Spring Boot filter

在Spring Boot中自定义filter

本文我们将会讲解如何在Spring Boot中自定义filter并指定执行顺序。

定义Filter很简单，我们只需要实现Filter接口即可，同时我们可指定@Order来确定其执行顺序，我们定义两个filter如下：

1@Slf4j
2@Component
3@Order(1)
4public class TransactionFilter implements Filter {
5
6    @Override
7    public void doFilter(
8    ServletRequest request,
9    ServletResponse response,
10    FilterChain chain) throws IOException, ServletException
11
12    {
13
14        HttpServletRequest req = (HttpServletRequest) request;
15        log.info(
16                "Starting a transaction for req : {}",
17                req.getRequestURI());
18
19        chain.doFilter(request, response);
20        log.info(
21                "Committing a transaction for req : {}",
22                req.getRequestURI());
23    }
24
25    // other methods
26}
27
28@Slf4j
29@Component
30@Order(2)
31public class RequestResponseLoggingFilter implements Filter {
32
33    @Override
34    public void doFilter(
35            ServletRequest request,
36            ServletResponse response,
37            FilterChain chain) throws IOException, ServletException {
38
39        HttpServletRequest req = (HttpServletRequest) request;
40        HttpServletResponse res = (HttpServletResponse) response;
41        log.info(
42                "Logging Request {} : {}", req.getMethod(),
43                req.getRequestURI());
44        chain.doFilter(request, response);
45        log.info(
46                "Logging Response :{}",
47                res.getContentType());
48    }
49
50    // other methods
51}

注意在Spring Boot中我们需要使用@Component来实例化Filter从而在Spring Boot中生效。

@Order指定了两个fiter的顺序。

上面的例子我们指定了两个fiter对于所有的url生效，如果我们希望filter对于特定的某些url生效该怎么办呢？

我们可使用FilterRegistrationBean来手动注册对于的Filter：

1@Bean
2    public FilterRegistrationBean<UrlFilter> loggingFilter(){
3        FilterRegistrationBean<UrlFilter> registrationBean
4                = new FilterRegistrationBean<>();
5
6        registrationBean.setFilter(new UrlFilter());
7        registrationBean.addUrlPatterns("/users/*");
8
9        return registrationBean;
10    }

上面我们同时指定了filter对应的urlPatttern。

本文的例子可以参考 https://github.com/ddean2009/learn-springboot2/tree/master/springboot-filter

更多教程请参考 flydean的博客