SpringBoot系列——Filter 過濾器

　　前言

　　本文記錄一下在SpringBoot項目中是如何使用Filter過濾器

 

　　代碼、測試

　　Filter過濾器是servlet包下面的東西，因此我們不需要再額外引包

　　方法一

　　直接實現Filter接口，並使用@Component注解標注為組件自動注入bean

package cn.huanzi.qch.springbootfilter.filter;

import org.springframework.stereotype.Component;

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

@Component
public class TestFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;

        System.out.println("TestFilter,"+request.getRequestURI());

        //執行
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {

    }
}

　　查看日志可以發現，SpringBoot已經幫我們注入了一個filter，攔截路徑是/*，攔截所有，如果我們需要進一步攔截具體的則需要我們自己在代碼里控制

 

 

　　方法二

　　實現Filter接口，用@WebFilter注解，指定攔截路徑以及一些參數，同時需要在啟動類使用@ServletComponentScan掃描帶@WebFilter、@WebServlet、@WebListener並將幫我們注入bean


　　請看官網介紹：https://docs.spring.io/spring-boot/docs/2.1.5.RELEASE/reference/htmlsingle/#boot-features-embedded-container-servlets-filters-listeners-scanning

 

package cn.huanzi.qch.springbootfilter.filter;

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

//配置攔截路徑
@WebFilter(filterName = "testFilter",urlPatterns = {"/test"})
public class TestFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;

        System.out.println("TestFilter,"+request.getRequestURI());

        //執行
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {

    }
}

package cn.huanzi.qch.springbootfilter;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

//自動掃描與當前類的同包以及子包
@ServletComponentScan
@SpringBootApplication
public class SpringbootFilterApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootFilterApplication.class, args);
    }

}

 　　查看日志發現，以及幫我們注入了testFilter，攔截路徑是/test

　　只指定攔截路徑，不設置filterName一樣可以注入

//配置攔截路徑
@WebFilter({"/test"})

 

　　方法三

 　　當然了，我們也可以既使用@Component同時也使用@WebFilter

package cn.huanzi.qch.springbootfilter.filter;

import org.springframework.stereotype.Component;

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


//配置攔截路徑
@WebFilter(filterName = "testFilter",urlPatterns = {"/test"})
@Component
public class TestFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;

        System.out.println("TestFilter,"+request.getRequestURI());

        //執行
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {

    }
}

package cn.huanzi.qch.springbootfilter;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

//自動掃描與當前類的同包以及子包
@ServletComponentScan
@SpringBootApplication
public class SpringbootFilterApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootFilterApplication.class, args);
    }

}

　　但是做會注入兩個bean，如果你的@WebFilter沒有指定filterName或者指定的名稱與類名相同，由於注入兩個相同名稱的bean，程序啟動報錯，叫我們修改其中一個的名字，或者啟用覆蓋bean

　　這里建議如果你硬要采用第三種方法，最好啟用覆蓋，因為改名將會注入兩個bean，處理邏輯一樣但攔截路徑不一樣，這並不是我們想要的，例如：

　　啟用覆蓋

#啟用覆蓋同名bean
spring.main.allow-bean-definition-overriding=true

　　PS：這里額外說一點，如果我們采用第三種方法，@ServletComponentScan放在TestFilter類上@WebFilter也會被掃描到，不需要放在啟動類，第二種方法如果也這樣做就不行，估計是受到了@Component注解的影響

//配置攔截路徑
@WebFilter(filterName = "testFilter",urlPatterns = {"/test"})
@ServletComponentScan
@Component
public class TestFilter implements Filter

 

 

　　后記

　　Filter過濾器暫時先記錄到這，以后再進行補充

 

　　代碼開源

　　代碼已經開源、托管到我的GitHub、碼雲：

　　GitHub：https://github.com/huanzi-qch/springBoot

　　碼雲：https://gitee.com/huanzi-qch/springBoot