Java：如何从控制器返回后对Filter进行拦截

Question

I have implemented a Filter like this but this triggers only when the request is coming in. I would like to intercept the response on its way out ie when the response is returned from controller.

I know about Spring Interceptors which give you the functionality to handle the request before and after it hits the controller. I would like to do something like that.

public class ServiceSessionManagementInterceptor implements Filter{

@Override
public void init(FilterConfig filterConfig) throws ServletException {
    // TODO Auto-generated method stub

}

@Override
public void doFilter(ServletRequest request, ServletResponse response,  FilterChain chain) throws IOException, ServletException {
    // TODO Auto-generated method stub
    Map<String, String[]> maps = request.getParameterMap();

    System.out.println("test");
chain.doFilter(request, response);  
}

@Override
public void destroy() {
    // TODO Auto-generated method stub

}

}

Answer 1

The doFilter() is where magic happens. Whatever you put before it will be executed before the servlet and everything you put after it will be executed after the servlet service() method returns (including a forward/include, etc.).

@Override
public void doFilter(ServletRequest request, ServletResponse response,  FilterChain chain) throws IOException, ServletException {

    System.out.println("before");
    chain.doFilter(request, response);  
    System.out.println("after");
}

This way you could wrap the ServletRequest and ServletResponse objects with your own implementations to add functionality, ex: compression.

Note that a Spring Interceptor is called before and after the handler method gets executed. A servlet Filter gets executed before and after a Servlet .