没有特殊的注释来表示servlet筛选器。您只需声明一个Filter类型的@Bean(或FilterRegistrationBean)。在Boot自己的EndpointWebMvcAutoConfiguration中有一个例子(为所有响应添加自定义头);

如果你只声明一个过滤器，它将被应用到所有的请求。如果您还添加了一个FilterRegistrationBean，您可以另外指定要应用的单个servlet和url模式。

注意:

从Spring Boot 1.4开始，FilterRegistrationBean不再弃用，而是简单地将包从org.springframework. Boot .context. embedd.filterregistrationbean移动到org.springframework.boot.web.servlet.FilterRegistrationBean

过滤器，顾名思义，用于对资源的请求或资源的响应执行过滤，或同时对两者执行过滤。Spring Boot提供了一些选项来在Spring Boot应用程序中注册自定义过滤器。让我们看看不同的选项。

1. 定义Spring Boot过滤器和调用顺序

实现Filter接口，在Spring Boot中创建一个新的过滤器。

@Configuration
@Order(Ordered.HIGHEST_PRECEDENCE)
public class CustomFilter implements Filter {

    private static final Logger LOGGER = LoggerFactory.getLogger(CustomFilter.class);

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        LOGGER.info("########## Initiating Custom filter ##########");
    }

    @Override
    public void doFilter(ServletRequest servletRequest,
                         ServletResponse servletResponse,
                         FilterChain filterChain)
                         throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;

        LOGGER.info("Logging Request  {} : {}", request.getMethod(), request.getRequestURI());

        // Call next filter in the filter chain
        filterChain.doFilter(request, response);

        LOGGER.info("Logging Response :{}", response.getContentType());
    }

    @Override
    public void destroy() {
        // TODO: 7/4/2018
    }
}

让我们快速看一下上面代码中的一些要点

@Component注释注册的过滤器。 为了以正确的顺序触发过滤器，我们需要使用@Order注释。 @ component @Order (1) 公共类CustomFirstFilter实现了Filter { ｝ @ component @Order (2) 公共类CustomSecondFilter实现了Filter { ｝

在上面的代码中，CustomFirstFilter将在CustomSecondFilter之前运行。

数字越低，优先级越高

2. URL模式

如果基于约定的映射不够灵活，我们可以使用FilterRegistrationBean对应用程序进行完全控制。在这里，不要为过滤器类使用@Component注释，而是使用FilterRegistrationBean注册过滤器。

public class CustomURLFilter implements Filter {

    private static final Logger LOGGER = LoggerFactory.getLogger(CustomURLFilter.class);

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        LOGGER.info("########## Initiating CustomURLFilter filter ##########");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;

        LOGGER.info("This Filter is only called when request is mapped for /customer resource");

        // Call the next filter in the filter chain
        filterChain.doFilter(request, response);
    }

    @Override
    public void destroy() {

    }
}

使用FilterRegistrationBean注册自定义过滤器。

@Configuration
public class AppConfig {

    @Bean
    public FilterRegistrationBean < CustomURLFilter > filterRegistrationBean() {
        FilterRegistrationBean < CustomURLFilter > registrationBean = new FilterRegistrationBean();
        CustomURLFilter customURLFilter = new CustomURLFilter();

        registrationBean.setFilter(customURLFilter);
        registrationBean.addUrlPatterns("/greeting/*");
        registrationBean.setOrder(2); // Set precedence
        return registrationBean;
    }
}

没有特殊的注释来表示servlet筛选器。您只需声明一个Filter类型的@Bean(或FilterRegistrationBean)。在Boot自己的EndpointWebMvcAutoConfiguration中有一个例子(为所有响应添加自定义头);

如果你只声明一个过滤器，它将被应用到所有的请求。如果您还添加了一个FilterRegistrationBean，您可以另外指定要应用的单个servlet和url模式。

注意:

从Spring Boot 1.4开始，FilterRegistrationBean不再弃用，而是简单地将包从org.springframework. Boot .context. embedd.filterregistrationbean移动到org.springframework.boot.web.servlet.FilterRegistrationBean

用一个Spring原型(如@Component)注释你的过滤器。在Spring @Configuration中注册一个Filter类型的@Bean。在Spring @Configuration中用FilterRegistrationBean类型注册一个@Bean。

使用Spring注册过滤器大约有四种不同的选项。

首先，我们可以创建一个实现Filter或扩展HttpFilter的Spring bean:

@Component
public class MyFilter extends HttpFilter {

    @Override
    protected void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain) 
        throws IOException, ServletException {
        // Implementation details...

        chain.doFilter(request, response);
    }
}

其次，我们可以创建一个扩展GenericFilterBean的Spring bean:

@Component
public class MyFilter extends GenericFilterBean {

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain)
  throws IOException, ServletException {
    //Implementation details...

        chain.doFilter(currentRequest, servletResponse);
    }
}

我们也可以使用FilterRegistrationBean类:

@Configuration
public class FilterConfiguration {

    private final MyFilter myFilter;

    @Autowired
    public FilterConfiguration(MyFilter myFilter) {
        this.myFilter = myFilter;
    }

    @Bean
    public FilterRegistrationBean<MyFilter> myFilterRegistration() {
        FilterRegistrationBean<DateLoggingFilter> filterRegistrationBean = new FilterRegistrationBean<>();
        filterRegistrationBean.setFilter(myFilter);
        filterRegistrationBean.setUrlPatterns(Collections.singletonList("/*"));
        filterRegistrationBean.setDispatcherTypes(DispatcherType.REQUEST);
        filterRegistrationBean.setOrder(Ordered.LOWEST_PRECEDENCE - 1);
        return filterRegistrationBean;
    }
}

最后，我们可以使用@ServletComponentScan的@WebFilter注释:

@WebFilter(urlPatterns = "/*", dispatcherTypes = {DispatcherType.REQUEST})
public class MyFilter extends HttpFilter {

    @Override
    protected void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
  throws IOException, ServletException {
        // Implementation details...

        chain.doFilter(request, response);
    }
}

你也可以使用@WebFilter来创建一个过滤器。这样就行了。

@Configuration
public class AppInConfig
{
    @Bean
    @Order(1)
    public FilterRegistrationBean aiFilterRegistration()
    {
        FilterRegistrationBean registration = new FilterRegistrationBean();
        registration.setFilter(new TrackingFilter());
        registration.addUrlPatterns("/**");
        registration.setOrder(1);
        return registration;
    }

    @Bean(name = "TrackingFilter")
    public Filter TrackingFilter()
    {
        return new TrackingFilter();
    }
}