SpringBoot注册Filter的两种实现方式

springboot版本：2.2.5

一、filter注册

springboot中添加filter有两种方式：

1、实现方法一

package com.example.demo.filter1;

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 org.springframework.stereotype.Component;

/**

* Springboot实现filter的方式一：

* 实现Filter接口，并使用@Component注解

* 需要注意的是：这个方式注册的filter的执行顺序优先级较低

* @author Administrator

*

*/

@Component

public class FilterSample1 implements Filter {

@Override

public void init(FilterConfig filterConfig) throws ServletException {

System.out.println("这里是"+this.getClass().getName()+"的init");

}

@Override

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)

throws IOException, ServletException {

System.out.println("这里是"+this.getClass().getName()+"的doFilter");

chain.doFilter(request,response);

}

@Override

public void destroy() {

System.out.println("这里是"+this.getClass().getName()+"的doFilter");

}

2、实现方法二

package com.example.demo.filter2;

import java.io.IOException;

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

public class FilterSample2 implements Filter{

@Override

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)

throws IOException, ServletException {

System.out.println("这里是"+this.getClass().getName()+"的doFilter");

chain.doFilter(request,response);

}

package com.example.demo.filter2;

import java.util.ArrayList;

import org.springframework.boot.web.servlet.FilterRegistrationBean;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

/**

* Springboot注册filter方法二：

* 同样要实现filter接口，但filter注册使用@Bean的方式进行注册，可以设置filter顺序

* @author Administrator

*

*/

@Configuration

public class WebConfig {

@Bean

public FilterRegistrationBean<FilterSample2> filterSample2() {

FilterRegistrationBean<FilterSample2> registrationBean = new FilterRegistrationBean<FilterSample2>();

FilterSample2 myFilter = new FilterSample2();

registrationBean.setFilter(myFilter);

ArrayList<String> urls = new ArrayList<>();

urls.add("/*");//配置过滤规则

registrationBean.setUrlPatterns(urls);

registrationBean.setOrder(3);

return registrationBean;

}

二、Springboot自带filter

Springboot默认启用了三个filter，他们是requestContextFilter，characterEncodingFilter，formContentFilter，可以通过在application.yml中设置debug: true来验证如下：

2020-03-17 22:13:17.254 DEBUG 2700 — [ main] o.s.b.w.s.f.OrderedRequestContextFilter : Filter 'requestContextFilter' configured for use
2020-03-17 22:13:17.255 DEBUG 2700 — [ main] s.b.w.s.f.OrderedCharacterEncodingFilter : Filter 'characterEncodingFilter' configured for use
2020-03-17 22:13:17.255 DEBUG 2700 — [ main] o.s.b.w.s.f.OrderedFormContentFilter : Filter 'formContentFilter' configured for use