這里介紹兩種幾種種自定義filter的方式

• 通過@WebFilter+@ServletComponentScan的方式
• 通過配置FilterRegistrationBean的方式
• 通過加注解@component等注入的方式

1.通過@WebFilter+@ServletComponentScan的方式

filter類

package com.d4c.custombean.filter;

import lombok.extern.slf4j.Slf4j;
import org.springframework.core.annotation.Order;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;

@Slf4j
@Order(1)
@WebFilter(filterName = "firstName",urlPatterns = "/hello/*")
public class FirstFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        log.info("FirstFilter init--------");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        log.info("FirstFilter doFilter--------");
        filterChain.doFilter(servletRequest,servletResponse);
    }

    @Override
    public void destroy() {
        log.info("FirstFilter destroy--------");
    }
}

啟動(dòng)類上要加@ServletComponentScan

package com.d4c.custombean;

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

@ServletComponentScan
@SpringBootApplication
public class CustomBeanApplication {
    public static void main(String[] args) {
        SpringApplication.run(CustomBeanApplication.class, args);
    }
}

@WebFilter常用屬性

過濾器的urlPatterns的過濾路徑規(guī)則：

• 1.全路徑匹配： /hello/do.html
• 2.部分路徑匹配： /hello/*
• 3.通配符匹配 ：/*
• 4.后綴名匹配 ：*.html(注意:前面不加/)

@Order
@Orde注解是決定著執(zhí)行順序，而不是類的初始化順序。order數(shù)字越小，優(yōu)先級(jí)越高。最好，統(tǒng)一用一種方式定義filter，否則@Order可能不起作用（混亂）。

2.通過配置FilterRegistrationBean的方式

filter類

package com.d4c.custombean.filter;

import lombok.extern.slf4j.Slf4j;

import javax.servlet.*;
import java.io.IOException;

@Slf4j
public class SecondFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        log.info("SecondFilter init--------");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        log.info("SecondFilter doFilter--------");
        filterChain.doFilter(servletRequest,servletResponse);
    }

    @Override
    public void destroy() {
        log.info("SecondFilter destroy--------");
    }
}

配置類

package com.d4c.custombean.config;

import com.d4c.custombean.filter.SecondFilter;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MyRegisterBean {

    @Bean
    public FilterRegistrationBean filterRegistrationBean(){
        FilterRegistrationBean bean = new FilterRegistrationBean();
        //注冊(cè)自定義過濾器
        bean.setFilter(new SecondFilter());
        //過濾器名稱
        bean.setName("second filter bean");
        //過濾所有路徑
        bean.addUrlPatterns("/do/*");
        //優(yōu)先級(jí)，數(shù)字越小，優(yōu)先級(jí)越高
        bean.setOrder(2);
        return bean;
    }
}

3.通過加注解@Component等注入的方式

雖然這種方式能實(shí)現(xiàn)filter，但是不推薦。最好第一種或第二種方式選其一

filter類

package com.d4c.custombean.filter;

import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;

@Slf4j
@Order(3)
//或者用@Configuration
@Component   
public class ThirdFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        log.info("ThirdFilter init--------");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        log.info("ThirdFilter doFilter--------");
        filterChain.doFilter(servletRequest,servletResponse);
    }

    @Override
    public void destroy() {
        log.info("ThirdFilter destroy--------");
    }
}