Spring @WebFilter 注解定义过滤器

@Slf4j
@Order(1)
@WebFilter(filterName = "myFilter", urlPatterns = {"/asyncResultGet/*"}, initParams = {@WebInitParam(name = "author", value = "Jaemon")})
public class MyFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig)
            throws ServletException {
        // 得到过滤器的名字
        log.info("过滤器初始化={}", filterConfig.getFilterName());

        // 得到在web.xml文件中配置的初始化参数
        String author = filterConfig.getInitParameter("author");
        log.info("author={}", author);

        // 返回过滤器的所有初始化参数的名字的枚举集合。
        Enumeration<String> initParameterNames = filterConfig.getInitParameterNames();
        log.info("是否存在初始化参数集={}", initParameterNames.hasMoreElements());
        while (initParameterNames.hasMoreElements()) {
            String paramName = initParameterNames.nextElement();
            log.info("paramName={}", paramName);
        }
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
            throws IOException, ServletException {
        // 对 request 和 response 进行一些预处理
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        log.info("execute before");
        // 让目标资源执行，放行
        filterChain.doFilter(request, response);
        log.info("execute after");
    }

    @Override
    public void destroy() {
        log.info("过滤器销毁");
    }
}

• @Order注解表示执行过滤顺序，值越小，越先执行
• filterName： 指定过滤器的 name 属性
• urlPatterns: 指定过滤的地址(不包含上下文)
• initParams: 指定过滤器初始化参数

注意： Application 入口中需要加入 ​​@ServletComponentScan​​ 注解

通过继承 Spring 的​​org.springframework.web.filter.OncePerRequestFilter​​来实现过滤器

@Slf4j
@Component
public class MyFilter extends OncePerRequestFilter {
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        logger.info("过滤器执行");

        filterChain.doFilter(request, response);
    }
}