過濾器簡介

過濾器依賴Servlet容器，屬于Servlet規(guī)范的一部分。 在實現(xiàn)上基于Servlet容器的函數(shù)回調(diào)，可以對幾乎所有請求進行過濾。 Filter的生命周期由Servlet容器管理。

過濾器執(zhí)行流程

過濾器配置使用方式一

@Order(1) // 指定過濾器的執(zhí)行順序@WebFilter(filterName = 'CostTimeFilter', urlPatterns = '/*' , initParams = { @WebInitParam(name = 'URL', value = 'http://localhost:8080')})public class CostTimeFilter implements Filter { private String url; /** * filter對象只會創(chuàng)建一次，init方法也只會執(zhí)行一次。 */ @Override public void init(FilterConfig filterConfig) throws ServletException { this.url = filterConfig.getInitParameter('URL'); System.out.println('Filter init...'); } /** * 主要的業(yè)務代碼編寫方法 */ @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...'); } /** * 在銷毀Filter時自動調(diào)用。 */ @Override public void destroy() { System.out.println('Filter destroy...'); }}

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

@SpringBootApplication@ServletComponentScan // 掃描 Servlet 相關的組件public class SpringBootFilterApplication { public static void main(String[] args) { SpringApplication.run(SpringBootFilterApplication.class, args); }}

過濾器配置方式二

public class CostTimeFilter implements Filter { private String url; /** * filter對象只會創(chuàng)建一次，init方法也只會執(zhí)行一次。 */ @Override public void init(FilterConfig filterConfig) throws ServletException { this.url = filterConfig.getInitParameter('URL'); System.out.println('Filter init...'); } /** * 主要的業(yè)務代碼編寫方法 */ @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...'); } /** * 在銷毀Filter時自動調(diào)用。 */ @Override public void destroy() { System.out.println('Filter destroy...'); }}

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

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