springboot 过滤器配置

  

过滤器是什么?
它是基于Servlet 技术实现的， 简单的来说，过滤器就是起到过滤的作用，在web项目开发中帮我们过滤一些指定的 url做一些特殊的处理。 过滤器主要做什么？

过滤掉一些不需要的东西，例如一些错误的请求、修改请求和相应的内容（以此为案例）、拿来过滤未登录用户。

1.创建一个MyFilter.java实现Filter接口

MyFilter文件代码如下

import org.springframework.context.annotation.Configuration;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class MyFilter implements Filter {

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletResponse resp = (HttpServletResponse) response;
        HttpServletRequest res = (HttpServletRequest) request;
        System.out.println("当前过滤到的路径："+res.getRequestURI());
        /**
         * 这是的代码是为了前后分离 允许跨域
         */
        resp.setHeader("Access-Control-Allow-Origin","*");
        resp.setHeader("Access-Control-Allow-Credentials", "true");
        resp.setHeader("Access-Control-Allow-Methods", "POST, GET, PATCH, DELETE, PUT");
        resp.setHeader("Access-Control-Max-Age", "3600");
        resp.setHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");

        chain.doFilter(request, response);  //放行
        // request.getRequestDispatcher("/api/open/unLogin").forward(request,response); //重定向
    }

}

2. FilterRegistrationBean 实现

创建 FilterConfig文件

FilterConfig文件代码如下：

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import xyz.ark.backstage_12.filter.MyFilter;

import java.util.ArrayList;
import java.util.List;

@Configuration
public class FilterConfig {

    @Bean
    public MyFilter myFilter(){
        return new MyFilter();
    }

    @Bean
    public FilterRegistrationBean filterRegistrationBean(){
        FilterRegistrationBean filterRegistrationBean  = new FilterRegistrationBean();

        //设置过滤器
        filterRegistrationBean.setFilter(myFilter());  //设置过滤器名称

        filterRegistrationBean.setName("header");  //设置名称

        List list = new ArrayList();
        list.add("/*");   //拦截路径
        filterRegistrationBean.setUrlPatterns(list);

        filterRegistrationBean.setOrder(1);  //设置访问优先级 值越小越高

        return filterRegistrationBean;
    }

}