptor can only be used in EJB components and CDI Beans.Other types of Java classes (such as Pojos) cannot be annotated using interceptors.
2. The interceptor is intercepted before and after the method execution, but the constructor of the class cannot be intercepted.
3. The interceptor can use the @Aroundinvoke annotation to declare a method that will be executed before and after the interception method.The signature of this method must contain a parameter of a javax.interceptor.invocityContext type and return a value of an Object type.
4. The interceptor can continue to execute the interception method through the proceed () method provided by InvocationContext.
5. If you need to pass additional parameters to the interceptor, you can inject other dependencies by using @inject or @Resource on the interceptor class.
This is an example of using the Javax Interceptor API.By using the interceptor, we can uniformly processes the method without modifying the original code to improve the maintenance and reused of code.At the same time, when writing the interceptor, you should also pay attention to complying with the above precautions to ensure the correct use of the interceptor.
