Spring Boot自定义Filter

Filter功能

Filter使用户可以改变一个Request和修改一个Response。Filter不是一个Servlet，它不能产生一个Response，它能够在一个Request到达Servlet之前预处理Request，也可以在离开 Servlet时处理Response。换种说法，Filter其实是一个 “Servlet Chaining” (Servlet链)。

一个Filter包括：

• 在servlet被调用之前截获
• 在servlet被调用之前检查servlet request
• 根据需要修改request头和request数据
• 根据需要修改response头和response数据
• 在servlet被调用之后截获

自定义Filter

第一种方法（稍麻烦）

1、实现Filter 方法

@Slf4j
public class MyFilter implements Filter {
    @Override
    public void destroy() {

    }

    @Override
    public void doFilter(ServletRequest sRequest, ServletResponse sResponse, FilterChain filterChain)
            throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) sRequest;
        HttpServletResponse response = (HttpServletResponse) sResponse;
        String requestURI = request.getRequestURI();
        StringBuffer requestURL = request.getRequestURL();
        log.info("requestURI: " + requestURI + ", requestURL: " + requestURL);
        filterChain.doFilter(request, response);
    }

    @Override
    public void init(FilterConfig config) {

    }
}

2、加载Filter配置

@Configuration
@Slf4j
public class WebConfiguration {
    @Bean
    public FilterRegistrationBean testFilterRegistration() {
        // 新建过滤器注册类
        FilterRegistrationBean<Filter> registration = new FilterRegistrationBean<>();
        // 添加自定义过滤器
        registration.setFilter(new MyFilter());
        // 设置过滤器的URL模式
        registration.addUrlPatterns("/*");
        registration.addInitParameter("paramName", "paramValue");
        // 设置拦截器的名称
        registration.setName("MyFilter");
        // 设置过滤器顺序
        registration.setOrder(1);
        return registration;
    }
}

第二种方法（简洁，推荐使用这种）

1、添加 @WebFilter 自定义MyFilter,

@WebFilter(filterName = "myFilter", urlPatterns = "/*")
@Slf4j
public class MyFilter implements Filter {
    @Override
    public void destroy() {

    }

    @Override
    public void doFilter(ServletRequest sRequest, ServletResponse sResponse, FilterChain filterChain)
            throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) sRequest;
        HttpServletResponse response = (HttpServletResponse) sResponse;
        String requestURI = request.getRequestURI();
        StringBuffer requestURL = request.getRequestURL();
        log.info("requestURI: " + requestURI + ", requestURL: " + requestURL);
        filterChain.doFilter(request, sResponse);
    }

    @Override
    public void init(FilterConfig config) {

    }
}

2、在Application 启动类 添加 @ServletComponentScan 注解