【知识积累】springboot使用DelegatingFilterProxy

一、使用

package com.darren.center.springboot.config;

import com.darren.center.springboot.context.ContextFilter;
import com.darren.center.springboot.context.ContextHelper;
import com.darren.center.springboot.filter.Filter1;
import com.darren.center.springboot.filter.Filter2;
import com.darren.center.springboot.filter.WebComponentFilter;
import com.darren.center.springboot.filter.WebComponentFilterChain;
import com.darren.center.springboot.id.CacheIDGenerator;
import com.darren.center.springboot.id.IDGenerator;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.filter.DelegatingFilterProxy;

@Configuration
public class WebConfiguration {

    @Bean
    public IDGenerator idGenerator(){
        return new CacheIDGenerator();
    }

    @Bean
    public ContextHelper contextHelper(){
        return new ContextHelper();
    }

    @Bean
    public WebComponentFilterChain webComponentFilterChain(){
        return new WebComponentFilterChain();
    }

    @Bean
    public ContextFilter contextFilter(){
        return new ContextFilter();
    }

    @Bean
    public Filter1 filter1(){
        return new Filter1();
    }

    @Bean
    public Filter2 filter2(){
        return new Filter2();
    }


    @Bean(name = "webComponentFilter")
    public WebComponentFilter webComponentFilter(){
        return new WebComponentFilter();
    }

    @Bean
    public FilterRegistrationBean filterRegistrationBean(){
        FilterRegistrationBean registrationBean = new FilterRegistrationBean();
        registrationBean.setFilter(new DelegatingFilterProxy());
        registrationBean.addUrlPatterns("/*");
        //被代理filter
        registrationBean.addInitParameter("targetBeanName", "webComponentFilter");
        //指明作用于filter的所有生命周期
        registrationBean.addInitParameter("targetFilterLifecycle", "true");
        registrationBean.setName("WebComponentFilter");
        registrationBean.setOrder(1);
        registrationBean.setEnabled(false);
        return registrationBean;
    }

}

package com.darren.center.springboot.filter;

import com.darren.center.springboot.context.ContextFilter;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

@Slf4j
public class WebComponentFilter implements Filter{

    @Autowired
    private WebComponentFilterChain webComponentFilterChain;
    @Autowired
    private ContextFilter contextFilter;
    @Autowired
    private Filter1 filter1;
    @Autowired
    private Filter2 filter2;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        List filters = new ArrayList<>();
        filters.add(contextFilter);
        filters.add(filter1);
        filters.add(filter2);
        webComponentFilterChain.setFilters(filters);
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        if (webComponentFilterChain != null){
            webComponentFilterChain.handler(request, response);
        }
        filterChain.doFilter(request, response);
    }

    @Override
    public void destroy() {

    }

}

二、源码解析

1、类关系图

2、作用

DelegatingFilterProxy类是Filter的子类，是Filter的代理，通过Spring容器来管理Filter的生命周期。

3、查看GenericFilterBean

4、查看DelegatiingFilterProxy的initFilterBean实现

"targetFilterLifecycle"指明作用于Filter的所有生命周期

5、查看DelegatiingFilterProxy的doFilter

调用被代理Filter的doFilter方法