springboot版本：2.2.5

一、filter註冊

springboot中新增filter有兩種方式：

1、實現方法一

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實現filter的方式一：
 * 實現Filter介面，並使用@Component註解
 * 需要注意的是：這個方式註冊的filter的執行順序優先順序較低
 * @author Administrator
 *
 */
@Component
public class FilterSample1 implements Filter {

  @Override
  public void init(FilterConfig filterConfig) throws ServletException {
    System.out.println("這裡是"+this.getClass().getName()+"的init");
    
  }

  @Override
  public void doFilter(ServletRequest request,ServletResponse response,FilterChain chain)
      throws IOException,ServletException {
    System.out.println("這裡是"+this.getClass().getName()+"的doFilter");
    chain.doFilter(request,response);
  }

  @Override
  public void destroy() {
    System.out.println("這裡是"+this.getClass().getName()+"的doFilter");
    
  }
}

2、實現方法二

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,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註冊filter方法二：
 * 同樣要實現filter介面，但filter註冊使用@Bean的方式進行註冊，可以設定filter順序
 * @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("/*");//配置過濾規則
    registrationBean.setUrlPatterns(urls);
    registrationBean.setOrder(3);
    return registrationBean;
  }
}

二、Springboot自帶filter

Springboot預設啟用了三個filter，他們是requestContextFilter，characterEncodingFilter，formContentFilter，可以通過在application.yml中設定debug: true來驗證如下：

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

三、檢視應用中註冊了哪些filter

#application.yml
debug: true

如上圖，啟用debug模式，檢視日誌可得：

標藍部分詳細內容如下：

2020-03-17 22:13:17.244 DEBUG 2700 --- [ main] o.s.b.w.s.ServletContextInitializerBeans :
Mapping filters:
filterRegistrationBean urls=[/*] order=3,
characterEncodingFilter urls=[/*] order=-2147483648,
formContentFilter urls=[/*] order=-9900,
requestContextFilter urls=[/*] order=-105,
filterSample1 urls=[/*] order=2147483647

可以看出，該應用註冊了五個filter，執行順序由order決定

到此這篇關於SpringBoot註冊Filter的兩種實現方式的文章就介紹到這了,更多相關SpringBoot註冊Filter內容請搜尋我們以前的文章或繼續瀏覽下面的相關文章希望大家以後多多支援我們！