一.Web开发使用 Controller 基本上可以完成大部分需求,但是我们还可能会用到 Servlet、 Filter、 Listener 等等
二.在 spring boot 中的三种实现方式
方法一:通过注册 ServletRegistrationBean、 FilterRegistrationBean 和 ServletListenerRegistrationBean 获得控制
/**
* 自定义 servlet *
* @author wujing */
public class CustomServlet extends HttpServlet {
/** *
*/
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println("servlet get method");
doPost(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println("servlet post method");
response.getWriter().write("hello world");
} }
/**
* 自定义 filter *
* @author wujing */
public class CustomFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
System.out.println("init filter");
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
System.out.println("do filter");
chain.doFilter(request, response);
}
@Override
public void destroy() {
System.out.println("destroy filter");
}
}
/**
* 自定义 listener *
* @author wujing */
public class CustomListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent sce) {
System.out.println("contextInitialized");
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
System.out.println("contextDestroyed");
}
}
注册 bean
@Bean
public ServletRegistrationBean servletRegistrationBean() {
return new ServletRegistrationBean(new CustomServlet(), "/roncoo");
}
@Bean
public FilterRegistrationBean filterRegistrationBean() {
return new FilterRegistrationBean(new CustomFilter(), servletRegistrationBean());
}
@Bean
public ServletListenerRegistrationBean<CustomListener> servletListenerRegistrationBean() {
return new ServletListenerRegistrationBean<CustomListener>(new CustomListener());
}
方法二:通过实现 ServletContextInitializer 接口直接注册
implements ServletContextInitializer {
@Override
public void onStartup(ServletContext servletContext) throws ServletException {
servletContext.addServlet("customServlet", new CustomServlet()).addMapping("/roncoo");
servletContext.addFilter("customFilter", new CustomFilter())
.addMappingForServletNames(EnumSet.of(DispatcherType.REQUES T), true, "customServlet");
servletContext.addListener(new CustomListener());
}
方法三:在SpringBootApplication 上使用@ServletComponentScan 注解后,直接通过@WebServlet、 @WebFilter、@WebListener 注解自动注册
