Spring Boot - 注册过滤器

过滤器

Token 验证过滤器，如果没有携带 Token 说明没有登录，或服务器没有颁发合法的 Token 给客户端。

file:[TokenFilter.java]
public class TokenFilter extends HttpFilter {

    @Override
    protected void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws IOException, ServletException {
        response.setContentType("application/json;charset=utf-8");
        String token = request.getHeader("Token");

        if (token == null) {
            R r = new R(500, null, "您没有登陆！");
            String json = JSON.toJSONString(r);
            response.getWriter().write(json);
        } else {
            filterChain.doFilter(request, response);
        }
    }

}

在配置跨域过滤器设置响应头要记得添加 Token，否则从前端过来的请求携带的是其他字段就会被拒绝，出现跨域。如果请求头是其他的字段，如 Authorization，Access-Control-Allow-Headers 就得包含这个字段。

file:[CorsFilter.java]
public class CorsFilter extends HttpFilter {

    @Override
    protected void doFilter(HttpServletRequest request,
                            HttpServletResponse response,
                            FilterChain chain) throws IOException, ServletException {
        response.addHeader("Access-Control-Allow-Origin", request.getHeader("Origin"));
        response.addHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");
        response.addHeader("Access-Control-Allow-Headers", "Token, Content-Type");
        chain.doFilter(request, response);
    }

}

配置类

file:[FilterConfig.java]
@Configuration
public class FilterConfig {

    @Bean
    public FilterRegistrationBean<CorsFilter> corsFilter() {
        FilterRegistrationBean<CorsFilter> bean = new FilterRegistrationBean<>();
        bean.setFilter(new CorsFilter());
        bean.addUrlPatterns("/*"); // 匹配的 URL
        bean.setOrder(1); // 设置优先级
        return bean;
    }

    @Bean
    public FilterRegistrationBean<TokenFilter> authFilter() {
        FilterRegistrationBean<TokenFilter> bean = new FilterRegistrationBean<>();
        bean.setFilter(new TokenFilter());
        bean.addUrlPatterns("/api/auth/*"); // 设置需要过滤的 URL 匹配模式
        bean.setOrder(2);
        return bean;
    }
}

多个过滤器之间需要合理地设置执行顺序，就如上两个过滤器，跨域的问题是首要的，所以设置 1，数字越小代表优先级越高。其次，经过 Token 校验过滤器，合法就允许访问，不合法就阻止访问。