自定义 Servlet
代码语言：javascript复制 编写 Servlet
public class ServletTest extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setContentType("text/html;charset=utf-8");
resp.getWriter().write("自定义 Servlet");
}
}
注册 Servlet
将 Servelt 注册成 Bean。在上文创建的 WebConfig 类中添加如下代码：
@Bean
public ServletRegistrationBean servletRegistrationBean() {
return new ServletRegistrationBean(new ServletTest(),"/servletTest");
}结果如下:
自定义过滤器/第三方过滤器
代码语言：javascript复制编写过滤器
public class TimeFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
System.out.println("=======初始化过滤器=========");
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
throws IOException, ServletException {
long start = System.currentTimeMillis();
filterChain.doFilter(request, response);
System.out.println("filter 耗时：" (System.currentTimeMillis() - start));
}
@Override
public void destroy() {
System.out.println("=======销毁过滤器=========");
}
}
注册过滤器
要是该过滤器生效，有两种方式：
1.使用 @Component 注解
2.添加到过滤器链中，此方式适用于使用第三方的过滤器。将过滤器写到 WebConfig 类中，如下：
@Bean
public FilterRegistrationBean timeFilter() {
FilterRegistrationBean registrationBean = new FilterRegistrationBean();
TimeFilter timeFilter = new TimeFilter();
registrationBean.setFilter(timeFilter);
List<String> urls = new ArrayList<>();
urls.add("/*");
registrationBean.setUrlPatterns(urls);
return registrationBean;
}结果如下:
自定义监听器
代码语言：javascript复制编写监听器
public class ListenerTest implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent sce) {
System.out.println("监听器初始化...");
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
}
}
注册监听器
注册监听器为 Bean，在 WebConfig 配置类中添加如下代码：
@Bean
public ServletListenerRegistrationBean<ListenerTest> servletListenerRegistrationBean() {
return new ServletListenerRegistrationBean<ListenerTest>(new ListenerTest());
}
针对自定义 Servlet、Filter 和 Listener 的配置，还有另一种方式：
@SpringBootApplication
public class SpringbootWebApplication implements ServletContextInitializer {
@Override
public void onStartup(ServletContext servletContext) throws ServletException {
// 配置 Servlet
servletContext.addServlet("servletTest",new ServletTest())
.addMapping("/servletTest");
// 配置过滤器
servletContext.addFilter("timeFilter",new TimeFilter())
.addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST),true,"/*");
// 配置监听器
servletContext.addListener(new ListenerTest());
}
public static void main(String[] args) {
SpringApplication.run(SpringbootWebApplication.class, args);
}
}结果如下:
自定义拦截器
代码语言：javascript复制编写拦截器
使用 @Component 让 Spring 管理其生命周期：
@Component
public class TimeInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("========preHandle=========");
System.out.println(((HandlerMethod)handler).getBean().getClass().getName());
System.out.println(((HandlerMethod)handler).getMethod().getName());
request.setAttribute("startTime", System.currentTimeMillis());
return true;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)
throws Exception {
System.out.println("========postHandle=========");
Long start = (Long) request.getAttribute("startTime");
System.out.println("耗时:" (System.currentTimeMillis() - start));
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception exception)
throws Exception {
System.out.println("========afterCompletion=========");
Long start = (Long) request.getAttribute("startTime");
System.out.println("耗时:" (System.currentTimeMillis() - start));
System.out.println(exception);
}
}
注册拦截器
编写拦截器后，我们还需要将其注册到拦截器链中，如下配置：
@Configuration
public class WebConfig extends WebMvcConfigurerAdapter{
@Autowired
private TimeInterceptor timeInterceptor;
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(timeInterceptor);
}
}请求一个 controller ，结果如下：
