简单了解SpringBoot过滤器及使用方式

@Order(1) // 指定过滤器的执行顺序
@WebFilter(filterName = "CostTimeFilter", urlPatterns = "/*" , initParams = {
    @WebInitParam(name = "URL", value = "http://localhost:8080")})
public class CostTimeFilter implements Filter {
  private String url;
  /**
   * filter对象只会创建一次，init方法也只会执行一次。
   */
  @Override
  public void init(FilterConfig filterConfig) throws ServletException {
    this.url = filterConfig.getInitParameter("URL");
    System.out.println("Filter init...");
  }

  /**
   * 主要的业务代码编写方法
   */
  @Override
  public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
  	long start = System.currentTimeMillis();
    System.out.println(start + " Filter doFilter before...");
    filterChain.doFilter(servletRequest, servletResponse);
  	long end = System.currentTimeMillis();
    System.out.println(end + "Filter doFilter after...");
  }

  /**
   * 在销毁Filter时自动调用。
   */
  @Override
  public void destroy() {
    System.out.println("Filter destroy...");
  }
}

@RestController
public class IndexContoller {
  @RequestMapping("/query")
  public void query() throws Exception {
    System.out.println("IndexContoller query...");
  }
}

@SpringBootApplication
@ServletComponentScan // 扫描 Servlet 相关的组件
public class SpringBootFilterApplication {
  public static void main(String[] args) {
    SpringApplication.run(SpringBootFilterApplication.class, args);
  }
}

public class CostTimeFilter implements Filter {
  private String url;
  /**
   * filter对象只会创建一次，init方法也只会执行一次。
   */
  @Override
  public void init(FilterConfig filterConfig) throws ServletException {
    this.url = filterConfig.getInitParameter("URL");
    System.out.println("Filter init...");
  }

  /**
   * 主要的业务代码编写方法
   */
  @Override
  public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
  	long start = System.currentTimeMillis();
    System.out.println(start + " Filter doFilter before...");
    filterChain.doFilter(servletRequest, servletResponse);
  	long end = System.currentTimeMillis();
    System.out.println(end + "Filter doFilter after...");
  }

  /**
   * 在销毁Filter时自动调用。
   */
  @Override
  public void destroy() {
    System.out.println("Filter destroy...");
  }
}

@Configuration
public class FilterConfig {
  @Bean
  public FilterRegistrationBean registFilter() {
    FilterRegistrationBean registration = new FilterRegistrationBean();
    registration.setFilter(new CostTimeFilter());
    registration.addUrlPatterns("/*");
    registration.setName("CostTimeFilter");
    registration.setOrder(1);
    return registration;
  }
}