在SpringBoot中使用过滤器

在SpringBoot中使用过滤器

1.实现Filter接口

可以重写Filter中的三个方法

name	说明
init(FilterConfig)	创建filter时会调用一次
doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)	拦截客户端请求时调用
destroy()	销毁filter时会调用一次

2.注册拦截器

方式1: 注解注册

通过@WebFilter(filterName, urlPatterns)注解来说明这是一个过滤器

参数	说明
filterName	过滤器名字
urlPatterns	拦截的路径

然后在主启动类上使用@ServletComponentScan注解开启扫描

加上这个注解可以扫描@Servlet、@Filter、@Listener

方式2: 配置类方式注入

@Configuration
public class FilterConfig {
    @Autowired
    private Filter1 filter;

    @Bean
    public FilterRegistrationBean filter() {
        //通过FilterRegistrationBean注入Bean
        FilterRegistrationBean registration = new FilterRegistrationBean();
        //设置过滤器
        registration.setFilter(filter);
        //设置过滤器名和拦截路径
        registration.setName("filter");
        registration.addUrlPatterns("/*");
        //设置优先级别
        registration.setOrder(1);
        return registration;
    }
}

例子

@WebFilter(filterName = "loginCheckFilter", urlPatterns = "/*")
public class LoginCheckFilter implements Filter {
    //路径匹配器
    public static final AntPathMatcher PATH_MATCHER = new AntPathMatcher();

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;

        //获取请求的uri
        String requestURI = request.getRequestURI();

        //判断是否需要处理
        String[] urls = new String[]{
                //不需要处理的路径
                "/employee/login",
                "/employee/logout",
                "/backend/**",
                "/front/**",
                "/common/**"
        };
        if (check(urls, requestURI)) {
            //不用处理, 放行
            filterChain.doFilter(request, response);
            return;
        } else if (request.getSession().getAttribute("employee") != null) {
            //网页端验证有没有登录
            Long id = (Long) request.getSession().getAttribute("employee");
            BaseContext.setCurrentId(id);
            //已登录, 放行
            filterChain.doFilter(request, response);
            return;
        } else {
            //未登录, 拦截
            response.getWriter().write(JSON.toJSONString(R.error("NOTLOGIN")));
            return;
        }
    }

    /**
     * 匹配请求路径是否不需要处理
     *
     * @param urls
     * @param requestURI
     * @return
     */
    private boolean check(String[] urls, String requestURI) {
        for (String url : urls) {
            if (PATH_MATCHER.match(url, requestURI)) {
                return true;
            }
        }
        return false;
    }
}