一使用@WebFilter注解

@WebFilter写在类上

@WebFilter常用属性

过滤器实现方法

写filter类实现javax.servlet.Filter接口，加@WebFilter注解，不可以设置filter执行顺序

package com.jsong.wiki.blog.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;

@WebFilter(filterName = "testfilter",urlPatterns ={"/blog/*"})
public class AnnotatedRequestFitler implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.printf("filter");
        filterChain.doFilter(servletRequest,servletResponse);
    }

    @Override
    public void destroy() {

    }
}

在有@Configuration的配置类上添加@ServletComponentScan，也可以直接加在启动类上

@ServletComponentScan没有参数时默认自动扫描当前类所在的包，也可以指定扫描的包

package com.jsong.wiki.blog.filter;

import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.context.annotation.Configuration;

@ServletComponentScan(value = "com.jsong.wiki.blog.filter")
@Configuration
public class TestConfig {
}

过滤器配置好了，当访问http://localhost:8080/blog/test时，控制台就会打印出来filter

二配置Bean

写一个filter类实现javax.servlet.Filter接口

package com.jsong.wiki.blog.filter;

import org.springframework.stereotype.Component;

import javax.servlet.*;
import java.io.IOException;

public class RequestFilter implements Filter {


    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.printf("hello");
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {

    }
}

在配置类的bean中实例化这个Filter

package com.jsong.wiki.blog.config;

import com.jsong.wiki.blog.filter.RequestFilter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.servlet.Filter;

@Configuration
public class FilterConfig {

    @Bean
    public Filter registerRequestFilter() {
        return new RequestFilter();
    }
}

三 FilterRegistrationBean（推荐），可以配置filter顺序

和方式差不多，首先创建一个filter类实现javax.servlet.Filter接口
注意要在类上写一个@Component注解，把这个类交给容器托管

package com.jsong.wiki.blog.filter;

import org.springframework.stereotype.Component;

import javax.servlet.*;
import java.io.IOException;

@Component
public class RequestFilter implements Filter {


    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.printf("hello");
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {

    }
}

在配置类中，通过FilterRegistrationBean管理这个filter

package com.jsong.wiki.blog.config;

import com.jsong.wiki.blog.filter.RequestFilter;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.servlet.Filter;

@Configuration
public class FilterConfig {

//    @Bean
//    public Filter registerRequestFilter() {
//        return new RequestFilter();
//    }

    @Bean
    public FilterRegistrationBean registration(RequestFilter filter) {
        FilterRegistrationBean bean = new FilterRegistrationBean(filter);
        bean.addUrlPatterns("/blog/*");
        // 排序
        bean.setOrder(1);
        return bean;
    }
}