SpringBoot中使用Filter（过滤器）

目录1. 入门1.1 编写实体类1.2 编写过滤器1.3 编写Controller1.4 在启动类上开启servlet组件扫描（@ServletComponentScan）1.5 测试并观察控制台打印情况2. 进阶2.1 过滤器简单介绍2.2 编写过滤器类2.3?编写过滤器配置类2.4?Controller和实体类和之前一样，启动类的servlet组件扫描可去除2.5?启动程序并观察控制台* *##### 1. 入门###### 1.1 编写实体类 @Component @Data @AllArgsConstructor @NoArgsConstructor public class Message { private Date date; private String msg ; private String title; }###### 1.2 编写过滤器 @WebFilter(urlPatterns = "/message/“,filterName = “filter1”) public class MessageFilter1 extends HttpFilter { @Override protected void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException { if(”/message/echo".equals(request.getRequestURI())) { String title = request.getParameter(“title”); System.out.println(“【filter1】拦截到的请求的title参数内容为:”+title); } // 将请求传递给链中的下一个过滤器或目标Servlet chain.doFilter(request,response); } }###### 1.3 编写Controller @RestController @RequestMapping(“/message”) public class MessageController { @Resource private Message message ; @RequestMapping(“/echo”) public Message echo(String msg,String title) { message.setTitle(title); message.setMsg(msg); return message; } }###### 1.4 在启动类上开启servlet组件扫描（@ServletComponentScan） @SpringBootApplication @ServletComponentScan //开启servlet组件扫描 public class MicrobootWebApplication { public static void main(String[] args) { SpringApplication.run(MicrobootWebApplication.class, args); } }###### 1.5 测试并观察控制台打印情况 http://localhost:8083/message/echo?msg=西红柿战争&title=两败俱伤拦截成功##### 2. 进阶###### 2.1 过滤器简单介绍过滤器（Filter）是Java Web应用中一种用于处理请求（request）和响应（response）的组件过滤器和拦截器的执行顺序：* 过滤器（预处理）* 过滤器（后处理）* 拦截器（前处理）* 控制器方法（Controller)* 拦截器（后处理）* 过滤器（后处理）###### 2.2 编写过滤器类 //过滤器1,因为有了配置类，不再需要添加@WebFilter注解 public class MessageFilter1 extends HttpFilter { @Override protected void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException { if(“/message/echo”.equals(request.getRequestURI())) { String title = request.getParameter(“title”); System.out.println(“【filter1】拦截到的请求的title参数内容为:”+title); } chain.doFilter(request,response); } } public class MessageFilter2 extends HttpFilter { @Override protected void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException { if(“/message/echo”.equals(request.getRequestURI())) { String msg = request.getParameter(“msg”); System.out.println(“【filter2】拦截到的请求的title参数内容为:”+msg); } chain.doFilter(request,response); } }###### 2.3编写过滤器配置类 //过滤器配置类 @Configuration public class WebFilterConfig { @Bean public FilterRegistrationBean getFilter1Registration() { FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(); filterRegistrationBean.setFilter(this.getMessageFilter1()); //设置过滤器名称和路径，在过滤器类写了的话，这里不用重复写 filterRegistrationBean.setName(“filter”); filterRegistrationBean.addUrlPatterns(“/*”); //设置过滤器执行顺序，数字越小，越早进行过滤，也可设置为负数 filterRegistrationBean.setOrder(1); return filterRegistrationBean; } @Bean public FilterRegistrationBean getFilter2Registration() { FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(); filterRegistrationBean.setFilter(this.getMessageFilter2()); //设置过滤器执行顺序 filterRegistrationBean.setOrder(2); return filterRegistrationBean; } @Bean public MessageFilter1 getMessageFilter1() { return new MessageFilter1(); } @Bean public MessageFilter2 getMessageFilter2() { return new MessageFilter2(); } }###### 2.4Controller和实体类和之前一样，启动类的servlet组件扫描可去除 //@ServletComponentScan //开启servlet组件扫描 public class MicrobootWebApplication { public static void main(String[] args) { SpringApplication.run(MicrobootWebApplication.class, args); } }###### 2.5启动程序并观察控制台 http://localhost:8083/message/echo?msg=西红柿战争&title=两败俱伤filter1比filter2先启用，执行成功。