过滤器和拦截器

https://blog.csdn.net/reggergdsg/article/details/52962774
注意：(通过gulimall和smbms项目区分)
1.过滤器要实现Filter接口，重写doFilter方法

/**
 * 判断是否退出登录
 * */
public class SysFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

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

        System.out.println("SysFilter doFilter()===========");
        HttpServletRequest rq = (HttpServletRequest)request;
        HttpServletResponse rp = (HttpServletResponse)response;
        User userSession = (User)rq.getSession().getAttribute("userSession");
        if(null == userSession){
            rp.sendRedirect(rq.getContextPath()+"/error.jsp");
        }else{
            chain.doFilter(request, response);
        }
    }

    @Override
    public void destroy() {

    }

}

2.拦截器要继承 HandlerInterceptorAdapter 类（不是Interceptor，区别ibatis包里有个interceptor接口），重写preHandle,postHandle方法

/**
 * 权限(Token)验证
 *
 * @author Mark sunlightcs@gmail.com
 */
@Component
public class AuthorizationInterceptor extends HandlerInterceptorAdapter {
    @Autowired
    private JwtUtils jwtUtils;

    public static final String USER_KEY = "userId";

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        Login annotation;
        if(handler instanceof HandlerMethod) {
            annotation = ((HandlerMethod) handler).getMethodAnnotation(Login.class);
        }else{
            return true;
        }

        if(annotation == null){
            return true;
        }

        //获取用户凭证
        String token = request.getHeader(jwtUtils.getHeader());
        if(StringUtils.isBlank(token)){
            token = request.getParameter(jwtUtils.getHeader());
        }

        //凭证为空
        if(StringUtils.isBlank(token)){
            throw new RRException(jwtUtils.getHeader() + "不能为空", HttpStatus.UNAUTHORIZED.value());
        }

        Claims claims = jwtUtils.getClaimByToken(token);
        if(claims == null || jwtUtils.isTokenExpired(claims.getExpiration())){
            throw new RRException(jwtUtils.getHeader() + "失效，请重新登录", HttpStatus.UNAUTHORIZED.value());
        }

        //设置userId到request里，后续根据userId，获取用户信息
        request.setAttribute(USER_KEY, Long.parseLong(claims.getSubject()));

        return true;
    }
}

3.过滤器定义过滤路径和过滤器是在web.xml里，可以定义多个过滤器

web.xml

拦截器定义拦截方法和拦截器是通过配置文件或者xml文件配置

/**
 * MVC配置
 *
 * @author Mark sunlightcs@gmail.com
 */
@Configuration
public class WebMvcConfig implements WebMvcConfigurer {
    @Autowired
    private AuthorizationInterceptor authorizationInterceptor;
    @Autowired
    private LoginUserHandlerMethodArgumentResolver loginUserHandlerMethodArgumentResolver;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(authorizationInterceptor).addPathPatterns("/app/**");
    }

    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
        argumentResolvers.add(loginUserHandlerMethodArgumentResolver);
    }
}

4.拦截器是spring的，基于动态代理实现，过滤器是servlet的