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Controller

1.4 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 {@Overrideprotected 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Servletchain.doFilter(request,response);}
}

1.3 编写Controller

@RestController
@RequestMapping("/message")
public class MessageController {@Resourceprivate 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 {@Overrideprotected 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 {@Overrideprotected 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 {@Beanpublic 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;}@Beanpublic FilterRegistrationBean getFilter2Registration() {FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();filterRegistrationBean.setFilter(this.getMessageFilter2());//设置过滤器执行顺序filterRegistrationBean.setOrder(2);return filterRegistrationBean;}@Beanpublic MessageFilter1 getMessageFilter1() {return new MessageFilter1();}@Beanpublic 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。