基于Servlet实现 Filter 拦截器

import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.annotation.WebFilter; import javax.servlet.http.HttpFilter; @WebFilter(urlPatterns = "/MyServlet") public class Filter01 extends HttpFilter { @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { response.getWriter().println("Filter01 before"); chain.doFilter(request, response); // pass the request to the next filter or servlet response.getWriter().println("Filter01 after"); } }