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，所以咱們不須要再額外引包

　　方法一

　　直接實現Filter接口，並使用@Component註解標註爲組件自動注入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() {

    }
}

　　查看日誌能夠發現，SpringBoot已經幫咱們注入了一個filter，攔截路徑是/*，攔截全部，若是咱們須要進一步攔截具體的則須要咱們本身在代碼裏控制

 

 

　　方法二

　　實現Filter接口，用@WebFilter註解，指定攔截路徑以及一些參數，同時須要在啓動類使用@ServletComponentScan掃描帶@WebFilter、@WebServlet、@WebListener並將幫咱們注入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);
    }

}

 　　查看日誌發現，以及幫咱們注入了testFilter，攔截路徑是/test

　　只指定攔截路徑，不設置filterName同樣能夠注入

//配置攔截路徑
@WebFilter({"/test"})

 

　　方法三

 　　固然了，咱們也能夠既使用@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);
    }

}

　　可是作會注入兩個bean，若是你的@WebFilter沒有指定filterName或者指定的名稱與類名相同，因爲注入兩個相同名稱的bean，程序啓動報錯，叫咱們修改其中一個的名字，或者啓用覆蓋bean

　　這裏建議若是你硬要採用第三種方法，最好啓用覆蓋，由於更名將會注入兩個bean，處理邏輯同樣但攔截路徑不同，這並非咱們想要的，例如：

　　啓用覆蓋

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

　　PS：這裏額外說一點，若是咱們採用第三種方法，@ServletComponentScan放在TestFilter類上@WebFilter也會被掃描到，不須要放在啓動類，第二種方法若是也這樣作就不行，估計是受到了@Component註解的影響

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

 

 

　　後記

　　Filter過濾器暫時先記錄到這，之後再進行補充

 

　　代碼開源

　　代碼已經開源、託管到個人GitHub、碼雲：

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

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