AdviceFilter.java

package com.hwlcn.security.web.servlet;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;


public abstract class AdviceFilter extends OncePerRequestFilter {


    private static final Logger log = LoggerFactory.getLogger(AdviceFilter.class);

    /**
     * 开始执行过滤方法前的操作
     *
     * @param request
     * @param response
     * @return
     * @throws Exception
     */
    protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {
        return true;
    }

    /**
     * 执行过滤后的操作
     *
     * @param request
     * @param response
     * @throws Exception
     */
    @SuppressWarnings({"UnusedDeclaration"})
    protected void postHandle(ServletRequest request, ServletResponse response) throws Exception {

    }

    /**
     * 不管失败与否 都要执行的操作
     *
     * @param request
     * @param response
     * @param exception
     * @throws Exception
     */
    @SuppressWarnings({"UnusedDeclaration"})
    public void afterCompletion(ServletRequest request, ServletResponse response, Exception exception) throws Exception {
    }

    protected void executeChain(ServletRequest request, ServletResponse response, FilterChain chain) throws Exception {
        chain.doFilter(request, response);
    }


    public void doFilterInternal(ServletRequest request, ServletResponse response, FilterChain chain)
            throws ServletException, IOException {
        Exception exception = null;

        try {

            boolean continueChain = preHandle(request, response);
            if (log.isTraceEnabled()) {
                log.trace("Invoked preHandle method.  Continuing chain?: [" + continueChain + "]");
            }

            if (continueChain) {
                executeChain(request, response, chain);
            }

            postHandle(request, response);
            if (log.isTraceEnabled()) {
                log.trace("Successfully invoked postHandle method");
            }

        } catch (Exception e) {
            exception = e;
        } finally {
            cleanup(request, response, exception);
        }
    }


    protected void cleanup(ServletRequest request, ServletResponse response, Exception existing)
            throws ServletException, IOException {
        Exception exception = existing;
        try {
            afterCompletion(request, response, exception);
            if (log.isTraceEnabled()) {
                log.trace("Successfully invoked afterCompletion method.");
            }
        } catch (Exception e) {
            if (exception == null) {
                exception = e;
            } else {
                if (log.isDebugEnabled()) {
                    log.debug("afterCompletion implementation threw an exception.  This will be ignored to " +
                            "allow the original source exception to be propagated.", e);
                }
            }
        }
        if (exception != null) {
            if (exception instanceof ServletException) {
                throw (ServletException) exception;
            } else if (exception instanceof IOException) {
                throw (IOException) exception;
            } else {
                if (log.isDebugEnabled()) {
                    String msg = "Filter execution resulted in an unexpected Exception " +
                            "(not IOException or ServletException as the Filter API recommends).  " +
                            "Wrapping in ServletException and propagating.";
                    log.debug(msg);
                }
                throw new ServletException(exception);
            }
        }
    }
}