SpringBoot使用ServletAPI和拦截器
1、如何去使用ServletAPI：
package com.boot.servlet.api.bootservlet.servlet;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;@WebServlet(name = "MyServlet",urlPatterns = "/my")public class MyServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("执行了servlet的请求");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request,response);}}
1.1、在创建一个Filter的类，代码如下:
package com.boot.servlet.api.bootservlet.filter;import javax.servlet.*;import javax.servlet.annotation.WebFilter;import java.io.IOException;@WebFilter(filterName = "MyFilter",urlPatterns = "/*")public class MyFilter implements Filter {public void destroy() {}public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {System.out.println("执行了Filter");chain.doFilter(req, resp);}public void init(FilterConfig config) throws ServletException {}}
1.2、创建了一个Listener的类，代码如下：
package com.boot.servlet.api.bootservlet.filter;package com.boot.servlet.api.bootservlet.listener;import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;import javax.servlet.annotation.WebListener;@WebListenerpublic class MyListener implements ServletContextListener{public MyListener() {}public void contextInitialized(ServletContextEvent sce) {System.out.println("servlet容器启动");}@Overridepublic void contextDestroyed(ServletContextEvent servletContextEvent) {System.out.println("servlet容器销毁");}}
上面的配置是使用的注解的方式来配置的。
在SpringBoot如何去使用ServletAPI呢？
第一种方式：使用注解的方式：@ServletComponentScan去启动。使用这个注解的条件必须是servlet和listener还有filter的类上必须有带有注解的才可以。
代码如下：
package com.boot.servlet.api.bootservlet.filter;package com.boot.servlet.api.bootservlet;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.web.servlet.ServletComponentScan;@SpringBootApplication@ServletComponentScanpublic class BootServletApplication {public static void main(String[] args) {SpringApplication.run(BootServletApplication.class, args);}}
然后启动下boot项目：输出的就是监听器监听到的。
去请求下MyServlet,这时的servlet的Api就引入成功了。
第二种方式：通过配置类的方式来配置，代码如下：
package com.boot.servlet.api.bootservlet.config;import com.boot.servlet.api.bootservlet.filter.MyFilter;import com.boot.servlet.api.bootservlet.listener.MyListener;import com.boot.servlet.api.bootservlet.servlet.MyServlet;import org.springframework.boot.SpringBootConfiguration;import org.springframework.boot.web.servlet.FilterRegistrationBean;import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;import org.springframework.boot.web.servlet.ServletRegistrationBean;import org.springframework.context.annotation.Bean;import java.util.Arrays;@SpringBootConfigurationpublic class ServletConfiguration {@Beanpublic ServletRegistrationBean<MyServlet> registrationBean(){ServletRegistrationBean<MyServlet> bean=new ServletRegistrationBean<>(new MyServlet(),"/my");return bean;}@Beanpublic FilterRegistrationBean<MyFilter> filterFilterRegistrationBean(){FilterRegistrationBean<MyFilter> bean=new FilterRegistrationBean<>();bean.setFilter(new MyFilter());bean.setUrlPatterns(Arrays.asList("/*"));return bean;}@Beanpublic ServletListenerRegistrationBean<MyListener> servletListenerRegistrationBean(){ServletListenerRegistrationBean<MyListener> listener=new ServletListenerRegistrationBean<>();listener.setListener(new MyListener());return listener;}}
启动项目运行下：这时也被监听到。
再次访问下：
这时过滤器和servlet的请求也都打印了出来。
上面就是引入servletAPI的方式。
2、如何在springBoot中使用拦截器：
代码如下：
2.1、写一个拦截器去实现HandlerInterceptor：
package com.boot.servlet.api.bootservlet.interceptor;import org.springframework.web.servlet.HandlerInterceptor;import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class MyInterceptor implements HandlerInterceptor {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {return true;}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("postHandle");}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("afterCompletion");}}
2.2、写一个配置类来注册拦截器，代码如下：
package com.boot.servlet.api.bootservlet.config;import com.boot.servlet.api.bootservlet.interceptor.MyInterceptor;import org.springframework.boot.SpringBootConfiguration;import org.springframework.web.servlet.config.annotation.InterceptorRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;@SpringBootConfigurationpublic class MyWebMvcConfiguration extends WebMvcConfigurationSupport {@Overrideprotected void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(new MyInterceptor());}}
2.3、拦截器主要拦截的是controller,所以新建个controller,代码如下：
package com.boot.servlet.api.bootservlet.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.GetMapping;@Controllerpublic class TestController {@GetMapping("/index")public void index(){}}
2.4、启动下项目并访问：这时就会拦截请求了。
总结：上面就是如何使用Servlet的API以及拦截器
