玩转springboot之springboot注册servlet

springboot注册servlet

有时候在springboot中依然需要注册servlet，filter，listener，就以servlet为例来进行说明，另外两个也都类似

使用@WebServlet注解

在servlet3.0之后，servlet注册支持注解注册，而不需要在web.xml中进行配置，类似的，对于Filter使用@WebFilter注解，对于Listener使用@WebListener注解

@WebServlet(name = "helloWorldServlet",urlPatterns = "/helloWorldServlet",
initParams = {
        @WebInitParam(name = "name",value = "张三")
})
public class HelloWorldServlet extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String name = getServletConfig().getInitParameter("name");
        System.out.println("helloWorldServlet ---- doPost");
        resp.getOutputStream().println(name);
    }
}

使用ServletRegistrationBean

springboot为注册servlet专门提供了一个bean，可以使用该bean进行注册，类似的对于Filter提供了FilterRegistrationBean，对于Listener提供了ServletListenerRegistrationBean

@Configuration
public class ServletRegistConfig {

    @Bean
    public ServletRegistrationBean registServlet(){
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean();
        // servlet
        servletRegistrationBean.setServlet(new RegistServlet());
        List<String> urlMappings = new ArrayList<>();
        urlMappings.add("/registServlet");
        // 地址映射
        servletRegistrationBean.setUrlMappings(urlMappings);
        // servlet名称
        servletRegistrationBean.setName("registServlet");

        Map<String,String> initMap = new HashMap<>();
        initMap.put("name","李四");
        // servlet的初始参数
        servletRegistrationBean.setInitParameters(initMap);

        return servletRegistrationBean;

    }
}

动态注册

springboot中还提供了动态注册的方式，需要实现ServletContextInitializer接口

@Component
public class ServletRegistConfiguration implements ServletContextInitializer {
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        ServletRegistration.Dynamic dynamic = servletContext.addServlet("registServlet", RegistServlet.class);
        // 地址映射
        dynamic.addMapping("/regist");
        // servlet的初始参数
        dynamic.setInitParameter("name","王五");
    }
}

https://zhhll.icu/2021/框架/springboot/基础/11.springboot注册servlet/

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