拦截器（Interceptor）与过滤器（Filter）

@Component
public class UserAccessInterceptor implements HandlerInterceptor {

    private final Logger logger = LoggerFactory.getLogger(UserAccessInterceptor.class);

    @Resource
    private UserService userService;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
        //1.获取headers里的author-Cookie
     //2.根据cookie使用userService查找当前user
     //3.存在且激活 当前用户信息设置到ThreadLocal return true；
     //4.不存在 或 未激活 return false;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) {
    
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
        //销毁ThreadLocal的用户信息
    }

@Configuration
public class WebInterceptorConfig extends WebMvcConfigurationSupport {

    @Autowired
    private UserAccessInterceptor userAccessInterceptor;
  //不拦截的URL集合
    private static List<String> exclusionUrlList=new ArrayList<>();

    static {
        exclusionUrlList.add("/favicon.ico");
        exclusionUrlList.add("/**/*.css");
        exclusionUrlList.add("/**/*.js");
        exclusionUrlList.add("/ok");
        exclusionUrlList.add("/");
        exclusionUrlList.add("/console/**");
        exclusionUrlList.add("/index");
    }

    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(this.userAccessInterceptor)
                .addPathPatterns("/**")
                .excludePathPatterns(exclusionUrlList);
        super.addInterceptors(registry);
    }

}

<mvc:interceptors>  
<!-- 使用bean定义一个Interceptor，直接定义在mvc:interceptors根下面的Interceptor将拦截所有的请求 -->  
<bean class="com.baidu.interceptor.UserAccessInterceptor"/>  
    <mvc:interceptor>  
         <mvc:mapping path="/**"/>  
         <mvc:exclude-mapping path="/parent/**"/>  
         <bean class="com.baidu.interceptor.UserAccessInterceptor" />  
    </mvc:interceptor>  
</mvc:interceptors>

public class TestFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
 
    }
 
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("我是Filter,执行filterChain.doFilter(request,response)之前。");
        filterChain.doFilter(request,response);
        System.out.println("我是Filter,执行filterChain.doFilter(request,response)之后。");
    }
 
    @Override
    public void destroy() {
 
    }

@Slf4j
@Configuration
public class TestFilterConfiguration {//不拦截路径
    private static List<String> exclusionUrlList=new ArrayList<>();
    //拦截路径
    private static List<String> inclusionUrlList=new ArrayList<>();

    static {
        exclusionUrlList.add("/favicon.ico");
        exclusionUrlList.add("/**/*.css");
        exclusionUrlList.add("/**/*.js");
        exclusionUrlList.add("/ok");
        inclusionUrlList.add("/api/**");
    }

    @Bean
    public FilterRegistrationBean filterRegistration() {
        FilterRegistrationBean<Filter> registration = new FilterRegistrationBean<>();
        registration.setFilter(new TestFilter());
        registration.addInitParameter(FILTER_INIT_PARAM_EXCLUSION_URLS,String.join(",", exclusionUrlList));
        registration.addInitParameter(AJAX_URL_PATTERNS,String.join(",", inclusionUrlList));
        registration.addUrlPatterns("/*");
        registration.setName("testFilter");
     return registration;
    }

}

//1.初始化Filter

@Component
public class TestFilter3 implements Filter{
    @Override
    public void init(javax.servlet.FilterConfig filterConfig) throws ServletException {
        System.out.println("##############Filter3 init##############");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //在DispatcherServlet之前执行
        System.out.println("##############doFilter3 before##############");
        filterChain.doFilter(servletRequest, servletResponse);
        // 在视图页面返回给客户端之前执行，但是执行顺序在Interceptor之后
        System.out.println("##############doFilter3 after##############");
    }

    @Override
    public void destroy() {
        System.out.println("##############Filter3 destroy##############");
    }
}

//2.注册到config

@Configuration
public class FilterConfig {

    @Bean
    public FilterRegistrationBean testFilter3RegistrationBean() {
        FilterRegistrationBean registration = new FilterRegistrationBean(new TestFilter3());
        registration.addUrlPatterns("/hello");
        registration.setOrder(1); // 值越小越靠前，此处配置有效
        return registration;
    }

    @Bean
    public FilterRegistrationBean testFilter4RegistrationBean() {
        FilterRegistrationBean registration = new FilterRegistrationBean(new TestFilter4());
        registration.addUrlPatterns("/hello");
        registration.setOrder(2);
        return registration;
    }
}

<filter>
    <filter-name>CharacterEncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>
    <init-param>
        <param-name>forceEncoding</param-name>
        <param-value>true</param-value>
    </init-param>
</filter>

<filter-mapping>
    <filter-name>CharacterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>