1 执行的先后顺序

@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...");
}

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion");
    }

• 执行的先后顺序

• System.out.println("before...");

• preHandle()

• chain.doFilter(request, response);

  • Servlet的doService()方法

• postHandle()

• afterCompletion()

• System.out.println("after...");