Using Interceptor

Interceptors are like Servlet Filters somehow, but they are managed by IoC container. WebWind will get all interceptors from IoC container automatically. Interceptor can be used to do transaction, logging, and other things.

It is easy to define an interceptor:

import org.expressme.webwind.*;

@InterceptorOrder(0)
public class PerformanceInterceptor implements Interceptor {
    public void intercept(Execution execution, InterceptorChain chain) throws Exception {
        long start = System.currentTimeMillis();
        try {
            chain.doInterceptor(execution);
        }
        finally {
            long last = System.currentTimeMillis() - start;
            System.out.println("Execute " + last + " ms for URL: " + execution.request.getRequestURI());
        }
    }
}

But don't forget to call chain.doInterceptor(execution), otherwise the process of HTTP request cannot be continued to next interceptor and the method which handles URL.

More than one interceptors are linked as a chain. @InterceptorOrder is used to specify the orders of interceptors. The lower value has higher priority.