Spring Boot之 Servlet、Fiter、Listener的使用
新建项目：
Servlet的使用
新建MyServlet类
package com.adagio.chat.servlet;import java.io.IOException;import java.io.PrintWriter;import java.io.Writer;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet( name = "myservlet", urlPatterns = {"/myservlet1", "/myservlet2"})public class MyServlet extends HttpServlet { @Override public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException{ Writer writer = response.getWriter(); writer.write("Hello World"); }} 启动类添加注解 @ServletComponentScan(basePackages = {"com.adagio.chat.servlet"})
启动运行访问：和
-
servlet的使用很简单：
添加注解 @WebServlet
配置name，可以不用配置
配置路径，urlPatterns 可以配置多值
Filter的使用
使用方式和Servlet十分类似
package com.adagio.chat.servlet;import java.io.IOException;import javax.servlet.FilterChain;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.annotation.WebFilter;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.web.filter.OncePerRequestFilter;//@WebFilter(servletNames = "myservlet")@WebFilter(urlPatterns = "/myservlet1")public class MyFilter extends OncePerRequestFilter { @Override protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { ServletContext servletContext = getServletContext(); servletContext.log("url myservlet was filter"); filterChain.doFilter(request, response); }} 可以直接使用servletNames过滤，如@WebFilter(servletNames = "myservlet")，访问和都会在控制台打印日志
也可以使用@WebFilter(urlPatterns = "/myservlet1")，访问上面两个链接，只有访问这个地址才会打印日志
Listener的使用
使用方式也是类似的
package com.adagio.chat.servlet;import javax.servlet.ServletContext;import javax.servlet.ServletRequestEvent;import javax.servlet.ServletRequestListener;import javax.servlet.annotation.WebListener;import javax.servlet.http.HttpServletRequest;@WebListenerpublic class MyListener implements ServletRequestListener { @Override public void requestDestroyed(ServletRequestEvent sre) { HttpServletRequest request = (HttpServletRequest)sre.getServletRequest(); ServletContext servletContext = request.getServletContext(); servletContext.log("request was destroyed"); } @Override public void requestInitialized(ServletRequestEvent sre) { HttpServletRequest request = (HttpServletRequest)sre.getServletRequest(); ServletContext servletContext = request.getServletContext(); servletContext.log("request was initialized"); }} 访问 观察控制台
执行顺序
2017-09-10 16:11:18.247 INFO 7692 --- [io-8080-exec-10] o.a.c.c.C.[Tomcat].[localhost].[/] : request was initialized2017-09-10 16:11:18.271 INFO 7692 --- [io-8080-exec-10] o.a.c.c.C.[Tomcat].[localhost].[/] : url myservlet was filter2017-09-10 16:11:18.271 INFO 7692 --- [io-8080-exec-10] o.a.c.c.C.[Tomcat].[localhost].[/] : servlet was doGet2017-09-10 16:11:18.275 INFO 7692 --- [io-8080-exec-10] o.a.c.c.C.[Tomcat].[localhost].[/] : request was destroyed
先监听器的初始化，再经过滤器，然后执行doGet方法，最后执行监听器的消亡
使用注入的方式注册
效果和上面的方式一样的，具体实现见代码
package com.adagio.chat.spring.boot;import java.io.IOException;import javax.servlet.FilterChain;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.annotation.WebFilter;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.web.context.request.RequestAttributes;import org.springframework.web.context.request.RequestContextHolder;import org.springframework.web.context.request.ServletRequestAttributes;import org.springframework.web.filter.OncePerRequestFilter;public class MyFilter2 extends OncePerRequestFilter { @Override protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {// ServletContext servletContext = getServletContext();// // //动态获取URI// String requestURI = request.getRequestURI();// // servletContext.log("url "+requestURI+" was filter from MyFilter2"); doSomething(); filterChain.doFilter(request, response); } /** * 当没有request的时候，可以使用这种方式获取request */ public void doSomething(){ RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes(); ServletRequestAttributes servletRequestAttributes = (ServletRequestAttributes)requestAttributes; HttpServletRequest request = servletRequestAttributes.getRequest(); ServletContext servletContext = getServletContext(); //动态获取URI String requestURI = request.getRequestURI(); servletContext.log("url "+requestURI+" was filter from MyFilter2"); }} package com.adagio.chat.spring.boot;import java.io.IOException;import java.io.PrintWriter;import java.io.Writer;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class MyServlet2 extends HttpServlet { @Override public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException{ ServletContext servletContext = request.getServletContext(); servletContext.log("servlet2 was doGet"); Writer writer = response.getWriter(); writer.write("Hello World From MyServlet2"); }} package com.adagio.chat;import javax.servlet.DispatcherType;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.web.servlet.FilterRegistrationBean;import org.springframework.boot.web.servlet.ServletComponentScan;import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;import org.springframework.boot.web.servlet.ServletRegistrationBean;import org.springframework.context.annotation.Bean;import com.adagio.chat.servlet.MyListener;import com.adagio.chat.spring.boot.MyFilter2;import com.adagio.chat.spring.boot.MyServlet2;@SpringBootApplication@ServletComponentScan(basePackages = {"com.adagio.chat.servlet"})public class ChatApplication { public static void main(String[] args) { SpringApplication.run(ChatApplication.class, args); } @Bean public static ServletRegistrationBean servletRegistrationBean(){ ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(); servletRegistrationBean.setServlet(new MyServlet2()); servletRegistrationBean.addUrlMappings("/spring/boot/myservelt2"); servletRegistrationBean.setName("myservlet2"); return servletRegistrationBean; } @Bean public static FilterRegistrationBean filterRegistrationBean(){ FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(); filterRegistrationBean.setFilter(new MyFilter2());// filterRegistrationBean.addUrlPatterns("/spring/boot/myservelt2"); filterRegistrationBean.addServletNames("myservlet2"); filterRegistrationBean.setDispatcherTypes(DispatcherType.REQUEST, DispatcherType.FORWARD, DispatcherType.INCLUDE); return filterRegistrationBean; } /** * 监听器会监听所有请求 * 可以重复注册监听器 * @return */ @Bean public static ServletListenerRegistrationBean servletListenerRegistrationBean(){ ServletListenerRegistrationBean servletListenerRegistrationBean = new ServletListenerRegistrationBean<>(new MyListener()); return servletListenerRegistrationBean; } } 急事慢做：成长是长时间努力、积累和进步的结果，是水到渠成的事情，绝不是心急就能做到的。
生长速度越快的树木，其致密度就越低，生命往往也越短暂；而松树、柏树、胡杨等树种，要上百年才能成材，用起来却可千年不朽。 - 俞敏洪