web原生组件注入：Servlet、Filter、Listener

红太狼 2023-10-04 16:32 31阅读 0赞

#### web原生组件注入：Servlet、Filter、Listener ####

**方法一：使用Servlet API**

在servlet包下新建MyServlet继承HttpServlet，用到的注释

//指定原生servlet组件都放在了哪里
    @ServletComponentScan(basePackages = "com.gis507.admin")
    
    //直接响应，未经过spring的拦截器
    @WebServlet(urlPatterns = "/my")
    
    //servlet的拦截规则，servlet是/* ,srping是/**
    @WebFilter(urlPatterns = {
        "/css/*","/images/*"})
    
    //监听器
    @WebListener

**MyServlet要继承HttpServlet，可以重写doGet方法，同时在主程序类中添加包扫描**

@WebServlet(urlPatterns = "/my")
    public class MyServlet extends HttpServlet {
        
    
    
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            resp.getWriter().write("66666");
        }
    }

**MyFilter实现Filter接口，添加注释可以设置过滤规则**

public class MyFilter implements Filter {
        
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
        
            log.info("MyFilter初始化完成");
        }
    
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        
            log.info("MyFilter工作");
        }
    
        @Override
        public void destroy() {
        
            log.info("MyFilter销毁");
        }
    }

**ContextListener实现ServletContextListener，可以重写contextInitialized和contextDestory方法**

@WebListener
    public class MyServletContextListener implements ServletContextListener {
        
    
        @Override
        public void contextInitialized(ServletContextEvent sce) {
        
            log.info("MyServletContextListener开始工作");
        }
    
        @Override
        public void contextDestroyed(ServletContextEvent sce) {
        
            log.info("MyServletContextListener销毁");
        }
    }

**方式二：使用RegistrationBean**

MyFilter、MyServlet、MyServletContextListener三个类正常些，只是使用spring中的RegistrationBean方法，在MyRegistConfig类中编写

主要是三个方法：

public ServletRegistrationBean myservlet()\{\}

public FilterRegistrationBean myFilter()\{\}

public ServletListenerRegistrationBean myListener()\{\}

//(proxyBeanMethods = true):保证我们以来的组件始终是单实例的
    @Configuration
    public class MyRegistConfig {
        
    
        @Bean
        public ServletRegistrationBean myservlet(){
        
            MyServlet myServlet = new MyServlet();
    
            return new ServletRegistrationBean(myServlet,"/my","/my02");
        }
    
        @Bean
        public FilterRegistrationBean myFilter(){
        
    
            MyFilter myFilter = new MyFilter();
    //        return new FilterRegistrationBean(myFilter,myservlet());//拦截myServlt()规定的路径，就是/my,/my02
            FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(myFilter);
            filterRegistrationBean.setUrlPatterns(Arrays.asList("/my","/css/*"));
            return filterRegistrationBean;
        }
    
        @Bean
        public ServletListenerRegistrationBean myListener(){
        
            MyServletContextListener myServletContextListener = new MyServletContextListener();
            return new ServletListenerRegistrationBean(myServletContextListener);
        }
    }

在编写三个方法的时候主要是设计三个类的方法的使用。