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  在Springboot项目中，常用的自定义过滤器的方式有两种：

@WebFilter和FilterRegistrationBean，下面通过案列分别使用两种方式来实现自定义Filter。

一、@WebFilter

  此注解常用的属性有以下三种：

@WebFilter的方式可以通过控制过滤器命名的先后顺序来控制多个过滤器之间的顺序执行，例如：filterName="a"会比filterName="b"的过滤器先执行。

新建一个Springboot项目，新建一个Filter包，创建一个类MyFilter

package org.magic.springbootLogin.filter;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.annotation.WebFilter;import javax.servlet.http.HttpServletRequest;/** * @author: magic * @date: 2021/4/14 * @description: 写一个自己的过滤器 * @WebFilter：用于将一个类声明为Filter, * filterName:String 指定该Filter的名称 * urlPatterns:String 指定该Filter所拦截的Url * value:String 与urlPatterns一致 */@WebFilter(urlPatterns = "/userController/*",filterName = "myFilter")public class MyFilter implements Filter {
     @Override  public void init(FilterConfig filterConfig) throws ServletException {
       System.out.println("MyFilter被初始化了");  }  @Override  public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
       HttpServletRequest req= (HttpServletRequest) request;    System.out.println(req.getRequestURI());    System.out.println(req.getMethod());    System.out.println("执行了MyFilter");    filterChain.doFilter(request, response);  }  @Override  public void destroy() {
       System.out.println("MyFilter被销毁了");  }}

然后在项目的启动类上添加注解@ServletComponentScan，

二、FilterRegistrationBean

  此种方式就是通过向容器中注入自定义Bean对象来实现自定义过滤器

还是新建一个springboot项目，新建一个MyFilter，

package org.magic.springbootLogin.filter;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.annotation.WebFilter;import javax.servlet.http.HttpServletRequest;/** * @author: magic * @date: 2021/4/14 * @description: 写一个自己的过滤器 */public class MyFilter implements Filter {
     @Override  public void init(FilterConfig filterConfig) throws ServletException {
       System.out.println("MyFilter被初始化了");  }  @Override  public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
       HttpServletRequest req= (HttpServletRequest) request;    System.out.println(req.getRequestURI());    System.out.println(req.getMethod());    System.out.println("执行了MyFilter");    filterChain.doFilter(request, response);  }  @Override  public void destroy() {
       System.out.println("MyFilter被销毁了");  }}

新建一个config包，在里面新建一个FilterConfig:

package org.magic.springbootLogin.config;import java.util.Collection;import javax.servlet.Filter;import org.magic.springbootLogin.filter.MyFilter;import org.springframework.boot.web.servlet.FilterRegistrationBean;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;/** * @author: magic * @date: 2021/4/14 * @description: */@Configurationpublic class FilterConfig {
     @Bean  public MyFilter getMyFilter() {
       return new MyFilter();  }  @Bean  public FilterRegistrationBean
   
     getFilterRegistrationBean(MyFilter myFilter) {
       FilterRegistrationBean
    
      filter = new FilterRegistrationBean<>();    filter.setFilter(myFilter);    filter.addUrlPatterns("/userController/*");    filter.setName("myFilter");    filter.setOrder(1);    return filter;  }}
    
   

!!!

启动项目，发现过滤器也被初始化了：

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